Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the progressive degeneration of upper and lower motor neurons in the brainstem and spinal cord,leading to muscle weakness,para...Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the progressive degeneration of upper and lower motor neurons in the brainstem and spinal cord,leading to muscle weakness,paralysis,and respiratory failure (Morgan and Orrell,2016).展开更多
This paper begins with the overthrow of the concept of combining ability in crossbreeding by the concept of heritability.The reason is that general combining ability changes with the number and kind of pure strains in...This paper begins with the overthrow of the concept of combining ability in crossbreeding by the concept of heritability.The reason is that general combining ability changes with the number and kind of pure strains in the foundation stock and hence special combining ability changes also,so that work with different kinds of pure strains in the foundation stock cannot be compared.Hence combining ability is useless as a parameter to predict the amount of heterosis expected in the next generation.On the other hand,since each cross has a separate heritability,it can be applied to a cross population just as successfully as in purebreeding.Since the same concept holds in both cases,resort to any other concept would be superfluous.That's why combining ability must be rejected.Another reason(not given in the full text)is,an infinite number of pure strains would be required in the foundation stock for its results to be comparable with those of the heritability theory,which disposes of its utility altogether.The main content of the thesis is then the centennial enigma of heterosis can be resolved by Descarte's theoretic method of deduction.Accordingly we start from the definition of heterosis.H=F¡-MP,where H is heterosis,F,is the first generation offspring,MP is the mean of the parents or midparent,and from the use of a binomial random variable and its extention to the multinomial case derive the basic relations of heterosis with its components.Starting with second degree statistics,we obtain Vn=Vr,-2cov(F,,MP)+Vup,where V and cov stand for variance and covariance.The equations of heterosis are v„=(1/2)Na²+(1/4)Nd’+Vr(F,)=additive dominance F,epistasis Vup=(1/2)Na’+(1/2)V1,additive parental epistasis V„=(1/4)Nd’+V(F)+(1/2)V1,dominance F,epistasis parental epistasis.where N is number of genes controlling a trait,a=(P1-P,)12,d is deviation from midparent,while the variance components are all indicated by their names under the repective terms.It turns out that all these can be easily computed from the data so that the problem becomes a simple one which any college student may solve.In other words,the right answers are found when the right questions are asked.Who had ever shown that the heritability principle is inapplicable in crossbreeding,e.g.,in a crossing of two pure strains?From this cue arose the realization that the F,of a cross of two pure strains must also be a Mendelian population,with p and q both equal to 1/2 which simplifies the algebra outright.This Heritability Theory of Heterosis,or HTH in capital letters,re-sts on 2 initial anguments:1)Since 0.5+0.5=1,crossing two pure strains gives a population which is only a special case of pure-breeding,thereforea heritability coefficient must exist for the F1;2)Our problem reduces to that of finding that coefficient;the an-swer is given by the additive component divided by Ve.,i.e.,(1/2)No'1 Vp..which is readily found from the solution of the het-erosis equations.Thus the elemnal enigma of heterosis is resolved!This happened at the end of the 20th century.We now come to the second point of the discovery,the new genetic parameter crossheritability which will rise in size with the increase of the number of times it's used and form the link between breeding and evolution.The advent of the Age of Evolution Engineering in the 21st century marks a totally new era,showing that artificial will ultimately supercede natural selection,with the long span of time element eliminated.For agriculture at least,it means there is no limit to the increase of food supply by the new method,with the concentra-tion of desirable genes by hybridization in place of the old theory of their fixation.Genetic gain is achieved through artificial selec-tion,with an 80%saving of time,labor and cost by adoption of the new method.Applied to a further increase in all kinds of agri-cultural products including hybrd rice,it means that a huge eacalation,in fact a New Green Revolution,on a much langer scale than that of any such before,is in view,provided it is adopted in our research and educational institutions as early as possible,ere its spread elsewhere.The possibilities from the evolution point of view can only be pictured by science fiction.展开更多
Plutella xylostella,a major pest of cruciferous vegetables worldwide,has developed resistance to diamide insecticides.Thiotraniliprole,a novel synthetic diamide insecticide,exhibits excellent activity against P.xylost...Plutella xylostella,a major pest of cruciferous vegetables worldwide,has developed resistance to diamide insecticides.Thiotraniliprole,a novel synthetic diamide insecticide,exhibits excellent activity against P.xylostella.In the present study,we aimed to confirm the resistance risk,cross-resistance,and mechanisms of resistance to thiotraniliprole in P.xylostella.After 40 consecutive generations of thiotraniliprole selection,we obtained a thiotraniliprole-resistance P.xylostella strain with a 5141.58-fold resistance ratio(RR)to thiotraniliprole.The overall realized heritability(h^(2))value of resistance was estimated as 0.9 using threshold trait analysis,indicating that the risk of developing resistance to thiotraniliprole is high in P.xylostella.The thiotraniliprole-resistant(TR)strain showed noticeable cross-resistance to chlorantraniliprole(RR=44670.05),cyantraniliprole(RR=7038.58),and tetrachlorantraniliprole(RR=1506.01),but no cross-resistance to tolfenpyrad,indoxacarb,diafenthiuron,or abamectin compared with the susceptible(S)strain.The enzyme assay data showed that the activities of glutathione-S transferase(GST),carboxylesterase(CarE),and the content of cytochrome P450 monooxygenase(P450s)were significantly higher in the TR strain than in the S strain.Sequencing of the full-length PxRyR cDNA revealed the gene site I4790K in the TR strain with a 100%frequency.This mutation in PxRyR likely underlies the high-level cross-resistance between thiotraniliprole and three other diamide insecticides.These findings provide valuable information for optimizing resistance management strategies to delay thiotraniliprole resistance development and ensure sustainable control of P.xylostella.展开更多
[Objective] The aim was to estimate the heritability and genetic correlations of growth traits of Chinese shrimp Fenneropenaeus chinensis so as to provide basis and technical parameters for the breeding and selecting ...[Objective] The aim was to estimate the heritability and genetic correlations of growth traits of Chinese shrimp Fenneropenaeus chinensis so as to provide basis and technical parameters for the breeding and selecting of Chinese shrimp.[Method] 51 full-sib families（including 35 half-sib families）of the Chinese shrimp F.chinensis were obtained by artificial insemination.Four growth traits of these families were measured,including body length,cephalothorax length,abdorminal segment length and body weight.According to quantitative genetics theory,the heritability of each growth trait,genetic and phenotypic correlation among these traits was statistically studied.[Result] The heritability was 0.36-0.51 for body length,0.14-0.24 for cephalothorax length,0.25-0.50 for abdominal segment length,and 0.04-0.29 for body weight.High and positive genetic correlations were obtained among growth traits.The genetic correlation between body weight and abdominal segment length was the highest（0.92）,followed by body length and abdominal segment length（0.91）,body length and body weight（0.88）,body weight and cephalothorax length（0.87）,abdominal segment length and cephalothorax length（0.86）,while the genetic correlation between body length and cephalothorax length was the lowest（0.83）.[Conclusion] The phenotypic correlation of body length,cephalothorax length,abdorminal segment length and body weight of Chinese shrimp F.chinensis were from 0.80 to 0.90 with extremely significant difference（P0.01）among the four growth traits by t-test.展开更多
Using 3 sterile lines and 12 restorer of glutinous sorghum as experimental materials,36 hybrid combinations（3×12 NCⅡ） were designed to analyze the combining ability and heritability of six main agronomic trait...Using 3 sterile lines and 12 restorer of glutinous sorghum as experimental materials,36 hybrid combinations（3×12 NCⅡ） were designed to analyze the combining ability and heritability of six main agronomic traits,including plant height,panicle length,growth period,1 000-grain weight,per panicle grains and per panicle grain weight.The results showed that except per panicle grain number all other five agronomic traits have remarkable or extremely remarkable general combining ability and specific combining ability.Six agronomic traits were found to be control by additive genetic effect.Most of these agronomic traits are more easily influenced by restorers than sterile lines,suggesting that more attention should be paid to select restores in hybrid glutinous sorghum breeding.The narrow-sense heritability of these agronomic traits were in order growth period plant height per panicle grain weight panicle length 1 000-grain weight per panicle grains.展开更多
Five cytoplasmic male sterile （CMS） lines were used as parents in an incomplete diallet cross and six restorer lines of rice design （Nc II design）. Thirty hybrid combinations with the same growth period were selec...Five cytoplasmic male sterile （CMS） lines were used as parents in an incomplete diallet cross and six restorer lines of rice design （Nc II design）. Thirty hybrid combinations with the same growth period were selected as experimental ma- terials to investigate the heterosis, combined ability and heredity of Cd content in brown rice of indica hybrid rice. According to the results, Cd content in brown rice showed a significantly negative heterosis; the general combining ability and specific combination ability of Cd content in CMS and restorer lines both reached extremely significant level （P〈0.01）, indicating that both genetic improvement of parents and e- valuation of combinations are important to the breeding of hybrid combinations with low accumulation of Cd; the broad-sense heritabitity and narrow-sense heritability of Cd content were both relatively high with slight differences, which respectively reached 97.73% and 80.10%, indicating that Cd content in brown rice mainly de- pends on the additive action of genes; in addition, parent improvement showed bet- ter effect on the selection of early generation.展开更多
Fifteen combinations crossed by five JA cytoplasmic male sterile lines （A1, A2, A3, A4, A5） and three restoring lines （R1, R2, R3） were selected to analyze the combining ability and heritability of nine main agron...Fifteen combinations crossed by five JA cytoplasmic male sterile lines （A1, A2, A3, A4, A5） and three restoring lines （R1, R2, R3） were selected to analyze the combining ability and heritability of nine main agronomic characters of Brassica na-pus L. to definite the application potential of these parent materials. The result showed that （i） the general combining ability （GCA） of male parents was R3＆gt;R2＆gt;R1 and that of female parents was A4＆gt;A1＆gt;A2＆gt;A5＆gt;A3; （i ） the special combining ability （SCA） of A2＆#215;R3 in plant height, number of branches, number of pods per plant and yield per plant was the best. The yield per plant of A2＆#215;R3, A1＆#215;R1 and A2＆#215;R1 ranked the first three places in the 15 combinations; （i i） the broad heritability of yield per plant was the highest, and that of the height of branches was the lowest. The com-prehensive characters of R3, A2 and A4 were better, which could be used to create new materials; （iv） good offspring were more likely to be chosen from the combina-tion with higher parental GCA, so the GCA and SCA should be considered com-prehensively when choosing parent and determining the optimal combinations.展开更多
We analyzed the survival data of the offspring from 21 sires and 42 dams of turbot. The results show that the cumulative survival rates for turbot from 2 to 18 months range from 17.5% to 28.5% main mortality occurred ...We analyzed the survival data of the offspring from 21 sires and 42 dams of turbot. The results show that the cumulative survival rates for turbot from 2 to 18 months range from 17.5% to 28.5% main mortality occurred during months 2-5; and the highest survival rates of families were 97.9%, 98.8%, 99.4%, 99.7% during months 2-5, 5-6, 6-8, 8-11, and ll-18, respectively, and 99.5%, being 53.5%, 23.8%, 19.5%, 14.9%, and 13.2% higher, respectively, than the mean values in each period. In all periods, the estimated heritabilities for survival were very low without significant difference from zero （P〉0.05） （values ranged from 0.06 to 0.12）, indicating low additive genetic effects. The genetic correlations of survival among families in different periods were all positive, but low in magnitude （values range from 0.03 to 0.31）. Genetic correlations between long-term survival and other periods＇ survival had negative values （-0.06 and -0.15） and three positive values （0.16, 0.12 and 0.14）. Genetic correlations between survival and weight were all positive, except for survival at months 2-5 and weight at 18 months, which was not significantly negative （-0.18）.展开更多
To quantify the response to selection, heritability and genetic correlations between weight and size ofLitopenaeus vannamei, the body weight （BW）, total length （TL）, body length （BL）, first abdominal segment dep...To quantify the response to selection, heritability and genetic correlations between weight and size ofLitopenaeus vannamei, the body weight （BW）, total length （TL）, body length （BL）, first abdominal segment depth （FASD）, third abdominal segment depth （TASD）, first abdominal segment width （FASW）, and partial carapace length （PCL） of 5-month-old parents and of offspring were measured by calculating seven body measurings of offspring produced by a nested mating design. Seventeen half-sib families and 42 full-sib families ofL. vannamei were produced using artificial fertilization from 2-4 dams by each sire, and measured at around five months post-metamorphosis. The results show that heritabilities among various traits were high： 0.515±0.030 for body weight and 0.394±0.030 for total length. After one generation of selection, the selection response was 10.70% for offspring growth. In the 5th month, the realized heritability for weight was 0.296 for the offspring generation. Genetic correlations between body weight and body size were highly variable. The results indicate that external morphological parameters can be applied during breeder selection for enhancing the growth without sacrificing animals for determining the body size and breed ability; and selective breeding can be improved significantly, simultaneously with increased production.展开更多
The objectives of this present research were to assess the heritability of growth traits under low temperature conditions in turbot（Scophthalmus maximus L.）, and to analyze the correlation between body weight（BW） ...The objectives of this present research were to assess the heritability of growth traits under low temperature conditions in turbot（Scophthalmus maximus L.）, and to analyze the correlation between body weight（BW） and body length（BL）. There were 536 individuals from 25 full- and half-sib families involved in this study. During the entire 90-day period, which was initiated at 233 dph（day old） and ended at 323 dph, the individuals＇ BW and BL were weighed consecutively six times every 18 days. The heritability of BW and BL and the correlation between these two traits were estimated based on an individual animal model with the derivative-free restricted maximum likelihood（DFREML） method. These results showed that the specific growth rates（SGR） of 25 families was from 0.75±0.11 to 1.05±0.14 under water temperature of 10.5–12°C. In addition, the heritability of BW and BL estimated under low-temperature were 0.32±0.04 and 0.47±0.06, respectively. The BW had a medium heritability（0.2–0.4）, and the BL had a high heritability（〉0.45）, which suggested that selection for increased weight and length was feasible. Moreover, there was potential for mass selection on growth. The genetic and phenotypic correlations between BW and BL were 0.95±0.01 and 0.91±0.01（P 〈 0.01）, respectively. A significant correlation between BW and BL showed that BL could be instead of BW for indirect selection, which could be effectively implemented in the breeding program.展开更多
We estimated the reproductive success of adult brood fish and the heritability of growthrelated traits for large yellow croaker （Larimichthys crocea）. We created two independent full-factorial cross groups （1 and 2...We estimated the reproductive success of adult brood fish and the heritability of growthrelated traits for large yellow croaker （Larimichthys crocea）. We created two independent full-factorial cross groups （1 and 2） by crossing 4 malesx4 females and 4 males^3 females, respectively. We measured the body weight （BW）, body length （BL）, and body height （BH） of 281 individuals from group 1 and 318 individuals from group 2 at 20 months post hatch （harvest age）. We also collected a tissue sample from each individual. The parents and offspring were genotyped using six polymorphic mierosatellites. Of the 599 offspring, 99.2% were assigned to a single pair of parents. In both groups, some parent pairs produced a large number of offsprings while other pairs did not produce any offspring. The genetic diversity and putative No were lower in the offsprings than in the parents in both groups. The heritability estimates at 20-month age were 0.13±0.10 for BW, 0.19±0.13 for BL, and 0.09±0.06 for BH. The genetic and phenotype correlation between BW, BL, and BH was close to 1. The results provide basic information for selective breeding and further genetic characterization of large yellow croaker.展开更多
Intraspecific trait variation and heritability in different environmental conditions not only suggest a potential for an evolutionary response but also have important ecological consequences at the population, communi...Intraspecific trait variation and heritability in different environmental conditions not only suggest a potential for an evolutionary response but also have important ecological consequences at the population, community, and ecosystem levels. However, the contribution of quantitative trait variation within a grassland species to evolutionary responses or ecological consequences is seldom documented. Leymus chinensis is an important dominant species in semi-arid grasslands of China, which has seriously suffered from drought and high temperature stresses in recent decades. In the present study, we measured variation and heritability of 10 quantitative traits, namely the number of tillers, maximum shoot height, number of rhizomes, maximum rhizome length, rhizome mass, aboveground mass, root mass, maximum net photosynthetic rate(Pmax), specific leaf area(SLA), and leaf length to leaf width ratio(LL/LW), for 10 genotypes of L. chinensis under one non-stress(Ck) condition and three environmental stress conditions(i.e., drought(Dr), high temperature(Ht), and both drought and high temperature(DrHt)). Result indicated that(1) the interaction of genotype and environmental condition(G×E) was significant for 6 traits but not significant for the other 4 traits as shown by two-way analysis of variance(ANOVA), suggesting that different selection forces were placed for different traits on the factors dominating phenotypic responses to different environmental conditions. Moreover, these significant G×E effects on traits indicated significantly different phenotypic adaptive responses among L. chinensis genotypes to different environmental conditions. Additionally, individuals could be grouped according to environmental condition rather than genotype as shown by canonical discriminant analysis, indicating that environmental condition played a more important role in affecting phenotypic variation than genotype;(2) by one-way ANOVA, significant differences among L. chinensis genotypes were found in all 10 traits under Ck and Dr conditions, in 8 traits under Dr Ht condition and only in 4 traits under Ht condition; and(3) all 10 traits showed relatively low or non-measurable broad-sense heritability(H_2) under stress conditions. However, the lowest H_2 value for most traits did not occur under DrHt condition, which supported the hypothesis of 'unfavorable conditions have unpredictable effects' rather than 'unfavorable conditions decrease heritability'. Results from our experiment might aid to improve predictions on the potential impacts of climate changes on L. chinensis and eventually species conservation and ecosystem restoration.展开更多
Ammonia,toxic to aquaculture organisms,represents a potential problem in aquaculture systems,and the situation is exacerbated in closed and intensive shrimp farming operations,expecially for Litopenaeus vannamei.Asses...Ammonia,toxic to aquaculture organisms,represents a potential problem in aquaculture systems,and the situation is exacerbated in closed and intensive shrimp farming operations,expecially for Litopenaeus vannamei.Assessing the potential for the genetic improvement of resistance to ammonia in L.vannamei requires knowledge of the genetic parameters of this trait.The heritability of resistance to ammonia was estimated using two descriptors in the present study:the survival time(ST) and the survival status at half lethal time(SS_(50)) for each individual under high ammonia challenge.The heritability of ST and SS_(50) were low(0.154 4±0.044 6 and 0.147 5±0.040 0,respectively),but they were both significantly different from zero(P<0.01).Moreover,these two estimates were basically the same and showed no significant differences from each other(P>0.05),suggesting that ST and SS_(50) could be used as suitable indicators for resistance to ammonia.There were also positive phenotypic and genetic correlation between resistance to ammonia and body weight,which means that resistance to ammonia can be enhanced by the improvement of husbandry practices that increase the body weight.The results from the present study suggest that the selection for higher body weight does not have any negative consequences for resistance to ammonia.In addition to quantitative genetics,tools from molecular genetics can be applied to selective breeding programs to improve the efficiency of selection for traits with low heritability.展开更多
The aim of the present study is to detect the potential of the base population from diallel crosses of eight introduced strains of the Pacific white shrimp（Litopenaeus vannamei） for improving the yield. Heterosis an...The aim of the present study is to detect the potential of the base population from diallel crosses of eight introduced strains of the Pacific white shrimp（Litopenaeus vannamei） for improving the yield. Heterosis and heritability were estimated for pond survival at commercial farm conditions for the base population that included 207 full-sib families from a nested mating design by artificial insemination. Among all the hybrids,the heterosis ranged from –11.37%（UA1×UA2） to 20.53%（UA3×SIN） with an average of 0.953%. The results showed that more than half of the hybrids（51.85%） have negative heterosis for survival rate, but most of the hybrids with positive heterosis have high estimates. The high proportion of negative heterosis for survival rate reminders us that the survival trait also should be considered in the crossbreeding program to avoid yield decrease. However, high positive heterosis manifested in most of the hybrids for survival indicates the usefulness of these hybrids for improving the survival to obtain higher yield by crossbreeding in this breeding program. The heritability estimate for pond survival was 0.092±0.043 when genetic groups were included in the pedigree, and it was significantly different from zero（P〈0.05）. The results from this study also indicated that significant improvement for survival is possible through selection in L. vannamei.展开更多
Pacific whiteleg shrimp （Litopenaeus vannamei） is an economically relevant shrimp species in many Asian countries. The specific objective of the current research was to assess microsatellite markers in screening the...Pacific whiteleg shrimp （Litopenaeus vannamei） is an economically relevant shrimp species in many Asian countries. The specific objective of the current research was to assess microsatellite markers in screening the fast- growth of domesticated L. vannamei stocks to establish a founder population for breeding-selection plans. The post.larvae produced by the reproduction of second generation broodstock were cultured in the same conditions throughout a five months growing period. Ninety juvenile shrimp were selected from the slow-, medium- and the fast-growth groups, and ten microsatellite markers were used to investigate their genetic diversity, and to understand the improvement of a breeding-selection scheme. Ten polymorphic loci （markers） （M1-M10） were produced at ten loci in this sample, among them Primer M8 was the highest polymorphic locus and M7 was the lowest one. A specific locus was found in the fast-growth group using Primer M5. The longest genetic distance （0.481） was determined between the fast- and medium-growth groups and the shortest （0.098） was between the slow- and medium-growth groups; therefore, the largest genetic identity （0.946） was observed between the slow- and medium-growth groups and the smallest （0.667） was observed between the medium- and fast-growth groups. The Unweighted Paired Group with Arithmetic Average （UPGMA） dendrogram based on Nei＇s genetic distances provided two different groups; the first consist of the slow- and medium-growth groups and the second the fast- growth group. Selection response and realized heritability for growth were 11.55% and 31.26%, respectively. Therefore, this set of microsatellite markers would provide a useful tool in shrimp breeding schemes.展开更多
Activation of the hypothalamic-pituitary-adrenal （HPA） axis liberates glucocorticoids, which provides an acute indication of an individual＇s response to stressors. The heritability of the stress response in wild ma...Activation of the hypothalamic-pituitary-adrenal （HPA） axis liberates glucocorticoids, which provides an acute indication of an individual＇s response to stressors. The heritability of the stress response in wild mammals, however, remains poorly documented. We quantified the cortisol stress response of female Richardson＇s ground squirrels （RGSs） to handling and physical restraint, testing for： （1） the effects of individual age, time of day, and sample latency; （2） repeatability within individuals; （3） narrow-sense heritability; and （4） differences among individuals owing to potential genetic and/or environmental effects. We detected a positive linear relationship between baseline plasma cortisol （BL-cortisol） concentration and stress-induced plasma cortisol （Sl-cortisol） concentration that defined each individual＇s cortisol stress response. BL-cortisol, SI-cortisol, and stress response did not differ according to the time the sample was taken, or by subject age. Cortisol stress response was highly repeatable within individuals, had a mother-offspring heritability of h2 =0.40 ± 0.24 （mean ±SE）, full-sibling heritability of h2s = 0.37 ± 0.71, and half-sibling heritabil- ity of hHS^2 = 0.75 ± 1.41. Stress responses of sibling groups, immediate-family groups, and squir- rels within a given area did not differ, whereas those of individuals from more distantly related matrilines did. Our results highlight the natural variability in HPA axis reactivity among individuals by quantifying both BL- and SI-cortisol levels, demonstrate partial heritability of the stress response that is not attributable to environmental variation, and suggest that at least part of an indi- vidual＇s stress response can be accounted for by differences in matrilineal history.展开更多
Gene expression variation can be considered as a phenotype,and it plays an important role in both acclimation and adaption.However,genetic variation of gene expression received much less attention than traditional com...Gene expression variation can be considered as a phenotype,and it plays an important role in both acclimation and adaption.However,genetic variation of gene expression received much less attention than traditional commercial traits in aquaculture.To estimate the genetic variation and heritability of gene transcription in clam Meretrix petechialis,five Vibrio resistance-related genes were selected for gene expression analysis in the digestive gland,and an animal linear model was used to analyze data from quantitative real-time PCR(qRT-PCR).Among the five genes,BIRC7 showed significant additive genetic variations,the heritability of this gene of 12-month-and 15-month-old clams were 0.84±0.32 and 0.91±0.34,respectively.The heritability of other four genes(Bax,NFIL3,Big-Def,and CTL9)expression were low-tomoderate but not significantly expressed.Additionally,no significant phenotypic and genetic correlations between the BIRC7 transcription trait and body size were detected.This study highlights that certain gene expression variation is heritable and provides a reference for indirect selection of M.petechialis with high Vibrio resistance.展开更多
The investigation was carried out in focusing the genetic variability for different traits of wheat influenced by heat tolerance mechanism to find out relationships among phenological, physiological and yield contribu...The investigation was carried out in focusing the genetic variability for different traits of wheat influenced by heat tolerance mechanism to find out relationships among phenological, physiological and yield contributing traits. Spring wheat cultivar of 25 genotypes were selected and cultivated under late sowing condition at the Regional Wheat Research Institute, Shympur, Rajshahi, Bangladesh from December, 2016 to April, 2017. Significant variability among the genotypes exposed for different traits related to heat tolerance. Results showed that the genotypes G24, G10, G01, G13, G16, G25 and G14 </span><span style="font-family:Verdana;">ranked as better category considering maximum number of traits in mean</span><span style="font-family:Verdana;"> performance indicating their tolerance to heat stress under late sowing condition. Phenotypic variances (<i>σ<sub>g</sub><sup style="margin-left:-6px;">2</sup></i>) of all traits were greater than those of genotypic variances (<i>σ<sub>g</sub><sup style="margin-left:-6px;">2</sup></i>). The same trends were also found in their co-efficient of variances. The phenotypic co-efficient of variances (PCV) of all traits were greater compare to those of genotypic co-efficient of variances (GCV) and their values were closer to each other. The heading days (HD), canopy temperature at vegetative stage (CT</span><sub><span style="font-family:Verdana;">vg</span></sub><span style="font-family:Verdana;">), canopy temperature at grain filling stage </span><span><span style="font-family:Verdana;">(CT</span><sub><span style="font-family:Verdana;">gf</span></sub><span style="font-family:Verdana;">), biomass, plant height (PH), spike/m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> (SPM), spikelet/spike (SPS), </span></span><span style="font-family:Verdana;">grain/</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">spike (GPS), thousand grain weight (TGW) and yield exhibited higher heritability (<i></span><span style="font-family:Verdana;">h<sub>b</sub><sup style="margin-left:-6px;">2</sup></span><span style="font-family:""><span style="font-family:Verdana;"></i>) estimated under irrigated late sowing (ILS) condition. Under the same ILS condition SPAD, SPM, SPS, GPS, TGW and yield showed moderate to high genetic advance (GA) obtained through computing their mean percentage (%) and the rest traits HD, maturity days (MD), CT</span><sub><span style="font-family:Verdana;">vg</span></sub><span style="font-family:Verdana;">, CT</span><sub><span style="font-family:Verdana;">gf</span></sub><span style="font-family:Verdana;">, biomass, PH and harvest index (HI) exposed smaller genetic advance (% mean). The co-efficient of variation (CV%) of all attributes in all genotypes were significantly lower (1.36</span></span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">- 6.96). Both heritability and genetic advance were found lower for MD, SPAD and HI indicated their non additive genetic effects for </span><span style="font-family:Verdana;">which these traits might not be recommended for selection. However, </span><span style="font-family:Verdana;">spike/m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">spikelet/spike, grain/spike, thousand grain weight and yield belonged to </span><span style="font-family:Verdana;">higher heritability and high to moderate genetic advance in mean percentage (%) along with wide genetic variation and lower environmental influence in heat stress situation indicated the most likely heritability due to the effects of additive genes that might be suggested as effective process of selection for these traits in heat stress condition.展开更多
Ridgetail white prawn Exopalaemon carinicauda is an important economic marine species in China.To improve the germplasm quality of cultured E.carinicauda,for the fi rst time,we estimated the heritability of ammonia to...Ridgetail white prawn Exopalaemon carinicauda is an important economic marine species in China.To improve the germplasm quality of cultured E.carinicauda,for the fi rst time,we estimated the heritability of ammonia tolerance and survival of E.carinicauda,covering 263 full-sib families in multiple generations.Analysis models including binary linear animal model(BLA),binary linear sire-dam model(BLSD),probit threshold animal model(PTA),and probit threshold sire-dam model(PTSD)were used.The estimated heritability of tolerance to ammonia in diff erent models ranged from 0.09 to 0.22,and that of survival rate ranged from 0.06 to 0.16.Concerning the tolerance to ammonia,both the PTSD and BLSD models showed comparatively better prediction accuracies(0.48 and 0.47,respectively)than PTA and BLA models(0.40 and 0.26,respectively),while to the survival rate,all four models presented relatively low predictive abilities(0.16-0.26).This study provided important information for the future breeding program of E.carinicauda.展开更多
文摘Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the progressive degeneration of upper and lower motor neurons in the brainstem and spinal cord,leading to muscle weakness,paralysis,and respiratory failure (Morgan and Orrell,2016).
文摘This paper begins with the overthrow of the concept of combining ability in crossbreeding by the concept of heritability.The reason is that general combining ability changes with the number and kind of pure strains in the foundation stock and hence special combining ability changes also,so that work with different kinds of pure strains in the foundation stock cannot be compared.Hence combining ability is useless as a parameter to predict the amount of heterosis expected in the next generation.On the other hand,since each cross has a separate heritability,it can be applied to a cross population just as successfully as in purebreeding.Since the same concept holds in both cases,resort to any other concept would be superfluous.That's why combining ability must be rejected.Another reason(not given in the full text)is,an infinite number of pure strains would be required in the foundation stock for its results to be comparable with those of the heritability theory,which disposes of its utility altogether.The main content of the thesis is then the centennial enigma of heterosis can be resolved by Descarte's theoretic method of deduction.Accordingly we start from the definition of heterosis.H=F¡-MP,where H is heterosis,F,is the first generation offspring,MP is the mean of the parents or midparent,and from the use of a binomial random variable and its extention to the multinomial case derive the basic relations of heterosis with its components.Starting with second degree statistics,we obtain Vn=Vr,-2cov(F,,MP)+Vup,where V and cov stand for variance and covariance.The equations of heterosis are v„=(1/2)Na²+(1/4)Nd’+Vr(F,)=additive dominance F,epistasis Vup=(1/2)Na’+(1/2)V1,additive parental epistasis V„=(1/4)Nd’+V(F)+(1/2)V1,dominance F,epistasis parental epistasis.where N is number of genes controlling a trait,a=(P1-P,)12,d is deviation from midparent,while the variance components are all indicated by their names under the repective terms.It turns out that all these can be easily computed from the data so that the problem becomes a simple one which any college student may solve.In other words,the right answers are found when the right questions are asked.Who had ever shown that the heritability principle is inapplicable in crossbreeding,e.g.,in a crossing of two pure strains?From this cue arose the realization that the F,of a cross of two pure strains must also be a Mendelian population,with p and q both equal to 1/2 which simplifies the algebra outright.This Heritability Theory of Heterosis,or HTH in capital letters,re-sts on 2 initial anguments:1)Since 0.5+0.5=1,crossing two pure strains gives a population which is only a special case of pure-breeding,thereforea heritability coefficient must exist for the F1;2)Our problem reduces to that of finding that coefficient;the an-swer is given by the additive component divided by Ve.,i.e.,(1/2)No'1 Vp..which is readily found from the solution of the het-erosis equations.Thus the elemnal enigma of heterosis is resolved!This happened at the end of the 20th century.We now come to the second point of the discovery,the new genetic parameter crossheritability which will rise in size with the increase of the number of times it's used and form the link between breeding and evolution.The advent of the Age of Evolution Engineering in the 21st century marks a totally new era,showing that artificial will ultimately supercede natural selection,with the long span of time element eliminated.For agriculture at least,it means there is no limit to the increase of food supply by the new method,with the concentra-tion of desirable genes by hybridization in place of the old theory of their fixation.Genetic gain is achieved through artificial selec-tion,with an 80%saving of time,labor and cost by adoption of the new method.Applied to a further increase in all kinds of agri-cultural products including hybrd rice,it means that a huge eacalation,in fact a New Green Revolution,on a much langer scale than that of any such before,is in view,provided it is adopted in our research and educational institutions as early as possible,ere its spread elsewhere.The possibilities from the evolution point of view can only be pictured by science fiction.
基金Supported by the Zhejiang Provincial Public Welfare Technology Application Research Program(No:LGN21C140001).
文摘Plutella xylostella,a major pest of cruciferous vegetables worldwide,has developed resistance to diamide insecticides.Thiotraniliprole,a novel synthetic diamide insecticide,exhibits excellent activity against P.xylostella.In the present study,we aimed to confirm the resistance risk,cross-resistance,and mechanisms of resistance to thiotraniliprole in P.xylostella.After 40 consecutive generations of thiotraniliprole selection,we obtained a thiotraniliprole-resistance P.xylostella strain with a 5141.58-fold resistance ratio(RR)to thiotraniliprole.The overall realized heritability(h^(2))value of resistance was estimated as 0.9 using threshold trait analysis,indicating that the risk of developing resistance to thiotraniliprole is high in P.xylostella.The thiotraniliprole-resistant(TR)strain showed noticeable cross-resistance to chlorantraniliprole(RR=44670.05),cyantraniliprole(RR=7038.58),and tetrachlorantraniliprole(RR=1506.01),but no cross-resistance to tolfenpyrad,indoxacarb,diafenthiuron,or abamectin compared with the susceptible(S)strain.The enzyme assay data showed that the activities of glutathione-S transferase(GST),carboxylesterase(CarE),and the content of cytochrome P450 monooxygenase(P450s)were significantly higher in the TR strain than in the S strain.Sequencing of the full-length PxRyR cDNA revealed the gene site I4790K in the TR strain with a 100%frequency.This mutation in PxRyR likely underlies the high-level cross-resistance between thiotraniliprole and three other diamide insecticides.These findings provide valuable information for optimizing resistance management strategies to delay thiotraniliprole resistance development and ensure sustainable control of P.xylostella.
基金Supported by National Natural Science Foundation of China(40706052)China Agriculture Research System(CARS-47)~~
文摘[Objective] The aim was to estimate the heritability and genetic correlations of growth traits of Chinese shrimp Fenneropenaeus chinensis so as to provide basis and technical parameters for the breeding and selecting of Chinese shrimp.[Method] 51 full-sib families（including 35 half-sib families）of the Chinese shrimp F.chinensis were obtained by artificial insemination.Four growth traits of these families were measured,including body length,cephalothorax length,abdorminal segment length and body weight.According to quantitative genetics theory,the heritability of each growth trait,genetic and phenotypic correlation among these traits was statistically studied.[Result] The heritability was 0.36-0.51 for body length,0.14-0.24 for cephalothorax length,0.25-0.50 for abdominal segment length,and 0.04-0.29 for body weight.High and positive genetic correlations were obtained among growth traits.The genetic correlation between body weight and abdominal segment length was the highest（0.92）,followed by body length and abdominal segment length（0.91）,body length and body weight（0.88）,body weight and cephalothorax length（0.87）,abdominal segment length and cephalothorax length（0.86）,while the genetic correlation between body length and cephalothorax length was the lowest（0.83）.[Conclusion] The phenotypic correlation of body length,cephalothorax length,abdorminal segment length and body weight of Chinese shrimp F.chinensis were from 0.80 to 0.90 with extremely significant difference（P0.01）among the four growth traits by t-test.
基金Supported by National Sorghum Industry Technology Development System(CARS-06-01-05)Financial Genetic Breeding Program of Sichuan Province(2011JYGC11-031)+2 种基金Key R&D Program for Sorghum Breeding of Sichuan Province during the 12th Five Year PeriodScience&Technology Pillar Program in Sichuan ProvinceYouth Funds of Sichuan Academy of Agricultural Sciences(2012QNJJ-023)~~
文摘Using 3 sterile lines and 12 restorer of glutinous sorghum as experimental materials,36 hybrid combinations（3×12 NCⅡ） were designed to analyze the combining ability and heritability of six main agronomic traits,including plant height,panicle length,growth period,1 000-grain weight,per panicle grains and per panicle grain weight.The results showed that except per panicle grain number all other five agronomic traits have remarkable or extremely remarkable general combining ability and specific combining ability.Six agronomic traits were found to be control by additive genetic effect.Most of these agronomic traits are more easily influenced by restorers than sterile lines,suggesting that more attention should be paid to select restores in hybrid glutinous sorghum breeding.The narrow-sense heritability of these agronomic traits were in order growth period plant height per panicle grain weight panicle length 1 000-grain weight per panicle grains.
基金Supported by Youth Fund Project of Sichuan Academy of Agricultural Sciences(2009QNJJ015)~~
文摘Five cytoplasmic male sterile （CMS） lines were used as parents in an incomplete diallet cross and six restorer lines of rice design （Nc II design）. Thirty hybrid combinations with the same growth period were selected as experimental ma- terials to investigate the heterosis, combined ability and heredity of Cd content in brown rice of indica hybrid rice. According to the results, Cd content in brown rice showed a significantly negative heterosis; the general combining ability and specific combination ability of Cd content in CMS and restorer lines both reached extremely significant level （P〈0.01）, indicating that both genetic improvement of parents and e- valuation of combinations are important to the breeding of hybrid combinations with low accumulation of Cd; the broad-sense heritabitity and narrow-sense heritability of Cd content were both relatively high with slight differences, which respectively reached 97.73% and 80.10%, indicating that Cd content in brown rice mainly de- pends on the additive action of genes; in addition, parent improvement showed bet- ter effect on the selection of early generation.
基金Supported by the National High Technology Research and Development Program of China(863 Program,2011AA10A104)Special Funds of the Modern Agricultural Industry Technology System(CAES-13)+5 种基金National Science and Technology Support Program(2010BAD01B08,2011BAD35B04)Sichuan Breeding Key Project(2011NZ0098-5)Financial Genetic Engineering Program of Sichuan Province(2011JYGC04013)Special Funds for Sichuan Agricultural Innovation Team ConstructionOutstanding Youth AcademicTechnical Leader Training Program of Sichuan Province(2010JQ0054)~~
文摘Fifteen combinations crossed by five JA cytoplasmic male sterile lines （A1, A2, A3, A4, A5） and three restoring lines （R1, R2, R3） were selected to analyze the combining ability and heritability of nine main agronomic characters of Brassica na-pus L. to definite the application potential of these parent materials. The result showed that （i） the general combining ability （GCA） of male parents was R3＆gt;R2＆gt;R1 and that of female parents was A4＆gt;A1＆gt;A2＆gt;A5＆gt;A3; （i ） the special combining ability （SCA） of A2＆#215;R3 in plant height, number of branches, number of pods per plant and yield per plant was the best. The yield per plant of A2＆#215;R3, A1＆#215;R1 and A2＆#215;R1 ranked the first three places in the 15 combinations; （i i） the broad heritability of yield per plant was the highest, and that of the height of branches was the lowest. The com-prehensive characters of R3, A2 and A4 were better, which could be used to create new materials; （iv） good offspring were more likely to be chosen from the combina-tion with higher parental GCA, so the GCA and SCA should be considered com-prehensively when choosing parent and determining the optimal combinations.
基金Supported by the Earmarked Fund for Modern Agro-Industry Technology Research System (No Nycytx-50)National Sustain Plan of China (No2006BAD01A12012)+1 种基金Agriculture Commonweal Scientific Research Plan (NoNyhyzx07-046)the Yellow Sea Fisheries Research Institute Scientific and Research Fund (No 2009-ts-11)
文摘We analyzed the survival data of the offspring from 21 sires and 42 dams of turbot. The results show that the cumulative survival rates for turbot from 2 to 18 months range from 17.5% to 28.5% main mortality occurred during months 2-5; and the highest survival rates of families were 97.9%, 98.8%, 99.4%, 99.7% during months 2-5, 5-6, 6-8, 8-11, and ll-18, respectively, and 99.5%, being 53.5%, 23.8%, 19.5%, 14.9%, and 13.2% higher, respectively, than the mean values in each period. In all periods, the estimated heritabilities for survival were very low without significant difference from zero （P〉0.05） （values ranged from 0.06 to 0.12）, indicating low additive genetic effects. The genetic correlations of survival among families in different periods were all positive, but low in magnitude （values range from 0.03 to 0.31）. Genetic correlations between long-term survival and other periods＇ survival had negative values （-0.06 and -0.15） and three positive values （0.16, 0.12 and 0.14）. Genetic correlations between survival and weight were all positive, except for survival at months 2-5 and weight at 18 months, which was not significantly negative （-0.18）.
基金Supported by National Higb Technology Research and Development Program of China (863 Program) (No. 2006AA10A406)the Key Laboratory of Marine Biology,Instihite of Oceanology,Chinese Academy of Sciences (No. IaF201002)
文摘To quantify the response to selection, heritability and genetic correlations between weight and size ofLitopenaeus vannamei, the body weight （BW）, total length （TL）, body length （BL）, first abdominal segment depth （FASD）, third abdominal segment depth （TASD）, first abdominal segment width （FASW）, and partial carapace length （PCL） of 5-month-old parents and of offspring were measured by calculating seven body measurings of offspring produced by a nested mating design. Seventeen half-sib families and 42 full-sib families ofL. vannamei were produced using artificial fertilization from 2-4 dams by each sire, and measured at around five months post-metamorphosis. The results show that heritabilities among various traits were high： 0.515±0.030 for body weight and 0.394±0.030 for total length. After one generation of selection, the selection response was 10.70% for offspring growth. In the 5th month, the realized heritability for weight was 0.296 for the offspring generation. Genetic correlations between body weight and body size were highly variable. The results indicate that external morphological parameters can be applied during breeder selection for enhancing the growth without sacrificing animals for determining the body size and breed ability; and selective breeding can be improved significantly, simultaneously with increased production.
基金The National High Technology Research and Development Program of China under contract No.2012AA10A408-7the Special Funding for Basic Scientific Research of Yellow Sea Fisheries Research Institute under contract No.2010-cb-04
文摘The objectives of this present research were to assess the heritability of growth traits under low temperature conditions in turbot（Scophthalmus maximus L.）, and to analyze the correlation between body weight（BW） and body length（BL）. There were 536 individuals from 25 full- and half-sib families involved in this study. During the entire 90-day period, which was initiated at 233 dph（day old） and ended at 323 dph, the individuals＇ BW and BL were weighed consecutively six times every 18 days. The heritability of BW and BL and the correlation between these two traits were estimated based on an individual animal model with the derivative-free restricted maximum likelihood（DFREML） method. These results showed that the specific growth rates（SGR） of 25 families was from 0.75±0.11 to 1.05±0.14 under water temperature of 10.5–12°C. In addition, the heritability of BW and BL estimated under low-temperature were 0.32±0.04 and 0.47±0.06, respectively. The BW had a medium heritability（0.2–0.4）, and the BL had a high heritability（〉0.45）, which suggested that selection for increased weight and length was feasible. Moreover, there was potential for mass selection on growth. The genetic and phenotypic correlations between BW and BL were 0.95±0.01 and 0.91±0.01（P 〈 0.01）, respectively. A significant correlation between BW and BL showed that BL could be instead of BW for indirect selection, which could be effectively implemented in the breeding program.
基金Supported by the Special Fund for Agro-Scientific Research in the Public Interest (No. 200903029-4)Key Project of Science and Technology Department of Fujian Province (No. 2010N0021)the Foundation for Young Professors of Jimei University (No. 2009C002)
文摘We estimated the reproductive success of adult brood fish and the heritability of growthrelated traits for large yellow croaker （Larimichthys crocea）. We created two independent full-factorial cross groups （1 and 2） by crossing 4 malesx4 females and 4 males^3 females, respectively. We measured the body weight （BW）, body length （BL）, and body height （BH） of 281 individuals from group 1 and 318 individuals from group 2 at 20 months post hatch （harvest age）. We also collected a tissue sample from each individual. The parents and offspring were genotyped using six polymorphic mierosatellites. Of the 599 offspring, 99.2% were assigned to a single pair of parents. In both groups, some parent pairs produced a large number of offsprings while other pairs did not produce any offspring. The genetic diversity and putative No were lower in the offsprings than in the parents in both groups. The heritability estimates at 20-month age were 0.13±0.10 for BW, 0.19±0.13 for BL, and 0.09±0.06 for BH. The genetic and phenotype correlation between BW, BL, and BH was close to 1. The results provide basic information for selective breeding and further genetic characterization of large yellow croaker.
基金funded by the National Key Research and Development Program of China (2016YFC0500706)the National Natural Science Foundation of China (31570427, 31770505)the China Scholarship Council (201606205032)
文摘Intraspecific trait variation and heritability in different environmental conditions not only suggest a potential for an evolutionary response but also have important ecological consequences at the population, community, and ecosystem levels. However, the contribution of quantitative trait variation within a grassland species to evolutionary responses or ecological consequences is seldom documented. Leymus chinensis is an important dominant species in semi-arid grasslands of China, which has seriously suffered from drought and high temperature stresses in recent decades. In the present study, we measured variation and heritability of 10 quantitative traits, namely the number of tillers, maximum shoot height, number of rhizomes, maximum rhizome length, rhizome mass, aboveground mass, root mass, maximum net photosynthetic rate(Pmax), specific leaf area(SLA), and leaf length to leaf width ratio(LL/LW), for 10 genotypes of L. chinensis under one non-stress(Ck) condition and three environmental stress conditions(i.e., drought(Dr), high temperature(Ht), and both drought and high temperature(DrHt)). Result indicated that(1) the interaction of genotype and environmental condition(G×E) was significant for 6 traits but not significant for the other 4 traits as shown by two-way analysis of variance(ANOVA), suggesting that different selection forces were placed for different traits on the factors dominating phenotypic responses to different environmental conditions. Moreover, these significant G×E effects on traits indicated significantly different phenotypic adaptive responses among L. chinensis genotypes to different environmental conditions. Additionally, individuals could be grouped according to environmental condition rather than genotype as shown by canonical discriminant analysis, indicating that environmental condition played a more important role in affecting phenotypic variation than genotype;(2) by one-way ANOVA, significant differences among L. chinensis genotypes were found in all 10 traits under Ck and Dr conditions, in 8 traits under Dr Ht condition and only in 4 traits under Ht condition; and(3) all 10 traits showed relatively low or non-measurable broad-sense heritability(H_2) under stress conditions. However, the lowest H_2 value for most traits did not occur under DrHt condition, which supported the hypothesis of 'unfavorable conditions have unpredictable effects' rather than 'unfavorable conditions decrease heritability'. Results from our experiment might aid to improve predictions on the potential impacts of climate changes on L. chinensis and eventually species conservation and ecosystem restoration.
基金Supported by the National High Technology Research and Development Program of China(863 Program)(No.2012AA10A404)the Qingdao Postdoctoral Science Foundation Funded Project(No.Q51201403)+3 种基金the National Natural Science Foundation of China(Nos.31302179,31172402)the 948 Project from the Ministry of Agriculture of China(No.2015-Z17)the Improved Agricultural Breeds Engineering Project of Shandong Province-the Taishan Scholar Program for seed industry "Multi-Tarits Selective Breeding of New Variety and Its Industrialization"the Fundamental Research Funds for the Yellow Sea Fisheries Research Institute Chinese Academy of Fishery Sciences(No.20603022013011)
文摘Ammonia,toxic to aquaculture organisms,represents a potential problem in aquaculture systems,and the situation is exacerbated in closed and intensive shrimp farming operations,expecially for Litopenaeus vannamei.Assessing the potential for the genetic improvement of resistance to ammonia in L.vannamei requires knowledge of the genetic parameters of this trait.The heritability of resistance to ammonia was estimated using two descriptors in the present study:the survival time(ST) and the survival status at half lethal time(SS_(50)) for each individual under high ammonia challenge.The heritability of ST and SS_(50) were low(0.154 4±0.044 6 and 0.147 5±0.040 0,respectively),but they were both significantly different from zero(P<0.01).Moreover,these two estimates were basically the same and showed no significant differences from each other(P>0.05),suggesting that ST and SS_(50) could be used as suitable indicators for resistance to ammonia.There were also positive phenotypic and genetic correlation between resistance to ammonia and body weight,which means that resistance to ammonia can be enhanced by the improvement of husbandry practices that increase the body weight.The results from the present study suggest that the selection for higher body weight does not have any negative consequences for resistance to ammonia.In addition to quantitative genetics,tools from molecular genetics can be applied to selective breeding programs to improve the efficiency of selection for traits with low heritability.
基金The National Natural Science Foundation of China under contract No.31302179the Taishan Scholar Program for Seed Industry+4 种基金the Introduction of International Advanced Agricultural Science and Technology Plan under contract No.2016-X39the Special Fund for Basic Scientific Research Business of Central Public Research Institutes under contract No.2015B04XK01China Postdoctoral Science Foundation under contract No.2015M572095Qingdao Scientific Research Foundation under contract No.14-2-4-52-jch5Jiangsu Province Science and Technology Support Project under contract No.BE2014414
文摘The aim of the present study is to detect the potential of the base population from diallel crosses of eight introduced strains of the Pacific white shrimp（Litopenaeus vannamei） for improving the yield. Heterosis and heritability were estimated for pond survival at commercial farm conditions for the base population that included 207 full-sib families from a nested mating design by artificial insemination. Among all the hybrids,the heterosis ranged from –11.37%（UA1×UA2） to 20.53%（UA3×SIN） with an average of 0.953%. The results showed that more than half of the hybrids（51.85%） have negative heterosis for survival rate, but most of the hybrids with positive heterosis have high estimates. The high proportion of negative heterosis for survival rate reminders us that the survival trait also should be considered in the crossbreeding program to avoid yield decrease. However, high positive heterosis manifested in most of the hybrids for survival indicates the usefulness of these hybrids for improving the survival to obtain higher yield by crossbreeding in this breeding program. The heritability estimate for pond survival was 0.092±0.043 when genetic groups were included in the pedigree, and it was significantly different from zero（P〈0.05）. The results from this study also indicated that significant improvement for survival is possible through selection in L. vannamei.
基金The Agricultural Science and Technology Achievement Transformation Fund Project of Ministry of Science and Technology,China under contract No.2012GB2E200361the Key Laboratory of Marine Biology,Institute of Oceanlogy,Chinese Academy of Sciences+1 种基金Qianjiang distinguished experts of HangzhouExtension and Demonstration Program in Desalting Culture of Litopenaeus Vannamei New Breed"Ke Hai 1",Northwest A&F University,China under contract No.XNY2013-4
文摘Pacific whiteleg shrimp （Litopenaeus vannamei） is an economically relevant shrimp species in many Asian countries. The specific objective of the current research was to assess microsatellite markers in screening the fast- growth of domesticated L. vannamei stocks to establish a founder population for breeding-selection plans. The post.larvae produced by the reproduction of second generation broodstock were cultured in the same conditions throughout a five months growing period. Ninety juvenile shrimp were selected from the slow-, medium- and the fast-growth groups, and ten microsatellite markers were used to investigate their genetic diversity, and to understand the improvement of a breeding-selection scheme. Ten polymorphic loci （markers） （M1-M10） were produced at ten loci in this sample, among them Primer M8 was the highest polymorphic locus and M7 was the lowest one. A specific locus was found in the fast-growth group using Primer M5. The longest genetic distance （0.481） was determined between the fast- and medium-growth groups and the shortest （0.098） was between the slow- and medium-growth groups; therefore, the largest genetic identity （0.946） was observed between the slow- and medium-growth groups and the smallest （0.667） was observed between the medium- and fast-growth groups. The Unweighted Paired Group with Arithmetic Average （UPGMA） dendrogram based on Nei＇s genetic distances provided two different groups; the first consist of the slow- and medium-growth groups and the second the fast- growth group. Selection response and realized heritability for growth were 11.55% and 31.26%, respectively. Therefore, this set of microsatellite markers would provide a useful tool in shrimp breeding schemes.
文摘Activation of the hypothalamic-pituitary-adrenal （HPA） axis liberates glucocorticoids, which provides an acute indication of an individual＇s response to stressors. The heritability of the stress response in wild mammals, however, remains poorly documented. We quantified the cortisol stress response of female Richardson＇s ground squirrels （RGSs） to handling and physical restraint, testing for： （1） the effects of individual age, time of day, and sample latency; （2） repeatability within individuals; （3） narrow-sense heritability; and （4） differences among individuals owing to potential genetic and/or environmental effects. We detected a positive linear relationship between baseline plasma cortisol （BL-cortisol） concentration and stress-induced plasma cortisol （Sl-cortisol） concentration that defined each individual＇s cortisol stress response. BL-cortisol, SI-cortisol, and stress response did not differ according to the time the sample was taken, or by subject age. Cortisol stress response was highly repeatable within individuals, had a mother-offspring heritability of h2 =0.40 ± 0.24 （mean ±SE）, full-sibling heritability of h2s = 0.37 ± 0.71, and half-sibling heritabil- ity of hHS^2 = 0.75 ± 1.41. Stress responses of sibling groups, immediate-family groups, and squir- rels within a given area did not differ, whereas those of individuals from more distantly related matrilines did. Our results highlight the natural variability in HPA axis reactivity among individuals by quantifying both BL- and SI-cortisol levels, demonstrate partial heritability of the stress response that is not attributable to environmental variation, and suggest that at least part of an indi- vidual＇s stress response can be accounted for by differences in matrilineal history.
基金Supported by the China Agriculture Research System(No.CARS-49)the National Natural Science Foundation of China(No.31772845)+1 种基金the Science and Technology Service Network Initiative of the Chinese Academy of Sciences(No.KFJ-STS-ZDTP-049)the Foundation of Zhejiang Key Laboratory of Exploitation and Preservation of Coastal Bio-Resource(No.J2018001)
文摘Gene expression variation can be considered as a phenotype,and it plays an important role in both acclimation and adaption.However,genetic variation of gene expression received much less attention than traditional commercial traits in aquaculture.To estimate the genetic variation and heritability of gene transcription in clam Meretrix petechialis,five Vibrio resistance-related genes were selected for gene expression analysis in the digestive gland,and an animal linear model was used to analyze data from quantitative real-time PCR(qRT-PCR).Among the five genes,BIRC7 showed significant additive genetic variations,the heritability of this gene of 12-month-and 15-month-old clams were 0.84±0.32 and 0.91±0.34,respectively.The heritability of other four genes(Bax,NFIL3,Big-Def,and CTL9)expression were low-tomoderate but not significantly expressed.Additionally,no significant phenotypic and genetic correlations between the BIRC7 transcription trait and body size were detected.This study highlights that certain gene expression variation is heritable and provides a reference for indirect selection of M.petechialis with high Vibrio resistance.
文摘The investigation was carried out in focusing the genetic variability for different traits of wheat influenced by heat tolerance mechanism to find out relationships among phenological, physiological and yield contributing traits. Spring wheat cultivar of 25 genotypes were selected and cultivated under late sowing condition at the Regional Wheat Research Institute, Shympur, Rajshahi, Bangladesh from December, 2016 to April, 2017. Significant variability among the genotypes exposed for different traits related to heat tolerance. Results showed that the genotypes G24, G10, G01, G13, G16, G25 and G14 </span><span style="font-family:Verdana;">ranked as better category considering maximum number of traits in mean</span><span style="font-family:Verdana;"> performance indicating their tolerance to heat stress under late sowing condition. Phenotypic variances (<i>σ<sub>g</sub><sup style="margin-left:-6px;">2</sup></i>) of all traits were greater than those of genotypic variances (<i>σ<sub>g</sub><sup style="margin-left:-6px;">2</sup></i>). The same trends were also found in their co-efficient of variances. The phenotypic co-efficient of variances (PCV) of all traits were greater compare to those of genotypic co-efficient of variances (GCV) and their values were closer to each other. The heading days (HD), canopy temperature at vegetative stage (CT</span><sub><span style="font-family:Verdana;">vg</span></sub><span style="font-family:Verdana;">), canopy temperature at grain filling stage </span><span><span style="font-family:Verdana;">(CT</span><sub><span style="font-family:Verdana;">gf</span></sub><span style="font-family:Verdana;">), biomass, plant height (PH), spike/m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> (SPM), spikelet/spike (SPS), </span></span><span style="font-family:Verdana;">grain/</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">spike (GPS), thousand grain weight (TGW) and yield exhibited higher heritability (<i></span><span style="font-family:Verdana;">h<sub>b</sub><sup style="margin-left:-6px;">2</sup></span><span style="font-family:""><span style="font-family:Verdana;"></i>) estimated under irrigated late sowing (ILS) condition. Under the same ILS condition SPAD, SPM, SPS, GPS, TGW and yield showed moderate to high genetic advance (GA) obtained through computing their mean percentage (%) and the rest traits HD, maturity days (MD), CT</span><sub><span style="font-family:Verdana;">vg</span></sub><span style="font-family:Verdana;">, CT</span><sub><span style="font-family:Verdana;">gf</span></sub><span style="font-family:Verdana;">, biomass, PH and harvest index (HI) exposed smaller genetic advance (% mean). The co-efficient of variation (CV%) of all attributes in all genotypes were significantly lower (1.36</span></span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">- 6.96). Both heritability and genetic advance were found lower for MD, SPAD and HI indicated their non additive genetic effects for </span><span style="font-family:Verdana;">which these traits might not be recommended for selection. However, </span><span style="font-family:Verdana;">spike/m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">spikelet/spike, grain/spike, thousand grain weight and yield belonged to </span><span style="font-family:Verdana;">higher heritability and high to moderate genetic advance in mean percentage (%) along with wide genetic variation and lower environmental influence in heat stress situation indicated the most likely heritability due to the effects of additive genes that might be suggested as effective process of selection for these traits in heat stress condition.
基金Supported by the National Key R&D Program of China(No.2018YFD0901302)the China Agriculture Research System-48(No.CARS-48)。
文摘Ridgetail white prawn Exopalaemon carinicauda is an important economic marine species in China.To improve the germplasm quality of cultured E.carinicauda,for the fi rst time,we estimated the heritability of ammonia tolerance and survival of E.carinicauda,covering 263 full-sib families in multiple generations.Analysis models including binary linear animal model(BLA),binary linear sire-dam model(BLSD),probit threshold animal model(PTA),and probit threshold sire-dam model(PTSD)were used.The estimated heritability of tolerance to ammonia in diff erent models ranged from 0.09 to 0.22,and that of survival rate ranged from 0.06 to 0.16.Concerning the tolerance to ammonia,both the PTSD and BLSD models showed comparatively better prediction accuracies(0.48 and 0.47,respectively)than PTA and BLA models(0.40 and 0.26,respectively),while to the survival rate,all four models presented relatively low predictive abilities(0.16-0.26).This study provided important information for the future breeding program of E.carinicauda.
