An elite backcrossed inbred line Z550 with increased grains per panicle was identified from advanced backcrosses between Nipponbare and Xihui 18 by simple sequence repeat(SSR) marker-assisted selection(MAS). Z550 carr...An elite backcrossed inbred line Z550 with increased grains per panicle was identified from advanced backcrosses between Nipponbare and Xihui 18 by simple sequence repeat(SSR) marker-assisted selection(MAS). Z550 carries 13 substitution segments distributed on chromosomes 1, 6, 7, 8, 9, 10, and 12, with an average substitution length of 1.68 Mb. Compared with the Nipponbare parental line, plant height, panicle length, spikelets per panicle, grains per panicle, and grain weight for Z550 were significantly increased. While the grain width of Z550 was significantly narrower, and the seed setting ratio(81.43%) was significantly lower than that of Nipponbare, it is still sufficient for breeding purposes. Quantitative trait loci(QTLs) mapping for important agronomic traits was conducted with the F_2 population derived from Nipponbare crossed with Z550 using the restricted maximum likelihood(REML) method. A total of 16, including 12 previously unreported QTLs were detected, with contribution rates ranging from 1.46 to 10.49%. Grains per panicle was controlled by 8 QTLs, 5 of which increased number of grains whereas 3 decreased it. qGPP-1, with the largest contribution(10.49%), was estimated to increase grains per panicle by 30.67, while q GPP-9, with the minimum contribution rate(2.47%), had an effect of increasing grains per panicle by 15.79. These results will be useful for further development of single segment substitution lines with major QTLs, and for research of their molecular functions via QTL cloning.展开更多
Oysters are of the most economically important bivalves worldwide.It has high nutritional value and is regarded as a good source of proteins,lipids,glycogen,and amino acids.C.gigas and C.angulata are allopatric congen...Oysters are of the most economically important bivalves worldwide.It has high nutritional value and is regarded as a good source of proteins,lipids,glycogen,and amino acids.C.gigas and C.angulata are allopatric congeneric dominant oysters that are widely cultivated in the northern and southern coast of China,and have shown remarkable differentiation in the nutritional content.Interspecific hybridization and backcross of the two species are effective ways to improve the nutritional quality of the oyster.Sixteen progenies were constructed based on a 4×4 diallel crosses among broodstock of C.gigas(G),C.angulata(A)and their hybrids GA(H)and AG(R).The glycogen,fatty acids,and amino acids performance of these progenies were evaluated in 22 months after fertilization.The glycogen content of AA was significantly lower than that of the other 15 progenies(P<0.05),while only the GH progeny was significantly higher than the GG(P<0.05),with a heterosis value of 21.06%.The backcross progenies GR exhibited significantly higher saturated fatty acids,eicosapentaenoic acid(EPA),and polyunsaturated fatty acids(PUFAs)content than those of GG(P<0.05),and did not show significant differences from AA.The AA showed significantly higher content of total amino acids(TAAs)than GG(P<0.05).The AH progeny displayed significantly higher taurine(Tau)content than GG(P<0.05),and the heterosis value was 27.88%.Therefore,the backcross breeding was shown an effective way to improve the glycogen,fatty acids,and TAAs of GG,and the glycogen of AA.This study provided useful information to characterize the benefits of backcrossing in nutritional quality,which will facilitate the production of differentiated products and increase the efficiency of the oyster industry.展开更多
Indian mustard is recognized as a resilient and economically important oilseed crop.However,its potential remains untapped due to the limited availability of short-duration,high-yielding varieties capable of out-compe...Indian mustard is recognized as a resilient and economically important oilseed crop.However,its potential remains untapped due to the limited availability of short-duration,high-yielding varieties capable of out-competing other rabi crops.Considering this notion,we have evaluated twenty-one F_(2) and six BC1F1 populations derived from seven diversified parents of Brassica juncea following a Randomized Complete Block Design at Sher-e-Bangla Agricultural University.Based on key agronomic traits,the genetic components,heterosis,inbreeding depression,and gene action were studied to select early maturing and high-yielding populations.The percentage of heterosis was manifested in various cross-combinations,including P4×P6(91.45%for yield per plant)and P5×P6(28.52%for thousand seed weight),emerging as promising candidates for increasing productivity while managing negative inbreeding effects.Conversely,significant inbreeding depression was noted in traits like days to siliquae maturity and yield,particularly in crosses,P1×P2(6.29%)and P3×P5(21.74%),underscoring the need for careful selection in breeding programs to mitigate these effects.Variance analysis indicated that both additive and non-additive genetic interactions play a pivotal role in the inheritance patterns of the traits of interest.Among the six backcrosses,one promising line was(P5×P6)×P5,demonstrating early maturity(107.00 DAS)with improved seed yield(12.47 g).This combination exhibited the potential for enhancing the adaptability and productivity by maintaining the maturity index and accelerating yield.Furthermore,significant phenotypic variation across yield-contributing traits was notable,whereas thousand seed weight and yield per plant showed high broad-sense and narrow-sense of heritability.Besides,positive correlations between seed yield and its attributing traits were noted,suggesting potential avenues for selection breeding.Collectively,the ob-tained findings enhance the understanding of genetic mechanisms underlying heterosis and inbreeding depres-sion in B.juncea,providing insights and effective strategies for developing superior cultivars with optimized agronomic traits.展开更多
To improve agronomic traits of partial waxy wheat, crossing between Chinese Baihuomai and wheat cultivars PH85-16, Jinan 17, and Yannong 15 was performed. The progeny plants were further backcrossed to these cultivars...To improve agronomic traits of partial waxy wheat, crossing between Chinese Baihuomai and wheat cultivars PH85-16, Jinan 17, and Yannong 15 was performed. The progeny plants were further backcrossed to these cultivars as recurrent parents for five generations. To get homozygous plants with the null allele at the Wx-D1 locus, self-pollination was carried out in the BC5F1 generation. Through another three generations, 6 partial waxy wheat lines were obtained, which had similar agronomic performance as their recurrent parents and carried the null allele at the Wx-D1 locus. In each generation, the Wx-D1 locus was identified by a PCR-based DNA marker and the agronomic traits were examined in progeny plants. The results from this study indicate that the use of backcrossing with a PCR-based DNA marker was useful in waxy wheat breeding. These partial waxy wheat lines can be used in field production.展开更多
[Objective] This study was to investigate the restoring ability of normal indica red rice Ruby and to carry out its restoring gene mapping. [Method] Normal indica red rice Ruby was hybridized with the sterile lines Zh...[Objective] This study was to investigate the restoring ability of normal indica red rice Ruby and to carry out its restoring gene mapping. [Method] Normal indica red rice Ruby was hybridized with the sterile lines Zhenxian 97A, D62A, G46A and D702A to prepare their F1, BC1 and F2 progenies, and the pollen fertilities of these progenies were investigated. Meanwhile the restoring genes were mapped using SSLP. [ Result] For the sterile lines tested, Ruby has a gene to restore their fertilities. This gene is located on the chromosome 7 and shows a genetic distance of 7.4 cM with RM182. Unlike the clustering distribution of the restoring genes on chromosome 10, it is a specific restoring gene. [ Conclusion] it is feasible to breed restoring genes controlling red color characters via transgene and backcross.展开更多
The present study aimed at breeding new rice germplasms with similar genome but significantly differed in heat tolerance during the grain filling stage.A total of 791 BC1F8 backcross recombinant lines,derived from the...The present study aimed at breeding new rice germplasms with similar genome but significantly differed in heat tolerance during the grain filling stage.A total of 791 BC1F8 backcross recombinant lines,derived from the cross of Xieqingzao B /N22 //Xieqingzao B,were used as materials.Each rice line was separated evenly into two groups,and the heat tolerance of all rice lines were evaluated at natural high temperature in fields.The rice lines with heat tolerant index higher than 90% or lower than 40% were selected to compare the phenotypic characters and further identify heat tolerance at the early milky stage in a phytotron.Rice lines with similar phenotypic characters but significantly differed in heat tolerance at the milky stage were analyzed by 887 simple sequence repeat markers that were evenly distributed on the 12 rice chromosomes.In the result,12(6 pairs) rice lines with similar phenotypic characters but significantly differed in heat tolerance at the milky stage were obtained.Molecular marker analysis indicated that the genomic polymorphism between 703T and 704S was the smallest in the 6 pairs of rice lines,with only 16 polymorphic sites,including 22 different alleles.The application of these two backcross introgression rice lines for future study on the mechanisms of heat tolerance in rice at the milky stage will be theoretically beneficial in reducing the interference caused by genetic differences from experimental materials.展开更多
Salinity-alkalinity is incipient abiotic stress that impairs plant growth and development.Rice(Oryza sativa)is a major food crop greatly affected by soil salinity and alkalinity,requiring tolerant varieties in the sal...Salinity-alkalinity is incipient abiotic stress that impairs plant growth and development.Rice(Oryza sativa)is a major food crop greatly affected by soil salinity and alkalinity,requiring tolerant varieties in the saline-alkali prone areas.Understanding the molecular and physiological mechanisms of saline-alkali tolerance paves the base for improving saline-alkali tolerance in rice and leads to progress in breeding.This review illustrated the physiological consequences,and molecular mechanisms especially signaling and function of regulating genes for saline-alkali tolerance in rice plants.We also discussed QTLs regarding saline-alkali tolerance accordingly and ways of deployment for improvement.More efforts are needed to identify and utilize the identified QTLs for saline-alkali tolerance in rice.展开更多
A set of 240 introgression lines derived from the advanced backcross population of a cross between a japonica cultivar,Xiushui 09,and an indica breeding line,IR2061,was developed to dissect QTLs affecting cold toleran...A set of 240 introgression lines derived from the advanced backcross population of a cross between a japonica cultivar,Xiushui 09,and an indica breeding line,IR2061,was developed to dissect QTLs affecting cold tolerance （CT） at seedling stage and heat tolerance （HT） at anthesis.Survival rate of seedlings （SRS） and spikelet fertility （SF）,the index traits of CT and HT,showed significant differences between the two parents under stresses.A total of four QTLs （qSRS1,qSRS7,qSRS11a and qSRS11b） for CT were identified on chromosomes 1,7,11,and the Xiushui 09 alleles increased SRS at all loci except qSRS7.Four QTLs for SF were identified on chromosomes 4,5,6,and 11.These QTLs could be classified into two major types based on their behaviors under normal and stress conditions.The first was QTL expressed only under normal condition;and the second QTL was apparently stress induced and only expressed under stress.Among them,two QTLs （qSF4 and qSF6） which reduced the trait difference between heat stress and normal conditions must have contributed to HT because of their obvious contribution to trait stability,and the IR2061 allele at the qSF6 and the Xiushui 09 allele at the qSF4 improved HT,respectively.No similar QTL was found between CT at seedling stage and HT at anthesis.Therefore,it is possible to breed a new variety with CT and HT by pyramiding the favorable CT-and HT-improved alleles at above loci from Xiushui 09 and IR2061,respectively,through marker-assisted selection （MAS）.展开更多
Further improvement of rice productivity remains a challenge. Breeding is perceived as an important option to increase rice yield. However, the genetic progress of grain yield in most rice breeding programs was slow i...Further improvement of rice productivity remains a challenge. Breeding is perceived as an important option to increase rice yield. However, the genetic progress of grain yield in most rice breeding programs was slow in the last decades. Although great progress in rice genomics and molecular biology has been achieved, the effect of such technological innovations on rice breeding is far small. Marker-assisted selection （MAS） for a few target quantitative trait loci （QTLs） has significant effects in improving qualitative traits, such as disease resistance. The success of MAS has therefore motivated breeders to identify and use major QTLs for yield and yield component traits. In this review, we summarized the recent methods in QTL identification, including novel statistical methods for linkage and association mapping, special population types, and whole-genome sequencing. We reviewed the successful application of marker-assisted gene introgression and gene pyramiding to improve grain yield and discussed the design of efficient MAS schemes to further increase the success rate of breeding programs. The use of well-characterized major QTLs through introgression and gene pyramiding is proven effective in improving grain yield, particularly yield under abiotic stress. Major QTLs that are stable across genetic background and growing environments are often found in less adapted germplasms, such as landraces and wild relatives. Advanced backcross QTL analysis and introgression lines, which integrate QTL discovery and utilization, are important methods for exploiting major QTLs contained in such germplasms. Next-generation sequencing substantially increases mapping resolution and accelerates the identification of casual genes underlying major QTLs. Practical guidelines derived from theoretical and empirical studies are given to guide the design of efficient marker-assisted gene introgression and pyramiding schemes.展开更多
Pyricularia oryzae anamorph of Magnaporthe oryzae is one of the most notorious fungal pathogens causing severe economic loss in rice production worldwide. Various methods, viz. cultural, biological and molecular appro...Pyricularia oryzae anamorph of Magnaporthe oryzae is one of the most notorious fungal pathogens causing severe economic loss in rice production worldwide. Various methods, viz. cultural, biological and molecular approaches, are utilized to counteract this pathogen. Moreover, some tolerant or resistant rice varieties have been developed with the help of breeding programmes. Isolation and molecular characterization of different blast resistance genes now open the gate for new possibilities to elucidate the actual allelic variants of these genes via various molecular breeding and transgenic approaches. However, the behavioral pattern of this fungus breakups the resistance barriers in the resistant or tolerant rice varieties. This host-pathogen barrier will be possibly countered in future research by comparative genomics data from available genome sequence data of rice and M. oryzae for durable resistance. Present review emphasized fascinating recent updates, new molecular breeding approaches, transgenic and genomics approaches(i.e. mi RNA and genome editing) for the management of blast disease in rice. The updated information will be helpful for the durable, resistance breeding programme in rice against blast pathogen.展开更多
Using an accession of common wild rice （Oryza rufipogon Griff.） collected from Yuanjiang County, Yunnan Province, China, as the donor and an elite cultivar 93-11, widely used in two-line indica hybrid rice productio...Using an accession of common wild rice （Oryza rufipogon Griff.） collected from Yuanjiang County, Yunnan Province, China, as the donor and an elite cultivar 93-11, widely used in two-line indica hybrid rice production in China, as the recurrent parent, an advanced backcross populations were developed. Through genotyping of 187 SSR markers and investigation of six yield-related traits of two gen- erations （BC4F2 and BC4F4）, a total of 26 QTLs were detected by employing single point analysis and interval mapping in both genera-tions. Of the 26 QTLs, the alleles of 10 （38.5%） QTLs originating from O. rufipogon had shown a beneficial effect for yield-related traits in the 93-11 genetic background. In addition, five QTLs controlling yield and its components were newly identified, indicating that there are potentially novel alleles in Yuanjiang common wild rice. Three regions underling significant QTLs for several yield-related traits were detected on chromosome 1, 7 and 12. The QTL clusters were founded and corresponding agronomic traits of those QTLs showed highly significant correlation, suggesting the pleiotropism or tight linkage. Fine-mapping and cloning of these yield-related QTLs from wild rice would be helpful to elucidating molecular mechanism of rice domestication and rice breeding in the future.展开更多
HMW-GS 5 + 10 was introduced to four major wheat cultivars Kehan9, Kefeng3, Longmai20 and Kenda4 through 5 or 6 consecutive backcrosses. No significant difference in protein content and dry gluten content was observed...HMW-GS 5 + 10 was introduced to four major wheat cultivars Kehan9, Kefeng3, Longmai20 and Kenda4 through 5 or 6 consecutive backcrosses. No significant difference in protein content and dry gluten content was observed between cultivars containing 5 + 10 and 2 + 12 or 3 + 12 (P>0.1). In cultivars containing HMW-GS 5 + 10, the ratio of wet gluten content to dry gluten content was 2. 9 - 5.0% (P<0. 01) lower than the ratio from the cultivars containing 2 + 12 or 3 + 12, the ratio of Zeleny sedimentation volume to dry gluten content was 4. 5 - 13. 4% (P<0.05) higher. The degree of softening in cultivars having 5 + 10 was 15 -25 FU (P<0. 01) lower, while the maximum resistance was 82 - 193 EU (P<0. 05) higher. Backcrosses with biochemical marker assisted selection in the improvement of quality in wheat cultivars was discussed.展开更多
[ Objective] This study was to explore the inheritance of BC1 F3 to excellent characteristics of parents（ Elymus dahuricus, Hordeum brevisubu/atum）, heterosis and fertility restoration. E Methodl The agronomic chara...[ Objective] This study was to explore the inheritance of BC1 F3 to excellent characteristics of parents（ Elymus dahuricus, Hordeum brevisubu/atum）, heterosis and fertility restoration. E Methodl The agronomic characters such as growth period, growth rate, pollen fertility, fecundity, reproducibility and fresh grass output of Elymus dahudcus, Hordeum brevisubu/atum and BC1 F3 were comparatively studied. E Result l The growth dynamic of the BC1 F3 lined tended to like that of its parent Hordeum brevisubu/atum; although growing periods of various lines were different, they were close to that of Hordeurn brevisubulatum. There were differences in pollen fertility and seed setting, the pollen fertility rate of YF3-93 was higher than recurrent parent Hordeum brevisubulatum, its seed setting rate in open pollination was also higher. Some lines had low pollen fertility rate and seed setting rate, such as the pollen fertility rate of PF3-52. There were significant differences in the output among BC1 F3 lines, e.g. the heterosis （HP） of YF3-64, YF3-74 and YF3-83 were 75.53%, 75.12% and 66.16%, respectively; however, the yields of PF3- 52, PF3-15 and PF3-42 were lower than their parents. ~ Conclusion] This study provided reference for breeding new varieties of forage which is suitable to drought and saline environment.展开更多
Future demands for increased productivity and resilience to abiotic/biotic stresses of major crops require new technologies of breeding by design(BBD)built on massive information from functional and population genomic...Future demands for increased productivity and resilience to abiotic/biotic stresses of major crops require new technologies of breeding by design(BBD)built on massive information from functional and population genomics research.A novel strategy of breeding by selective introgression(BBSI)has been proposed and practiced for simultaneous improvement,genetic dissection and allele mining of complex traits to realize BBD.BBSI has three phases:a)developing large numbers of trait-specific introgression lines(ILs)using backcross breeding in elite genetic backgrounds as the material platform of BBD;b)efficiently identifying genes or quantitative trait loci(QTL)and mining desirable alleles affecting different target traits from diverse donors as the information platform of BBD;and c)developing superior cultivars by BBD using designed QTL pyramiding or marker-assisted recurrent selection.Phase(a)has been implemented massively in rice by many Chinese research institutions and IRRI,resulting in the development of many new green super rice cultivars plus large numbers of ILs in 30+elite genetic backgrounds.Phase(b)has been demonstrated in a series of proof-of-concept studies of high-efficiency genetic dissection of rice yield and tolerance to abiotic stresses using ILs and DNA markers.Phase(c)has also been implemented by designed QTL pyramiding,resulting in a prototype of BBD in several successful cases.The BBSI strategy can be easily extended for simultaneous trait improvement,efficient gene and QTL discovery and allele mining of complex traits using advanced breeding lines from crosses between a common"backbone"parent and a set of elite parents in conventional pedigree breeding programs.BBSI can be relatively easily adopted by breeding programs with small budgets,but the BBSI-based BBD strategy can be fully and more efficiently implemented by large seed companies with sufficient capacity.展开更多
Bacterial leaf blight of rice (BLB), caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive diseases in Asian rice fields. A high-quality rice variety, LT2, was used as the recipient parent.IRBB21, wh...Bacterial leaf blight of rice (BLB), caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive diseases in Asian rice fields. A high-quality rice variety, LT2, was used as the recipient parent.IRBB21, which carries the Xa21 gene, was used as the donor parent. The resistance gene Xa21 was introduced into LT2 by marker-assisted backcrossing. Three Xoo races were used to inoculate the improved lines following the clipping method. Eleven BC_3F_3 lines carrying Xa21 were obtained based on molecular markers and agronomic performance. The 11 lines were then inoculated with the three Xoo races. All the 11 improved lines showed better resistance to BLB than the recipient parent LT2. Based on the level of resistance to BLB and their agronomic performance, five lines (BC_3F_3 5.1.5.1, BC_3F_3 5.1.5.12, BC_3F_3 8.5.6.44, BC_3F_3 9.5.4.1 and BC_3F_3 9.5.4.23) were selected as the most promising for commercial release. These improved lines could contribute to rice production in terms of food security.展开更多
The backcross(BC) breeding strategy has been increasingly used for developing high yielding varieties with improved abiotic stress tolerances in rice. In this study, 189Huang-Hua-Zhan(HHZ) introgression lines(ILs) dev...The backcross(BC) breeding strategy has been increasingly used for developing high yielding varieties with improved abiotic stress tolerances in rice. In this study, 189Huang-Hua-Zhan(HHZ) introgression lines(ILs) developed from three different selection schemes were evaluated for yield related traits under drought stress and non-stress conditions in the target and off-season winter nursery environments to assess the selection efficiency of BC breeding for improving different complex traits, and led us to five important results. The first result indicated that the primary target traits should be selected first in the target environments(TEs) in order to achieve the maximum genetic gain. Secondly, BC breeding for drought tolerance(DT) in rice was almost equally effective by strong phenotypic selection in the main target environments and in the winter-season of Hainan.Thirdly, exploiting genetic diversity in the subspecific gene pools is of great importance for future genetic improvement of complex traits in rice. Fourthly, considerable genetic gain can be effectively achieved by selection for secondary target traits among the ILs with the primary traits. Finally, the developed ILs provide useful materials for future genetic/genomic dissection and molecular breeding of complex traits.展开更多
This study focus on developing new salinity tolerance and high yielding rice lines, using markers assisted backrossing (MABC). Total of 500 SSR markers on 12 rice chromosomes were screened for parental polymorphic mar...This study focus on developing new salinity tolerance and high yielding rice lines, using markers assisted backrossing (MABC). Total of 500 SSR markers on 12 rice chromosomes were screened for parental polymorphic markers. Of which, 52 primers in the Saltol region were checked with the two parents varieties to identify polymorphic primers for screening the Saltol region of the breeding populations. For each backcross generation of ASS996/FL478, approx. 500 plants were screened with 63 polymorphic markers distributed on 12 chromosomes. The two BC1F1 plants P284 and P307 which had the highest recipient alleles up to 89.06% and 86.36%, were chosen for the next backcrossing. Three BC2F1 plants with the recipient alleles up to 94.03% and 93.18% were used to develop BC3F1 generation. The best BC3F1 plant was P284-112-209 with all the recipient alleles and Saltol region. The four plants P307-305-21, P284-112-195, P284-112-198, P284-112-213 were the second ranking with only one loci heterozygous (applied 63 markers covered on 12 chromosomes). These five plants were chosen as the breeding lines for result of Saltol-AS996 introgression. The breeding line BC4F1 having 100% genetic background of donor variety is ready for develop new salinity tolerant variety ASS996-Saltol to cope with climate change.展开更多
Deep rooting is an important trait in rice drought resistance.Genetic resources of deep-rooting varieties are valuable in breeding of water-saving and drought-resistant rice.In the present study,234BC2F7 backcross int...Deep rooting is an important trait in rice drought resistance.Genetic resources of deep-rooting varieties are valuable in breeding of water-saving and drought-resistant rice.In the present study,234BC2F7 backcross introgression lines were derived from a cross of Dongye 80(an accession of Dongxiang wild rice as the donor parent)and R974(an indica restorer line as the recurrent parent).A genetic linkage map containing 1977 bin markers was constructed by ddRADSeq for QTL analysis.Thirty-one QTLs for four root traits(the number of deep roots,the number of shallow roots,the total number of deep roots and the ratio of deep roots)were assessed on six rice chromosomes in two environments(2020 Shanghai and 2021 Hainan).Two of the QTLs,qDR5.1 and qTR5.2,were located on chromosome 5 in a 70-kb interval.They were detected in both environments.qDR5.1 explained 13.35%of the phenotypic variance in 2020 Shanghai and 12.01%of the phenotypic variance in 2021 Hainan.qTR5.2 accounted for 10.88%and 10.93%of the phenotypic variance,respectively.One QTL(qRDR2.2)for the ratio of deep roots was detected on chromosome 2 in a 210-kb interval and accounted for 6.72%of the phenotypic variance in 2020.The positive effects of these three QTLs were all from Dongxiang wild rice.Furthermore,nine and four putative candidate genes were identified in qRDR2.2 and qDR5.1/qTR5.2,respectively.These findings added to our knowledge of the genetic control of root traits in rice.In addition,this study will facilitate the future isolation of candidate genes of the deep-rooting trait and the utilization of Dongxiang wild rice in the improvement of rice drought resistance.展开更多
Understanding the genetic mechanism underlying folate biosynthesis and accumulation in rice would be beneficial for breeding high folate content varieties as a cost-effective approach to addressing widespread folate d...Understanding the genetic mechanism underlying folate biosynthesis and accumulation in rice would be beneficial for breeding high folate content varieties as a cost-effective approach to addressing widespread folate deficiency in developing countries. In this study, the inheritance of rice grain folate content was investigated in the Lemont/Teqing recombinant inbred lines and the Koshihikari/Kasalath//Koshihikari backcross inbred lines. 264 F12 recombinant inbred lines（RILs） and 182 BC1F10 backcross inbred lines（BILs） with their parents planted in randomized complete blocks with two replicates in 2010, and RILs harvested in 2008 were used for QTL detection using inclusive composite interval mapping（ICIM） method. In the RIL population, two QTLs, denoted by qQTF-3-1 and qQTF-3-2（QTF, quantitative total folate）, explaining 7.8% and 11.1-15.8% of the folate content variation were detected in one or two years, respectively. In the BIL population, a QTL, denoted by qQTF-3-3, was detected, explaining 25.3% of the variation in folate content. All the positive alleles for higher folate content were from the high-folate parents, i.e., Teqing and Kasalath. The known putative folate biosynthesis genes do not underlie the QTLs detected in this study and therefore may be novel loci affecting folate content in milled rice. QTLs identified in this study have potential value for marker assisted breeding for high-folate rice variety.展开更多
Background:Genetic improvement in fiber quality is one of the main challenges for cotton breeders.Quantitative trait loci(QTL)mapping provides a powerful approach to dissect the molecular mechanism in fiber quality tr...Background:Genetic improvement in fiber quality is one of the main challenges for cotton breeders.Quantitative trait loci(QTL)mapping provides a powerful approach to dissect the molecular mechanism in fiber quality traits.In present study,F14 recombinant inbred line(RIL)population was backcrossed to paternal parent for a paternal backcross(BC/P)population,deriving from one upland cotton hybrid.Three repetitive BC/P field trials and one maternal backcross(BC/M)field trial were performed including both two BC populations and the original RIL population.Results:In total,24 novel QTLs are detected for fiber quality traits and among which 13 QTLs validated previous results.Thirty-five QTLs in BC/P populations explain 5.01%–22.09%of phenotype variation(PV).Among the 35 QTLs,23 QTLs are detected in BC/P population alone.Present study provides novel alleles of male parent for fiber quality traits with positive genetic effects.Particularly,qFS-Chr3–1 explains 22.09%of PV in BC/P population,which increaseds 0.48 cN·tex−1 for fiber strength.A total of 7,2,8,2 and 6 QTLs explain over 10.00%of PV for fiber length,fiber uniformity,fiber strength,fiber elongation and fiber micronaire,respectively.In RIL population,six common QTLs are detected in more than one environment:qFL-Chr1–2,qFS-Chr5–1,qFS-Chr9–1,qFS-Chr21–1,qFM-Chr9–1 and qFM-Chr9–2.Two common QTLs of qFE-Chr2–2(TMB2386-SWU12343)and qFM-Chr9–1(NAU2873-CGR6771)explain 22.42%and 21.91%of PV.The region between NAU4034 and TMB1296 harbor 30 genes(379 kb)in A05 and 42 genes(49 kb)in D05 for fiber length along the QTL qFL-Chr5–1 in BC/P population,respectively.In addition,a total of 142 and 46 epistatic QTLs and QTL×environments(E-QTLs and QQEs)are identified in recombinant inbred lines in paternal backcross(RIL-P)and paternal backcross(BC/P)populations,respectively.Conclusions:The present studies provide informative basis for improving cotton fiber quality in different populations.展开更多
基金supported by the National Key R&D Program of China (2017YFD0100202)the Chongqing Science and Technology Commission Special Project, China (cstc2016shms-ztzx0017)the Southwestern University Basic Operating Expenses Special Innovation Team Project, China (XDJK2017A004)
文摘An elite backcrossed inbred line Z550 with increased grains per panicle was identified from advanced backcrosses between Nipponbare and Xihui 18 by simple sequence repeat(SSR) marker-assisted selection(MAS). Z550 carries 13 substitution segments distributed on chromosomes 1, 6, 7, 8, 9, 10, and 12, with an average substitution length of 1.68 Mb. Compared with the Nipponbare parental line, plant height, panicle length, spikelets per panicle, grains per panicle, and grain weight for Z550 were significantly increased. While the grain width of Z550 was significantly narrower, and the seed setting ratio(81.43%) was significantly lower than that of Nipponbare, it is still sufficient for breeding purposes. Quantitative trait loci(QTLs) mapping for important agronomic traits was conducted with the F_2 population derived from Nipponbare crossed with Z550 using the restricted maximum likelihood(REML) method. A total of 16, including 12 previously unreported QTLs were detected, with contribution rates ranging from 1.46 to 10.49%. Grains per panicle was controlled by 8 QTLs, 5 of which increased number of grains whereas 3 decreased it. qGPP-1, with the largest contribution(10.49%), was estimated to increase grains per panicle by 30.67, while q GPP-9, with the minimum contribution rate(2.47%), had an effect of increasing grains per panicle by 15.79. These results will be useful for further development of single segment substitution lines with major QTLs, and for research of their molecular functions via QTL cloning.
基金Supported by the Key Research and Development Program of Shandong(No.2022LZGC015)the National Key R&D Program of China(No.2022YFD2400304)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA24030105)the Key Technology Research and Industrialization Demonstration Projects of Qingdao(No.22-3-3-hygg-2-hy)the China Agriculture Research System of MOF and MARA(No.CARS-49)。
文摘Oysters are of the most economically important bivalves worldwide.It has high nutritional value and is regarded as a good source of proteins,lipids,glycogen,and amino acids.C.gigas and C.angulata are allopatric congeneric dominant oysters that are widely cultivated in the northern and southern coast of China,and have shown remarkable differentiation in the nutritional content.Interspecific hybridization and backcross of the two species are effective ways to improve the nutritional quality of the oyster.Sixteen progenies were constructed based on a 4×4 diallel crosses among broodstock of C.gigas(G),C.angulata(A)and their hybrids GA(H)and AG(R).The glycogen,fatty acids,and amino acids performance of these progenies were evaluated in 22 months after fertilization.The glycogen content of AA was significantly lower than that of the other 15 progenies(P<0.05),while only the GH progeny was significantly higher than the GG(P<0.05),with a heterosis value of 21.06%.The backcross progenies GR exhibited significantly higher saturated fatty acids,eicosapentaenoic acid(EPA),and polyunsaturated fatty acids(PUFAs)content than those of GG(P<0.05),and did not show significant differences from AA.The AA showed significantly higher content of total amino acids(TAAs)than GG(P<0.05).The AH progeny displayed significantly higher taurine(Tau)content than GG(P<0.05),and the heterosis value was 27.88%.Therefore,the backcross breeding was shown an effective way to improve the glycogen,fatty acids,and TAAs of GG,and the glycogen of AA.This study provided useful information to characterize the benefits of backcrossing in nutritional quality,which will facilitate the production of differentiated products and increase the efficiency of the oyster industry.
基金funded by Bangladesh Academy of Sciences(BAS),and Fund ID:BAS-USDA SAU CR02.
文摘Indian mustard is recognized as a resilient and economically important oilseed crop.However,its potential remains untapped due to the limited availability of short-duration,high-yielding varieties capable of out-competing other rabi crops.Considering this notion,we have evaluated twenty-one F_(2) and six BC1F1 populations derived from seven diversified parents of Brassica juncea following a Randomized Complete Block Design at Sher-e-Bangla Agricultural University.Based on key agronomic traits,the genetic components,heterosis,inbreeding depression,and gene action were studied to select early maturing and high-yielding populations.The percentage of heterosis was manifested in various cross-combinations,including P4×P6(91.45%for yield per plant)and P5×P6(28.52%for thousand seed weight),emerging as promising candidates for increasing productivity while managing negative inbreeding effects.Conversely,significant inbreeding depression was noted in traits like days to siliquae maturity and yield,particularly in crosses,P1×P2(6.29%)and P3×P5(21.74%),underscoring the need for careful selection in breeding programs to mitigate these effects.Variance analysis indicated that both additive and non-additive genetic interactions play a pivotal role in the inheritance patterns of the traits of interest.Among the six backcrosses,one promising line was(P5×P6)×P5,demonstrating early maturity(107.00 DAS)with improved seed yield(12.47 g).This combination exhibited the potential for enhancing the adaptability and productivity by maintaining the maturity index and accelerating yield.Furthermore,significant phenotypic variation across yield-contributing traits was notable,whereas thousand seed weight and yield per plant showed high broad-sense and narrow-sense of heritability.Besides,positive correlations between seed yield and its attributing traits were noted,suggesting potential avenues for selection breeding.Collectively,the ob-tained findings enhance the understanding of genetic mechanisms underlying heterosis and inbreeding depres-sion in B.juncea,providing insights and effective strategies for developing superior cultivars with optimized agronomic traits.
基金This work was supported by the grant from the National High Technology Research and Development Program of China (No. 2004AA212130).
文摘To improve agronomic traits of partial waxy wheat, crossing between Chinese Baihuomai and wheat cultivars PH85-16, Jinan 17, and Yannong 15 was performed. The progeny plants were further backcrossed to these cultivars as recurrent parents for five generations. To get homozygous plants with the null allele at the Wx-D1 locus, self-pollination was carried out in the BC5F1 generation. Through another three generations, 6 partial waxy wheat lines were obtained, which had similar agronomic performance as their recurrent parents and carried the null allele at the Wx-D1 locus. In each generation, the Wx-D1 locus was identified by a PCR-based DNA marker and the agronomic traits were examined in progeny plants. The results from this study indicate that the use of backcrossing with a PCR-based DNA marker was useful in waxy wheat breeding. These partial waxy wheat lines can be used in field production.
基金Supported by Sci-tech Program for Excellent Young Scientists of Sichuan Province(01ZQ052)~~
文摘[Objective] This study was to investigate the restoring ability of normal indica red rice Ruby and to carry out its restoring gene mapping. [Method] Normal indica red rice Ruby was hybridized with the sterile lines Zhenxian 97A, D62A, G46A and D702A to prepare their F1, BC1 and F2 progenies, and the pollen fertilities of these progenies were investigated. Meanwhile the restoring genes were mapped using SSLP. [ Result] For the sterile lines tested, Ruby has a gene to restore their fertilities. This gene is located on the chromosome 7 and shows a genetic distance of 7.4 cM with RM182. Unlike the clustering distribution of the restoring genes on chromosome 10, it is a specific restoring gene. [ Conclusion] it is feasible to breed restoring genes controlling red color characters via transgene and backcross.
基金supported by the National Natural Science Foundation of China(Grant No.30671230)the Natural Science Foundation of Jiangxi Province,China(Grant No.2007GZN0253)
文摘The present study aimed at breeding new rice germplasms with similar genome but significantly differed in heat tolerance during the grain filling stage.A total of 791 BC1F8 backcross recombinant lines,derived from the cross of Xieqingzao B /N22 //Xieqingzao B,were used as materials.Each rice line was separated evenly into two groups,and the heat tolerance of all rice lines were evaluated at natural high temperature in fields.The rice lines with heat tolerant index higher than 90% or lower than 40% were selected to compare the phenotypic characters and further identify heat tolerance at the early milky stage in a phytotron.Rice lines with similar phenotypic characters but significantly differed in heat tolerance at the milky stage were analyzed by 887 simple sequence repeat markers that were evenly distributed on the 12 rice chromosomes.In the result,12(6 pairs) rice lines with similar phenotypic characters but significantly differed in heat tolerance at the milky stage were obtained.Molecular marker analysis indicated that the genomic polymorphism between 703T and 704S was the smallest in the 6 pairs of rice lines,with only 16 polymorphic sites,including 22 different alleles.The application of these two backcross introgression rice lines for future study on the mechanisms of heat tolerance in rice at the milky stage will be theoretically beneficial in reducing the interference caused by genetic differences from experimental materials.
基金funded by the Key-Area Research and Development Program of Guangdong Province,China(Grant No.2020B020219004)the Hainan Yazhou Bay Seed Lab(Grant No.B21HJ0216)the Agricultural Science and Technology Innovation Program and the Cooperation and Innovation Mission,China(Grant No.CAAS-ZDXT202001)。
文摘Salinity-alkalinity is incipient abiotic stress that impairs plant growth and development.Rice(Oryza sativa)is a major food crop greatly affected by soil salinity and alkalinity,requiring tolerant varieties in the saline-alkali prone areas.Understanding the molecular and physiological mechanisms of saline-alkali tolerance paves the base for improving saline-alkali tolerance in rice and leads to progress in breeding.This review illustrated the physiological consequences,and molecular mechanisms especially signaling and function of regulating genes for saline-alkali tolerance in rice plants.We also discussed QTLs regarding saline-alkali tolerance accordingly and ways of deployment for improvement.More efforts are needed to identify and utilize the identified QTLs for saline-alkali tolerance in rice.
基金funded by the Project of the 863 Program(2010AA101803)the 948 Program of China(2006-G51 and 2010-G2B)
文摘A set of 240 introgression lines derived from the advanced backcross population of a cross between a japonica cultivar,Xiushui 09,and an indica breeding line,IR2061,was developed to dissect QTLs affecting cold tolerance （CT） at seedling stage and heat tolerance （HT） at anthesis.Survival rate of seedlings （SRS） and spikelet fertility （SF）,the index traits of CT and HT,showed significant differences between the two parents under stresses.A total of four QTLs （qSRS1,qSRS7,qSRS11a and qSRS11b） for CT were identified on chromosomes 1,7,11,and the Xiushui 09 alleles increased SRS at all loci except qSRS7.Four QTLs for SF were identified on chromosomes 4,5,6,and 11.These QTLs could be classified into two major types based on their behaviors under normal and stress conditions.The first was QTL expressed only under normal condition;and the second QTL was apparently stress induced and only expressed under stress.Among them,two QTLs （qSF4 and qSF6） which reduced the trait difference between heat stress and normal conditions must have contributed to HT because of their obvious contribution to trait stability,and the IR2061 allele at the qSF6 and the Xiushui 09 allele at the qSF4 improved HT,respectively.No similar QTL was found between CT at seedling stage and HT at anthesis.Therefore,it is possible to breed a new variety with CT and HT by pyramiding the favorable CT-and HT-improved alleles at above loci from Xiushui 09 and IR2061,respectively,through marker-assisted selection （MAS）.
基金supported by the National Natural Science Foundation of China(Grant Nos.31221004 and 31271700)National Basic Research Program of China(Grant No.2013CBA01405)the Chinese 863 Program(Grant No.2012AA10A302)
文摘Further improvement of rice productivity remains a challenge. Breeding is perceived as an important option to increase rice yield. However, the genetic progress of grain yield in most rice breeding programs was slow in the last decades. Although great progress in rice genomics and molecular biology has been achieved, the effect of such technological innovations on rice breeding is far small. Marker-assisted selection （MAS） for a few target quantitative trait loci （QTLs） has significant effects in improving qualitative traits, such as disease resistance. The success of MAS has therefore motivated breeders to identify and use major QTLs for yield and yield component traits. In this review, we summarized the recent methods in QTL identification, including novel statistical methods for linkage and association mapping, special population types, and whole-genome sequencing. We reviewed the successful application of marker-assisted gene introgression and gene pyramiding to improve grain yield and discussed the design of efficient MAS schemes to further increase the success rate of breeding programs. The use of well-characterized major QTLs through introgression and gene pyramiding is proven effective in improving grain yield, particularly yield under abiotic stress. Major QTLs that are stable across genetic background and growing environments are often found in less adapted germplasms, such as landraces and wild relatives. Advanced backcross QTL analysis and introgression lines, which integrate QTL discovery and utilization, are important methods for exploiting major QTLs contained in such germplasms. Next-generation sequencing substantially increases mapping resolution and accelerates the identification of casual genes underlying major QTLs. Practical guidelines derived from theoretical and empirical studies are given to guide the design of efficient marker-assisted gene introgression and pyramiding schemes.
文摘Pyricularia oryzae anamorph of Magnaporthe oryzae is one of the most notorious fungal pathogens causing severe economic loss in rice production worldwide. Various methods, viz. cultural, biological and molecular approaches, are utilized to counteract this pathogen. Moreover, some tolerant or resistant rice varieties have been developed with the help of breeding programmes. Isolation and molecular characterization of different blast resistance genes now open the gate for new possibilities to elucidate the actual allelic variants of these genes via various molecular breeding and transgenic approaches. However, the behavioral pattern of this fungus breakups the resistance barriers in the resistant or tolerant rice varieties. This host-pathogen barrier will be possibly countered in future research by comparative genomics data from available genome sequence data of rice and M. oryzae for durable resistance. Present review emphasized fascinating recent updates, new molecular breeding approaches, transgenic and genomics approaches(i.e. mi RNA and genome editing) for the management of blast disease in rice. The updated information will be helpful for the durable, resistance breeding programme in rice against blast pathogen.
基金supported by grants from the Project of Conservation and Utilization of Agro-Wild Plants of the Ministry of Agriculture of Chinathe National High-Tech Research and Development ("863") Program of China (No. 2006AA100101)the "111" Project (No. B06003)
文摘Using an accession of common wild rice （Oryza rufipogon Griff.） collected from Yuanjiang County, Yunnan Province, China, as the donor and an elite cultivar 93-11, widely used in two-line indica hybrid rice production in China, as the recurrent parent, an advanced backcross populations were developed. Through genotyping of 187 SSR markers and investigation of six yield-related traits of two gen- erations （BC4F2 and BC4F4）, a total of 26 QTLs were detected by employing single point analysis and interval mapping in both genera-tions. Of the 26 QTLs, the alleles of 10 （38.5%） QTLs originating from O. rufipogon had shown a beneficial effect for yield-related traits in the 93-11 genetic background. In addition, five QTLs controlling yield and its components were newly identified, indicating that there are potentially novel alleles in Yuanjiang common wild rice. Three regions underling significant QTLs for several yield-related traits were detected on chromosome 1, 7 and 12. The QTL clusters were founded and corresponding agronomic traits of those QTLs showed highly significant correlation, suggesting the pleiotropism or tight linkage. Fine-mapping and cloning of these yield-related QTLs from wild rice would be helpful to elucidating molecular mechanism of rice domestication and rice breeding in the future.
基金supported by the National Natural Science Foundation of China(39770461)Science and Technology Department of Heilongjiang Province.
文摘HMW-GS 5 + 10 was introduced to four major wheat cultivars Kehan9, Kefeng3, Longmai20 and Kenda4 through 5 or 6 consecutive backcrosses. No significant difference in protein content and dry gluten content was observed between cultivars containing 5 + 10 and 2 + 12 or 3 + 12 (P>0.1). In cultivars containing HMW-GS 5 + 10, the ratio of wet gluten content to dry gluten content was 2. 9 - 5.0% (P<0. 01) lower than the ratio from the cultivars containing 2 + 12 or 3 + 12, the ratio of Zeleny sedimentation volume to dry gluten content was 4. 5 - 13. 4% (P<0.05) higher. The degree of softening in cultivars having 5 + 10 was 15 -25 FU (P<0. 01) lower, while the maximum resistance was 82 - 193 EU (P<0. 05) higher. Backcrosses with biochemical marker assisted selection in the improvement of quality in wheat cultivars was discussed.
文摘[ Objective] This study was to explore the inheritance of BC1 F3 to excellent characteristics of parents（ Elymus dahuricus, Hordeum brevisubu/atum）, heterosis and fertility restoration. E Methodl The agronomic characters such as growth period, growth rate, pollen fertility, fecundity, reproducibility and fresh grass output of Elymus dahudcus, Hordeum brevisubu/atum and BC1 F3 were comparatively studied. E Result l The growth dynamic of the BC1 F3 lined tended to like that of its parent Hordeum brevisubu/atum; although growing periods of various lines were different, they were close to that of Hordeurn brevisubulatum. There were differences in pollen fertility and seed setting, the pollen fertility rate of YF3-93 was higher than recurrent parent Hordeum brevisubulatum, its seed setting rate in open pollination was also higher. Some lines had low pollen fertility rate and seed setting rate, such as the pollen fertility rate of PF3-52. There were significant differences in the output among BC1 F3 lines, e.g. the heterosis （HP） of YF3-64, YF3-74 and YF3-83 were 75.53%, 75.12% and 66.16%, respectively; however, the yields of PF3- 52, PF3-15 and PF3-42 were lower than their parents. ~ Conclusion] This study provided reference for breeding new varieties of forage which is suitable to drought and saline environment.
基金funded by the National Key Research&Development Program of China(2017YFD0100100)Key-Area Research&Development Program of Guangdong Province(2020B020219004)+2 种基金Shenzhen Basic Research Special Project(2020231601)Agricultural Science and Technology Innovation Programthe Cooperation and Innovation Mission(CAAS2021-01)。
文摘Future demands for increased productivity and resilience to abiotic/biotic stresses of major crops require new technologies of breeding by design(BBD)built on massive information from functional and population genomics research.A novel strategy of breeding by selective introgression(BBSI)has been proposed and practiced for simultaneous improvement,genetic dissection and allele mining of complex traits to realize BBD.BBSI has three phases:a)developing large numbers of trait-specific introgression lines(ILs)using backcross breeding in elite genetic backgrounds as the material platform of BBD;b)efficiently identifying genes or quantitative trait loci(QTL)and mining desirable alleles affecting different target traits from diverse donors as the information platform of BBD;and c)developing superior cultivars by BBD using designed QTL pyramiding or marker-assisted recurrent selection.Phase(a)has been implemented massively in rice by many Chinese research institutions and IRRI,resulting in the development of many new green super rice cultivars plus large numbers of ILs in 30+elite genetic backgrounds.Phase(b)has been demonstrated in a series of proof-of-concept studies of high-efficiency genetic dissection of rice yield and tolerance to abiotic stresses using ILs and DNA markers.Phase(c)has also been implemented by designed QTL pyramiding,resulting in a prototype of BBD in several successful cases.The BBSI strategy can be easily extended for simultaneous trait improvement,efficient gene and QTL discovery and allele mining of complex traits using advanced breeding lines from crosses between a common"backbone"parent and a set of elite parents in conventional pedigree breeding programs.BBSI can be relatively easily adopted by breeding programs with small budgets,but the BBSI-based BBD strategy can be fully and more efficiently implemented by large seed companies with sufficient capacity.
文摘Bacterial leaf blight of rice (BLB), caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive diseases in Asian rice fields. A high-quality rice variety, LT2, was used as the recipient parent.IRBB21, which carries the Xa21 gene, was used as the donor parent. The resistance gene Xa21 was introduced into LT2 by marker-assisted backcrossing. Three Xoo races were used to inoculate the improved lines following the clipping method. Eleven BC_3F_3 lines carrying Xa21 were obtained based on molecular markers and agronomic performance. The 11 lines were then inoculated with the three Xoo races. All the 11 improved lines showed better resistance to BLB than the recipient parent LT2. Based on the level of resistance to BLB and their agronomic performance, five lines (BC_3F_3 5.1.5.1, BC_3F_3 5.1.5.12, BC_3F_3 8.5.6.44, BC_3F_3 9.5.4.1 and BC_3F_3 9.5.4.23) were selected as the most promising for commercial release. These improved lines could contribute to rice production in terms of food security.
基金funded by the National High Technology Research and Development Program of China (2012AA101101) from the Ministry of Science and Technology of Chinathe National Science Foundation Project (30570996)+1 种基金the Program of Introducing International Super Agricultural Science and Technology (#2011-G2B) from the Ministry of Agriculture of Chinathe Bill & Melinda Gates Foundation Project (OPP51587)
文摘The backcross(BC) breeding strategy has been increasingly used for developing high yielding varieties with improved abiotic stress tolerances in rice. In this study, 189Huang-Hua-Zhan(HHZ) introgression lines(ILs) developed from three different selection schemes were evaluated for yield related traits under drought stress and non-stress conditions in the target and off-season winter nursery environments to assess the selection efficiency of BC breeding for improving different complex traits, and led us to five important results. The first result indicated that the primary target traits should be selected first in the target environments(TEs) in order to achieve the maximum genetic gain. Secondly, BC breeding for drought tolerance(DT) in rice was almost equally effective by strong phenotypic selection in the main target environments and in the winter-season of Hainan.Thirdly, exploiting genetic diversity in the subspecific gene pools is of great importance for future genetic improvement of complex traits in rice. Fourthly, considerable genetic gain can be effectively achieved by selection for secondary target traits among the ILs with the primary traits. Finally, the developed ILs provide useful materials for future genetic/genomic dissection and molecular breeding of complex traits.
文摘This study focus on developing new salinity tolerance and high yielding rice lines, using markers assisted backrossing (MABC). Total of 500 SSR markers on 12 rice chromosomes were screened for parental polymorphic markers. Of which, 52 primers in the Saltol region were checked with the two parents varieties to identify polymorphic primers for screening the Saltol region of the breeding populations. For each backcross generation of ASS996/FL478, approx. 500 plants were screened with 63 polymorphic markers distributed on 12 chromosomes. The two BC1F1 plants P284 and P307 which had the highest recipient alleles up to 89.06% and 86.36%, were chosen for the next backcrossing. Three BC2F1 plants with the recipient alleles up to 94.03% and 93.18% were used to develop BC3F1 generation. The best BC3F1 plant was P284-112-209 with all the recipient alleles and Saltol region. The four plants P307-305-21, P284-112-195, P284-112-198, P284-112-213 were the second ranking with only one loci heterozygous (applied 63 markers covered on 12 chromosomes). These five plants were chosen as the breeding lines for result of Saltol-AS996 introgression. The breeding line BC4F1 having 100% genetic background of donor variety is ready for develop new salinity tolerant variety ASS996-Saltol to cope with climate change.
基金supported by the National Modern Agricultural Industry Technology System Construction Program of China(Grant No.20212BBF63001)the Open Competition Program of Jiangxi Provincial Science and Technology in China(Grant No.20213AAF01001)+2 种基金the Jiangxi Provincial Science and Technology Support Program in China(Grant No.20203BBF63033)the Jiangxi Modern Agricultural Research Collaborative Innovation Project in China(Grant No.JXXTCX202111)the Open Project of State Key Laboratory of Rice Biology in China(Grant No.20200101)。
文摘Deep rooting is an important trait in rice drought resistance.Genetic resources of deep-rooting varieties are valuable in breeding of water-saving and drought-resistant rice.In the present study,234BC2F7 backcross introgression lines were derived from a cross of Dongye 80(an accession of Dongxiang wild rice as the donor parent)and R974(an indica restorer line as the recurrent parent).A genetic linkage map containing 1977 bin markers was constructed by ddRADSeq for QTL analysis.Thirty-one QTLs for four root traits(the number of deep roots,the number of shallow roots,the total number of deep roots and the ratio of deep roots)were assessed on six rice chromosomes in two environments(2020 Shanghai and 2021 Hainan).Two of the QTLs,qDR5.1 and qTR5.2,were located on chromosome 5 in a 70-kb interval.They were detected in both environments.qDR5.1 explained 13.35%of the phenotypic variance in 2020 Shanghai and 12.01%of the phenotypic variance in 2021 Hainan.qTR5.2 accounted for 10.88%and 10.93%of the phenotypic variance,respectively.One QTL(qRDR2.2)for the ratio of deep roots was detected on chromosome 2 in a 210-kb interval and accounted for 6.72%of the phenotypic variance in 2020.The positive effects of these three QTLs were all from Dongxiang wild rice.Furthermore,nine and four putative candidate genes were identified in qRDR2.2 and qDR5.1/qTR5.2,respectively.These findings added to our knowledge of the genetic control of root traits in rice.In addition,this study will facilitate the future isolation of candidate genes of the deep-rooting trait and the utilization of Dongxiang wild rice in the improvement of rice drought resistance.
基金supported by grants from the National Basic Research Program of China(2007CB10880-1,2013CB127000)
文摘Understanding the genetic mechanism underlying folate biosynthesis and accumulation in rice would be beneficial for breeding high folate content varieties as a cost-effective approach to addressing widespread folate deficiency in developing countries. In this study, the inheritance of rice grain folate content was investigated in the Lemont/Teqing recombinant inbred lines and the Koshihikari/Kasalath//Koshihikari backcross inbred lines. 264 F12 recombinant inbred lines（RILs） and 182 BC1F10 backcross inbred lines（BILs） with their parents planted in randomized complete blocks with two replicates in 2010, and RILs harvested in 2008 were used for QTL detection using inclusive composite interval mapping（ICIM） method. In the RIL population, two QTLs, denoted by qQTF-3-1 and qQTF-3-2（QTF, quantitative total folate）, explaining 7.8% and 11.1-15.8% of the folate content variation were detected in one or two years, respectively. In the BIL population, a QTL, denoted by qQTF-3-3, was detected, explaining 25.3% of the variation in folate content. All the positive alleles for higher folate content were from the high-folate parents, i.e., Teqing and Kasalath. The known putative folate biosynthesis genes do not underlie the QTLs detected in this study and therefore may be novel loci affecting folate content in milled rice. QTLs identified in this study have potential value for marker assisted breeding for high-folate rice variety.
基金the National Key R&D Program for Crop Breeding(2016YFD0101407)to Hua JP.
文摘Background:Genetic improvement in fiber quality is one of the main challenges for cotton breeders.Quantitative trait loci(QTL)mapping provides a powerful approach to dissect the molecular mechanism in fiber quality traits.In present study,F14 recombinant inbred line(RIL)population was backcrossed to paternal parent for a paternal backcross(BC/P)population,deriving from one upland cotton hybrid.Three repetitive BC/P field trials and one maternal backcross(BC/M)field trial were performed including both two BC populations and the original RIL population.Results:In total,24 novel QTLs are detected for fiber quality traits and among which 13 QTLs validated previous results.Thirty-five QTLs in BC/P populations explain 5.01%–22.09%of phenotype variation(PV).Among the 35 QTLs,23 QTLs are detected in BC/P population alone.Present study provides novel alleles of male parent for fiber quality traits with positive genetic effects.Particularly,qFS-Chr3–1 explains 22.09%of PV in BC/P population,which increaseds 0.48 cN·tex−1 for fiber strength.A total of 7,2,8,2 and 6 QTLs explain over 10.00%of PV for fiber length,fiber uniformity,fiber strength,fiber elongation and fiber micronaire,respectively.In RIL population,six common QTLs are detected in more than one environment:qFL-Chr1–2,qFS-Chr5–1,qFS-Chr9–1,qFS-Chr21–1,qFM-Chr9–1 and qFM-Chr9–2.Two common QTLs of qFE-Chr2–2(TMB2386-SWU12343)and qFM-Chr9–1(NAU2873-CGR6771)explain 22.42%and 21.91%of PV.The region between NAU4034 and TMB1296 harbor 30 genes(379 kb)in A05 and 42 genes(49 kb)in D05 for fiber length along the QTL qFL-Chr5–1 in BC/P population,respectively.In addition,a total of 142 and 46 epistatic QTLs and QTL×environments(E-QTLs and QQEs)are identified in recombinant inbred lines in paternal backcross(RIL-P)and paternal backcross(BC/P)populations,respectively.Conclusions:The present studies provide informative basis for improving cotton fiber quality in different populations.
