Genetic diversity at Gli_1, Gli_2 and Glu_1 loci was investigated in 89 Sichuan wheat (Triticum aestivum L.) landraces by using acid polyacrylamide gel electrophoresis (APAGE) and SDS_PAGE. In these landraces, a total...Genetic diversity at Gli_1, Gli_2 and Glu_1 loci was investigated in 89 Sichuan wheat (Triticum aestivum L.) landraces by using acid polyacrylamide gel electrophoresis (APAGE) and SDS_PAGE. In these landraces, a total of 32 gliadin and 3 high_molecular_weight (HMW) glutenin patterns were observed. In total, 14, 15 and 5 alleles were identified at Gli_1, Gli_2 and Glu_1, respectively. At each locus, the alleles in higher frequency were Gli_A1a (89%), Gli_B1h (46%), Gli_D1a (65%), Gli_A2a (64%), Gli_B2j (45%), Gli_D2a (48%), Glu_A1c (99%), Glu_B1b (99%) and Glu_D1a (100%). The Nei's genetic variation index (H) of Sichuan wheat landraces was 0.370?6, varying from 0 to 0.708?7. The highest genetic diversity was found at Gli_B2 locus, while the lowest was found at Glu_D1. The genetic diversity at Gli loci was higher than that of Glu_1 loci among these landraces, but it was much lower than that of modern wheat cultivars. These results indicated a narrow genetic base of Sichuan wheat landraces. In this study, “Chengdu_guangtou” had the identical gliadin and HMW_glutenin patterns with “Chinese Spring”, further supporting the proposal that “Chinese Spring” is a strain of “Chengdu_guangtou”.展开更多
Genetic diversity of 54 maize landraces from southwest China was tested using bulk DNA samples and 42 microsatellite （SSR） loci distributed on 10 chromosomes of maize. A total of 256 alleles were detected among the ...Genetic diversity of 54 maize landraces from southwest China was tested using bulk DNA samples and 42 microsatellite （SSR） loci distributed on 10 chromosomes of maize. A total of 256 alleles were detected among the landraces. At each locus, the number of alleles varied from 2 to 9, with an average of 6.1. On the basis of the genetic similarity coefficients, clustering analysis separated the landraces into four groups. The landraces collected from the same region were mostly grouped together. To reveal the genetic structure and genetic diversity within landraces, 165 individuals from 11 landraces were analyzed. Individual DNA samples proved to be superior to bulk DNA samples in identifying genetic diversity of landraces. A total of 330 alleles were detected in the 11 landraces. According to the results of the individual DNA sampling analysis, estimates of the mean number of alleles ‘A’, the effective allelic number ‘Ae’, the observed heterozygosity ‘Ho’, and expected heterozygosity ‘He’ were 7.86, 3.90, 0.69, and 0.37, respectively. An obvious genetic deviation from Hardy-Weinberg expectation was observed both among and within landraces and a considerable genetic variation was revealed within rather than among landraces. In addition, genetic diversity of landraces was greater in Sichuan than in the other three regions. It can be concluded that maize landraces in southwest China were initially introduced to Sichuan and from there to adjacent areas.展开更多
[Objective] The aim of this study was to screen rice strip virus （RSV）-resistant landraces. [Method] The resistance of 119 rice landraces to rice stripe virus was identified in field spontaneously infected with sma...[Objective] The aim of this study was to screen rice strip virus （RSV）-resistant landraces. [Method] The resistance of 119 rice landraces to rice stripe virus was identified in field spontaneously infected with smal plant-hopper. [Result] There were 55 landraces resistant to rice strip disease in 56 indica rice landraces, but on-ly two resistant to rice strip disease in 63 japonica rice landraces. [Conclusion] The results revealed that there were abundant rice landscapes resistant to RSV in Chi-na, and these varieties can be used to develop more genes resistant to RSV.展开更多
The nucleotide sequences in exon 7 of a disintegrin and metalloproteinase with thrombospondin motifs-1(ADAMTS-1)gene in Landrace pig were obtained with cloning and sequencing by using PCR-RFLP technique in this experi...The nucleotide sequences in exon 7 of a disintegrin and metalloproteinase with thrombospondin motifs-1(ADAMTS-1)gene in Landrace pig were obtained with cloning and sequencing by using PCR-RFLP technique in this experiment.Sequence alignment results showed that the C/G substitution in exon 7 induced amino acid change(Arg → Pro).AA,BB and AB genotypes were found in Landrace pig by PvuⅡ-RFLP.Correlation analysis between genotypes and reproductive traits indicated that ADAMTS-1 was significantly correlated with litter size(LS)and number born alive(NBA).展开更多
Waxy maize landraces are abundant inYunnan and Guizhou of China. Genetic diversity of waxy maize landraces from Yunnan and Guizhou were analyzed using SSR markers. We screened 38 landraces with 50 primers that generat...Waxy maize landraces are abundant inYunnan and Guizhou of China. Genetic diversity of waxy maize landraces from Yunnan and Guizhou were analyzed using SSR markers. We screened 38 landraces with 50 primers that generated 3 to 6 polymorphic bands, with an average of 4.13 bands. Shannon＇s information indices for genetic diversity of the 14 waxy maize landraces from Yunnan varied from 4.9571 to 42.1138 and averaged 26.5252; Shannon＇s information indices for genetic diversity of the 24 waxy maize landraces from Guizhou varied from 22.0066 to 40.6320 and averaged 32.3156. For the 14 waxy maize landraces from Yunnan, the within-landrace genetic diversity accounted for 45.40% and the among-landrace genetic diversity accounted for 54.60% of the total genetic diversity observed. For the 24 waxy maize landraces from Guizhou, the within-landrace genetic diversity accounted for 50.76% and the among-landrace genetic diversity accounted for 49.24% of the total observed. Some individual landraces possessed as much as 96.86% of the total genetic diversity occurring among landraces within origins. Differentiation between geographic origins accounted for only 3.14% of the total genetic diversity. Both Yunnan and Guizhou would be the diversity centers and the original centers of waxy maize.展开更多
All rice plant developmental stages are severely affected by soil salinity. Salinity-induced ionic and osmotic stresses affect stomata closure and gaseous exchange, and reduce transpiration and the rate of carbon assi...All rice plant developmental stages are severely affected by soil salinity. Salinity-induced ionic and osmotic stresses affect stomata closure and gaseous exchange, and reduce transpiration and the rate of carbon assimilation, and hence decrease plant yield. Understanding the response of rice plants toward salinity stress at the genetic level and developing salt-tolerant varieties are the vital mandates for its effective management. This review described the present status of salt-tolerance achieved in rice by various mechanisms including the ion homeostasis(Na^+/H^+, OsNHX antiporters), compatible organic solutes(glycine betaine and proline), antioxidative genes(OsECS, OsVTE1, OsAPX and OsMSRA4.1), salt responsive regulatory elements(transcription factors, cis-acting elements and miRNAs) and genes ecoding protein kinases(MAPKs, SAPKs and STRKs). Further, the future perspective of developing salt-tolerant varieties lies in exploring halotolerant gene homologs from rice varieties, especially the landraces. Genetic diversity among rice landraces can serve as a valuable resource for future studies toward variety improvement through breeding and genome editing. Further, identification, multiplication, preservation and utilization of biodiversity among landraces are the urgent buffers to be saved as a heritage for future generations to come.展开更多
A field trial was conducted to investigate main morphological and physiological changes of different maize landraces to low-P stress at the stage of seedling. P-deficiency significantly decreased root volume, total le...A field trial was conducted to investigate main morphological and physiological changes of different maize landraces to low-P stress at the stage of seedling. P-deficiency significantly decreased root volume, total leaf area, and plant dry weight, but greatly increased density of root hairs and root top ratio. In addition, P-deficiency induced the significant enhancement of phosphorus utilization efficiency and the amount of proline, malondialdehye （MDA）, acid phosphatase （APase）, peroxidase （POD） and superoxide dismutase （SOD）, but the significant reduction of P uptake and soluable protein content. Since P-deficiency had smaller effects on the P-tolerant maize landraces DP-44, DP-32 and DP-33 as compared with P-sensitive landraces DP-29 and DP-24, it was demonstrated that differences of tolerance to P-deficiency existed among different maize landraces. The results based on the correlation analysis showed that the economic yield of maize landraces had relationships with their morphological and physiological characteristics under P-deficiency.展开更多
Based on the genetic clustering from 42 microsatellite （SSR） markers with a combination of their geographic origin and germplasm characteristics, 124 maize landraces from Wuling Mountain region in China were used fo...Based on the genetic clustering from 42 microsatellite （SSR） markers with a combination of their geographic origin and germplasm characteristics, 124 maize landraces from Wuling Mountain region in China were used for constructing a core collection. Four evaluating parameters for maize landrace core collection, including mean difference percentage （MD）, variance difference percentage （VD）, coincidence rate of range （CR）, and variable rate of coefficient of variation （VR）, were assessed With 20 quantitative traits. It was shown that genetic relationships among landraces in Wuling Mountain region had the tendency to associate with their geographic origins. The 124 landraces were clustered into 18 subgroups when the coefficient of genetic similarity （GS） is 0.28. Eighteen landraces, each of which was from one subgroup, were applied to construct the core collection with a sampling percentage of 15%. Comparison of the initial and core collection indicated that there existed no significant differences in most quantitative traits. An average of 6.3 and 6.5 alleles were detected in the initial and core collection, respectively. Mean polymorphism information content in the core collection （0.75） was higher than that in the initial one （0.72）. MD was lesser than 20% and CR was more than 80%. The results showed that the sampling strategy would be feasible for constructing the core collection that well represents the genetic diversity of the initial one.展开更多
Maize landraces White Dent and Golden Queen played a very important role in the pre-hybrid era of maize production in China. However, dozens of accessions with the same names of White Dent and Golden Queen are preserv...Maize landraces White Dent and Golden Queen played a very important role in the pre-hybrid era of maize production in China. However, dozens of accessions with the same names of White Dent and Golden Queen are preserved in China National Genebank （CNG）. The present study investigated the genetic diversity of these two important groups of maize landraces, as well as the relationships within and among them. Thirty-four landrace accessions with the name of White Dent and 10 with Golden Queen preserved in CNG were fingerprinted with 52 simple sequence repeats with tailed primer M13. Summary statistics including average number of alleles per locus, gene diversity/expected heterozygosity, and observed heterozygosity were carried out using PowerMarker ver. 3.25 software. The test of Hardy-Weinberg equilibrium （HWE） and linkage disequilibrium （LD） of all the 44 maize landrace accessions were also performed by PowerMarker. We observed a significant differentiation in terms of the average number of alleles between White Dent and Golden Queen （6.44 alleles per locus in White Dent, 4.48 in Golden Queen）, while both groups of maize landraces had a relatively high but similar gene diversity （0.61 of White Dent, 0.63 of Golden Queen）. The fixation index （FST） was only 0.0044, while the percentage of loci deviated from Hardy-Weinberg equilibrium within these two groups of White Dent and Golden Queen was 32.69 and 3.92%, respectively. The rather high genetic diversity and average number of alleles per locus confirmed that both groups of landraces had a rather broad germplasm base. The extremely low fixation index showed that there was little genetic variation between White Dent and Golden Queen and the molecular variation within these two groups was remarkably high, indicating no genetic drift between White Dent and Golden Queen and suggesting different improvement approaches to these two important groups of landraces. Hardy-Weinberg equilibrium test revealed that the group of White Dent was deviated from HWE, whereas Golden Queen was under HWE.展开更多
Eighty-five rice(Oryza sativa L.)varieties,including 82 rice landraces collected from 17villages in Yunnan Province of China and three standard varieties representing typical Indica and Japonica ecotypes,were studied ...Eighty-five rice(Oryza sativa L.)varieties,including 82 rice landraces collected from 17villages in Yunnan Province of China and three standard varieties representing typical Indica and Japonica ecotypes,were studied using simple sequence repeat(SSR)markers to estimate their genetic diversity for the purpose of strategic conservation.Nineteen selected SSR primer pairs amplified a total of 83 SSR alleles,with molecular weight ranging from 100 to 500 bp,from the 85 rice varieties.An UPGMA dendrogram based on the cluster analysis of genetic similarity of the SSR alleles showed a significant genetic variation among the included rice varieties,with the similarity coefficients varying between 0.152 and 0.900.However,genetic diversity of the rice varieties collected from Yunnan was unevenly distributed over their geographical locations.Two distinct groups were identified from the cluster analysis of the 85rice varieties at the similarity coefficient level of 0.152,with one group that included almost all accessions of Indica ecotype and another group that contained all accessions of Japonica ecotype.Varieties that shared the same names but collected from different villages did not always show a close genetic relationship,indicating misidentification of some varieties by local farmers.It is concluded from this study that conservation of genetic diversity in rice landraces is urgently necessary in Yunnan,given their high level of diversity,but an appropriate strategy needs to be followed to guarantee the effectiveness of conservation activities.Properly selected SSR primer pairs might provide an ideal method for identifying Indica and Japonica ecotypes for rice conservation and breeding programs.展开更多
Three popular traditional rice landraces, namely Kalajeera, Machakanta and Haladichudi, from Koraput, India were used to analyse the leaf traits and antioxidant defence for drought tolerance. When rice plants were exp...Three popular traditional rice landraces, namely Kalajeera, Machakanta and Haladichudi, from Koraput, India were used to analyse the leaf traits and antioxidant defence for drought tolerance. When rice plants were exposed to different levels of drought stress by varying concentrations of polyethylene glycol （PEG） 6000, seed germination and growth parameters were significantly declined in all the rice landraces compared to the control. Drought stress also altered the leaf phenotypic traits based on chlorophyll fluorescence parameters and chlorophyll index, with more significant differences in susceptible variety IR64 than in traditional landraces. Furthermore, activities of antioxidative enzymes and proline and protein contents overtly increased under drought stress. The traditional rice landraces showed higher relative ratios for different parameters compared to the susceptible variety IR64. Taken together, the traditional landraces had superior leaf physiological efficiency compared to the susceptible and tolerant check varieties under drought stress.展开更多
The phenotypic diversity of 274 Ethiopian durum wheat accessions was analyzed, taking their geographic origins into account. The aim was to assess the extent and patterns of agronomically important phenotypic variatio...The phenotypic diversity of 274 Ethiopian durum wheat accessions was analyzed, taking their geographic origins into account. The aim was to assess the extent and patterns of agronomically important phenotypic variation across districts of origin and altitude classes for major qualitative traits using diversity index and multivariate methods. Eight qualitative and three quantitative traits were scored for 2740 plants and analyzed for diversity. The Shannon–Weaver diversity(H′) index was used to estimate phenotypic diversity. The estimated H′ ranged from monomorphic for glume hairiness to highly polymorphic for other traits. The highest(0.86) H′ was obtained for seed degree of shriveling, possibly indicating the differential responses of the genotypes to water deficit during later growth stages. With respect to district of origin, the highest(0.72) and lowest(0.44) H′ values were obtained for the Bale and SNNP districts, respectively. With respect to altitude, the highest(0.76) and lowest(0.62) H′ values were recorded for altitudes 1600–2000and > 3000 m above sea levels, respectively. Principal components analysis explained substantial variation contributed by district of origin and altitude range. Genotypes were clustered into three groups by districts of origin and altitude class, with relatively strong bootstrap values of 57 and 62 for the former and latter, respectively. It could be concluded that Ethiopian durum wheat landraces are very diverse both within and among districts of origin and altitude classes. This wealth of genetic diversity should be exploited for wheat improvement of yield and for resistance to biotic and abiotic stresses, particularly terminal drought.展开更多
Understanding genetic diversity and population structure of landraces is important in utilization of these germplasm in breeding programs. In the present study, a total of 143 core maize landraces from the South Maize...Understanding genetic diversity and population structure of landraces is important in utilization of these germplasm in breeding programs. In the present study, a total of 143 core maize landraces from the South Maize Region （SR） of China, which can represent the general profile of the genetic diversity in the landraces germplasm of SR, were genotyped by 54 DNA microsatellite markers. Totally, 517 alleles （ranging from 4 to 22） were detected among these landraces, with an average of 9.57 alleles per locus. The total gene diversity of these core landraces was 0.61, suggesting a rather higher level of genetic diversity. Analysis of population structure based on Bayesian method obtained the samilar result as the phylogeny neighbor-joining （N J） method. The results indicated that the whole set of 143 core landraces could be clustered into two distinct groups. All landraces from Guangdong, Hainan, and 15 landraces from Jiangxi were clustered into group 1, while those from the other regions of SR formed the group 2. The results from the analysis of genetic diversity showed that both of groups possessed a similar gene diversity, but group 1 possessed relatively lower mean alleles per locus （6.63） and distinct alleles （91） than group 2 （7.94 and 110, respectively）. The relatively high richness of total alleles and distinct alleles preserved in the core landraces from SR suggested that all these germplasm could be useful resources in germplasm enhancement and maize breeding in China.展开更多
Erhualian and Landrace breeds are typical genetically obese and lean pigs, respectively. To compare the fecal methanogenic Archaeal community between these two pig breeds, fecal samples from different growth phase pig...Erhualian and Landrace breeds are typical genetically obese and lean pigs, respectively. To compare the fecal methanogenic Archaeal community between these two pig breeds, fecal samples from different growth phase pigs were collected and used for PCR-denaturing gradient gel electrophoresis （DGGE） with two primer pairs （344fGC/519r and 519f/915rGC） and real-time PCR analysis. Results showed that a better separation and higher quality of bands pattern were obtained in DGGE proifles using primers 344fGC/519r as compared with primers 519f/915rGC. Sequencing of DGGE bands showed that the predominant methanogens in the feces of Erhualian and Landrace pigs belonged to Methanobrevibacter spp. and Methanosphaera spp. Real-time PCR analysis revealed that there was no signiifcant difference in the numbers of fecal total methanogens between Erhualian and Landrace pigs;however, pig growth phase affected the numbers of 16S rRNA genes of total methanogens and Methanobrevibacter smithii. Dissociation curves of methyl coenzyme-M reductase subunit A （mcrA） gene fragments ampliifed with real-time PCR showed all samples possessed a single peak at 82＆#176;C, which might be associated with M. smithii. Samples from the same growth phase of each breed showed good replicative dissociation curves. The results suggest that the growth phase （including diet factor） other than genotype of pig may affect the fecal methanogenic Archaeal community of pigs.展开更多
Powdery mildew, caused by Blumeria graminis f. sp. tritici （Bgt）, is one of the most damaging diseases to wheat in the world. The cultivation of resistant varieties of wheat is essential for controlling the powdery ...Powdery mildew, caused by Blumeria graminis f. sp. tritici （Bgt）, is one of the most damaging diseases to wheat in the world. The cultivation of resistant varieties of wheat is essential for controlling the powdery mildew epidemic. Wheat landraces are important resources of resistance to many diseases. Mapping powdery mildew resistance genes from wheat landraces will promote the development of new varieties with disease resistance. The Chinese wheat landrace Baiyouyantiao possesses characteristic of disease resistance to powdery mildew. To identify the resistance gene in this landrace, Baiyouyantiao was crossed with the susceptible cultivar Jingshuang 16 and seedlings of parents and F1, BC1, F2, and F~：3 were tested with Bgt isolate E09. The genetic results showed that the resistance of Baiyouyantiao to E09 was controlled by a single recessive gene, tentatively designated PmBYYT. An Illumina wheat 90K single-nucleotide polymorphism （SNP） array was applied to screen polymorphisms between F2-resistant and F2-susceptible DNA bulks for identifying the chromosomal location of PmBYYT. A high percentage of polymorphic SNPs between the resistant and susceptible DNA bulks was found on chro- mosome 7B, indicating that PmBYYT may be located on this chromosome. A genetic linkage map of PmBYYTconsisting of two simple sequence repeat markers and eight SNP markers was developed. The two flanking markers were SNP markers W7BL-8 and W7BL-15, with genetic distances of 3 and 2.9 cM, respectively. The results of this study demonstrated the rapid characterization of a wheat disease resistance gene and SNP marker development using the 90K SNP assay. The flanking markers of gene PmBYYTwill benefit marker-assisted selection （MAS） and map-based cloning in breeding wheat cultivars with powdery mildew resistance.展开更多
Genetic diversity of rice landraces from lowland and upland accessions of China was investigated using 66 polymorphic simple sequence repeat （SSR） markers. The total number of alleles detected from all 324 tested ac...Genetic diversity of rice landraces from lowland and upland accessions of China was investigated using 66 polymorphic simple sequence repeat （SSR） markers. The total number of alleles detected from all 324 tested accessions was 555 with an average allele number （Na） of 8.409 per locus, the average effective number of alleles （Ne） of 3.574 and the average Shannon＇s information index （I） of 1.378. The genetic diversity was higher for the indica landraces compared to the japonica landraces, and the upland landraces were more genetically diverse than the lowland landraces. The SSR markers, RM72, RM232, RM219, RM241, RM224 and RM3 showed the highest rates of polymorphism and these SSR markers were suitable to assess the genetic diversity of rice germplasm resources. A dendrogram of 324 accessions of lowland and upland landraces showed that all rice accessions were mainly subdivided into two groups, japonica and indica, with some being intermediate. The distribution of lowland and upland landraces among the japonica and indica rice groups was distinct, with obvious differentiation between the lowland and upland landraces in japonica rice, but no such clear distinction in indica rice.展开更多
[Objective] The paper was to explore the causes of phosphorus(P)efficiency of rice in Yunnan Province,and to provide strategy for ecological and environmental protection.[Method]Using 703 accessions of secondary core ...[Objective] The paper was to explore the causes of phosphorus(P)efficiency of rice in Yunnan Province,and to provide strategy for ecological and environmental protection.[Method]Using 703 accessions of secondary core collections from 16 prefectures of five regions in Yunnan Province,two treatments of low available P(6.26mg/kg)versus normal P(available P 40mg/kg),and invalid P(available P 0.02 mg/kg)versus normal P(available P 70 mg/kg)were set,and zonal characteristics of phosphorus efficiency and the activation characteristics of invalid P of rice landraces were investigated.[Result] Phosphorus efficiency and the activation characteristics of invalid P in soils from rice landraces of Yunnan Province had the similar identification indexes,viz.the relative indexes of four traits(tillering ability or effective panicle,root weight,biomass,and straw weight)could be the screening indexes of gene type of secondary core collection with phosphorus efficiency,which also reflected the zonal characteristics of phosphorus efficiency and the activation characteristics of invalid P in soils of 16 prefectures among five regions.On the contrary,the relative panicle length,node length under panicle,leaf length,leaf width and plant height could only be the assistant indexes of identification for phosphorus efficiency.There were similar zonal characteristics between phosphorus efficiency and the activation characteristics of invalid P in soils of rice landraces in Yunnan Province.[Conclusion] The study had great importance to the conservation and utilization of biological diversity,which would make contribution to second green revolution of "less input,multiple output,promote health,and protect the environment".展开更多
The number of B chromosomes （Bs） in 54 maize landraces from Southwest China was tested by means of cytological observations. Nine landraces with Bs were observed. A map, showing the geographic distribution of the la...The number of B chromosomes （Bs） in 54 maize landraces from Southwest China was tested by means of cytological observations. Nine landraces with Bs were observed. A map, showing the geographic distribution of the landraces with Bs, was plotted. It was found that southeastern Sichuan Province in China was the main distribution area of the landraces with Bs in Southwest China. In order to obtain information on relationships between Bs and genetic variation, genetic diversity both among and within 11 landraces was evaluated. For each SSR marker, the number of alleles ranged from 3 to 12 with an average of 7.86, which revealed a high level of genetic diversity among maize landraces in Southwest China. Based on SSRs data, higher genetic variation was found in the landraces with 2B, and the genetic distance between the landraces with and without Bs was higher. The results together with the principal component analysis （PCA） supported the hypothesis that maize landraces in Southwest China were first introduced to the middle part of southwest Sichuan, China. At the same time, the effect of Bs on genetic variation was discussed.展开更多
For clarifying the hierarchical patterns of population structure of soybean landraces in China, the seven clusters previously identified using Bayesian clustering of 1 504 soybean landraces based on SSR markers genoty...For clarifying the hierarchical patterns of population structure of soybean landraces in China, the seven clusters previously identified using Bayesian clustering of 1 504 soybean landraces based on SSR markers genotyping data were further analyzed. Using the largest value of AK, these landraces could be split into 20 sub-clusters, which was supported by highly significant pairwise Fst-values and generally in accordance with the geographic origin and sowing types. The autumn-sowing types ended up in one distinct sub-cluster from the otherwise summer-sowing type, where the autumn- sowing types are most likely derived from. The division into 20 sub-clusters explained 7.3% of the genetic variation, next to 9.7% present among the seven clusters, 81.1% residing among landraces within sub-clusters, and 1.9% within the landraces. The distribution pattern of genetic diversity among the sub-clusters of each cluster was uneven, with two HSuM sub-clusters （Central China） and some South China sub-clusters showing significantly higher level of genetic diversity.展开更多
Genetic diversity of 48 sweetpotato landraces randomly sampled from Anhui,Fujian, Henan and Guangdong provinces in China was analyzed using RAPD, ISSR and AFLP markers. Thirty RAPD primers, 14 ISSR primers and 9 AFL...Genetic diversity of 48 sweetpotato landraces randomly sampled from Anhui,Fujian, Henan and Guangdong provinces in China was analyzed using RAPD, ISSR and AFLP markers. Thirty RAPD primers, 14 ISSR primers and 9 AFLP primer pairs generated 227, 249 and 260 polymorphic bands, respectively. AFLP markers were better than RAPD and ISSR markers in terms of the number of polymorphic bands detected and the experimental stability. These three molecular markers revealed the similar results that Chinese landraces exhibited a high level of genetic diversity, and the genetic variation of Guangdong landraces was significantly higher than those of the landraces from the other three regions. These results supported the hypothesis that China was a secondary center of sweetpotato diversity. The present results also supported the view that sweetpotato was first introduced to Guangdong and from there spread to other regions of China. The dendrogram based on the combined RAPD, ISSR and AFLP dataset could separate the 48 landraces into two groups: One mainly including 8 landraces from Guangdong and the other consisting of the remaining landraces from Guangdong and landraces from the other three regions. Thus, the utilization of Guangdong landraces should be specially considered in sweetpotato breeding.展开更多
文摘Genetic diversity at Gli_1, Gli_2 and Glu_1 loci was investigated in 89 Sichuan wheat (Triticum aestivum L.) landraces by using acid polyacrylamide gel electrophoresis (APAGE) and SDS_PAGE. In these landraces, a total of 32 gliadin and 3 high_molecular_weight (HMW) glutenin patterns were observed. In total, 14, 15 and 5 alleles were identified at Gli_1, Gli_2 and Glu_1, respectively. At each locus, the alleles in higher frequency were Gli_A1a (89%), Gli_B1h (46%), Gli_D1a (65%), Gli_A2a (64%), Gli_B2j (45%), Gli_D2a (48%), Glu_A1c (99%), Glu_B1b (99%) and Glu_D1a (100%). The Nei's genetic variation index (H) of Sichuan wheat landraces was 0.370?6, varying from 0 to 0.708?7. The highest genetic diversity was found at Gli_B2 locus, while the lowest was found at Glu_D1. The genetic diversity at Gli loci was higher than that of Glu_1 loci among these landraces, but it was much lower than that of modern wheat cultivars. These results indicated a narrow genetic base of Sichuan wheat landraces. In this study, “Chengdu_guangtou” had the identical gliadin and HMW_glutenin patterns with “Chinese Spring”, further supporting the proposal that “Chinese Spring” is a strain of “Chengdu_guangtou”.
基金This work was supported by the National High Technology Research and Development Program of China (No. 2004BA525B04)Changjiang Scholars and Innovative Research Team in University (No. IRTO453).
文摘Genetic diversity of 54 maize landraces from southwest China was tested using bulk DNA samples and 42 microsatellite （SSR） loci distributed on 10 chromosomes of maize. A total of 256 alleles were detected among the landraces. At each locus, the number of alleles varied from 2 to 9, with an average of 6.1. On the basis of the genetic similarity coefficients, clustering analysis separated the landraces into four groups. The landraces collected from the same region were mostly grouped together. To reveal the genetic structure and genetic diversity within landraces, 165 individuals from 11 landraces were analyzed. Individual DNA samples proved to be superior to bulk DNA samples in identifying genetic diversity of landraces. A total of 330 alleles were detected in the 11 landraces. According to the results of the individual DNA sampling analysis, estimates of the mean number of alleles ‘A’, the effective allelic number ‘Ae’, the observed heterozygosity ‘Ho’, and expected heterozygosity ‘He’ were 7.86, 3.90, 0.69, and 0.37, respectively. An obvious genetic deviation from Hardy-Weinberg expectation was observed both among and within landraces and a considerable genetic variation was revealed within rather than among landraces. In addition, genetic diversity of landraces was greater in Sichuan than in the other three regions. It can be concluded that maize landraces in southwest China were initially introduced to Sichuan and from there to adjacent areas.
文摘[Objective] The aim of this study was to screen rice strip virus （RSV）-resistant landraces. [Method] The resistance of 119 rice landraces to rice stripe virus was identified in field spontaneously infected with smal plant-hopper. [Result] There were 55 landraces resistant to rice strip disease in 56 indica rice landraces, but on-ly two resistant to rice strip disease in 63 japonica rice landraces. [Conclusion] The results revealed that there were abundant rice landscapes resistant to RSV in Chi-na, and these varieties can be used to develop more genes resistant to RSV.
文摘The nucleotide sequences in exon 7 of a disintegrin and metalloproteinase with thrombospondin motifs-1(ADAMTS-1)gene in Landrace pig were obtained with cloning and sequencing by using PCR-RFLP technique in this experiment.Sequence alignment results showed that the C/G substitution in exon 7 induced amino acid change(Arg → Pro).AA,BB and AB genotypes were found in Landrace pig by PvuⅡ-RFLP.Correlation analysis between genotypes and reproductive traits indicated that ADAMTS-1 was significantly correlated with litter size(LS)and number born alive(NBA).
基金the National Natural Science Foundation of China for supporting this research(39770464).
文摘Waxy maize landraces are abundant inYunnan and Guizhou of China. Genetic diversity of waxy maize landraces from Yunnan and Guizhou were analyzed using SSR markers. We screened 38 landraces with 50 primers that generated 3 to 6 polymorphic bands, with an average of 4.13 bands. Shannon＇s information indices for genetic diversity of the 14 waxy maize landraces from Yunnan varied from 4.9571 to 42.1138 and averaged 26.5252; Shannon＇s information indices for genetic diversity of the 24 waxy maize landraces from Guizhou varied from 22.0066 to 40.6320 and averaged 32.3156. For the 14 waxy maize landraces from Yunnan, the within-landrace genetic diversity accounted for 45.40% and the among-landrace genetic diversity accounted for 54.60% of the total genetic diversity observed. For the 24 waxy maize landraces from Guizhou, the within-landrace genetic diversity accounted for 50.76% and the among-landrace genetic diversity accounted for 49.24% of the total observed. Some individual landraces possessed as much as 96.86% of the total genetic diversity occurring among landraces within origins. Differentiation between geographic origins accounted for only 3.14% of the total genetic diversity. Both Yunnan and Guizhou would be the diversity centers and the original centers of waxy maize.
基金Director,University Institute of Engineering and Technology and Department of Science and Technology-Science and Engineering Research Board(Grant No.SB/FT/LS-442/2012)for financial support。
文摘All rice plant developmental stages are severely affected by soil salinity. Salinity-induced ionic and osmotic stresses affect stomata closure and gaseous exchange, and reduce transpiration and the rate of carbon assimilation, and hence decrease plant yield. Understanding the response of rice plants toward salinity stress at the genetic level and developing salt-tolerant varieties are the vital mandates for its effective management. This review described the present status of salt-tolerance achieved in rice by various mechanisms including the ion homeostasis(Na^+/H^+, OsNHX antiporters), compatible organic solutes(glycine betaine and proline), antioxidative genes(OsECS, OsVTE1, OsAPX and OsMSRA4.1), salt responsive regulatory elements(transcription factors, cis-acting elements and miRNAs) and genes ecoding protein kinases(MAPKs, SAPKs and STRKs). Further, the future perspective of developing salt-tolerant varieties lies in exploring halotolerant gene homologs from rice varieties, especially the landraces. Genetic diversity among rice landraces can serve as a valuable resource for future studies toward variety improvement through breeding and genome editing. Further, identification, multiplication, preservation and utilization of biodiversity among landraces are the urgent buffers to be saved as a heritage for future generations to come.
文摘A field trial was conducted to investigate main morphological and physiological changes of different maize landraces to low-P stress at the stage of seedling. P-deficiency significantly decreased root volume, total leaf area, and plant dry weight, but greatly increased density of root hairs and root top ratio. In addition, P-deficiency induced the significant enhancement of phosphorus utilization efficiency and the amount of proline, malondialdehye （MDA）, acid phosphatase （APase）, peroxidase （POD） and superoxide dismutase （SOD）, but the significant reduction of P uptake and soluable protein content. Since P-deficiency had smaller effects on the P-tolerant maize landraces DP-44, DP-32 and DP-33 as compared with P-sensitive landraces DP-29 and DP-24, it was demonstrated that differences of tolerance to P-deficiency existed among different maize landraces. The results based on the correlation analysis showed that the economic yield of maize landraces had relationships with their morphological and physiological characteristics under P-deficiency.
基金the National High Tech-nology Research and Development Program of China(863 Program, 2004BA525B04)Program for Changjiang Scholars and Innovative Research Team in University of China (IRTO453)
文摘Based on the genetic clustering from 42 microsatellite （SSR） markers with a combination of their geographic origin and germplasm characteristics, 124 maize landraces from Wuling Mountain region in China were used for constructing a core collection. Four evaluating parameters for maize landrace core collection, including mean difference percentage （MD）, variance difference percentage （VD）, coincidence rate of range （CR）, and variable rate of coefficient of variation （VR）, were assessed With 20 quantitative traits. It was shown that genetic relationships among landraces in Wuling Mountain region had the tendency to associate with their geographic origins. The 124 landraces were clustered into 18 subgroups when the coefficient of genetic similarity （GS） is 0.28. Eighteen landraces, each of which was from one subgroup, were applied to construct the core collection with a sampling percentage of 15%. Comparison of the initial and core collection indicated that there existed no significant differences in most quantitative traits. An average of 6.3 and 6.5 alleles were detected in the initial and core collection, respectively. Mean polymorphism information content in the core collection （0.75） was higher than that in the initial one （0.72）. MD was lesser than 20% and CR was more than 80%. The results showed that the sampling strategy would be feasible for constructing the core collection that well represents the genetic diversity of the initial one.
基金supported by the Special Program for Crop Germplasm Resources of the Ministry of Agriculture [(NB07-2130135-(25-30)-05]Natural Science Foundation of Beijing (6071003)+1 种基金Innovation Platform Program for Basic Research of Agricultural Breeding in Beijing (YZPT02-06)Scientific and Technological Key Project in Chongqing for Elite Variety Innovation of Rice and Maize (CSTC 2007AB1045)
文摘Maize landraces White Dent and Golden Queen played a very important role in the pre-hybrid era of maize production in China. However, dozens of accessions with the same names of White Dent and Golden Queen are preserved in China National Genebank （CNG）. The present study investigated the genetic diversity of these two important groups of maize landraces, as well as the relationships within and among them. Thirty-four landrace accessions with the name of White Dent and 10 with Golden Queen preserved in CNG were fingerprinted with 52 simple sequence repeats with tailed primer M13. Summary statistics including average number of alleles per locus, gene diversity/expected heterozygosity, and observed heterozygosity were carried out using PowerMarker ver. 3.25 software. The test of Hardy-Weinberg equilibrium （HWE） and linkage disequilibrium （LD） of all the 44 maize landrace accessions were also performed by PowerMarker. We observed a significant differentiation in terms of the average number of alleles between White Dent and Golden Queen （6.44 alleles per locus in White Dent, 4.48 in Golden Queen）, while both groups of maize landraces had a relatively high but similar gene diversity （0.61 of White Dent, 0.63 of Golden Queen）. The fixation index （FST） was only 0.0044, while the percentage of loci deviated from Hardy-Weinberg equilibrium within these two groups of White Dent and Golden Queen was 32.69 and 3.92%, respectively. The rather high genetic diversity and average number of alleles per locus confirmed that both groups of landraces had a rather broad germplasm base. The extremely low fixation index showed that there was little genetic variation between White Dent and Golden Queen and the molecular variation within these two groups was remarkably high, indicating no genetic drift between White Dent and Golden Queen and suggesting different improvement approaches to these two important groups of landraces. Hardy-Weinberg equilibrium test revealed that the group of White Dent was deviated from HWE, whereas Golden Queen was under HWE.
文摘Eighty-five rice(Oryza sativa L.)varieties,including 82 rice landraces collected from 17villages in Yunnan Province of China and three standard varieties representing typical Indica and Japonica ecotypes,were studied using simple sequence repeat(SSR)markers to estimate their genetic diversity for the purpose of strategic conservation.Nineteen selected SSR primer pairs amplified a total of 83 SSR alleles,with molecular weight ranging from 100 to 500 bp,from the 85 rice varieties.An UPGMA dendrogram based on the cluster analysis of genetic similarity of the SSR alleles showed a significant genetic variation among the included rice varieties,with the similarity coefficients varying between 0.152 and 0.900.However,genetic diversity of the rice varieties collected from Yunnan was unevenly distributed over their geographical locations.Two distinct groups were identified from the cluster analysis of the 85rice varieties at the similarity coefficient level of 0.152,with one group that included almost all accessions of Indica ecotype and another group that contained all accessions of Japonica ecotype.Varieties that shared the same names but collected from different villages did not always show a close genetic relationship,indicating misidentification of some varieties by local farmers.It is concluded from this study that conservation of genetic diversity in rice landraces is urgently necessary in Yunnan,given their high level of diversity,but an appropriate strategy needs to be followed to guarantee the effectiveness of conservation activities.Properly selected SSR primer pairs might provide an ideal method for identifying Indica and Japonica ecotypes for rice conservation and breeding programs.
文摘Three popular traditional rice landraces, namely Kalajeera, Machakanta and Haladichudi, from Koraput, India were used to analyse the leaf traits and antioxidant defence for drought tolerance. When rice plants were exposed to different levels of drought stress by varying concentrations of polyethylene glycol （PEG） 6000, seed germination and growth parameters were significantly declined in all the rice landraces compared to the control. Drought stress also altered the leaf phenotypic traits based on chlorophyll fluorescence parameters and chlorophyll index, with more significant differences in susceptible variety IR64 than in traditional landraces. Furthermore, activities of antioxidative enzymes and proline and protein contents overtly increased under drought stress. The traditional rice landraces showed higher relative ratios for different parameters compared to the susceptible variety IR64. Taken together, the traditional landraces had superior leaf physiological efficiency compared to the susceptible and tolerant check varieties under drought stress.
基金done through joint project between Mekelle University and Scuola Superiore Sant'Anna and the joint grant number is CDANR/ SSSA/42/2011The first author is further indebted to Scuola Superiore Sant'Anna, Italy for financial support given to the projectMekelle University for its support
文摘The phenotypic diversity of 274 Ethiopian durum wheat accessions was analyzed, taking their geographic origins into account. The aim was to assess the extent and patterns of agronomically important phenotypic variation across districts of origin and altitude classes for major qualitative traits using diversity index and multivariate methods. Eight qualitative and three quantitative traits were scored for 2740 plants and analyzed for diversity. The Shannon–Weaver diversity(H′) index was used to estimate phenotypic diversity. The estimated H′ ranged from monomorphic for glume hairiness to highly polymorphic for other traits. The highest(0.86) H′ was obtained for seed degree of shriveling, possibly indicating the differential responses of the genotypes to water deficit during later growth stages. With respect to district of origin, the highest(0.72) and lowest(0.44) H′ values were obtained for the Bale and SNNP districts, respectively. With respect to altitude, the highest(0.76) and lowest(0.62) H′ values were recorded for altitudes 1600–2000and > 3000 m above sea levels, respectively. Principal components analysis explained substantial variation contributed by district of origin and altitude range. Genotypes were clustered into three groups by districts of origin and altitude class, with relatively strong bootstrap values of 57 and 62 for the former and latter, respectively. It could be concluded that Ethiopian durum wheat landraces are very diverse both within and among districts of origin and altitude classes. This wealth of genetic diversity should be exploited for wheat improvement of yield and for resistance to biotic and abiotic stresses, particularly terminal drought.
基金supported by the Program for Germplasm Innovation and Utilization from the Minis-try of Agrculture of China (2006BAD13B03)Beijing Natural Science Foundation (6071003)Doctoral Foundation of Southwest University, China(SWUB2008037)
文摘Understanding genetic diversity and population structure of landraces is important in utilization of these germplasm in breeding programs. In the present study, a total of 143 core maize landraces from the South Maize Region （SR） of China, which can represent the general profile of the genetic diversity in the landraces germplasm of SR, were genotyped by 54 DNA microsatellite markers. Totally, 517 alleles （ranging from 4 to 22） were detected among these landraces, with an average of 9.57 alleles per locus. The total gene diversity of these core landraces was 0.61, suggesting a rather higher level of genetic diversity. Analysis of population structure based on Bayesian method obtained the samilar result as the phylogeny neighbor-joining （N J） method. The results indicated that the whole set of 143 core landraces could be clustered into two distinct groups. All landraces from Guangdong, Hainan, and 15 landraces from Jiangxi were clustered into group 1, while those from the other regions of SR formed the group 2. The results from the analysis of genetic diversity showed that both of groups possessed a similar gene diversity, but group 1 possessed relatively lower mean alleles per locus （6.63） and distinct alleles （91） than group 2 （7.94 and 110, respectively）. The relatively high richness of total alleles and distinct alleles preserved in the core landraces from SR suggested that all these germplasm could be useful resources in germplasm enhancement and maize breeding in China.
基金funding from the National Basic Research Program of China (2012CB124705,2013CB127603)the European Community’s Seventh Framework Programme (FP7/2007-2013) under the grant agreement n° 227549+1 种基金the Royal Dutch Academy of Sciences (KNAW) through Project 09CDP006the Fundamental Research Funds for the Central Universities,China (KYZ201153)
文摘Erhualian and Landrace breeds are typical genetically obese and lean pigs, respectively. To compare the fecal methanogenic Archaeal community between these two pig breeds, fecal samples from different growth phase pigs were collected and used for PCR-denaturing gradient gel electrophoresis （DGGE） with two primer pairs （344fGC/519r and 519f/915rGC） and real-time PCR analysis. Results showed that a better separation and higher quality of bands pattern were obtained in DGGE proifles using primers 344fGC/519r as compared with primers 519f/915rGC. Sequencing of DGGE bands showed that the predominant methanogens in the feces of Erhualian and Landrace pigs belonged to Methanobrevibacter spp. and Methanosphaera spp. Real-time PCR analysis revealed that there was no signiifcant difference in the numbers of fecal total methanogens between Erhualian and Landrace pigs;however, pig growth phase affected the numbers of 16S rRNA genes of total methanogens and Methanobrevibacter smithii. Dissociation curves of methyl coenzyme-M reductase subunit A （mcrA） gene fragments ampliifed with real-time PCR showed all samples possessed a single peak at 82＆#176;C, which might be associated with M. smithii. Samples from the same growth phase of each breed showed good replicative dissociation curves. The results suggest that the growth phase （including diet factor） other than genotype of pig may affect the fecal methanogenic Archaeal community of pigs.
基金funded by the National Key Research and Development Program of China (2017YFD0201701)the Special Fund for Agro-scientific Research in the Public Interest,China (201303016)the Science and Technology Project for Xingjiang Uygur Autonomous Region,China (2013911092)
文摘Powdery mildew, caused by Blumeria graminis f. sp. tritici （Bgt）, is one of the most damaging diseases to wheat in the world. The cultivation of resistant varieties of wheat is essential for controlling the powdery mildew epidemic. Wheat landraces are important resources of resistance to many diseases. Mapping powdery mildew resistance genes from wheat landraces will promote the development of new varieties with disease resistance. The Chinese wheat landrace Baiyouyantiao possesses characteristic of disease resistance to powdery mildew. To identify the resistance gene in this landrace, Baiyouyantiao was crossed with the susceptible cultivar Jingshuang 16 and seedlings of parents and F1, BC1, F2, and F~：3 were tested with Bgt isolate E09. The genetic results showed that the resistance of Baiyouyantiao to E09 was controlled by a single recessive gene, tentatively designated PmBYYT. An Illumina wheat 90K single-nucleotide polymorphism （SNP） array was applied to screen polymorphisms between F2-resistant and F2-susceptible DNA bulks for identifying the chromosomal location of PmBYYT. A high percentage of polymorphic SNPs between the resistant and susceptible DNA bulks was found on chro- mosome 7B, indicating that PmBYYT may be located on this chromosome. A genetic linkage map of PmBYYTconsisting of two simple sequence repeat markers and eight SNP markers was developed. The two flanking markers were SNP markers W7BL-8 and W7BL-15, with genetic distances of 3 and 2.9 cM, respectively. The results of this study demonstrated the rapid characterization of a wheat disease resistance gene and SNP marker development using the 90K SNP assay. The flanking markers of gene PmBYYTwill benefit marker-assisted selection （MAS） and map-based cloning in breeding wheat cultivars with powdery mildew resistance.
基金supported by the National Basic Research Program of China(Grant No.2010CB125904-5)the National Key Technology Research and Development Program of China(Grant No.2013BAD01B02-2)the Protective Program of Crop Germpalsm of China(Grant No.NB2012-2130135-25-01)
文摘Genetic diversity of rice landraces from lowland and upland accessions of China was investigated using 66 polymorphic simple sequence repeat （SSR） markers. The total number of alleles detected from all 324 tested accessions was 555 with an average allele number （Na） of 8.409 per locus, the average effective number of alleles （Ne） of 3.574 and the average Shannon＇s information index （I） of 1.378. The genetic diversity was higher for the indica landraces compared to the japonica landraces, and the upland landraces were more genetically diverse than the lowland landraces. The SSR markers, RM72, RM232, RM219, RM241, RM224 and RM3 showed the highest rates of polymorphism and these SSR markers were suitable to assess the genetic diversity of rice germplasm resources. A dendrogram of 324 accessions of lowland and upland landraces showed that all rice accessions were mainly subdivided into two groups, japonica and indica, with some being intermediate. The distribution of lowland and upland landraces among the japonica and indica rice groups was distinct, with obvious differentiation between the lowland and upland landraces in japonica rice, but no such clear distinction in indica rice.
基金Supported by National Natural Science Foundation of China(31060186)Exploitue of Emphases New Production from Yunnan Provincial Scientific and Technology Department(2010BB001)Kunming Scientific and Technology Bureau(Kunkejizi10N060204)
文摘[Objective] The paper was to explore the causes of phosphorus(P)efficiency of rice in Yunnan Province,and to provide strategy for ecological and environmental protection.[Method]Using 703 accessions of secondary core collections from 16 prefectures of five regions in Yunnan Province,two treatments of low available P(6.26mg/kg)versus normal P(available P 40mg/kg),and invalid P(available P 0.02 mg/kg)versus normal P(available P 70 mg/kg)were set,and zonal characteristics of phosphorus efficiency and the activation characteristics of invalid P of rice landraces were investigated.[Result] Phosphorus efficiency and the activation characteristics of invalid P in soils from rice landraces of Yunnan Province had the similar identification indexes,viz.the relative indexes of four traits(tillering ability or effective panicle,root weight,biomass,and straw weight)could be the screening indexes of gene type of secondary core collection with phosphorus efficiency,which also reflected the zonal characteristics of phosphorus efficiency and the activation characteristics of invalid P in soils of 16 prefectures among five regions.On the contrary,the relative panicle length,node length under panicle,leaf length,leaf width and plant height could only be the assistant indexes of identification for phosphorus efficiency.There were similar zonal characteristics between phosphorus efficiency and the activation characteristics of invalid P in soils of rice landraces in Yunnan Province.[Conclusion] The study had great importance to the conservation and utilization of biological diversity,which would make contribution to second green revolution of "less input,multiple output,promote health,and protect the environment".
文摘The number of B chromosomes （Bs） in 54 maize landraces from Southwest China was tested by means of cytological observations. Nine landraces with Bs were observed. A map, showing the geographic distribution of the landraces with Bs, was plotted. It was found that southeastern Sichuan Province in China was the main distribution area of the landraces with Bs in Southwest China. In order to obtain information on relationships between Bs and genetic variation, genetic diversity both among and within 11 landraces was evaluated. For each SSR marker, the number of alleles ranged from 3 to 12 with an average of 7.86, which revealed a high level of genetic diversity among maize landraces in Southwest China. Based on SSRs data, higher genetic variation was found in the landraces with 2B, and the genetic distance between the landraces with and without Bs was higher. The results together with the principal component analysis （PCA） supported the hypothesis that maize landraces in Southwest China were first introduced to the middle part of southwest Sichuan, China. At the same time, the effect of Bs on genetic variation was discussed.
基金supported by the National Basic Research Program of China (973 Program,2010CB125900 and 2004CB117203)the National Key Technologies R&D Program during the 11th Five-Year-Plan period (2006BAD13B05)+1 种基金the National Natural Science Foundation of China (30490251 and30471096)the Academy and Institute Foundation for Basic Scientific Research in Institute of Crop Sciences,Chinese Academy of Agricultural Sciences
文摘For clarifying the hierarchical patterns of population structure of soybean landraces in China, the seven clusters previously identified using Bayesian clustering of 1 504 soybean landraces based on SSR markers genotyping data were further analyzed. Using the largest value of AK, these landraces could be split into 20 sub-clusters, which was supported by highly significant pairwise Fst-values and generally in accordance with the geographic origin and sowing types. The autumn-sowing types ended up in one distinct sub-cluster from the otherwise summer-sowing type, where the autumn- sowing types are most likely derived from. The division into 20 sub-clusters explained 7.3% of the genetic variation, next to 9.7% present among the seven clusters, 81.1% residing among landraces within sub-clusters, and 1.9% within the landraces. The distribution pattern of genetic diversity among the sub-clusters of each cluster was uneven, with two HSuM sub-clusters （Central China） and some South China sub-clusters showing significantly higher level of genetic diversity.
基金This work was partly supported by the Outstanding Younger Science Foundation of China(30225028)the National High Tech R&D Program of China(863 Program,2003AA207140)the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of Ministry of Education,China.
文摘Genetic diversity of 48 sweetpotato landraces randomly sampled from Anhui,Fujian, Henan and Guangdong provinces in China was analyzed using RAPD, ISSR and AFLP markers. Thirty RAPD primers, 14 ISSR primers and 9 AFLP primer pairs generated 227, 249 and 260 polymorphic bands, respectively. AFLP markers were better than RAPD and ISSR markers in terms of the number of polymorphic bands detected and the experimental stability. These three molecular markers revealed the similar results that Chinese landraces exhibited a high level of genetic diversity, and the genetic variation of Guangdong landraces was significantly higher than those of the landraces from the other three regions. These results supported the hypothesis that China was a secondary center of sweetpotato diversity. The present results also supported the view that sweetpotato was first introduced to Guangdong and from there spread to other regions of China. The dendrogram based on the combined RAPD, ISSR and AFLP dataset could separate the 48 landraces into two groups: One mainly including 8 landraces from Guangdong and the other consisting of the remaining landraces from Guangdong and landraces from the other three regions. Thus, the utilization of Guangdong landraces should be specially considered in sweetpotato breeding.
