Genome-Wide Analysis for Yield-Related Agronomic and Biochemical Traits of Chinese and Bangladeshi Grass Pea Genotypes Using SSR Markers

Grass pea(Lathyrus sativus L.)is an imperative food crop cultured in dryland agricultural ecology.It is a vital source of dietary protein to millions of populaces living in low-income countries in South-East Asia and Africa.This study highlights the improvement of genomic properties and their application in marker-trait relationships for 17 yield-related characters in 400 grass pea genotypes from China and Bangladesh.These characters were assessed via 56 polymorphic markers using general linear model(GLM)(P+G+Q)and mixed linear model(MLM)(P+G+Q+K)in the tassel software based on the linkage disequilibrium and population structure analysis.Population structure analysis showed two major groups and one admixed group in the populace.Statistically significant loci pairs of linkage disequilibrium(LD)mean value(D′)was 0.479.A total of 99 and 61 marker-trait associations in GLM and MLM models allied to the 17 traits were accepted at a 5%level of significance.Among these markers,21 markers were associated with more than one trait;12 marker-trait associations passed the Bonferroni correction threshold.Both models found six markers C41936,C39067,C34100,C47146,C47638,and C43047 significantly associated with days to maturity,flower color,plant height,and seed per pod were detected in the Hebei and Liaoyang location(p≤0.01),and the interpretation rate(R^(2)value)11.2%to 43.6%.Conferring to the consequences,the association analysis methodology may operative system for quantitative,qualitative,and biochemical traits related to gene position mapping and support breeders in improving novel approaches for advancing the grass pea quality.

Genetic linkage mapping and QTL identification for salinity tolerance in Indian mustard(Brassica juncea L.Czern and Coss.)using SSR markers

Soil salinity is one of the major environmental constraints that limits crop yield and nearly 7%of the total area worldwide is affected by salinity.Salinity-induced oxidative stress causes membrane damage during germination and seedling growth.Indian mustard is a major oilseed crop in India and its production and productivity are severely affected by salt stress.Breeding Brassica cultivars for salinity tolerance by conventional means is very difficult and time-consuming.Therefore,understanding the molecular components associated with salt tolerance is needed to facilitate breeding for salt tolerance in Brassica.In this investigation,quantitative trait loci(QTLs)associated with salt tolerance were identified using F_(2:3)mapping population developed from a cross between CS52(salinity tolerant)and RH30(salinity sensitive).Parents and F_(2:3)were evaluated under controlled and salinity stress conditions for 14 morpho-physiological traits for two consecutive generations(F2 and F_(2:3)),explaining proportion of the phenotypic variance under control condition.Simple sequence repeat(SSR)markers were used for mapping studies.A genetic linkage map based on 42 simple sequence repeats(SSRs)markers was constructed covering 2298.5 cM(Haldane)to identify the loci associated with salt tolerance in Brassica juncea.Forty-one SSRs showing polymorphism in the parents(CS52 and RH30)were mapped on 8 linkage groups(C1–C8).One marker(nga 129)did not map to any of the linkage group and was excluded from mapping.Linkage group 5(C5;317.9 cM)was longest and linkage group 1(C1,255.0 cM)was shortest.Further,we identified 15 QTLs controlling 8 traits using F_(2:3)population.These QTLs explained 12.44–60.63%of the phenotypic variation with a LOD score range of 3.62–5.97.Out of these QTLs,QMI4.1 related to membrane injury showed 51.28%phenotypic variance with a LOD score of 3.34.QTL QBYP8.1 related to biological yield per plant showed 60.63%phenotypic variance at a LOD score of 3.62.The highest LOD score of 5.97 was recorded for QTL related to seed yield per plant(QSYP4.1).Major QTLs were QTL for biological yield per plant(QBYP8.1),QTL for siliquae per plant(QSP4.1),QTL for primary branches(QPB4.1),QTLs for seed per siliqua(QSS4.1,QSS4.2),QTL for seed yield per plant(QSYP4.1),and QTL for membrane injury(QMI8.1)which showed more than 50%phenotypic variance.These QTLs identified in our study need to be confirmed in other populations as well so that these can be used in marker-assisted selection and breeding to enhance salt tolerance in Brassica juncea.

Assessment of Genetic Diversity of Yunnan,Tibetan,and Xinjiang Wheat Using SSR Markers

A total of 206 SSR （Simple Sequence Repeats） primer pairs were used to detect genetic diversity in 52 accessions of three unique wheat varieties of western China. A total of 488, 472, and 308 allelic variants were detected in 31 Yunnan, 15 Tibetan and 6 Xinjiang wheat accessions with an average of PIC values 0.2764, 0.3082, and 0.1944, respectively. Substantial differences in allelic polymorphisms were detected by SSR markers in all the 21 chromosomes, the 7 homoeologous groups, and the three genomes （A, B, and D） in Yunnan, Tibetan, and Xinjiang wheat. The highest and lowest allelic polymorphisms in all the 21 chromosomes were observed in 3B and 1D chromosomes, respectively. The lowest and highest allelic polymorphisms among the seven homoeologous groups was observed in 6 and 3 homoeologous groups, respectively. Among the three genomes, B genome showed the highest, A the intermediate, and D the lowest allelic polymorphism. The genetic distance （GD） indexes within Yunnan, Tibetan, and Xinjiang wheat, and between different wheat types were calculated. The GD value was found to be much higher within Yunnan and Tibetan wheat than within Xinjiang wheat, but the GD value between Yunnan and Tibetan wheat was lower than those between Yunnan and Xinjiang wheat, and between Tibetan and Xinjiang wheat. The cluster analysis indicated a closer relationship between Yunnan and Tibetan wheat than that between Yunnan and Xinjiang wheat or between Tibetan and Xinjiang wheat.

Genetic Diversity of SSR Markers in Cultivated Hordeum vulgare L.in Qinghai Province

[Objective]The aim was to analyze genetic diversity of SSR markers in Hordeum vulgare L.in Qinghai Province and lay a foundation for screening and protecting some excellent H.vulgare cultivars.[Method]SSR markers were used to evaluate the genetic diversity of 42 cultivated H.vulgare from Qinghai Province.[Result]42 H.vulgare showed polymorphism in 7 SSR markers locus.A total of 24 alleles were identified,and the number of alleles per locus ranged from 1 to 6,with an average of 3.0.According to SSR markers polymorphism,42 H.vulgare could be divided into 4 groups,namely I,II,III and IV.[Result]The study indicated that cultivated H.vulgare from Qinghai Province is rich in genetic diversity,which will provide reference for selecting parent of H.vulgare breeding.

A Method for Rapid Identification of Ningza 11 Seeds Purity with SSR Markers

[Objective] This study aimed to establish a method for rapid identification of Ningza 11 seeds purity with SSR markers. [Method] Taking Ningza 11 hybrid seeds as experimental materials, a method for rapid identification of hybrid rape-seeds was established with SSR molecular markers; meanwhile, the test seeds were planted in the field for comparison and verification. [Result] A method for rapid identification of Ningza 11 seeds purity with SSR molecular markers was estab-lished： DNA from seeds germinated in the night was extracted by alkaline lysis method; the PCR amplification was performed for 2 h, and electrophoresis for 1.5 h, and a silver staining for 10 minutes. It took less than one day to from obtaining sampling seeds to obtaining the purity identification result, so a skil ed professional can complete the detection of at least 6 ×96 = 576 seeds per weekday. By using this set of detection system, the measured purity of seeds from nine samples was extremely significantly positively correlated to the actual purity identified in the field test, with a correlation coefficient of up to 0.984 （P〈0.01）. [Conclusion] This SSR-PCR molecular identification system can be applied for rapid and accurate identifi-cation of Ningza 11 hybrid seeds.

Genetic Structure of Malus sieversii Population from Xinjiang,China,Revealed by SSR Markers

One hundred and nine Malus sieversii accessions from four geographical populations located at Kuerdening in Mohe town, Gongliu County, Jiaowutuohai, in Xinyuan County, Daxigou in Houcheng County of Ily State, and Baerluke Mountain in Yumin County of Tacheng State, Xinjiang Uygur Autonomous Region of China were studied by SSR markers. The purpose of the study was to determine the genetic structure and diversity in these eco-geographical populations with eight pair SSR primers of apple. The results indicated that： an average of 16 bands was detected in the four populations. The percentage of polymorphic bands in Gongliu population （89.06%） was the highest in the four populations. The average Nei＇s gene diversity index was 0.257 for all the loci. Totally, 128 polymorphic loci were detected and the percentage of polymorphic loci （P） was 100%, 88.28%, 84.83%, 87.50%, and 87.12%, respectively, at the species level and Gongliu, Xinyuan, Huocheng, and Yumin population levels. The Nei＇s gene diversity index （H = 0.2619） and Shannon＇s information index （1 = 0.4082） in the species level were higher than in the population level. The Nei＇s gene diversity index and Shannon＇s information index in the four populations were Gongliu 〉 Huocheng 〉 Xinyuan 〉 Yumin. Gongliu population and Xinyuan population were the highest in genetic identity and the closest in genetic distance. Gene flow between the populations was 7.265 based on genetic differentiation coefficient （GST = 0.064）. The UPGMA cluster analysis indicated that the genetic relationships between the Gongliu and Xinyuan population were the closest, and the Yumin population were the farthest with the other three populations. The UPGMA cluster analysis indicated that the four geographical populations located in Gongliu, Xinyuan, Huocheng, and Yumin were relatively independent populations. Concurrently, there was also mild gene exchange between the populations. On the basis of the study of population genetic structure and the highest genetic diversity, Gongliu population should be given a high priority consideration in Malus sieversii population＇s in situ germplasm conservation.

Identification of the Parentage of Corn Variety Using SSR Markers

[Objective] The study was to explore the molecular interpretation standards on parentage in the seeds of corn variety. [Method] With 16 hybrids and their parents and 202 inbred elites as materials for screening primers, the artificial groups of two standard diad and two standard triad were respectively established as the verification materials. Genomic DNA of seedlings was extracted by using CTAB method. 137 pairs of SSR primers were selected for SSR amplification and product detection, which was used for the parentage identification of maize varieties. [ Result] Twenty pairs of corn primers with high polymorphism information content （ PIC value）, clearly amplified bands and good reproducibility were screened from 137 pairs of corn SSR primers tested. The identification results of using SSR molecular were consistent with the actual situation. [ Conclusion] It is feasible to identify the parentage of maize variety using SSR markers.

QTL Analysis of Grain Storage Durability for Maize Under Controlled Deterioration Conditions Using SSR Markers

[Objective] This study aimed to analyze the quantitative trait loci （QTLs） of grain storage durability for maize under controlled deterioration conditions by using SSR markers. [Method] The recombinant inbred line population F 2 derived from the cross of shen 137/02-50 was used to do the simple sequence repeats （SSRs） and QTL analysis. [Result] The 2 parents showed good polymorphisms. Three loci were detected on chromosome 1, chromosome 6 and chromosome 9, accounting for 41.2% of total phenotypic. [Conclusion] This study provided theoretical basis for using molecular marker to assist the breeding of storage durable maize varieties.

Bulked Segregant Analysis to Detect QTL Related to Heat Tolerance in Rice(Oryza sativa L.) Using SSR Markers

The study was undertaken to assess the genetic effect of quantitative trait loci （QTLs） conferring heat tolerance at flowering stage in rice. A population consisting of 279 F2 individuals from the cross between 996, a heat tolerant cultivar and 4628, a heat-sensitive cultivar, was analyzed for their segregation pattern of the difference of seed set rate under optimal temperature condition and high temperature condition. The difference of seed set rate under optimal temperature condition and high temperature condition showed normal distribution, indicating the polygenic control over the trait. To identify main effect of QTL for heat tolerance, the parents were surveyed with 200 primer pairs of simple sequence repeats （SSR）. The parental survey revealed 30% polymorphism between parents. In order to detect the main QTL association with heat tolerance, a strategy of combining the DNA pooling from selected segregants and genotyping was adopted. The association of putative markers identified based on DNA pooling from selected segregants was established by single marker analysis （SMA）. The results of SMA revealed that SSR markers, RM3735 on chromosome 4 and RM3586 on chromosome 3 showed significant association with heat tolerance respectively, accounted for 17 and 3% of the total variation respectively. The heat tolerance during flowering stage in rice was controlled by multiple gene. The SSR markers, RM3735 on chromosome 4 and RM3586 on chromosome 3 showed significant association with heat tolerance respectively, accounted for 17 and 3% of the total variation respectively. The two genetic loci, especially for RM3735 on chromosome 4, can be used in marker-assistant-selected method in heat tolerance breeding in rice.

Fingerprinting 146 Chinese chestnut(Castanea mollissima Blume)accessions and selecting a core collection using SSR markers

Chinese chestnut is an important nut tree around the world.Although the types of Chinese chestnut resources are abundant,resource utilization and protection of chestnut accessions are still very limited.Here,we fingerprinted and determined the genetic relationships and core collections of Chinese chestnuts using 18 fluorescently labeled SSR markers generated from 146 chestnut accessions.Our analyses showed that these markers from the tested accessions are highly polymorphic,with an average allele number(N_(a))and polymorphic information content(PIC)of 8.100 and 0.622 per locus,respectively.Using these strongly distinguishing markers,we successfully constructed unique fingerprints for 146 chestnut accessions and selected seven of the SSR markers as core markers to rapidly distinguish different accessions.Our exploration of the genetic relationships among the five cultivar groups indicated that Chinese chestnut accessions are divided into three regional type groups:group I(North China(NC)and Northwest China(NWC)cultivar groups),group II(middle and lower reaches of the Yangtze River(MLY)cultivar group)and group III(Southeast China(SEC)and Southwest China(SWC)cultivar groups).Finally,we selected 45 core collection members which represent the most genetic diversity of Chinese chestnut accessions.This study provides valuable information for identifying chestnut accessions and understanding the phylogenetic relationships among cultivar groups,which can serve as the basis for efficient breeding in the future.

Genetic Diversity of Maize Populations Developed by Two Kinds of Recurrent Selection Methods Investigated with SSR Markers

Two cycles of biparental mass selection （MS） and one cycle of half-sib-S3 family combining selection （HS-S3） for yield were carried out in 2 synthetic maize populations P4C0 and P5C0 synchronously. The genetic diversity of 8 maize populations, including both the basic populations and their developed populations, were evaluated by 30 SSR primers. On the 30 SSR loci, a total of 184 alleles had been detected in these populations. At each locus, the number of alleles varied from 2 to 14, with an average of 6.13. The number and ratio of polymorphic loci in both the basic populations were higher than those of their developed populations, respectively. There was nearly no difference after MS but decreased after HS-S3 in both the basic populations in the mean gene heterozygosity. The mean genetic distance changed slightly after MS but decreased in a bigger degree after HS-S3 in both the basic populations. Analyses on the distribution of genetic distances showed that the ranges of the genetic distance were wider after MS and most of the genetic distances in populations developed by HS-S3 were smaller than those in both the basic populations. The number of genotypes increased after MS but decreased after HS-S3 in both the basic populations. The genetic diversity of intra-population was much more than genetic diversity of inter-population in both the basic populations. All these indexes demonstrated that the genetic diversity of populations after MS was similar to their basic populations, and the genetic diversity was maintained during MS, whereas the genetic diversity of populations decreased after HS-S3. This result indicated that heterogeneity between some of the individuals in the developed populations increased after MS, whereas the populations become more homozygotic after HS-S3.

SSR Markers for Fusarium Head Blight Resistance QTLs in Three Wheat Populations

The objective of this research is to identify DNA markers linked to QTLs controlling FHB resistance in wheat, and to compare if the QTLs in three resistant germplasm are common. Three wheat recombinant inbred populations derived from the crosses between Alondra (susceptible) and three resistant lines, Wangshuibai, Sumai3, and 894037, respectively, were evaluated for reaction to Fusarium graminearum in greenhouse and in field conditions over years. Simple sequence repeat (SSR) markers were screened in the populations and regression analysis was used to identify markers associated with FHB resistance. For the population of Sumai3 (resistant)/Alondra (susceptible), which contained 161 recombinant inbred lines, two SSR markers located on chromosome 3B were found to be associated with resistant QTLs. These markers accounted for 2.66.7% phenotypic variation. The 894037 (resistant)/Alondra (susceptible) population was consisted of 147 recombinant inbred lines. A total of 59 SSR primers were screened in this population and seven of them were linked to resistant QTLs. The QTLs on chromosome 3B accounted for 47.4% phenotypic variation. Minor QTLs were also located on 2D, 7A, 6B, and 4B chromosomes, and the resistant QTLs on 2D and 4B chromosomes were from Alondra. The last population of 80 recombinant inbred lines was from the cross Wangshuibai (resistant)/Alondra (susceptible). A total of 120 SSR primers were screened in this population, eight of which were linked to resistant QTLs. These markers were located on 3B, 4B, 2D, 4D, and 6D (uncertain) chromosomes respectively. The QTLs on chromosome 3B accounted for 8.927.0% phenotypic variation. The resistant QTLs on chromosomes 4B and 6D (uncertain) were from Alondra. The other QTLs were from Wangshuibai. SSR markers linked to resistant QTLs on chromosome 3B were found in all three populations, and account for higher phenotypic variation. So these markers should be useful in marker assisted selection.

Assessment of wheat variety distinctness using SSR markers

Assessment of variety distinctness is important for both the registration and the protection of particular variety. However, the current testing system, which assesses a range of morphological characters of each pair of varieties grown side-by-side, is time-consuming and is not suitable for the assessment of hundreds of samples. The objective of this study was to develop a procedure for the assessment of wheat variety distinctness using simple sequence repeat（SSR） markers. A comparison between the molecular and morphological profile of 797 varieties was made. On the basis of the comparison, pairs of varieties with a genetic similarity value（GSV） ≤90% were deemed to be distinct, accounting for ~85% of varieties assessed in wheat regional trials. For the remaining ~15% of varieties, GSVs between different varieties were 〉90%, among which ~35% were not distinct and the other ~65% were distinct. Therefore, if given a GSV〉90%, the pairs of varieties should be morphologically assessed in the field. To avoid any errors in the assessments, we proposed the elimination of contaminant plants from the sample before comparing the varietal genotypes, scoring of the genotype at each locus with a pair of allele numbers when constructing a molecular profile, and faithfully recording two alleles at a non-homozygous locus. To reduce the workload and cost, a three-grade markers comparison among varieties is suggested. In addition, 80 SSR markers and a technical procedure for assessment of wheat variety distinctness have been proposed. Based on the procedure, the distinctness assessment of ~85% of all wheat varieties is completed in our laboratory annually. Consequently, total field assessment has been reduced considerably.

Association analysis of grain traits with SSR markers between Aegilops tauschii and hexaploid wheat(Triticum aestivum L.)

Seven important grain traits, including grain length（GL）, grain width（GW）, grain perimeter（GP）, grain area（GA）, grain length/width ratio（GLW）, roundness（GR）, and thousand-grain weight（TGW）, were analyzed using a set of 139 simple sequence repeat（SSR） markers in 130 hexaploid wheat varieties and 193 Aegilops tauschii accessions worldwide. In total, 1 612 alleles in Ae. tauschii and 1 360 alleles in hexaploid wheat（Triticum aestivum L.） were detected throughout the D genome. 197 marker-trait associations in Ae. tauschii were identified with 58 different SSR loci in 3 environments, and the average phenotypic variation value（R2） ranged from 0.68 to 15.12%. In contrast, 208 marker-trait associations were identified in wheat with 66 different SSR markers in 4 environments and the average phenotypic R2 ranged from 0.90 to 19.92%. Further analysis indicated that there are 6 common SSR loci present in both Ae. tauschii and hexaploid wheat, which are significantly associated with the 5 investigated grain traits（i.e., GA, GP, GR, GL, and TGW） and in total, 16 alleles derived from the 6 aforementioned SSR loci were shared by Ae. tauschii and hexaploid wheat. These preliminary data suggest the existence of common alleles may explain the evolutionary process and the selection between Ae. tauschii and hexaploid wheat. Furthermore, the genetic differentiation of grain shape and thousand-grain weight were observed in the evolutionary developmental process from Ae. tauschii to hexaploid wheat.

SSR markers development and their application in genetic diversity evaluation of garlic(Allium sativum)germplasm

Garlic(Allium sativum),an asexually propagated vegetable and medicinal crop,has abundant genetic variation.Genetic diversity evaluation based on molecular markers has apparent advantages since their genomic abundance,environment insensitivity,and non-tissue specific features.However,the limited number of available DNA markers,especially SSR markers,are insufficient to conduct related genetic diversity assessment studies in garlic.In this study,4372 EST-SSR markers were newly developed,and 12 polymorphic markers together with other 17 garlic SSR markers were used to assess the genetic diversity and population structure of 127 garlic accessions.The averaged polymorphism information content(PIC)of these 29 SSR markers was 0.36,ranging from 0.22 to 0.49.Seventy-nine polymorphic loci were detected among these accessions,with an average of 3.48 polymorphic loci per SSR.Both the clustering analyses based on either the genotype data of SSR markers or the phenotypic data of morphological traits obtained genetic distance divided the 127 garlic accessions into three clusters.Moreover,the Mantel test showed that genetic distance had no significant correlations with geographic distance,and weak correlations were found between genetic distance and the phenotypic traits.AMOVA analysis showed that the main genetic variation of this garlic germplasm collection existed in the within-population or cluster.Results of this study will be of great value for the genetic/breeding studies in garlic and enhance the utilization of these garlic germplasms.

The Genetic Relationship of Two New Colorful Sweet Osmanthus fragrans Cultivars Revealed by AFLP and SSR Markers

Osmanthus fragrans is well-known as an ornamental and agricultural plant noted for its unique fragrance.We investigated the genetic relationships between two new colorful O.fragrans cultivars,Ziyan Gongzhu and Qiannan Guifei,and their relationships with other O.fragrans using amplified fragment length polymorphism(AFLP)and simple sequence repeat(SSR),compared to the Changye Muxi species.55 AFLP primer pairs and 17 SSRs were screened;1103 and 45 amplification products were produced,of which 92.29%of the AFLP and 62.20%of the SSRs were polymorphic.At the population level,the number of effective alleles varied from 0.76 to 1.11,and the Shannon index(I)ranged from 0 to 0.11,indicating a narrow genetic base of O.fragrans cultivars.The genetic similarity varied from 0.61 to 0.80 between Ziyan Gongzhu and other O.fragrans cultivars,and 0.57 to 0.67 in the Qiannan Guifei and other cultivars.The unweighted pair group method with arithmetic mean(UPGMA)clustering revealed that Ziyan Gongzhu may belong to the O.fragrans Albus group.However,the Qiannan Guifei cultivar was clustered into a group,showing that it has great genetic variation.These results provide new molecular evidence for germplasm resources protection,and new cultivars for breeding.

Development of polymorphic SSR markers and their applicability in genetic diversity evaluation in Euptelea pleiosperma

Euptelea pleiosperma is a characteristic species of East Asian flora with both ornamental and scientific values.Based on the reduced-representation sequencing(RRS)technology of RAD-Seq,this study conducted high-throughput Illumina paired-end sequencing to find SSR marker information in the genome of E.pleiosperma,and to screen and verify polymorphism of SSR markers.We obtained 5.5G of high-quality data using RAD-Seq.The total number of contigs of the RAD tags was 299,376,with the maximum contig length of 2,062 bp and the average length of 445 bp.From these sequences,we identified 20,718 SSR loci,with a distribution density of one SSR per 6.45 kb(1/6.45 kb).Among all SSRs,dinucleotides(52.00%)were the most detected SSRs,followed by mononucleotides(21.63%).AG/CT was the dominant motif in the SSR loci,accounting for 34.8%.Primers were successfully designed for 14,593 loci,and 100 pairs of these primers were randomly selected for chemical synthesis and validated by SSR-PCR amplification in 20 individuals of E.pleiosperma.Seventy-nine primers were able to amplify the target bands.Cervus 3.0 software was used to analyze the selected 20 SSR loci with good polymorphism.For the 20 SSR markers,the number of alleles ranged from 4 to 9,and the observed heterozygosity and expected heterozygosity were from 0.35 to 0.75 and 0.541 to 0.875,respectively.The information content of polymorphic loci ranged from 0.463 to 0.848,with an average value of 0.638.Among them,there were 18 highly polymorphic loci,and 20 SSR loci did not deviate from the Hardy-Weinberg equilibrium.Furthermore,the 20 pairs of SSR primers were used to conduct PCoA analysis based on Nei’s genetic distance of 51 individuals from three populations.The results showed that these SSR markers could distinguish genetic differences based on different geographical locations.

Identification of Introgressed Lines by the SSR Markers and Agronomic Traits

The wild cotton cultivars and species have abundant genetic polymorphisms,and they possess lots of excellent genes,such as drought resistance,insect resistance,fine and strong fiber,and so on.

Genetic Analysis and Preliminary Mapping of a Highly Male-Sterile Gene in Foxtail Millet(Setaria italica L.Beauv.) Using SSR Markers

Breeding of male-sterile lines has become the mainstream for the heterosis utilization in foxtail millet,but the genetic basis of most male-sterile lines used for the hybrid is still an area to be elucidated.In this study,a highly male-sterile line Gao146A was investigated.Genetic analysis indicated that the highly male-sterile phenotype was controlled by a single recessive gene a single recessive gene.Using F 2 population derived from cross Gao146A/K103,one gene controlling the highly male- sterility,tentatively named as ms1,which linked to SSR marker b234 with genetic distance of 16.7 cM,was mapped on the chromosome VI.These results not only laid the foundation for fine mapping of this highly male-sterile gene,but also helped to accelerate the improvement of highly male-sterile lines by using molecular marker assisted breeding method.

Detection of Allelic Variation in Chinese Wheat (Triticum aestivum L.) Germplasm with Drought ToleranceUsing SSR Markers

Allelic variation in two domestic wheat landraces, Pingyaobaimai and Mazhamai, two cornerstone breeding materials and their derived cultivars with drought tolerance was detected by SSR (simple sequence repeat) markers. The clustering of 25 accessions showed that the similarity between Pingyaobaimai and Yandal817, the latter was developed from the former, was 0.71, the highest one of all accessions, but the similarities were very low between these two accessions and other accessions including their derived cultivars. A similar situation was revealed between Mazhamai and its derived cultivars. Pingyaobaimai and its three derived cultivars shared three alleles at loci Xgwm526, Xgwm538 and Xgwm126 on chromosome arms 2BL, 4BL and 5AL, respectively. There were six shared alleles in Mazhamai and its derived cultivars, in order of Xgwm157, Xgwm126, Xgwm212, Xgwm626, Xgwm471 and Xgwm44 on chromosome arms 2DL, 5AL, 5DL, 6BL, 7AS and 7DC, respectively. Only one shared allele was detected between the pedigrees of Pingyaobaimai and Mazhamai. The difference of shared alleles in two cornerstone breeding materials and their derived cultivars revealed the diversity in Chinese wheat germplasm with drought tolerance and the complication in genetic basis of drought tolerance in wheat.