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۱Quantitative Trait Loci Associated with Isolate Specific and Isolate Non–Specific Partial Resistance to Sclerotinia sclerotiorum in Sunflower
اطلاعات انتشار: Journal of Agricultural Science and Technology، هفدهم،شماره۱، ۲۰۱۵، سال
تعداد صفحات: ۱۴
Basal stem rot caused by Sclerotinia sclerotiorum (Lib.) de Bary is one of the most important diseases of sunflower. Quantitative trait loci (QTL) implicated in partial resistance to two isolates of S. sclerotiorum (SSU107 and SSKH41) were investigated using F9 recombinant inbred lines (RILs) from the cross between sunflower parental lines PAC2 and RHA266. Experiments were conducted in completely randomized design with 3–6 replications under controlled conditions. The reaction of genotypes to basal stem rot disease was evaluated by measuring the percentage of necrosis area three days after inoculation. Combined analysis of experiments showed significant interactions between sunflower genotypes and S. sclerotiorum isolates suggesting that partial resistance to S. sclerotiorum should be isolate–specific in sunflower. QTLs were mapped using an updated high–density SSR and SNP linkage map. The map consisted of 210 SSRs and 11 genederived markers placed in 17 linkage groups (LGs). The total map length was 1,653.1 cM with a mean density of 1 marker per 7.44 cM. A total of 14 QTLs were detected for partial resistance to two isolates. The phenotypic variance explained by QTLs (R2) ranged from 0.10 to 9.85. The sign of additive gene effects showed that favorable alleles for partial resistance to isolates came from both parents. Six QTLs were common between two isolates on LGs 1, 8 and 17, whereas the others were specific for each isolate. Colocalized QTLs on LG 1 were linked to the glutathione S–transferase gene (GST). The colocalized QTLs for partial resistance to basal stem rot isolates could be good candidates for marker assisted selection (MAS).

۲Comparative Assessment of IRAP, REMAP, ISSR, and SSR Markers for Evaluation of Genetic Diversity of Alfalfa (Medicago sativa L.)
اطلاعات انتشار: Journal of Agricultural Science and Technology، هفدهم،شماره۴، ۲۰۱۵، سال
تعداد صفحات: ۱۲
The effectiveness of IRAP, REMAP, SSR, and ISSR markers were investigated to assess genetic diversity among and within eight Medicago sativa L. populations. A total of 101, 119, 117 loci and 31 alleles were amplified using 10 IRAP, 14 REMAP, 16 ISSR and eight SSR primers, respectively. IRAP markers generated the maximum proportion of polymorphic loci per primer (PPLP) while the maximum value of percentage of polymorphic loci (PPL) was observed for SSR markers. ISSR markers showed the highest value of marker index (MI). The maximum amount of expected heterozygosity (He), effective number of alleles (Ne), and Shannon’s information index was produced by SSR markers. UPGMA cluster using Nei’s genetic distance coefficients and combined data of four markers separated the populations into three major groups. Correlation coefficients among pairwise genetic and geographic distance matrices, made on the basis of all studied markers, were calculated using Mantel's test. Regression and correlation analysis between genetic distance and geographic distance showed no significant correlations (p>0.05).

۳Genetic Diversity in Iranian Melon Populations and Hybrids Assessed by IRAP and REMAP Markers
اطلاعات انتشار: Journal of Agricultural Science and Technology، هفدهم،شماره۵، ۲۰۱۵، سال
تعداد صفحات: ۱۱
Retrotransposons (RTNs) constitute informative molecular markers for plant species because of their ability to integrate into a multitude of loci throughout the genome and thereby generate insertional polymorphisms between individuals. In the present study, RTN–based molecular markers, IRAP (inter–retrotransposon amplified polymorphism) and REMAP (retrotransposon–microsatellite amplified polymorphism), were applied to study RTN integration events and genetic diversity in 100 melon genotypes (88 genotypes from 11 populations, three inbred lines, and 9 hybrids). A total of 94 and 262 loci were amplified using 5 IRAP and 15 REMAP primers, respectively. The percentage of polymorphic loci (PPL) in populations ranged from 39% (Zivari Shahrood) to 48% (Shadegani E). The Mantel test between IRAP and REMAP cophenetic matrices evidenced no significant correlation (r= 0.29). IRAP+REMAP–based cluster analysis using UPGMA algorithm and Dice similarity coefficient depicted 6 groups among 100 melon genotypes. AMOVA revealed the higher level of genetic variation within populations (67%) compared to among populations (33%). The mean Fst values of all groups, except for group VI, were more than 0.20, demonstrating differentiation among the populations and genetic structure of the studied melon collection.
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