Fine Mapping A Major Boll Weight QTL And Fingerprint Studies In Upland Cotton Using SSRs

Traits of agronomic importance, as outlined in other crops, are determined by the interactions among many associated components. Boll weight in cotton is one of the yield associated traits which displayed composite inheritance pattern imputable to inherit complexity and allopolyploid nature of cultivated cotton. Molecular marker technology has broadened the method spectrum for detection, validation of quantitative trait loci (QTLs) and expression profiling of candidate genes conferring these QTLs. Bulk segregation Analysis (BSA) proposed an efficient strategy for identifying DNA markers linked to the genes or genomic regions of interest. Many important yield associated complex traits in plants were fine mapped and located on physical maps to fragments lengths of10-100Kb. Boll weight QTLs in cotton were mapped by many researchers using different mapping populations and assigned to different linkage groups or chromosomes in cotton genome. In present study, seventy-two bulk segregation primers were found and used to genotype F2-2012population. Major Boll weight QTL (qBW12) region was subjected to be enriched by SSRs present on both sides of flanking markers. Primers underlying and across both sides of qBW12were selected for further analysis in a relatively larger population (F2-2013) and flanked markers were detected (HAU4299and Mon_DPL0493) for qBW12. The locus explained13.5%of trait variation with a LOD peak of14.82and confidence interval3.33cM. Progeny testing of recombinants between adjacent markers, around flanking regions of the QTL, could aid to further delimit qBW12. Chromosome12was found homologous to D08, chromosome from D-genome progenitor of cultivated cotton, and consistently reported by many researchers as gene rich region.Selection of core SSR markers for fingerprinting upland cotton cultivars and hybridsPrecise identification of cotton cultivars and hybrids is requisite to facilitate management of germplasm resources and successful hybridization programs. Fingerprinting based on minimal core set of highly informative primers will be more enlightening to unveil genetic constitution among cotton cultivars and hybrids from distinct growing regions of china. Thirty-eight upland cotton cultivars and55hybrids were selected from three cotton growing regions of china mainland i.e. yellow river cotton valley (YRCV), Yangtze river cotton valley (YzRCV) and north west dry region (NWDR); featured with perceptible climatology. Twelve randomly selected cultivar and hybrids (representative sample of the three regions) were employed to reveal polymorphism across mapped SSRs. Sixty-six genome-covered polymorphic SSRs were employed to assess genetic relatedness among all accessions. The results showed a polymorphism information content range from0.34-0.86and resolving power0.04-2.45for genome-covered SSRs. Higher PIC and Rp values rendered selection of13highly informative potential core SSRs, whose average PIC and Rp values were0.80and1.64, respectively. Moreover, Jaccard’s similarity coefficients of genome-covered and potential core SSRs were compared and found to be related. Potential core SSRs substantiated clustering results of genome-covered SSRs and successfully discriminated all accession. Overall clustering pattern and revealed genetic constitution of tested material suggested that the13potential core SSRs could assure comparable results with higher resolution as compared to that of genome-covered SSRs.