Construction A Primary SSR Fingerprint Database For Cotton Cultivars

Cotton is the world’s leading natural fibre crop, as well as an important economiccrop. Authorizing and releasing high quality cultivars play an important role in theagricultural production. While in recent years, some significant breeding parents have beenutilized frequently resulting in the cotton cultivars genetic similarity and hard todistinguish on the basis of their phenotypic performance. Beside, the transgenic technologyhas added the situation since modify just a single genotype can produce a new cultivar. Allof which have made the cotton market disordered and hard to supervise in seed productionand trade. SSR fingerprint identification is of prime importance for ensuring good qualityseed. It is essential to construction a DNA fingerprint for the cotton cultivars.The main conclusions are summarized as follows:1) The40core primers were used for construction of132cotton cultivars DNAfingerprint database based on multiplex fluorescence detection technology. The132cottoncultivars included2010leading cultivars, DUS standard cultivars, source germplasms andlandrace standard cultivars. Forty primers produced a total of177fragments,166in whichwere polymorphic among the132cultivars with94.92%polymorphism. In this study weanalysis the main type of special peak. All of the conventional cotton conduct single or twopeaks; hybrids conduct two, three, or four peaks. Compared to the6%polyacrylamide gelelectrophoresis strained with silver nitrate, the fluorescence-based SSR detection cansignificantly increase the amount of information generated per assay and reduce labor costassociated with large scaled SSR genotyping.2) The40primer pairs amplified a total of262genotypes among the132cultivarswith an average of6.55. Genetic similarity coefficients among the132cultivars range from0.3202to0.9649with an average of0.7902, indicating that the cultivars used in our studyhad a vast genetic base. We have analysis the49leading cultivars,it showed that thehereditary basis of the conventional cultivars were narrower than the hybrid ones.3) In this study, we analysed6hybrids and their parental seeds purity using40coreprimer pairs based on the6%polyacrylamide gel electrophoresis strained with silvernitrate. Primer pairs with complementary band screened out from the core primers were101bands in total, with an average of16.8per primer pairs. There are36primer pairsshowed polymorphism among the40core primers. Each primer pair has one to sixheterozygous loci, with an average of2.97loci. The primer pairs M26is very special, as itshows polymorphism among all the hybrids. The primer pairs M26can be considered asthe primary primer because of its high polymorphism.4) Two methods including single locus on average and double loci difference wereemployed to inspect the purity of six hybrid cottons of correlationship between the SSR purity detection and the morphological identification. As it showed that the morphologicalidentification purity rate is much higher than the SSR purity detection; the single locus onaverage result was much higher than the double locus difference. However, either of theSSR detection method have significance of correlation with the morphologicalidentification. After we eliminated the SSR locus with high impurity displayed in theparent lines, the correlation became much better. The detection method of single locus onaverage had significance correlation with the morphological identification after calibration.Between EST-SSR and Genomic-SSR, EST-SSR had more significance correlation withthe morphological identification after calibration. There was some relativity at differentloci in the same chromosome, so it suggests us selecting the SSR loci with hypodispersionin the whole genome.