Screening Of SSR Core Primers And The Identification Of Genuineness And Purity On Hybrid Cotton

At present, the problems with cotton includ huge number of varieties, disorderly layout and quite a number of false seeds. These affect the cotton production and variety management badly. To ensure the genuineness of conventional varieties, the identification of purity is one of effective measures. SSR molecular marker technology has obvious advantages in the identification of seed genuineness and purity. However, because of the narrow genetic background of hybrid cotton, the low polymorphism in hybrid cotton varieties, the huge number of SSR markers, the common information differences in SSR markers and so on, SSR technology has not achieved a major breakthrough on the identification of hybrid cotton genuineness and purity. In this experiment, we selected a lot of primers to screen core primers for hybrid cotton varieties, indentified the genuineness and purity of three hybrid cotton varieties using core primers, simplified and optimized the identification technology and the statistic method, evaluated the genetic diversity of hybrid cotton varieties, and provided the theory and practice for new variety selection and thoroughbred breed. The main conclusions were as follows:1.42 cotton hybrids and cotton hybrid Huazamian H318 provided by Huazhong agricultural university,43 cotton hybrids were used as materials in total for screening 2200 pairs of SSR primers obtained from the Cotton Microsatellite Database(http://www.cottonssr.org), and 80 pairs of polymorphic primers with good comprehensive properties were screened.37 conventional hybrid varieties provided by breeders from different units were used to verify and evaluate these 80 pairs of primers, and 56 pairs of primers with distinct polymorphic bands, highly repeatable and high resolution were screened. The verification results showed that:these 56 pairs of core primers were typical, practical and reliable.2.56 pairs of primers generated 95 polymorphic loci in 37 conventional hybrid varieties, ranging from one to three, and a total of 161 genotypes were detected, ranging from two to seven, with the average number 1.69 of alleles per locus.10 pairs of core primers can be used to separate 37 conventional hybrid varieties totally, and these 10 pairs of core primers were suggested as the first-choice markers for the identification of variety genuineness and purity.3.37 conventional hybrid varieties were clustered and analyzed through NTSYS-PC V2.1 analysis software, and the results showed that 37 conventional hybrid varieties were basically divided into two subgroups included cotton of catchment of the Yangtze River and cotton of the Huanghe valley.4. We identified the purity of Ezamian No.10, C111 and Huazamian H318 by both molecular marker technology and field morphology methods. Two methods showed the same results about the relationship of three hybrids:Huazamian H318>Ezamian No.10>C111. However, the molecular marker technology results were lower than field morphology results.5. A new purity statistic method was presented and its results showed no significant differences from the results of the commonly used method. In theory, the new method can reveal the genetic information of each single plant and has a certain biological significance for the current study of hybrids.