Establishment And Application Of SSR Molecular Marker Identification System For Common Bean (Phaseolus Vulgaris L.)

Common bean(Phaseolus vulgaris L.)is one of the main edible beans in China.With the continual increase in breeding of new common bean varieties recent years,the phenomenon that common beans of the same varieties are named differently or those of different varieties but are named the same becomes more and more serious.Meanwhile,With the rapid development of protection for new varieties in China,the number of applying for protection rights for new varieties of common bean is increasing year by year.Therefore,It put forward a higher requirement to efficiency of rapid identification and DUS testing of common bean varieties.It is particularly urgent to establish a reliable variety identification system to regularize the common bean seed market and ensure the healthy development of common bean industry.Based on SSR molecular markers,this study established a common bean variety identification system and a variety fingerprint database,aiming at providing a strong technical support for the authenticity identification of common bean and a fast and reliable way for the DUS test assisting in screening similar varieties.It also evaluates the genetic diversity of standard varieties in the DUS test guidelines for common bean based on DNA molecular database of varieties,providing reference basis for the revision of the DUS test guidelines at the molecular level.The main conclusions of this study are as follows:1.Established an identification system and variety fingerprint database for common bean by SSR molecular marker33 pairs of high polymorphism SSR core primers uniformly distributed on the on the common bean genome were screened out,the SSR marker variety identification system and the SSR fingerprint database for 161 varieties for common bean were established.This set of core primers can identify 140 common bean varieties in the database,and it can cluster varieties according to germplasm sources,separate breeds with lower genetic similarity,and cluster closely related breeds into the same or similar group.The variety identification system and SSR fingerprint database can provide strong support for the authenticity identification of common bean varieties.2.Evaluated the feasibility of SSR fingerprint database assisting in selection similar varieties for DUS testAnalyzed the genetic diversity of 4 common bean varieties that have been authorized new variety rights and their similar varieties selected in the DUS test.The analysis results showed that the genetic similarity coefficient between different authorized varieties is low,but the genetic similarity between the authorized varieties and their similar varieties is high.The botanical traits are also very similar among the varieties with high genetic similarity.The field DUS test results of 7 varieties that can’t identified by core primers also showed that the botanical traits are highly similar among varieties with genetic similarity coefficient of 1.The above results showed that the results of screening similar varieties using a known variety botanical traits database are consistent with the results of screening similar varieties through the SSR fingerprint database,and further verify that the fingerprint database can be used to assist in the selection of approximate varieties for the DUS test.3.Analyzed the genetic diversity of standard varieties in the common bean DUS test guideBased on the established common bean SSR fingerprint database,the genetic diversity of26 standard varieties in the common bean DUS test guideline was analyzed.The results showed that most of the 26 standard varieties had long genetic distances with each other,indicating that genetic diversity among varieties was rich,and the selection of sample varieties was quite reasonable.Among them,only the genetic similarity coefficient between’Shuangyang Dahuapi’ and ’Dahuahuaquedan’ is higher than 0.8,and both of them only indicate one trait in the test guide.Further field comparison experiments can be carried out based on this result to reduce the number of standard varieties and further improve the efficiency of DUS testing.