Establishment And Application Of SSR Molecular Marker Identification System For Mustards(Brassica Juncea L.)

Mustard(Brassica juncea L.)is a characteristic vegetable native to China,belonging to the Brassica genus of the cruciferous family.In recent years,the number of mustard varieties newly selected by domestic and foreign universities,research institutes,and mustard vegetable seed companies has been increasing.The phenomenon of “one product with multiple names” and “one product with multiple products” in the Chinese mustard seed market has been increasing.Brand infringement is becoming more and more serious.Therefore,the establishment of a reliable mustard variety identification technology system is particularly important for regulating the mustard seed market,avoiding repeated collection and preservation of mustard varieties,and ensuring the healthy development of the mustard industry.In this paper,189 mustard varieties collected as the research object,based on SSR molecular markers,established a mustard variety identification technology system and variety DNA fingerprint database,analyzed the genetic diversity of 189 mustard varieties,and evaluated the SSR fingerprint database to assist screening DUS The feasibility of testing similar varieties is intended to provide help for the rapid identification of the authenticity of mustard varieties and to assist the DUS test of mustard varieties to screen similar varieties.The main findings are as follows:(1)25 pairs of SSR core primers with clear bands,stability and high polymorphism were screened out.The PIC value of the core primers ranged from 0.23 to 0.86,with an average of 0.493.A total of 175 allelic variants were detected in 189 mustard varieties,and the range of allelic variants was 3-21.A technology system for identification of mustard varieties based on SSR markers was established,and a DNA fingerprint database of 189 mustard varieties was constructed.(2)The genetic distance between 189 mustard varieties was between 0.023 and 1.00,with an average value of 0.472.UPGMA cluster analysis showed that 25 pairs of core primers could distinguish 173 mustard varieties.The tested varieties were divided into four groups.Mustard is distributed in various groups,and its genetic diversity is higher than root,stem and stalk mustard.The clustering results based on molecular markers are not completely consistent with the traditional classification of mustard according to eating parts.In addition,the results of genetic diversity among mustard varieties from different geographical sources showed that the genetic diversity of mustard varieties in Guangdong Province is relatively high.From the overall distribution,most of the mustard varieties in the same province are clustered together,with obvious regional characteristics.(3)The core primers determined in this study were used to analyze the genetic diversity of mustard varieties and their similar varieties,and the two authorized varieties and their similar varieties were gathered together,and the genetic similarity was high.The results showed that the results of screening similar varieties based on variety phenotypic traits data were consistent with the results of screening similar varieties based on molecular markers.It is further verified that the DNA fingerprint database of 189 mustard varieties constructed based on 25 pairs of core primers in this study can be applied to the DUS test to assist in the screening of similar varieties.