| Leaf color mutation is a widespread variation type in plant.Leaf color mutants have been identified in maize,rice,barley,Arabidopsis and many other plants.The typical of leaf color variation in plants is yellowing,which has become an important material for studying the mechanism of photosynthesis,chlorophyll biosynthesis,chloroplast development and its genetic control.Chinese cabbage(Brassica campestris L.ssp.pekenensis)takes leaves as photosynthetic and product organs,and leaf color variation has always been the focus of breeding workers.In this study,six yellowing mutants of Chinese cabbage,such as pem2~pem7,were produced by EMS mutagenesis with double haploid line ?FT‘.Based on the analysis and identification of the phenotypic,genetic and physiological characteristics of the mutant pem2~pem7,the Brpem2 gene of the mutant pem2 was located by BSR-Seq technique and SSR analysis.The main results are as follows.1.The mutant pem2~pem7 showed yellowing of the whole plant,and the yellowing phenotype was stable throughout the growth period.Genetic analysis showed that the mutation phenotypes of pem2~pem7 were caused by recessive mutation of nuclear gene.The results of allele analysis showed that the mutant genes of the six mutants were non-allelic.2.The content of photosynthetic pigments in the mutant pem2~pem7 was significantly lower than that in the wild type ’FT’,the net photosynthetic rate was lower than that in the wild type ’FT’,and the stacking degree of chloroplasts was lower.3.A large-scale F2 gene mapping population was constructed by crossing the mutant pem2 with the inbred line K23 of Chinese cabbage.The mutant gene Brpem2 was initially located in four segments of chromosome A10 by BSR-Seq technique.By SSR linkage analysis,the mutant gene Brpem2 was located between SSR 9-27 and SSR 15-13 markers on chromosome A10.The genetic distance was 0.03 c M and 0.03 c M,and the physical distance was 579.2 Kb.There were 60 genes in this region. |
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