Mapping Of Yellow Leaf Mutant Gene Lcm136 In Chinese Cabbage

Chinese Cabbage(Brassica rapa ssp.Pekinensis)is an important vegetable crop in East Asia.Leaf is not only the main edible organ,but also the main photosynthetic organ of cabbage.Leaf color mutants are important resources for the study of photosynthetic pigment metabolism and nuclear cytoplasmic interaction.One yellow leaf mutant(M136)was identified in the progeny of DH line(No.136)of Chinese cabbage.In this paper,the photosynthetic physiology and chloroplast ultrastructure of the yellow mutant and the wild type were analyzed,the yellow mutant gene was initially located,and the transcriptome differences between the wild type and the mutant were analyzed.The specific results are as follows:1.M136 was identified as a yellowing mutant at seedling stage,with normal green cotyledons and golden yellow young leaves.With the growth of leaves,the leaves gradually returned to green.When the commodity is mature,the whole leaf becomes green completely.2.It was found that the photosynthetic pigment content of M136 was significantly lower than that of wild-type 136 during yellowing,and the level of M136 pigment was only slightly lower than that of wild-type after returning to green.And the change of M136 has little effect on production,and there is almost no difference from the wild type 136 in the final dry weight analysis.The photosynthesis parameter of mutant M136 was significantly lower than that of wild type 136 when yellowing,and the situation improved after returning to green.Analysis of chlorophyll fluorescence parameters,the mutant M136 had weak chlorophyll electron transfer ability.At the same time,its chloroplast was defective.After returning to green,the chloroplast function was normal and its shape was slightly smaller.3.In multi generation breeding,the genetic characteristics of the mutant M136 followed Mendel's law,and it was judged that it was dominated by a single recessive nuclear gene(lcm 136).Using the second generation sequencing technology,the dominant pool(BG)and recessive pool(BW)of FT,M136 and F2 populations were sequenced in depth,and the yellow gene was located in the range of 6081599bp-6914748bp on A06 chromosome.4.The second generation sequencing technique was used to analyze the transcriptome of M136 and wild type 136 young true leaves,and M136 and 136 leaves after returning to green.759 genes were differentially expressed between the yellow leaves and wild-type leaves of M136,of which 419 were up-regulated and 340 were down regulated.Compared with wild type 136,there were 4375 genes differentially expressed,1774 of which were up-regulated and 2601 down regulated.In the study of gene function,go analysis was carried out on the difference genes found.Compared with wild type 136,there were 745 significantly different genes in M136 in the yellowing state,and 50 terms were significantly enriched;the yellowing process after returning to green Compared with wild type 136,there are 4307 genes with significant difference in M136.There are 50 terms significantly enriched.In KEGG analysis,compared with wild type 136,M136 in yellowing state has 411 significantly different genes,11 significantly enriched pathways;compared with wild type 136,M136 in returning green state has 2556 significantly different genes,9 significantly enriched pathways.