Cloning And Identification Of A Golden Leaf Gene Lcm2 In Chinese Cabbage

Chinese cabbage(Brassica rapa ssp.pekinensis)is the largest vegetable crop in China.The leaf is its main edible part,and the leaf is also the place where the cabbage is used for photosynthesis.Therefore,it is particularly important to study the various traits of Chinese cabbage,especially the leaf.With the sequencing of the Chinese cabbage genome sequence completed,it is the cabbage functional genome.The research provides a lot of reliable information(Wang et al.,2011).Leaf color mutants are increasingly being used in the study of gene function.This paper obtained a yellowing of Chinese cabbage leaves through EMS mutagenesis.The mutant lcm2,after determining its stable inheritance,analyzes the physiological characteristics of the mutant and the wild type,uses the improved mutmap technique to identify the mutation site,and clones the corresponding mutant gene lcm2,using the transcriptome sequencing technology.Further validation was performed on the mutation sites to find relevant metabolic pathways that may be involved in leaf yellowing.The main findings are as follows:1.Chinese cabbage yellowing mutant ’lcm2’ showed yellowing of leaf color throughout the growth stage.The light and pigment in the two were measured and found that the content of chlorophyll and carotenoids in ’lcm2’ was significantly reduced.However,the dry weight of the mutant plants at different times was slightly lower than that of the wild type at the same time,and there was no obvious light and capacity reduction,and they could grow and develop normally.2.Observe the chloroplast structure of ‘lcm2’ and ‘FT’ plants.The ‘lcm2’ chloroplast shows abnormal development and irregular shape,with no obvious basal structure.Compared with ‘FT’,the net photosynthetic rate of ‘lcm2’ decreased,and the photosynthetic capacity decreased.Comparison and analysis of the fluorescein kinetic parameters of the two plants revealed that both the photosynthetic efficiency and the electron transport rate of ‘lcm2’ plants were reduced.3.Prediction and cloning validation of the yellowing mutant gene using the modified Mutmap method resulted in the Brassica mutant gene BraA03000615 located on chromosome A03,named lcm2.Transcriptome analysis was performed on mutants and wild type to further verify the above localization results.744 differentially expressed genes were found by comparison with the reference genome and the participating genes,of which 328 genes were up-regulated in ’lcm2’,416 The DEGs were down-regulated in ’lcm2’.4.In GO function enrichment analysis,39 GO terms were significantly enriched,of which 29 were enriched in biological processes,7 were enriched in molecular function,and 3 were annotated to cellular components.in.Through the pathway analysis of DEGs through the KEGG database,DEGs were significantly enriched in 16 KEGG pathways.It is noteworthy that it contains three pathways that may be related to leaf color,including anthocyanin metabolic pathways and photosynthesis.Carbon fixation and light conversion pathways can provide reference for leaf color research.