Molecular Mechanism Of The Incomplete Albinism In Tea Leaves(Camellia Sinensis Cv. Huangshanzhong)

As a leafy plant,tea plant(Camellia sinensis(L.)O.Ktze.)widely planted is an important economic crop in the world.Because the characteristic chemical composition of tea with specific leaf color is closely related to its quality,the study on the color diversity of tea leaves has been widely concerned by the tea industry.In this study,single plant of albino tea plant in Huangshan population was used as the research material,and it was found that the white tea tree was different from the temperaturesensitive albino tea plant and light-sensitive albino tea plant,which changed with the change of temperature and light intensity.Therefore,studies were carried out on the components,tissue structure,gene expression differences and protein expression differences in the white tea plant,and the following results were obtained:(1)Through paraffin section,it was found that palisade tissue cells of the pallid leaves were arranged loosely,and the degree of tissue structure was significantly lower than that of the normal leaves.The ultrastructural analysis of the pallid leaves revealed that the chloroplasts of the pallid leaves were abnormally developed,with no obvious thylakoids and cavities.It was found through the comparative analysis of the contents of the contained substances that compared with the normal leaves,the chlorophyll content of the white leaves decreased significantly,and the caffeine content increased slightly.Compared with normal leaves,the total catechin content in the albino leaves decreased by 52.66%,while the total free amino acid content increased by 52.15%,in which the theanine content in the white leaves increased by 62.73%.(2)Through transcriptome analysis of white and normal leaves,a total of 3431 differential genes were obtained.Based on the analysis of the genes related to theanine and polyphenols biosynthesis in the characteristic metabolism of tea plant,it was found that the level of genes related to catechin metabolism pathway in the white leaves were lower than those in the normal leaves,while the genes related to theanine metabolism pathway were opposite.The analysis also showed that the expression patterns of different genes in chlorophyll biosynthesis or degradation,photosynthesis,chloroplast development and biosynthesis were affected.The gene expression of light capture antenna protein(LHC)in photosynthetic leaves was significantly lower than that in normal leaves,and the expression of different genes related to the synthesis of chlorophyll pathway was also lower than that in normal leaves.(3)A total of 95 differentially expressed proteins were obtained by proteomic analysis of the white and normal leaves of the albino tea plant.Through KEGG pathway enrichment analysis,the results showed that the oxidative phosphorylation,flavonoids biological pathways and styrene acrylic biosynthesis(phenylpropanoid biosynthesis)and other important pathways changed dramatically,and the metabolic pathway in photosynthesis,purine metabolism were affected.(4)Clp protease complex was found to be related to chloroplast development and leaf color in the screening of differential genes.The CsClpP5 gene was amplified in albino and normal leaves.Sequence analysis showed that the CsClpP5 gene cloned from the white leaves was 909 bp long and encoded 303 amino acids.However,the CsClpP5 gene amplified in the normal leaves was full length 903 bp,encoding 301 amino acids.Mutation of two amino acid sites was found by sequence alignment,and analysis of the phosphoric acid site revealed that the mutation site changed the phosphoric acid site of Clp P5.