Study On The Biological Characteristics And Mechanism Of Main Quality Formation Of The Albino Tea Plant (Camellia Sinensis Cv.'Huangshanbaicha')

Tea plant belongs to the Camellia group of Camellia family.Tea plant is an important woody cash crop and one of the three largest soft drinks in the world.Tea is the origined from China,which is the first country in the world to discover,cultivate and utilize tea resorces.As the largest tea-producing County in the history of China,Huangshan Shexian County,with its superior natural conditions,has bred abundant tea plants resources.In recent years,'Huangshanbaicha',a naturally varying albino new shoot tea plant in Shexian County,has become a wonderful brand in tea industry in Anhui province because of its ornamental jade-white buds and leaves with high amino acid content,which enriches tea products and increases the income of tea farmers in Anhui province.However,up to date,the studies on biological characteristics of Huangshanbaicha and the mechanism of albino formation are still very limited.In this study,the study on characteristics of 'Huangshanbaicha 1' was investgated.The chloroplast structure and main secondary metabolites during bud and leaf development were analyzed using transmission electron microscopy and high performance liquid chromatography(HPLC).In addition,RNA-seq technology was used to explor biological e the mechanism of the four stages(S0-S3)of leaf color change of local population('Huangshanzhong')and albino variety('Huangshanbaicha 1').The transcriptome data of different smples was analyzed through,examing on the changes of biosynthesis and gene expression of metabolic pathways,such as chloroplast,characteristic secondary metabolites(theanine(amino acid),catechin)of tea leaves,to eluciate the physiological and molecular mechanism of the formation of specific biological characteristics of'Huangshanbaicha'.The main results are obtained as following:1)A new provincial tea cultivar,‘Huangshanbaicha 1' was screened by variety evaluation experiment,which has better comprehensive characteristics with 10%free amino acid content in leaf.The research on short-spike cutting and rapid propagation,seedling nursery and hydroponic rooting technology of‘Huangshanbaicha'was performed,and a relatively complete rapid propagation technology system was estabolished.2)Through constant temperature cultivation,it was preliminarily determined that'Huangshanbaicha'was a temperature-sensitive tea plant,with a temperature threshold of 22>whitening to green>18 based on the research results,temperature was the main regulator in the process of starting whitening to green,and there was a certain correlation between greening and effective accumulated temperature.3)Through detecting the chloroplast ultrastructure of buds and leaves at different developmental stages with the population species of 'Huangshanzhong',which is the source of variation.It was found that the lamellar structure of grana,the number of starch grains and the saccular vacuoles of chloroplast were one of the main reasons for the low chlorophyll content and the albinism of leaves of 'Huangshanbaicha 1'.4)By comparing the transcriptome sequencing of buds and leaves of 'Huangshanbaicha'and 'Huangshanzhong' at different developmental stages,it was found that the changes of DVR,POR1 and POR2 expression involved in chlorophyll biosynthesis pathway is an important reason for the formation of white color of 'Huangshanbaicha';In regard to the study on the key genes expression changes leading to the pathway of amino acid synthesis,metabolism and transport,it was denied that the ability of amino acid synthesis of Huangshanbaichawas higher than that of Huangshan species.The results showed that the high content of amino acids in the buds and leaves of 'Huangshanbaicha' was not due to the strong accumulation mechanism,but mainly due to the weak consumption mechanism(the weakness of the process in catabolism and transportability),In the catechin metabolic pathway,the down-regulation of DFR1,ANS1 and ANS2 genes limited the synthesis of catechin precursors of 'Huangshanbaicha',which became the key limiting key factor for its lower content than that of 'Huangshanbaicha'.In addition,the expression level of PAL gene might be one of the limiting factors for produce less catechin content in the tea plants of 'Huangshanbaicha' than that of 'Huangshanzhong'..