| In order to understand the expression level changes of the genes involved in catechin biosynthesis pathway as well as the changes of catechins content in tea leaves with different leaf colors,leaves in different growth stages from five tea varieties,which growing in the same area were selected as experimental materials.Then the expression levels of genes ivolved in catechin biosynthesis pathway and the contents of catechins were measured,and the correlation between them was discussed.The main results are as follows:(1)The fresh stretched leaves of 'Longjing 43' were used as materials.Total RNA was extracted and used for synthesizing cDNA.Amplificating the OFRs of the DFR,LAR and ANR gene using the PCR.According to the results of bioinformatics analysis,the ORF of DFR gene is 1044 bp encoding 347 amino acids and the relative molecular mass of the DFR protein was 38.68 kD,the theoretical equipotential(PI)was 5.84,indicating it is a non-secreted protein with weak hydrophobicity.The ORF of LAR gene is 465 bp to encode 154 amino acids and the relative molecular mass of the LAR protein is 17.17 kD with the theoretical equipotential(PI)is 4.65,which is a hydrophobic non-secretory protein.The ORF of the ANR gene is 1014 bp to encode 337 amino acids,and the relative molecular mass of the protein is 36.29 kD with the PI is 6.11,indicating it is a hydrophilic non-secretory protein.(2)The contents of the contents of tea leaves with different leaf colors were determined by HPLC.The results showed that the chlorophyll contentsof leaves with different colors from high to low was ZJL>LJL>HL>BL>ZJZ>LJX>FDL>FDX>HG>BG>HH>BB,which was consistent with the leaf color in tea leaves.With the development of leaves of 'Baiye l' the total contents of catechins increased firstly and then decreased.The total contents of catechins in the fersh leaves of other varieties was higher than that of the matureleaves.In the fresh stretched leaves of all tea cultivars,the total catechins ranked in descending order were ZJZ>FDX>BG>HG>LJX>HH>BB.There was a significant difference in the total contents of catechins in the fresh and mature leaves of other varieties.However,the total contents of catechins in mature leaves was FDL>ZJL>LJL>BL>HL,with no significant difference.The content of ester catechins from high to low was:ZJZ>FDX>BG>HH>HG>FDL>LJL>LJX>HL>BL>ZJL>BB.The total amount of non-ester catechins was ZJZ>BG>FDX>ZJL>FDL>HH>BL>LJX>HL>HG>LJL>BB.The caffeine contentswereZJZ>FDX>BG>HH>HG>LJX>BB>ZJL>FDL>BL>LJL>HL.(3)Results of qRT-PCR showed that the genesDFR,LAR and ANR were generally down-regulated in matureleaves of different tea cultivars with different leaf colors,and there is no significant difference between theexpression levels of two normal green leaf tea cultivars.The expression levels of the three targent genes in the turned-green leavesup-regulatedcomparising with that of the albino leaves of 'Baiye l',and the expression levels of DFR and LAR in the leaves of albino tea plants was significantly up-regulated than that in normal green leaf tea varieties.However,the expression levelsof DFR and LAR in 'Zijuan' was slightly higher than that in green leaves of normal tea varieties with no significant difference.What's more,the expression levels of DFR in the green leaves resulted by shandow was significantly down-regulated than that in the normal albino leaves in 'Huangjinya',while there was no significant difference between the two of LAR and ANR.(4)The results of Pearson's correlation analysis showed that there was a certain correlation between catechin contents and the expression of genes involved in the catechin synthesis pathway in leaves of tea plants with different leaf colors.The resluts showed that the regulation of catechin contents by DFR,LAR and ANR was also applicable in tea cultivars with different leaf colors.Further study on the specific regulation mechanism of the genes was helpful to provide the basis for the directional breeding of tea plants. |
PDF Full Text Request