Genetic Analysis And QTL Mapping For Content Of Catechins In Tea Plant

Tea plant (Camellia sinensis (L.) O. Kuntze) is an important economic crop, distributed in morethan50countries and regions. Catechins are important secondary metabolites in tea plant, have directimpact on the tea quality, and they also have many health benefits. Catechins are complex quantity traits,their genetic mechanism is very complex, classical genetics method cannot explain that. The successfulapplication of genetic mapping and QTL location, make it possible to associate the catechins phenotypicvariation and genetic loci. It can insight into the genetic mechanism from the molecular level, enrichcatechins genetic theory, and provide necessary theoretical support for the research on tea plant breeding.In this study, a genetic map was constructed using F1generation of tea plant. The content of catechinswere detected, using high performance liquid chromatographic. Based on this map, with the analysis ofcatechins phenotypic traits variation, QTL analysis was conducted for four catechins components in teaplant. The main results are as follows:1. SSR markers were developed using the tea transcriptome data, and4713pairs of SSRs weredesigned with9239EST-SSRs in7589unigenes. Four hundred pairs of primers were selected, to makea screening of annealing temperature and parents polymorphism. And120pairs of SSR primers weresuitable for the construction of the genetic map.2. The content of catechins in F1generation were detected, using high performance liquidchromatographic for two years. The results showed that, the catechins content were less affected by year.Part of the individuals in F1population has the phenomenon of transgressive inheritance. The content ofEC, EGC, ECG and EGCG traits in F1population, were in line with the characteristicsof the noemaldistribution. The correlation analysis found that, four catechins components were very significantbetween any two of them. So they can be an ideal material to QTL analysis.3. For the first time, the tea catechins quality was studied with QTL mapping method. WithMapQTL4.0,9QTLs were detected related to the four components of catechins. These QTLs werefound on linkage group1,7,9,12in tea plant. Four QTLs were detected on linkage group1, threeQTLs were detected on linkage group7, and1QTL in linkage group9,12each. They were allsignificant effect QTLs, explained a significant part (>10%) of phenotypic variance. There were4QTLsfor EGC, explained31.0%of total variance. EC and EGCG both have2QTLs were detected, theexplaination of total variance were44.3%and58.6%, respectively. One QTL was detected for ECG,explained72.5%of total variance. Some QTLs for different traits detected in the same region on linkagegroup1. And there was only one stable QTL for each trait.