Genome-wide association study and candidate gene prediction of nerolidol and linalool primeveroside content in tea plants

Le résumé fourni par la source

Nerolidol and linalool are volatile terpene alcohols compounds widely distributed in plants. They are mainly existing in the form of primeveroside in tea plant tender shoots, and increasing their content is of great significance for improving the aroma quality of tea. The objective of this study is to reveal the genetic mechanism of nerolidol and linalool primeveroside in tea plants. 169 natural hybrid progenies were used as associated populations, and the contents of nerolidol and linalool primeveroside in tea plant tender shoots in three years were analyzed by using 675,245 single nucleotide polymorphism (SNP) markers evenly distributed uniformly on the chromosomes of tea genome. The results showed that the phenotypic variation of nerolidol and linalool primeveroside content were 60.83%-80.08%, and the broad-sense heritability were 51.29% and 61.87% respectively. Nerolidol and linalool primeveroside content were in normal distribution, suggesting that the traits have typical genetic characteristics of quantitative traits. A total of 50 significantly associated loci were detected by GWAS, and each locus contributed more than 20% to the variations of nerolidol and linalool primeveroside content, of which the maximum contribution rate of nerolidol primeveroside content (NPC) variation site was 38.73%, and the maximum contribution rate of linalool primeveroside content (LPC) variation site was 39.07%. Furthermore, the elite alles of the four major SNPs was identified by allelic variation effect analysis, among which one locus that could affected NPC and LPC simultaneously. Finally, a total of 59 genes were annotated in the confidence intervals of each significantly associated loci, and the most likely candidate genes were predicted according to the comparison with previous reports and gene functional annotations. These candidate genes were mainly involved in multiple biological processes such as sugar metabolism, transcriptional regulation, terpene biosynthesis. Among them, there were significant differences in the relative expression levels of 26 genes between green tea varieties and oolong tea varieties. This study provides new information for further dissecting the genetic mechanism of nerolidol and linalool primeveroside content in tea plants, and provides important gene resources for accelerating the breeding of new tea varieties with high quality.

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