Genome-wide identification of glutathione S-transferase gene family members in tea plant (Camellia sinensis) and their response to environmental stress.

Glutathione S-transferases (GSTs) are ubiquitous enzymes involved in the regulation of plant growth, development, and stress responses. Unfortunately, the comprehensive identification of GSTs in tea plant has not been achieved. In this study, a total of 88 CsGSTs proteins were identified and divided into eight classes, among which the tau class was the largest. Chromosomal localization analysis revealed an uneven distribution of CsGSTs across the tea plant genome. Tandem duplication is the main force driving tea plant CsGSTs expansion. CsGSTs structures and conserved motifs were similar. The analysis of cis-regulatory elements in promoter regions showed that CsGSTs can response to multiple stresses, and that MYB may be involved in the transcriptional regulation of CsGST. RNA-Seq data revealed that the expression of most GSTUs was associated with various stresses, including pathogen and insect attack, cold spells, drought and salt stresses, nitrogen nutrition, bud dormancy, and morphological development, and the expression of these CsGSTs was obviously different in eight tissues. In addition, we proved that CsGSTU19, localized at the nucleus and cell membrane, was involved in tea plant defense against temperature stresses and Co. camelliae infection. These findings provide references for the further functional analysis of GSTs in the future.