Characterization of the SET DOMAIN GROUP gene family members in Camellia sinensis and functional analysis of the SDG43 gene in abiotic stresses

Abstract Histone methylation mediated by SET Domain Group (SDG) proteins plays an important role in plant response to various abiotic stresses, regulating the expressions of many stress-inducible genes. However, little is known about the SDG genes in Camellia sinensis. In this study, we identified 46 CsSDGs by genome-wide search with the conserved SET domain. Phylogenetic tree, domain composition and gene structure analyses revealed that 46 CsSDGs were classified into five groups, including E(z), ASH1, TRX, SU(VAR) and class VI/VII genes. Furthermore, In silico and qRT-PCR analyses suggested the diverse expression patterns of the 46 CsSDGs in different tissues and in response to various abiotic stresses. To reveal the vital role of CsSDGs in plant responses to abiotic stresses, CsSDG43 was chosen for the functional analysis in hyperosmosis in Arabidopsis. Importantly, CsSDG43 significantly weakened the hyperosmotic tolerance by increasing water loss, reactive oxygen species (ROS) pressure and AHG3 expression in the overexpression lines compared with the wild type of Arabidopsis.