Genome-Wide Exploration of the Grape GLR Gene Family and Differential Responses of VvGLR3.1 and VvGLR3.2 to Low Temperature and Salt Stress

Grapes, one of the oldest tree species globally, are rich in vitamins. However, environmental conditions such as low temperature and soil salinization significantly affect grape yield and quality. The glutamate receptor (GLR) family, comprising highly conserved ligand-gated ion channels, regulates plant growth and development in response to stress. In this study, 11 members of the VvGLR gene family in grapes were identified using wholegenome sequence analysis. Bioinformatic methods were employed to analyze the basic physical and chemical properties, phylogenetic trees, conserved domains, motifs, expression patterns, and evolutionary relationships. Phylogenetic and collinear analyses revealed that the VvGLRs were divided into three subgroups, showing the high conservation of the grape GLR family. These members exhibited 2 glutamate receptor binding regions (GABAb and GluR) and 3-4 transmembrane regions (M1, M2, M3, and M4). Real-time quantitative PCR analysis demonstrated the sensitivity of all VvGLRs to low temperature and salt stress. Subsequent localization studies in Nicotiana tabacum verified that VvGLR3.1 and VvGLR3.2 proteins were located on the cell membrane and cell nucleus. Additionally, yeast transformation experiments confirmed the functionality of VvGLR3.1 and VvGLR3.2 in response to low temperature and salt stress. These findings highlight the significant role of the GLR family, a highly conserved group of ion channels, in enhancing grape stress resistance. This study offers new insights into the grape GLR gene family, providing fundamental knowledge for further functional analysis and breeding of stress-resistant grapevines.