Jia Tan, Yikang Hu, Harshraj Shinde, Kiflu Tesfamicael, and Carlos Rodriguez-Lopez*
*University of Kentucky, 1405 Veterans Drive, 105 Plant Science Building, Lexington, KY 40546 (carlos.rodriguezlopez@uky.edu)

Grapevine cultivar Vitis vinifera. L. cv. Cabernet Sauvignon is used for winemaking all over the world. Drought and heat stresses are two primary abiotic stresses that reduce grape quality and yield. Drought and heat tolerance are poorly characterized in perennial crops such as grapevine. In this study, RNA-sequencing analysis of leaf tissues of Cabernet Sauvignon plants under drought, heat, and combined stress was carried out. Physiological responses such as the stomatal conductance, stem water potential, and leaf temperature were also measured. Physiological data suggested a significant difference in stomatal conductance, leaf temperature, and stem water potential during stress, where no significant difference was observed during recovery. Data analysis with the criteria of a fold change  2 and a Padj value < 0.05 resulted in the identification of 533, 112, and 1117 differentially expressed genes (DEGs) for drought, heat, and combined stress, respectively. The combined stress resulted in significantly more differentially expressed genes than individual stress. Gene ontology analysis revealed DEGs associated with epigenetic changes during stress and after stress removal, such as histone modification, protein methylation, and protein alkyla- tion. Altered expression of those epigenetic change-related genes suggests potential establishment of epigenetic memory after stress removal.

Funding Support: Australian grape and wine authorities grants, Grant ID: VA1503