Foliar γ-aminobutyric acid and calcium synergistically enhance heat tolerance in strawberry via ROS scavenging and GABA shunt activation

γ-Aminobutyric acid (GABA), is a non-protein amino acid that accumulates in various plants when they experience stress.
The stress-induced synthesis of GABA includes the activation of glutamate decarboxylase (GAD) through a signal transduction
pathway that involves calcium /calmodulin. The aim of the present research was to examine how GABA application
affects the ability of strawberry plants (Fragaria × ananassa Duch. cv. Camarosa) to withstand heat. It also looked
into how calcium influences the plant’s reaction to heat stress and the control of GABA signaling. Results indicated that
treating strawberry plants with 5 mM GABA and 15 mM calcium chloride effectively reduced their heat induced damage.
These treatments increased POD activity by 42% and APX by 35% compared to heat-stressed controls, resulted in a
decrease in the production of reactive oxygen species, and enhanced water retention in plants under heat stress. The greatest
expression of genes associated with GABA during heat stress was observed with the 5 mM GABA treatment compared
to the control group. Furthermore, this study demonstrated that the heat tolerance regulated by calcium was closely linked
to a considerable increase in the expression of GABAT1 within 2 h of heat exposure in the leaves of the strawberry plants.