Thermal priming enhances heat tolerance in alfalfa (Medicago sativa L.) through activation of multiple metabolic pathways

Our findings demonstrate that thermal priming establishes a multi-faceted defense system in alfalfa through BR-mediated signaling. This coordinated response involves activation of the AsA-GSH cycle for reactive oxygen species (ROS) scavenging, upregulation of phenylpropanoid biosynthesis for structural reinforcement through lignin deposition, accumulation of unsaturated fatty acids to maintain membrane stability, and enhancement of spliceosome activity to ensure proper processing of heat-responsive transcripts. The sequential activation of these pathways during the priming phases creates a 'stress memory' that prepares plants for subsequent heat challenges. These insights advance our understanding of thermal priming mechanisms and provide potential targets for improving crop heat tolerance through molecular breeding strategies.