Abstract
Heat and waterlogging are critical abiotic stresses that threaten crop productivity, especially as climate change intensifies their frequency and severity. While both stresses independently disrupt essential physiological functions such as photosynthesis, respiration, and nutrient uptake, their underlying mechanisms and adaptive strategies exhibit key differences. This review presents a systematic comparison of plant responses to heat and waterlogging stress, focusing on both their shared and distinct impacts on plant physiology, biochemistry, and molecular regulation. We synthesize recent insights from omics technologies, including transcriptomic and metabolomics, to explore regulatory pathways, hormonal crosstalk (e.g., ABA–ethylene interactions), and metabolic shifts (e.g., fermentation vs. chaperone induction) that drive stress tolerance. This comparative analysis similarly demonstrates that effective plant resilience to climate extremes depends on the coordinated optimization of shared stress management hubs, such as antioxidant defense systems and hormonal crosstalk, together with the deployment of stress-specific adaptive strategies, including molecular chaperone induction under heat stress and anaerobic metabolic reprogramming under waterlogging. By integrating convergent and divergent regulatory pathways, this framework provides a mechanistic and conceptual guide for breeding and engineering crops with durable tolerance to multiple, increasingly co-occurring abiotic stresses.