Heat Stress Tolerance in Crops: New Frontiers for Climate-ready Agriculture

Abstract

Global agriculture faces an unprecedented challenge as rising temperatures, driven by anthropogenic climate change, increasingly compromise crop productivity and food security. Heat stress—defined as an elevation in temperature beyond the threshold that disrupts normal plant growth and development—threatens all major staple crops, including wheat, rice, maize, soybean, and grain legumes, with potentially catastrophic consequences for yields. This review synthesises current knowledge on the physiological, biochemical, and molecular mechanisms underlying heat stress responses in crop plants, while charting the most promising frontiers for developing climate-ready cultivars. The review examines how elevated temperatures impair membrane integrity, photosynthetic efficiency, and reproductive processes, and explores the complex signalling networks orchestrated by heat shock proteins, heat shock transcription factors, and epigenetic regulators that underpin acquired thermotolerance. It further evaluates the contribution of genetic, genomic, transgenic, and CRISPR-based approaches to improving heat tolerance, alongside agronomic interventions. Special attention is given to the integration of multi-omics platforms, high-throughput phenotyping, and genomic selection in accelerating the development of heat-tolerant varieties. The review identifies critical knowledge gaps—including the poorly understood role of thermosensors, non-coding RNAs, and combinatorial stress interactions—and proposes a roadmap for research that bridges fundamental plant science with applied crop improvement. Given that current trajectories of global warming could reduce yields of key staples by 2–6% per decade, investment in heat-tolerant crop development is both scientifically urgent and ethically imperative.