Drought priming enhances young spike development in wheat under drought stress during stem elongation

Drought stress is a significant environmental stressor that can have detrimental effects on crop yields, especially during stem elongation. Drought priming has emerged as a promising technique for enhancing plant drought tolerance. However, the effects of drought priming on the spike differentiation process and its physiological basis in wheat are not clear. In this study, we investigated the effects of drought priming on spike development under drought stress by applying drought priming at the three-leaf stage and drought stress during stem elongation. This study demonstrated that drought priming significantly increased the photosynthetic rate of flag leaves by approximately 25.7% and improved leaf water potential by 17.4% during drought stress. Moreover, it mitigated oxidative damage by reducing the hydrogen peroxide and malondialdehyde levels by 30.6 and 11.1%, respectively, during stem elongation. Drought priming also markedly enhanced the activities of two key carbon metabolism enzymes, hexokinase and fructokinase, by 170.0 and 236.0%, respectively. This improved carbon metabolism and stabilized spike differentiation, leading to increased spikelet and floret primordia formation. Ultimately, drought priming achieved a 13.8% increase in kernel number per spike, demonstrating its potential for improving grain yield under drought conditions. This study innovatively revealed the “carbon homeostasis-spike development” coordination mechanism underlying drought priming-enhanced reproductive stress tolerance. The findings advance our understanding of stress memory as it relates to spatiotemporal regulation in crops and offer transformative solutions for stabilizing wheat production under climate change scenarios.