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.
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Waterlogging stress is one of the main limiting factors for wheat production, especially in the middle and lower reaches of the Yangtze River in China. Improving the waterlogging tolerance of wheat is an important goal to achieve stable and increased yield in this region. In this study, by exploring the suitable use period and concentration of phytochlorin iron, its role in improving waterlogging stress tolerance was further evaluated mainly from the perspectives of plant photosynthesis and plant antioxidant capacity. The research results could provide the theoretical and technical support for waterlogging-resistant cultivation of wheat.
Using Yangmai 16 as material, three concentrations (0.0875, 0.126, and 0.194 mmol·L-1) of phytochlorin iron were set at anthesis and grain filling stages to screen the appropriate period and concentration for achieving a significant increase in wheat yield. Based on this, the effect of phytochlorin iron on wheat tolerance to waterlogging stress at anthesis stage was further evaluated.
Compared with control, treatment with a concentration of 0.126 mmol·L-1 phytochlorin iron at anthesis stage (A2) could significantly increase wheat grain yield by increasing the grain weight. Waterlogging stress at anthesis stage significantly reduced the chlorophyll content, net photosynthesis rate, and post-flowering dry matter accumulation and translocation to grain, resulting in grain yield reduction. However, compared with non-spraying treatment, AW2 treatment showed a higher photosynthetic pigment content, photosystem II stability, net photosynthetic rate. Meantime, the raised activities of antioxidant enzymes, reduced O2- production rate and H2O2 content, which showed correspondence with the reduced accumulation of malondialdehyde content, thus alleviated the damage of cell membrane lipid peroxidation and the yield reduction caused by waterlogging stress.
Spraying a concentration of 0.126 mmol·L-1 phytochlorin iron at anthesis stage could significantly increase wheat yield. Phytochlorin iron could alleviate the plant senescence, reduce damage to PSII, enhance the activity of antioxidant enzymes, reduce the damage of cell membrane lipid peroxidation, maintain higher photosynthetic rate, reduce the degree of yield reduction, and enhance wheat tolerance to waterlogging stress.
The impacts of drought stress on crop yield and quality are substantial. Drought priming during the early growth stage of plants has been shown to improve tolerance to drought stress during the reproductive stage, although its effects on grain quality remain elusive. This study investigated the influence of drought priming on starch and protein levels in grains under drought stress during grain filling. Our results revealed that drought stress leads to a reduction in the contents of starch and its constituents, while simultaneously increasing glutenin macropolymers and protein fractions. Notably, drought primed plants under drought stress (PD) exhibited mitigated declines in the contents of starch and its components, leading to improvements in starch swelling power and pasting properties. In addition, PD resulted in a slight increase in the protein fractions, limiting the overall rise in total protein content compared to drought stress alone. The results of our study underscore the efficacy of drought priming as a strategy to counteract the negative effects of drought stress on grain quality, particularly by minimizing starch losses and restraining protein content elevation.
Frequent drought events severely restrict global crop productivity, especially those occurring in the reproductive stages. Moderate drought priming during the earlier growth stages is a promising strategy for allowing plants to resist recurrent severe drought stress. However, the underlying mechanisms remain unclear. Here, we subjected wheat plants to drought priming during the vegetative growth stage and to severe drought stress at 10 days after anthesis. We then collected leaf samples at the ends of the drought priming and recovery periods, and at the end of drought stress for transcriptome sequencing in combination with phenotypic and physiological analyses. The drought-primed wheat plants maintained a lower plant temperature, with higher stomatal openness and photosynthesis, thereby resulting in much lower 1,000-grain weight and grain yield losses under the later drought stress than the non-primed plants. Interestingly, 416 genes, including 27 transcription factors (e.g., MYB, NAC, HSF), seemed to be closely related to the improved drought tolerance as indicated by the dynamic transcriptome analysis. Moreover, the candidate genes showed six temporal expression patterns and were significantly enriched in several stress response related pathways, such as plant hormone signal transduction, starch and sucrose metabolism, arginine and proline metabolism, inositol phosphate metabolism, and wax synthesis. These findings provide new insights into the physiological and molecular mechanisms of the long-term effects of early drought priming that can effectively improve drought tolerance in wheat, and may provide potential approaches for addressing the challenges of increasing abiotic stresses and securing food safety under global warming scenarios.
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