Saha Shukanta, Johnson Giles N
Department of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Manchester, United Kingdom.
Department of Botany, Faculty of Life and Earth Sciences, Jagannath University, Dhaka, Bangladesh.
Front Plant Sci. 2025 Aug 25;16:1603355. doi: 10.3389/fpls.2025.1603355. eCollection 2025.
Climate change is leading to increases in extreme weather events, notably increasing both droughts and floods, which undermine food security. Although each stress individually has been well studied, little is known about the response of cereals to successive water stresses, condition that often occurs in real-world scenarios. To address this gap, we have compared physiological responses of wheat and barley cultivars to cycles of drought and flooding. We show that these species show different responses to each other and that successive stresses result in different responses to single stresses. Plants were subjected to control, drought or flooding treatments for 15 days. Following that, previously stressed plants were exposed to a further stress - drought followed by flooding (D-F) or flooding followed by drought (F-D) for a further 15 days. These cereals showed contrasting responses both to drought or flooding alone and to successive stresses (D-F or F-D). Barley retained photosynthetic capacity when exposed to single- drought or flooding, whereas wheat responded to both stresses with significant declines in CO assimilation capacity by 41% and 31% in response to drought or flooding, respectively -primarily due to stomatal closure. However, the first exposure to water stress impacts the inhibition of photosynthesis during subsequent stress. The effect of subsequent water stress - drought or flood -was continued and aggravated by the previous stress in wheat. Importantly, non-stomatal factors were induced, which reduced Photosystem II efficiency (62% and 49%) and chlorophyll content (35% and 47%) in wheat under D-F and F-D stress. By contrast, barley retained its photosynthetic capacity under D-F stress by acclimating, with 41% reduced shoot growth, while F-D treatment induced abnormal stomatal development. Both treatments resulted in the accumulation of carbon in tissues. Overall, we conclude that sensitivity to a stress is increased by the exposure to a previous stress, with F-D stress having the largest effect, while barley is relatively more tolerant than wheat highlighting it as the more robust cereal crop under fluctuating water conditions.
气候变化正导致极端天气事件增加，尤其是干旱和洪水都在增多，这对粮食安全构成威胁。尽管对每种胁迫分别进行了充分研究，但对于谷类作物对连续水分胁迫的反应却知之甚少，而这种情况在现实世界中经常发生。为了填补这一空白，我们比较了小麦和大麦品种对干旱和洪涝循环的生理反应。我们发现，这些物种对彼此的反应不同，连续胁迫导致的反应也与单一胁迫不同。将植物进行15天的对照、干旱或洪涝处理。之后，之前受过胁迫的植物再接受15天的进一步胁迫——先干旱后洪涝（D-F）或先洪涝后干旱（F-D）。这些谷类作物对单独的干旱或洪涝以及连续胁迫（D-F或F-D）表现出截然不同的反应。大麦在遭受单一干旱或洪涝时仍保持光合能力，而小麦对这两种胁迫的反应是，二氧化碳同化能力分别显著下降41%和31%（分别对应干旱或洪涝）——主要是由于气孔关闭。然而，首次暴露于水分胁迫会影响后续胁迫期间光合作用的抑制。在小麦中，先前的胁迫会持续并加剧后续水分胁迫（干旱或洪涝）的影响。重要的是，非气孔因素被诱导，这降低了D-F和F-D胁迫下小麦光系统II的效率（分别降低62%和49%）以及叶绿素含量（分别降低35%和47%）。相比之下，大麦在D-F胁迫下通过适应保持了光合能力，地上部生长减少了41%，而F-D处理导致气孔发育异常。两种处理都导致组织中碳的积累。总体而言，我们得出结论，先前暴露于胁迫会增加对后续胁迫的敏感性，其中F-D胁迫的影响最大，而大麦比小麦相对更具耐受性，这表明在波动的水分条件下大麦是更具韧性的谷类作物。
