Integration of plant responses to multiple stressors over time: interactions between winter and summer

在全球环境变化的背景下，对多重胁迫的响应一直是植物研究中的一个关键课题。虽然人们一直关注植物对同时发生的胁迫的反应，如干旱和高温胁迫，但胁迫之间的相互作用也可以在时间上按顺序发生。在某些情况下，植物对初始胁迫的生理反应的变化可以降低对未来胁迫的脆弱性。然而，与这种“胁迫记忆”的潜在好处相反，植物对初始胁迫的反应条件下降会降低对未来胁迫的耐受能力。在生长季的背景下，已经广泛地研究了多种胁迫之间的这种相互作用。相比之下，尽管冬季条件的可变性可能会显著影响植物的生长季节表现，但关于冬季胁迫对夏季胁迫反应的遗留影响的研究尚不多见。在生态系统背景下考察植物对冬季条件变化的反应和夏季逆境耐受性之间的协同作用更加复杂。例如，霜冻不仅有可能损害越冬植物，而且还会影响土壤微生物、养分可获得性、土壤物理性质和水分，在检查整体植物反应时需要考虑这些因素的相互作用。*我将在我的研究计划中解决的首要问题是，冬季条件的变异性如何改变草本植物随后对夏季胁迫的反应。我推测，虽然冬季的霜冻损害会降低植物在夏季的表现，但冬季暴露在压力下仍有可能降低植物对夏季压力的脆弱性。我将验证这一假设，并通过受控环境和田间实验相结合的方式，探索土壤过程如何有助于冬季条件和夏季压力之间的相互作用。我的短期目标是研究霜冻暴露的时间和严重程度如何影响夏季干旱耐受性，在解释霜冻和干旱之间的相互作用时直接影响与间接影响的重要性，以及限制具有高应激记忆的植物利用延长的生长季长度的能力的性能权衡。我的长期目标是研究植物冬/夏胁迫相互作用在影响植物群落和生态系统水平过程中的更广泛意义，包括植物物种组成、土壤氮素有效性和保持以及植物凋落物分解。在影响方面，我的研究将为预测物种分布和生态系统功能变化以应对极端气候事件提供关键信息，并改变冬季过程融入植物和生态系统生态的方式。

Response to multiple stresses has been a key topic in plant research, particularly in the context of global environmental change. While there has been a focus on plant responses to stresses that occur simultaneously, such as drought and heat stress, interactions between stresses also can occur sequentially in time. In some cases changes in the physiology of a plant in response to an initial stress can decrease vulnerability to future stress. However, in contrast to the potential benefits of this 'stress memory,' declines in plant condition in response to the initial stress can decrease the ability to tolerate future stress. Such interactions between multiple stresses have been studied extensively in the context of the growing season. In contrast, studies of carryover effects of winter stress on summer stress responses are lacking, despite the potential for variability in winter conditions to influence plant growing season performance substantially. Synergies between plant responses to variability in winter conditions and stress tolerance over summer are further complicated when examined in an ecosystem context. For example, frost not only has the potential to damage overwintering plants, but it also can affect soil microorganisms, nutrient availability, soil physical properties and moisture, and the interactions of these factors need to be accounted for when examining overall plant responses. ***The overarching question I will address with my research program is how variability in winter conditions alters the subsequent responses of herbaceous plants to stress over summer. I hypothesize that while frost damage over winter can reduce the performance of plants over summer, exposure to stress over winter nevertheless has the potential to reduce the vulnerability of plants to summer stresses. I will test this hypothesis and explore how soil processes can contribute to interactions between winter conditions and summer stress using a combination of controlled environment and field experiments. My short term objective is to examine how the timing and severity of frost exposure affect summer drought tolerance, the importance of direct effects versus the indirect effects in explaining interactions between frost and drought, and the performance tradeoffs that limit the abilities of plants with high stress memory to capitalize on extended growing season length. My long term objective is to examine the broader significance of plant winter/summer stress interactions in influencing plant community and ecosystem level processes, including plant species composition, soil nitrogen availability and retention, and plant litter decomposition. In terms of impact, my research will provide crucial information for predicting changes in species distributions and ecosystem function in response to extreme climate events, and transform how winter processes are integrated into plant and ecosystem ecology. *** **