How does PAP, a stress-induced metabolite, regulate gene expression?

植物通常暴露于环境波动（如强光或水不足），这足以限制田间种植和温室种植环境中的作物产量。由这种胁迫诱导的损伤通常首先在叶绿体和线粒体内观察到，其中代谢的扰动迅速诱导氧化胁迫。这些扰动通过多种逆行信号通路从细胞器传递到细胞核，这些信号通路改变核基因表达，使植物能够调整其代谢和发育以耐受环境胁迫。然而，逆行信号在多大程度上可以调节植物体内平衡，以及通过什么机制（S），仍然是谜。许多非生物和生物主要与一天中的特定时间相关，推动生物计时机制的进化，使生物和非生物应力与白天或夜晚相关的预期。这些生物定时器（通常称为昼夜节律系统）随后被用来调节许多生理过程，包括生长，光合作用和开花时间。除了提供一个内源性的时间参考，日照长度的季节性变化需要昼夜节律系统与环境因素，如黄昏和黎明同步。这诱导了环境信号、内源性生物计时器和次优环境条件诱导的代谢变化之间的复杂相互作用。如果我们要充分利用作物的潜在产量，我们必须了解植物在日常环境波动中如何与环境相互作用。最近，有人提出昼夜节律系统作为代谢调控器（如蒸汽机），减缓新陈代谢，从而提高压力期间的生存率。与这个概念一致，我们已经证明了渗透压的应用减缓了昼夜节律系统。这导致通常在晚上表达的基因受到抑制。我们已经证明，一个信号代谢物，积累在响应渗透压是足以引起一个可比较的昼夜节律系统的延迟。这些数据表明，在代谢的变化所产生的应用程序的压力可以诱导基因表达的变化，最终改变植物behavior.The昼夜节律系统诱导约三分之一的植物基因组的节奏表达，但我们没有一个精确的了解如何在代谢的变化改变内源性生物计时器的步伐。重要的是，最初在实验主力拟南芥中鉴定的昼夜节律计时组件已被发现在整个植物界是保守的，已知时钟组件的天然等位基因在历史上被引入商业种植的大麦和番茄品种。这项研究将利用拟南芥中的遗传资源。这将允许在我们的理解被转移到诸如大麦和小麦之类的作物之前快速的进展。这些工作将促进我们对植物对渗透胁迫的反应的理解，并直接告知BBSRC的优先事项，以设计具有更大抗旱能力的作物，从而更有效地利用可用的水资源。

Plants are commonly exposed to environmental fluctuations (such as high light or insufficient water) which are sufficient to limit crop yield in both field-grown and glasshouse-grown contexts. Damage induced by such stresses is typically first observed within the chloroplast and mitochondria, where perturbations in metabolism rapidly induce oxidative stress. These perturbations are communicated from organelles to the nucleus via multiple retrograde signaling pathways that alter nuclear gene expression, allowing plants to adjust their metabolism and development to tolerate environmental stress. However, the extent to which retrograde signals can regulate plant homeostasis, and by what mechanism(s), remain enigmatic.Many abiotic and biotic are predominantly associated with specific times of day, driving the evolution of biological timing mechanisms that enable anticipation of biotic and abiotic stresses associated with either day or night. These biological timers (commonly referred to as the circadian system) have subsequently been co-opted to modulate many physiological processes including growth, photosynthesis, and flowering time. In addition to providing an endogenous timing reference, seasonal changes in daylength require that the circadian system is synchronized with environmental factors such as dusk and dawn. This induces a complex interplay between environmental signals, endogenous biological timers, and metabolic changes induced by sub-optimal environmental conditions. If we are to fully exploit the potential yield of crops it is vital that we understand how plants interact with their environment during daily environmental fluctuations.Recently, it has been suggested that the circadian system acts as a metabolic governor (as found on steam engines), slowing metabolism and consequently improving survival during periods of stress. In agreement with this concept we have demonstrated that application of osmotic stress slows the circadian system. This results in repression of genes normally expressed during the evening. We have demonstrated that a signaling metabolite that accumulates in response to osmotic stress is sufficient to induce a comparable delay in the circadian system. Such data demonstrates how changes in metabolism arising from the application of stress can induce changes in gene expression, ultimately altering plant behavior.The circadian system induces rhythmic expression of approximately one third of a plants genome but we do not have a precise understanding of how changes in metabolism alter the pace of the endogenous biological timer. Importantly, circadian timing components originally identified in the experimental workhorse Arabidopsis thaliana have been found to be conserved throughout the plant kingdom, with naturally-occurring alleles of known clock components being historically introduced into commercially grown varieties of barley and tomato. This study will take advantage of the genetic resources available in Arabidopsis. This will allow for rapid progress before our understanding is transferred into crops such as barley and wheat. Such work will advance our understanding of plants responses to osmotic stress and directly inform BBSRC's priorities to design crops with greater drought resilience that make more efficient use of available water resources.