Deciphering the molecular pathways and codeχ-specificity of stomatal closure – from model plants to crops

气孔是叶片底部的小孔，允许二氧化碳的吸收和蒸腾作用，但也为病原微生物提供了一个潜在的入口点。因此，调节气孔大小的保卫细胞对非生物和生物胁迫做出反应，如干旱和病原体侵染。可能通过气孔进入的微生物植物病原体包括细菌、卵菌和真菌，它们对不同植物物种的致病力差异很大。必须整合各种外部和内部信号，因为尽管气孔关闭阻止了病原体进入和水分损失，但植物的新陈代谢也因缺乏气体交换而降低。副作用包括光呼吸增加和由于缺乏蒸腾作用而导致的组织过热。然而，应用一种气孔关闭激动剂，诱导气孔均匀关闭，可以抵抗病原体侵染，并在短期干旱期间保护植物。人工关闭气孔可以用壳聚糖来诱导。壳聚糖是甲壳素的衍生物，甲壳素是一种著名的微生物相关分子模式(MAMP)，它被植物识别并诱导免疫反应。与甲壳素相比，壳聚糖有两个优点。首先，壳聚糖在水和弱酸中具有良好的溶解性，在溶液中可以更有效地利用。其次，也是更重要的是，我们发现保卫细胞中的壳聚糖感知与甲壳素感知不同，甲壳素感知可能允许通过定义的壳聚糖来靶向气孔关闭，而不会触发不必要的植物防御机制，从而降低植物的适应性。虽然壳聚糖已用于农业，但壳聚糖感知的确切机制和后续的信号通路在很大程度上还不清楚。这使得合成具有特定生物活性的壳聚糖变得具有挑战性。该项目的主要目标是确定能够提高植物对干旱和病原体攻击的抵抗力的特定壳聚糖。要做到这一点，需要全面了解壳聚糖的感知机制，不同壳聚糖编码的壳聚糖受体的特异性，以及潜在的信号通路。本研究将为深入了解植物对壳聚糖的感知和壳聚糖介导的信号转导途径提供帮助，并有助于开发新的作物改良策略。

Stomata are tiny pores on the undersides of leaves that allow for CO2 uptake and transpiration but also provide a potential entry point for pathogenic microbes. Therefore, guard cells, which regulate the size of the stomatal aperture, respond to abiotic and biotic stresses, such as drought and pathogen infestation. Microbial plant pathogens that may enter via the stomata include bacteria, oomycetes, and fungi, which vary significantly in their pathogenicity to different plant species. Various external and internal signals must be integrated because although stomatal closure prevents pathogen entry and water loss, the plant's metabolism is also reduced by the lack of gas exchange. Adverse effects include increased photorespiration and tissue overheating due to a lack of transpiration. Nevertheless, applying a stomatal closure agonist that induces a uniform stomatal closure could combat pathogen infestations and protect plants during short drought periods. Artificial stomatal closure can be induced, for example, by chitosan. Chitosan is a derivative of chitin, a well-known microorganism-associated molecular pattern (MAMP), which is recognized by plants and induces an immune response. There are two advantages of chitosan over chitin. First, chitosan has good solubility in water and weak acids and can be used more efficiently in solution. Second, and more importantly, we found that the chitosan perception in guard cells differs from chitin perception, which might allow targeting stomatal closure with defined chitosans without triggering unnecessary plant defense mechanisms that reduce plant fitness. Although chitosan is already used in agriculture, the exact mechanisms of chitosan perception and subsequent signaling pathways are largely unknown. This makes it challenging to synthesize specific biologically active chitosans. The main objective of this project is to identify specific chitosans that can enhance plant resilience to drought and pathogen attacks. To achieve this, a comprehensive understanding of the chitosan perception mechanism, the specificity of chitosan receptors for different chitosan codes, and the underlying signaling pathways are required. This research will provide a deeper understanding of chitosan perception and the chitosan-mediated signaling pathways in plants and help in the development of new strategies for crop improvement.