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

气孔是叶片下侧的微小孔隙，允许CO2吸收和蒸腾，但也为病原微生物提供了潜在的入口。因此，保卫细胞，调节气孔孔径的大小，响应非生物和生物胁迫，如干旱和病原体侵染。可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性显著不同。必须整合各种外部和内部信号，因为虽然气孔关闭防止病原体进入和水分流失，但植物的新陈代谢也因缺乏气体交换而减少。不利影响包括增加光呼吸和组织过热，由于缺乏蒸腾作用。然而，应用气孔关闭激动剂，诱导一个统一的气孔关闭可以打击病原体的侵扰，并在短期干旱期间保护植物。人工气孔关闭可以例如通过壳聚糖诱导。壳聚糖是几丁质的衍生物，几丁质是一种众所周知的微生物相关分子模式（MAMP），其被植物识别并诱导免疫应答。壳聚糖与甲壳素相比有两个优点。首先，壳聚糖在水和弱酸中具有良好的溶解性，并且可以在溶液中更有效地使用。第二，更重要的是，我们发现，壳聚糖在保卫细胞的感知不同于甲壳素的感知，这可能允许目标气孔关闭与定义的壳聚糖，而不会触发不必要的植物防御机制，降低植物的健身。尽管壳聚糖已经用于农业，但壳聚糖感知的确切机制和随后的信号通路在很大程度上尚不清楚。这使得合成特定的生物活性壳聚糖具有挑战性。该项目的主要目标是确定特定的壳聚糖，可以提高植物对干旱和病原体攻击的抵抗力。为了实现这一目标，需要全面了解壳聚糖的感知机制，壳聚糖受体对不同壳聚糖编码的特异性，以及潜在的信号传导途径。这项研究将提供更深入的了解壳聚糖的感知和壳聚糖介导的信号转导途径在植物中，并有助于作物改良的新策略的发展。

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.