CNGC mediated signal transduction and networking in plant immunity

为了满足日益增长的粮食生产需求，在农业生产中保护植物免受各种病原体和昆虫侵害的农用化学品的使用量在过去几十年中急剧增加。然而，这些化学品对环境的负面影响正在成为全世界的一个严重问题。此外，尽管这些农用化学品被广泛使用，但全球每年因植物病害造成的作物损失约为2 200亿美元。为了解决这些问题，培育抗病原体作物和环境友好型农用化学品至关重要。为此，在分子水平上了解植物自身的自然防御系统至关重要。在过去的十年中，人们对植物免疫的识别和信号转导进行了大量的研究。然而，病原体识别后的信号转导级联在很大程度上仍然未知。为了确定抗性信号通路的组成部分，我们对拟南芥抗性发生变化的突变体进行了筛选。通过这个筛选，我们确定了cpr22表现出各种防御反应的本构激活。在过去的四年半里，我们已经确定了cpr22基因是一个不寻常的嵌合环核苷酸门控离子通道基因（AtCNGC11/12），并报道了AtCNGC11/12的短暂表达诱导Ca2+依赖性程序性细胞死亡。我们关于AtCNGC11和12的数据，以及其他研究组关于AtCNGC2和4的数据，都有力地表明了CNGCs在植物免疫中的重要作用。然而，它们参与诱导耐药反应和cngc介导的信号转导级联的分子机制仍然很大程度上是未知的。本文旨在阐明CNGC介导的信号转导在植物免疫中的分子机制。这一建议的结果肯定会提高我们对CNGCs在植物免疫系统中的作用的理解，也有助于发现由病原体和农用化学品引起的农业/环境问题的实际解决方案。

To support the growing demand for food production, the usage of agrochemicals, which protect plants from various pathogens and insects in agricultural production, has increased dramatically over the last decades. However, the negative environmental effects of these chemicals are becoming a serious issue all over the world. Furthermore, despite of the extensive use of these agrochemicals, the worldwide crop loss caused by plant disease is approximately $220 billion annually. To address these issues, the generation of pathogen resistant crops and environmentally friendly agrochemicals are essential. For this aim, it is crucial to understand the plant's own natural defense system at the molecular level. During the past decade, extensive efforts have been made to understand the recognition and signal transduction in plant immunity. However, the signal transduction cascade following pathogen recognition is still largely unknown. In order to identify components of the resistance signaling pathway, we have conducted a screening for Arabidopsis mutants which show alterations in pathogen resistance. Through this screen we identified cpr22 that exhibits constitutive activation of various defense responses. In the past four and half years we have identified the cpr22 gene as an unusual chimeric cyclic nucleotide-gated ion channel gene (AtCNGC11/12) and reported that the transient expression of AtCNGC11/12 induces Ca2+-dependent programmed cell death. Our data about AtCNGC11 and 12, and the data from other research groups about AtCNGC2 and 4 strongly indicate significant roles of CNGCs in plant immunity. However the molecular mechanism of their involvement in the induction of resistance responses and the CNGC-mediated signal transduction cascade are still largely unknown. The aim of this proposal is to elucidate the molecular mechanism of CNGC mediated signal transduction in plant immunity. The outcome of this proposal certainly will improve our understanding of the role of CNGCs in the plant immune system and also contribute to discover practical solutions for agricultural/environmental issues caused by pathogens and agrochemicals.