Abstract：
Plants evolved, over millions of years, complex defense systems against pathogens. Once infected, the interaction between pathogen effector molecules and host receptors triggers plant immune responses, which include apoptosis, systemic immune response, among others. An important protein family responsible for pathogen effector recognition is the nucleotide binding site-leucine repeat rich (NBS-LRR) proteins. The NBS-LRR gene family is the largest disease resistance gene class in plants. These proteins are widely distributed in vascular plants and have a complex multigenic cluster distribution in plant genomes. To counteract the genetic load of such a large gene family on fitness cost, plants evolved a mechanism using post transcriptional gene silencing induced by small RNAs, particularly microRNAs. For the NBS-LRR gene family, the small RNAs involved in this silencing mechanism are mainly the microRNA482/2118 superfamily. This suppression mechanism is relieved upon pathogen infection, thus allowing increased NBS-LRR expression and triggering plant immunity. In this review, we will discuss the biogenesis of microRNAs and secondary RNAs involved in this silencing mechanism, biochemical and structural features of NBS-LRR proteins in response to pathogen effectors and the evolution of microRNA-based silencing mechanism with a focus on the miR482/2118 family. Furthermore, the biotechnological manipulation of microRNA expression, using both transgenic or genome editing approaches to improve cultivated plants will be discussed, with a focus on the miR482/2118 family in soybean.
摘要：
植物进化了，数百万年来，针对病原体的复杂防御系统。一旦被感染,病原体效应分子和宿主受体之间的相互作用引发植物免疫反应，其中包括细胞凋亡，全身免疫反应，在其他人中。负责病原体效应子识别的重要蛋白质家族是富含核苷酸结合位点-亮氨酸重复序列(NBS-LRR)的蛋白质。NBS-LRR基因家族是植物中最年夜的抗病基因类。这些蛋白质广泛分布在维管植物中，并且在植物基因组中具有复杂的多基因簇分布。为了抵消如此大的基因家族对健身成本的遗传负荷，植物进化出一种利用小RNA诱导的转录后基因沉默的机制，特别是microRNA。对于NBS-LRR基因家族，参与这种沉默机制的小RNA主要是microRNA482/2118超家族。这种抑制机制在病原体感染时得到缓解，从而允许增加NBS-LRR表达并触发植物免疫。在这次审查中,我们将讨论参与这种沉默机制的microRNAs和次级RNAs的生物发生，NBS-LRR蛋白响应病原体效应子的生化和结构特征以及基于microRNA的沉默机制的进化，重点是miR482/2118家族。此外，microRNA表达的生物技术操作，将讨论使用转基因或基因组编辑方法来改善栽培植物，重点研究了大豆中的miR482/2118家族。
