All plants harbor many microbial species including bacteria and fungi in their tissues. The interactions between the plant and these microbes could be symbiotic, mutualistic, parasitic or commensalistic. Mutualistic microorganisms are endophytic in nature and are known to play a role in plant growth, development and fitness. Endophytes display complex diversity depending upon the agro-climatic conditions and this diversity could be exploited for crop improvement and sustainable agriculture. Plant-endophyte partnerships are highly specific, several genetic and molecular cascades play a key role in colonization of endophytes in host plants leading to rapid changes in host and endophyte metabolism. This results in the accumulation of secondary metabolites, which play an important role in plant defense against biotic and abiotic stress conditions. Alkaloids are one of the important class of metabolites produced by Epichloë genus and other related classes of endophytes and confer protection against insect and mammalian herbivory. In this context, this review discusses the evolutionary aspects of the Epichloë genus along with key molecular mechanisms determining the lifestyle of Epichloë endophytes in host system. Novel hypothesis is proposed to outline the initial cellular signaling events during colonization of Epichloë in cool season grasses. Complex clustering of alkaloid biosynthetic genes and molecular mechanisms involved in the production of alkaloids have been elaborated in detail. The natural defense and advantages of the endophyte derived metabolites have also been extensively discussed. Finally, this review highlights the importance of endophyte-arbitrated plant immunity to develop novel approaches for eco-friendly agriculture.

中文翻译：

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草-Epichloë 相互作用的分子机制：通过内生菌驱动农业提高植物健康和免疫力

所有植物的组织中都含有许多微生物物种，包括细菌和真菌。植物与这些微生物之间的相互作用可以是共生的、共生的、寄生的或共生的。共生微生物本质上是内生的，已知在植物生长、发育和健康中发挥作用。根据农业气候条件，内生菌表现出复杂的多样性，这种多样性可用于作物改良和可持续农业。植物-内生菌伙伴关系是高度特异性的，几个遗传和分子级联在宿主植物中内生菌定植中起关键作用，导致宿主和内生菌代谢的快速变化。这导致次生代谢物的积累，其在植物防御生物和非生物胁迫条件中起重要作用。生物碱是 Epichloë 属和其他相关内生菌类产生的重要代谢物之一，可保护昆虫和哺乳动物食草动物。在此背景下，本综述讨论了 Epichloë 属的进化方面以及决定 Epichloë 内生菌在宿主系统中生活方式的关键分子机制。提出了新的假设来概述 Epichloë 在凉季草中定植期间的初始细胞信号事件。详细阐述了生物碱合成基因的复杂聚类和参与生物碱生产的分子机制。内生菌衍生代谢物的天然防御和优势也已被广泛讨论。最后，