植物内生菌增强植物对生物胁迫抗性的研究进展

植物在生长发育过程中因遭遇多种逆境的威胁而出现营养流失、产量大幅下降等问题，而使用传统的化学农药调控植物抗逆作用会对环境造成严重污染甚至危及人类健康，因此需要从天然成分中寻找合适的农药代替品。生活在每种植物体内的内生菌几乎都是植物微生态系统中的天然成分，因其特殊的生态位而可能对植物具有更加积极和直接的影响。然而目前，关于内生菌在提高宿主生物胁迫抗性等方面的作用机制还知之甚少。该文就植物内生菌的来源、多样性和对生物胁迫的抗性展开叙述。首先，总结了植物内生菌传播的主要方式，即水平传播和垂直传播；其次对内生菌种类的多样性以及在植物中的分布多样性进行了归纳与分析；最后，详细阐述了植物内生菌增强植物对生物胁迫应激耐受性(抗致病菌病害、抗虫害)的基本特点与作用机制，即植物内生菌可利用生态位竞争或营养位竞争产生的诱导抗性遏制病原菌感染，或合成抗生素类、生物碱类、几丁质类等次生代谢产物抑制病原菌或线虫的生长，从而防治病虫害。此外，基于内生菌增强植物生物胁迫抗性的研究现状进行了展望，为更加环保的生物防治制剂的开发与利用提供了参考。

Research progress on the function of plant endophytes in enhancing plant resistance to biological stresses

Plant growth and development can be threatened by a variety of adversities, which cause problems such as loss of nutrients and significant decrease of yied. Using traditional agrochemicals to regulate the plant resistence to stresses can result in the resistance in insect pests and diseases not only in traditional plant varieties but also in transgenic plants. These agrochemicals cannot be degraded by biological means, and cause environmental pollution. Also, prevalence of these chemicals can even cause severe health issues to the farmers, livestock, and consumers. Therefore, application of naturally available microbes is a safe and alternative complementary way to tackle the pests and phytopathogens. Endophytes living in almost every plant are natural components of plant microecosystems and may have more positive and direct effects on plants because of their special ecological niches. However, the mechanism of endophytic bacteria in improving host biostress resistance is still poorly understood. In this review, we describe the origin, diversity and resistance to biotic stress of endophytes. Firstly, we provide an overview of the transmission routes that endophyte can take to colonize plants, including vertically via seeds and pollen, and horizontally via soil, atmosphere, and insects; secondly, summarize and analyze the diversity of endophyte species and distribution diversity in plants; finally, the basic characteristics and action mechanisms of endophytes in enhancing the tolerance of plants to biotic stress(anti-pathogenic bacteria and insect resistence)are described in detail. Endophytes use niche competition or nutrient competition to promote plant induced resistance to inhibit pathogen infection, or use synthetic antibiotics, alkaloids, chitin and other secondary metabolites to inhibit the growth of pathogenic bacteria or nematodes, so as to prevent and control insect pests and diseases. In addition, based on the research status of endophyte enhancing plant biotic stress resistance, the future development direction is prospected, and this article provides reference for the development and utilization of more environmentally friendly biological control agents.