丛枝菌根真菌的抑病功能及其应用

The function and potential application of disease suppression by arbuscular mycorrhizal fungi

土传病害是引发连作障碍的关键因素,严重制约着我国集约化农业（特别是种植业）的可持续发展.丛枝菌根（Arbuscular mycorrhizal,AM）真菌能够提高宿主抗病性、抑制病原物生长及侵染发病,是农业生产上防控土传病害的重要有益资源,探索其抑病机制和应用技术是近年来的研究热点,但一直缺乏比较系统的理论认识.通过梳理相关研究进展发现,AM真菌主要在宿主根系、根际与植株等3个层面发挥抑病作用,其中根系防御主要包括AM真菌与病原物竞争生态位和构建机械防御屏障,根际防御主要包括调节根系分泌物与次生代谢产物及与拮抗菌协同抗病,而植株防御主要包括促进宿主对养分与水分的吸收和诱导宿主产生系统防御体系,因而提出AM真菌的“根系-根际-植株三级防御”理论.在应用技术方面,着重分析通过接种AM真菌或调动土著AM真菌来防控土传病害的技术研究现状,并对应用中存在的问题及其发展前景进行展望,一方面可通过建立AM真菌种质资源库或构建转基因工程菌来解决接种有效期及效果稳定性等问题,另一方面可通过改变施肥模式和调整耕作制度来高效调动土著AM真菌的抑病活性,旨在为利用AM真菌防控土传病害、促进集约化种植业可持续发展提供理论依据.

Soil-borne pathogens are among the key factors preventing continuous cropping, which severely restricts ihesustainable development of intensive agriculture （notably plant industries） in China. Arbuscular mycorrhizal fungi （AMF）, which can improve the disease resistance of their host plants and inhibit growth and infection by pathogens, are important beneficial resources that can prevent and/or control soil-borne diseases. Although the disease-suppression mechanisms and technological application of AMF have become hot topics for research in recent years, there is a relative lack of a systematic theoretical understanding of these topics. Based on a search and review of the relevant literature, the present study found that AMF act in disease suppression at three main points： in the root, the rhizosphere, and the plant. The root defense pathway of AMF involves niche competition and the construction of a physical defensive barrier against infection. The rhizosphere pathway involves the regulation of root exudates and secondary metabolites and the interaction with other antagonists. The plant pathway involves the improvement of nutrient and water uptake by AMF and the induction of the host＇s systemic defenses. Therefore, a ＂three-level defense＂ theory of AMF is proposed, i.e. the root-rhizosphere-plant defense system. Based on current research on soil-borne disease suppression via inoculation with AMF or stimulating indigenous AMF, the problems and developmental prospects facing the application of AMF were also discussed. One approach that has been suggested to solvesome of the problems association with the application of AMF, such as the limited term over which treatments remain effective and the low stability of their effects, is the establishment ofa germplasm bank of AMF, or the construction oftransgenic fungi. On the other hand, stimulating the disease suppression activity of indigenous AMF by changing fertilization patterns and/or the farming system used may also help to solve these problems. These efforts should be made to provide a theoretical basis for the exploiting of AMF for the prevention and control of soil-borne diseases, and the acceleration of the sustainable development of an intensive plant production industry in China.