植物激素调控丛枝菌根发育的作用机制研究进展

丛枝菌根（arbuscular mycorrhiza,AM）是土壤中AM真菌和绝大多数维管植物根系长期进化过程中相互识别、相互作用形成的互利共生体。AM的发育与功能效应依赖AM真菌-寄主植物之间精准的“分子对话”,同时受到环境条件特别是土壤养分水平、干旱和盐渍化的制约。植物激素作为低浓度的小分子有机物,是参与调控AM共生过程的重要信号分子。其中,主要有9种植物激素参与AM发育过程且分工各有不同：独脚金内酯（strigolactones,SLs）参与AM真菌-寄主植物之间最初的共生识别,脱落酸（abscisic acid,ABA）和油菜素内酯（brassinosteroid,BR）促进前期的菌丝入侵,但水杨酸（salicylic acid,SA）和乙烯（ethylene,ET）抑制前期的菌丝入侵,生长素（auxin,Aux）、ABA和BR促进随后的丛枝形成而ET和赤霉素（gibberellin,GA）的作用则相反,茉莉酸（jasmonic acid,JA）对菌丝入侵与丛枝形成均可能存在正调控或负调控作用。目前细胞分裂素（cytokinin,CTK）在AM发育中的作用尚不明确。更为复杂的是,通常植物激素信号之间的交叉互作决定AM的发育进程。本文针对AM发育过程总结了不同植物激素的调控作用特点和不同植物激素信号之间的互作（协同或拮抗）,以及胁迫条件下不同植物激素信号的可能调控机制。深入研究和系统阐明植物激素调控AM真菌-寄主植物共生的生理/分子机制,将有助于促进生物共生学理论研究及菌根技术的应用。

Mechanisms of phytohormones in regulating arbuscular mycorrhiza development

Arbuscular mycorrhiza (AM) is a symbiont formed by the interaction and mutual recognition of soil-born AM fungi and the roots of most vascular plants in the long-term evolution. The development and function of AM, limited by environmental conditions, especially the soil nutrient level, drought, and salinity, depend on the precise "molecular dialogue" between AM fungi and host plants. Phytohormones are low-molecular-weight organics with low concentration and act as crucial signaling molecules in the regulation of AM symbiosis. There are mainly nine phytohormones participating in regulating AM development with different effects. Strigolactones (SLs) act at the first symbiotic recognition between AM fungi and host plants. At the early stage, abscisic acid (ABA) and brassinosteroid (BR) promote the fungal invasion, whereas salicylic acid (SA) and ethylene (ET) inhibit the fungal invasion. Auxin (Aux), ABA, and BR promote the subsequent arbuscule formation, whereas ET and gibberellin (GA) suppress the arbuscule formation. Jasmonic acid (JA) may have both positive and negative regulating effects on fungal invasion and arbuscule formation. However, the role of cytokinin (CTK) remains unclear in AM development. In addition, the signaling crosstalk among phytohormones normally determines AM development. This review summarized the characteristics of different phytohormones and their associated signaling crosstalk (synergistic or antagonistic) in regulating AM development, and the possible regulation mechanisms of different phytohormone signals involved in AM development under stress conditions. The profound research and systematical illustration of the physiological/molecular mechanisms of phytohormones in regulating the symbiotic relationships between AM fungi and host plants, will help the study on symbiology and the application of mycorrhizal technology.