AM真菌提高植物抗逆性的机制

丛枝菌根(arbuscular mycorrhizae,AM)真菌是自然界中最广泛的植物共生真菌,可以提高宿主对生物和非生物逆境的抗性。AM真菌能通过改善养分吸收、增加渗透调节物质的积累,提高抗氧化酶类活性、强化渗透调节作用并维持植物内源激素平衡,增加生长素的合成,调节碳氮代谢,刺激胁迫诱导基因表达,增强植物根系及菌丝本身对重金属元素的固持作用等提高植物对非生物逆境(如干旱、高低温、重金属、盐碱)的抗性;并能通过构建菌丝网络,形成对根部入侵病原真菌的机械屏障,增强抗病性相关酶活性,合成与抗病性相关的次生代谢产物,增强抗病、虫相关基因的表达,菌丝传递抗虫防御信号,能提高邻近植株的抗虫性,增强植物的抗病虫能力。本文归纳了近几年来国内外有关AM真菌影响植物抗逆性及其作用机理的研究进展,并对AM真菌在促进植物抗逆性方面的研究作了展望。

Research progress on the mechanism of AM fungi for improving plant stress resistance

Arbuscular mycorrhizae (AM) fungi could increase plant resistance to biotic and abiotic stresses.AM fungi could improve plant resistance to abiotic stresses,including drought,high or low temperature,heavy metal,and salt.The mechanism includes improving plant nutrient absorption,the accumulation of osmotic adjustment substances and activities of antioxidative enzymes,strengthening the effects of osmotic adjustment and maintaining the balance of plant hormones,and increasing auxin synthesis,and regulating carbon and nitrogen metabolism.AM fungi could also induce plant defense gene expression and enhance the capacity of plant roots and mycelium to hold heavy metal.The mechanism of AM fungi for defense against plant disease and insects may include building the mycelium network that can form mechanical barriers for the pathogen that is invading,enhancing the activities of resistance-related enzymes,synthesizing secondary metabolites associated with disease and insect resistance,promoting the expression of genes related to diseases and pests,and transmission by mycelium of the signal of insect resistance defense to improve the insect resistance of adjacent plants.We summarize the effects of AM fungi on plant stress resistance and the mechanisms found both at home and abroad in recent years.