Abstract: [Objective amd Method]Exposed to the stress of pathogen fungus Verticillium dahliae,the changes of activities of defensive enzymes in root tissue,the contents of resistance related substances and ultra-microstructure of root cells of cotton seedlings which have been inoculated previously with two kinds of arbuscular mycorrhizal fungi (AMF,Glomus mosseae and Glomus etunicatum)have been investigated under the condition of pot cultivation in green house.[Result]The results indicated that for the cotton seedlings of susceptible variety (Gossypium hisuvm L. Cv Junmian No.1): (1) AMF inoculation were introduced to improve the contents and activities of defensive enzymes in root including phenylalanine ammonialyase (PAL),chitinase,peroxidase (POD),and especially in case of double inoculation,the contents and activities of the three enzymes have been improved significantly and a new band of POD isoenzyme has appeared. (2) AMF inoculation could increase the contents of total phenol and decrease the content of malondialdehyde (MDA) in root which indicated that incoulation of AMF could decrease membrane lipid peroxidtion of plant cell and control the injure of cell.(3) A series of structural changes occurred to the root cells which are favorable to improving tolerance of root system after AMF colonization,such as cell deformation and pyknosis,decrease in vacuole number and xylem expanded,and some more drastic change occurred in the case of double inoculation,the cell color became darker,palisade tissues and vessels deformed,mitochondria disappeared,the cell walls became thicker obviously and lignified,substance deposition occurred on cell walls. [Conclusion]The author therefore summarized that AMF could improve the tolerance of cotton to Verticillium wilt and protection effect on the plant.

摘要： [目的]探讨从枝菌真菌提高棉花黄萎病抗性的作用机理,在棉花上应用AM真菌提高棉花对黄萎病的抗性.[方法]温室盆栽条件下,研究了接种两种丛枝菌根真菌摩西球囊霉(Glomus mosseae)和幼套球囊霉(Glomus etunicatum)的棉花幼苗在黄萎病原菌(Verticillium dahliae)胁迫下,其根内防御性酶活性、抗性相关物质和根细胞超微结构的变化情况.[结果]感病品种军棉1号接种AM真菌后,(1)能够诱导根内防御性酶系苯丙氨酸解氨酶(PAL)、几丁质酶和过氧化物酶(POD)的积累,增加酶的含量,提高酶的活性,而接种AM真菌后再接种病原菌,其PAL、几丁质酶和POD活性均显著提高,明显高于其它处理,并增加了一条POD同工酶条带;(2)接种AM真菌能够增加根内酚类物质的含量,降低根内丙二醛的含量,表明接种AM真菌可减轻植株细胞的膜脂过氧化作用,缓解细胞的损伤.(3)棉花根系受到AM真菌的侵染后,根系细胞发生了一系列有利于提高对病原菌抵抗能力的结构性变化,如细胞发生变形固缩,液泡数量明显减少,木质部结构增多.而接种AM真菌后再接种病原菌,根系细胞发生更为剧烈的变化,包括细胞壁明显加宽,细胞颜色加深,栅栏组织和导管变形,导管处产生胶状物质,线粒体内折消失,细胞壁木质化,出现了细胞壁物质的沉积.[结论]提出了AM真菌提高棉花黄萎病抗性的防御机制和强化机制,并认为AM真菌的侵染对于植物起到了类似于"免疫"的作用,这种类似免疫的作用在AM真菌提高棉花黄萎病抗性的作用机制之中最为直接和重要.