Guenoune D, Galili S, Phillips D A., Volpin H, Chet I, Okon Y, Kapulnik Y
Agronomy and Natural Resources Department, Agricultural Research Organization, The Volcani Center, 50250, Bet Dagan, Israel
Plant Sci. 2001 Apr;160(5):925-932. doi: 10.1016/s0168-9452(01)00329-6.
Defense responses of alfalfa roots to the pathogenic fungus Rhizoctonia solani were reduced significantly in roots simultaneously infected with the vesicular arbuscular mycorrhizal (AM) fungus Glomus intraradices. R. solani induced five- to tenfold increases in the steady-state levels of chalcone isomerase and isoflavone reductase mRNAs a doubling of root peroxidase activity and a marked autofluorescence in the infected tissue. These changes were inhibited by the presence of G. intraradices. Interestingly, germination of G. intraradices spores and hyphal elongation were sensitive to low concentrations (2 µM) of medicarpin-3-O-glucoside, an isoflavonoid phytoalexin that accumulated both in roots colonized by the pathogenic fungus as well as in AM-treated roots receiving high P, where no colonization by the beneficial fungus occurred. These data support the hypothesis that during early stages of colonization by G. intraradices, suppression of defense-related properties is associated with the successful establishment of AM symbiosis.
在同时感染了泡囊丛枝菌根（AM）真菌根内球囊霉的苜蓿根中，苜蓿根对致病真菌立枯丝核菌的防御反应显著降低。立枯丝核菌可使查尔酮异构酶和异黄酮还原酶mRNA的稳态水平提高5至10倍，使根过氧化物酶活性加倍，并使受感染组织中出现明显的自发荧光。这些变化受到根内球囊霉的抑制。有趣的是，根内球囊霉孢子的萌发和菌丝伸长对低浓度（2µM）的3-O-葡萄糖基美迪紫檀素敏感，3-O-葡萄糖基美迪紫檀素是一种异黄酮类植物抗毒素，在被致病真菌定殖的根以及接受高磷处理且未被有益真菌定殖的AM处理根中均有积累。这些数据支持了这样一种假说，即在根内球囊霉定殖的早期阶段，防御相关特性的抑制与AM共生的成功建立有关。
