An investigation into the involvement of defense signaling pathways in components of the nonhost resistance of Arabidopsis thaliana to rust fungi also reveals a model system for studying rust fungal compatibility
An investigation into the involvement of defense signaling pathways in components of the nonhost resistance of Arabidopsis thaliana to rust fungi also reveals a model system for studying rust fungal compatibility
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DOI：
10.1094/mpmi.2003.16.5.398
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发表时间：
2003-05-01
影响因子：
3.5
通讯作者：
Heath, MC
中科院分区：
文献类型：
--
作者：
Mellersh, DG;Heath, MC
17份经豇豆锈病真菌（Uromyces vignae）接种的拟南芥（Arabidopsis thaliana）表现出多种非寄主抗性表达，尽管除了Ws-0外，感染菌丝通常在第一个吸器形成之前停止生长。与野生型植物相比，在拟南芥主抗性基因调控的两个信号级联中存在缺陷的ndr1或eds1突变体的真菌生长没有增加。然而，在Col-0背景下，葡萄球菌和其他两种锈菌在合成水杨酸（SA）酶缺陷的sid2突变体、缺乏SA依赖致病相关（PR）基因表达调节因子的npr1突变体和含有细菌水杨酸羟化酶的NahG植物中感染菌丝较长。在茉莉酸防御信号通路中存在缺陷的jar1突变体中，葡萄球菌和阑尾乌菌的侵染菌丝较长，而黑斑契契菌的侵染菌丝较长。然而，吸器的形成只在尿霉菌属、sid2突变体或NahG植物中增加。与非寄主植物中通常伴随吸器形成的敏感细胞死亡不同，拟南芥通常用胼胝体状材料包裹吸器。两种尿霉菌都在NahG植物中形成了生长菌落，表明植物和真菌之间成功的生物营养关系，但只有U. vignae在sid2突变体和环己亚胺处理的野生型植物中形成了生长菌落。在NahG烟草和番茄植株中没有生长菌落。这些数据表明，拟南芥对锈菌的非寄主抗性主要涉及防御基因表达对感染菌丝生长的限制。然而，在阻止尿真菌形成第一个吸器和建立足够的生物营养关系以支持真菌进一步生长的过程中，SA而不是SA依赖的PR基因参与了随后的研究。拟南芥与紫拟南芥的组合可以将这种模式植物强大的遗传能力应用于对锈病真菌的亲和性和非寄主抗性研究。
Seventeen accessions of Arabidopsis thaliana inoculated with the cowpea rust fungus Uromyces vignae exhibited a variety of expressions of nonhost resistance, although infection hypha growth typically ceased before the formation of the first haustorium, except in Ws-0. Compared with wildtype plants, there was no increased fungal growth in ndr1 or eds1 mutants defective in two of the signal cascades regulated by the major class of Arabidopsis host resistance genes. However, in the Col-0 background, infection hyphae of U. vignae and two other rust fungi were longer in sid2 mutants defective in an enzyme that synthesizes salicylic acid (SA), in npr1 mutants deficient in a regulator of the expression of SA-dependent pathogenesis related (PR) genes, and in NahG plants containing a bacterial salicylate hydroxylase. Infection hyphae of U. vignae and U. appendiculatus but not of Puccinia helianthi were also longer in jar1 mutants, which are defective in the jasmonic acid defense signaling pathway. Nevertheless, haustorium formation increased only for the Uromyces spp. and only in sid2 mutants or NahG plants. Rather than the hypersensitive cell death that usually accompanies haustorium formation in nonhost plants, Arabidopsis typically encased haustoria in calloselike material. Growing fungal colonies of both Uromyces spp., indicative of a successful biotrophic relationship between plant and fungus, formed in NahG plants, but only U. vignae formed growing colonies in the sid2 mutants and cycloheximide-treated wild-type plants. Growing colonies did not develop in NahG tobacco or tomato plants. These data suggest that nonhost resistance of Arabidopsis to rust fungi primarily involves the restriction of infection hypha growth as a result of defense gene expression. However, there is a subsequent involvement of SA but not SA-dependent PR genes in preventing the Uromyces spp. from forming the first haustorium and establishing a sufficient biotrophic relationship to support further fungal growth. The U. vignae-Arabidopsis combination could allow the application of the powerful genetic capabilities of this model plant to the study of compatibility as well as nonhost resistance to rust fungi.