Studies on parasitism acquirement by obligate parasites of plants and mechanisms of non-host resistance

(1)气传真菌对植物的侵染是由孢子附着在寄主表面开始的。大麦白粉病（Blumeria graminis）分生孢子接触寄主表面后立即释放细胞外基质（ECM）。ECM参与孢子的粘附和芽管出现位点的确定。因此，ECM是该真菌致病的初始关键。生理分析表明，该菌在胞外分泌多种细胞壁降解酶，分子生物学研究表明，这些酶的基因在分生孢子的形态发生过程中逐步表达。另一项生理学研究表明，大麦胚芽鞘中可通过B的成功感染合成或激活可接近性诱导因子。禾本科植物部分确定了该因子的特征。该因子的纯化及分子结构的确定仍需进一步研究。(2)我们发现肌动蛋白细胞骨架的重要性， 关于我们 防御机制对真菌入侵，使用几个肌动蛋白抑制剂。这些结果揭示了时间和空间控制抗性机制的重要性。在动物细胞中，Rac小GTP酶在肌动蛋白细胞骨架的重塑中发挥核心作用。为了研究植物Rac GTP酶的功能，我们克隆了烟草Rac基因并在烟草植物中过量表达。在过表达中对水杨酸的敏感性增加表明植物Rac蛋白参与诱导系统获得抗性。(3)测定了15个属33个白粉病分类群的核rDNA核苷酸序列，以推断这些真菌的系统发育关系。系统发育分析表明，钩丝壳septata是放置在原始基地的大型分支组成的所有其他白粉病类群。不包括U. septata分为五个主要的血统。菌丝状附属物长期以来一直被认为是一个祖先的字符可能是一个衍生的字符作为一个事件的结果，可能已经发生了多次独立的收敛。真孢子型无性型和棒状附着胞芽管被认为是假孢子型无性型和裂芽芽管的祖先特征。外生性和多囊闭囊藻也被认为是内生性和单囊闭囊藻的祖先特征。少

(1) Infection of plants by airborne fungi initiates from adhesion of spores onto host surfaces. Conidia of barley powdery mildew, Blumeria graminis, releases extracellular matrix (ECM) immediately after they contact host surfaces. ECM is involved in adhesion of spores and determination of emergence sites of germ tubes. Thus, ECM holds an initial key of pathogenesis of this fungus. Physiological analyses revealed that this fungus secreted various cell wall degrading enzymes in ECM and molecular biological studies showed that genes of these enzymes were expressed during morphogenesis of conidia step by step. Another physiological study showed that accessibility-inducing factor could be synthesized or activated in barley coleoptiles by successful infection of B. graminis. Characters of this factor were partially determined. Further studies are still necessary for purification of this factor and determination of its molecular structure.(2) We found the importance of actin cytoskeleton in d … More efense mechanism against fungal invasion, using several actin inhibitors. These results revealed the importance of temporal and spatial control of resistance machinery. In animal cells, Rac small GTPases play a central role in a remodeling of actin cytoskeleton. To investigate a function of plant Rac GTPases, we cloned tobacco Rac genes and overexpressed in tobacco plants. Increased sensitivity to salicylic acid in overexpressors suggest that plant Rac proteins are involved in an induction of systemic acquired-resistance.(3) The nucleotide sequences of the nuclear rDNA were determined for 33 powdery mildew taxa spanning 15 genera to infer the phylogenetic relationships for these fungi. Phylogenetic analyses revealed that Uncinula septata is placed in the primitive base to the large clade composed of all other powdery mildew taxa. Powdery mildews excluding U. septata are split into five major lineages. The mycelioid appendage which has long been regarded as an ancestral character may be a derived character as a result of an event that may have occurred multiple times independently due to convergence. Euoidium-type anamorph and clavate appressorial germ tube are considered to be ancestral characters to Pseudoidium-type anamorph and lobed germ tube. Ectophytic nature and polyascal cleistothecia are also regarded as ancestral features to endophytic nature and monoascal cleistothecia. Less