The study of the factors which are responsible for host-parasite specificity decided prior to penetration of plant pathogenic fungi

小麦白粉病菌（Blumeria graminis）是一种专性寄生菌，它只感染大麦，在进入寄主植物之前需要形成一个附着胞。真菌在寄主植物上形成附着胞（APP）是很重要的，因为真菌不能在人工培养基上孵育，而只能在活的寄主植物上孵育。到目前为止，人们认为APP的形成可以在宿主植物和非宿主植物上同样观察到，并且真菌和植物之间的特异性可以在穿透阶段或之后确定。然而，与寄主植物表面不同，我们发现附着胞的形成似乎在非寄主植物表面受到抑制。这些事实表明，真菌和植物之间的特异性可以在真菌试图渗透植物之前就确定了。在这项研究中，我们专注于化学成分，寄主-寄生虫特异性的决定因素，在各种植物表面，以确定哪些化学成分是负责附着胞的真菌形成。本文利用红外光谱和气相色谱分析鉴定了寄主植物表面上对真菌附着胞形成有效的物质，并确定了其化学结构，进而发现，先于附着胞芽管（AGT）出现的初生芽管（PGT）是诱导大麦感病的主要原因。它作为一种探针来识别宿主植物，并且PGT在AGT出现之前粘附在表面。这些结果发表在《生理分子植物病理学》和《追求植物发病机理的本质》上。

The powdery mildew fungus, Blumeria graminis an obligate parasite which infects only barley, needs to form an appressorium before it can penetrate the host plant. It is important for the fungus to form an appressorium(APP) on the host plant, because the fungus cannot be incubated on an artificial medium but only on a live host plant. So far it has been thought that APP formation could be observed equally both on the host plant and non-host plant, and the specificity between the fungus and the plants could be determined at the penetration stage or later. However, unlike on the host plant surface, we found that appressorial formation seemed to be inhibited on the non-host plant surfaces. These facts suggest that the specificity between the fungus and the plants could have been determined before the fungus tries to penetrate the plant. In this study, we focused on the chemical components, a decision factor for host-parasite specificity, on various plant surfaces to determine which chemical components are responsible for the appressorial formation of the fungus. Using infrared(IR) spectra and gas I iquid chromatography (GLC), we have identified the substance on the host plant surface that is effective for appressorial formation of the fungus and determined the chemical structure of it. Moreover, based on the results, we have found that the primary germ tube(PGT) which emerges prior to appressorial germ tube(AGT) is responsible for inducing susceptibility of the barley host plant. It acts as a probe to recognize the host plant, and the PGT adheres to the surface prior to AGT's emergence. These results were published in Physiological Molecular Plant Pathology and in "In Pursuit of the Essence of Plant Pathogenesis".