Analysis of host genes that expression was regulated by the signal molecules produced by phytopathogen

豌豆疫病病原菌Mycosphaerella pinnodes在发芽液中分泌两种信号分子，即诱导子和抑制子。激发子在植物上诱导非特异性的防御反应，而抑制子只在寄主植物上抑制诱导的防御反应。在本研究中，我们通过分离激发子处理和抑制处理诱导的cDNA克隆，通过差异筛选来研究亲和性建立的机制。作为激发子诱导的基因，我们首先从激发子处理的豌豆上胚轴制备的PolA+RNA中构建了5hr的cDNA文库。通过差异筛选，我们获得了90个激发子应答基因的候选基因克隆。对这些克隆的测序分析显示如下。1)紫云英诱导子可能通过诱导富含羟脯氨酸的糖蛋白和过氧化物酶的基因表达来增强植物细胞壁。2)推测多聚半乳糖…的cDNA更多的Acturonase抑制蛋白和内切几丁质酶表明，这些基因可能在不亲和相互作用中起作用。3)多个编码多胺生物合成酶的基因克隆的分离表明多胺在防御反应中的重要性。4)编码新型DOF型锌指转录因子的cDNA克隆与许多防御相关基因启动子区域的AAAG序列特异结合。这些结果表明，该蛋白在通过激发子介导的一系列防御反应相关基因的激活来调控复杂的转录调控网络中具有重要意义。另一方面，作为抑制反应基因，我们克隆了茉莉酸的早期根瘤蛋白、细胞壁降解酶和生物合成酶的同源基因。特别是在豌豆叶片上接种亲和病原菌，特异地诱导了茉莉酸生物合成酶的相应mRNA的表达。对这些易感基因的研究可能揭示建立亲和互作的机制。较少

Pea blight pathogen, Mycosphaerella pinodes secrets two kinds of signal molecules, elicitors and suppressors in a germination fluid. Elicitors induce defense response non-specifically on plants and suppressors negate the induced defense response on only host plant. In this study, we have promoted to isolate cDNA clones that are induced by elicitor-treatment to totally understand the defense response and by suppressor-treatment to characterize the mechanisms for the establishment of the compatibility by differential screenings.As elicitor-inducible genes, we have first constructed a cDNA library from polyA+RNA prepared from elicitor-treated pea epicotyls for 5hr. By the differential screening, we have isolated 90 cDNA clones as candidates for elicitor-responsive genes. Sequencing analysis of these clones revealed as follows. 1) M. pinodes elicitor might induce gene expressions of hydroxyproline-rich glycoprotein and peroxidase to strengthen plant cell wall. 2) Putative cDNAs for polygal … More acturonase inhibiting protein and endochitinase demonstrates that these genes might be effective in incompatible interactions. 3) Isolation of many cDNA clones encoding the enzymes for polyamine biosynthesis indicates the importance of polyamine in defense response. 4) A cDNA clone encoding novel Dof type zinc-finger transcription factor binds specially to AAAG sequence present in the promoter region of many defense-related genes. These results indicate that the significance of this protein in the regulation of complex network of transcriptional regulation by the elicitor-mediated activation of a number of defense response-related genes.On the other hands, as suppressor-responsive genes, cDNA clones encoding homologs of early nodulin, cell wall degrading enzymes and biosynthetic enzyme for jasmonic acid were isolated. Particularly, corresponding mRNA to jasmonic acid biosynthetic enzyme was specifically induced by the inoculation of compatible pathogen in pea leaves. The investigation of these susceptible specific genes might reveal the mechanism of the establishment of compatible interactions. Less