Studies on molecular mechanisms in the signal transduction cascade from signal perception to the expression of defense responsive genes in a plant-pathogen interaction

在本研究中，我们试图阐明真菌信号分子感知与防御应答基因表达之间信号转导级联的分子机制。我们的研究结果总结如下：1。豌豆质膜atp酶和多磷酸肌醇代谢受细枝霉菌的抑制因子和抑制因子的调控。然而，即使在从真菌的非寄主植物分离的质膜中，抑制因子也能非特异性地阻断它们。2 . m .pinodes- elcpt非特异性地增强了豌豆和豇豆细胞壁nacl可溶性组分中atp酶（NTPase）、过氧化物酶（peroxidase）和抗坏血酸氧化酶（asc）的活性，而抑制因子则以一种特异性的方式抑制了这些活性。激发子在分离的豌豆细胞壁中产生的超氧阴离子和尚未确定的感染抑制剂被抑制子抑制。另一方面，豇豆细胞壁上的这些基因被单独的抑制因子反向诱导。细胞壁上某些玻璃连蛋白样分子与质膜上玻璃连蛋白受体样分子的连接介导了植物抗毒素产生的信号转导。在PSPALs和PSCHSs的启动子序列中，我们发现了Box-1（与Box L同源）、Box-2（与Box P同源）和Box-4 （AT-box）等保守的序列基序，它们对启动子的反应至关重要。在PSCHSL中，直接重复的富含at的序列，TAAAATACT能够形成低迁移率复合物（LMC），通过凝胶迁移率转移实验和体外dna酶i足迹分析。研究发现，用碱性磷酸酶处理核因子可以消除LMC的形成，这表明核蛋白的磷酸化对于复杂机械的形成是必要的。Box1、Box2和G-box等顺式元件是激发子应答性CHS基因启动子所必需的。根据这些结果，我们提出了导致防御反应的信号转导流：1)信号分子被细胞壁上各自的受体感知；2)第二信使通过质膜上的玻璃体连接素受体样蛋白进入细胞；3)细胞膜内多磷酸肌醇代谢也被激活，产生第三信使；4)信使刺激核因子磷酸化；5)防御应答基因转录被激活；6)排斥反应在阴蒂处理过的植物组织中表达。少

In this study, we attempted to clarify the molecular mechanisms in the signal transduction cascade between perception of fungal signal molecules and the expression of defense responsive genes.Our findings are summarized as follows :1. ATPase and polyphosphoinositide metabolism in pea plasma membranes are regulated by the clicitor and suppressor from Mycosphaerella pinodes. The suppressor, however, blocked nonspecifically them even in plasma membranes isolated from non-host plants of the fungus.2. The M.pinodes-elcitor enhanced nonspecifically the activities of ATPase (NTPase), peroxidase and ascorbic acid oxidase in NaCl-soluble fraction from cell walls isolated from pea and cowpea, whereas the suppressor blocked these activities in a species-specific manner.3. Superoxide anion and as yet unidentified infection-inhibitor, that were generated in isolated pea cell wall by the elicitor, were inhibited by the suppressor. On the other hand, those in cowpea cell wall were inversely elicited … More by the suppressor alone.4. Signal transduction leading to phytoalexin production was mediated by connection of certain vitronectin-like molecules in cell wall and vitronectin receptor-like molecules on plasma membrane.5. In the promoter sequence of PSPALs and PSCHSs, we found conserved sequence motifs, such as Box-1 (homologous to Box L), Box-2 (homologous to Box P) and Box-4 (AT-box) that were essential for response to the elicitor.6. In PSCHSL the directly repeated AT-rich sequences, TAAAATACT were capable of forming a low mobility complex (LMC) by a gel mobility shift assay and in vitro DNase i-footprinting analysis. The finding, that treatment of the nuclear factors with alkaline phosphatase abolished LMC formation, indicates phosphorylation of nuclear protein (s) is necessary for the formaiton of complex machinery.7. The cis-elements such as Box1, Box2 and G-box were essential for the promoter of elicitor-responsive CHS genes.From these results, we propose the stream of signal transduction leading to defense responses as follows : 1) signal molecules are percepted by respective receptors on cell wall ; 2) the second messengers are carried out into the cells via vitronectin receptor-like proteins on the plasma membranes ; 3) polyphosphoinositide metabolism in plasma membranes is also activated to produce the 3rd messenger ; 4) the messenger stimulates phosphorylation of nuclear factor (s) ; 5) The transcription of defense responsive genes are activated ; 6) the rejection reaction is expressed in the clicitor-treated plant tissues. Less