Attempts to produce plants that control pathogens and plant growth promoting microbes

本研究的目的是培育能够控制根际植物病原体或促进植物生长的微生物的植物。研究了植物病原菌对假单胞菌HP72的控制机理。同时，我们还研究了如何控制植物生长促进菌如氮根瘤菌和氮螺旋菌的数量，揭示了假单胞菌HP72对病原菌的控制机制是由Phl的产生引起的。Phl的产生受rpsABCDE、rspR等多种基因的复杂调控。由于rpsABC蛋白具有转运蛋白样结构，因此它们被认为与导致ph产生的信号转导途径有关。在接下来的试验中，我们研究了枯氮根瘤菌ORS 571在拟南芥根系上的行为。ORS 571是一种自由生活条件下的固氮细菌，在拟南芥根系上表现出固氮能力。一些拟南芥菌株显示出允许细菌侵入根毛的能力。在藤根上形成的微菌落中，NifH活性主要在Y形细胞中观察到，细胞结构的发育被认为与固氮有关。我们还对植物生长促进菌和植物病害控制菌进行了筛选。最终分离出几种促进植物生长和控制植物病害的真菌。在此基础上，对其促生长和防病机理进行了研究。

The aim of this study is to create plants that can control plant pathogens or plant growth promoting microorganisms in the rhizosphere. We studied the mechanism of plant pathogen control by plant pathogen controlling Pseudomonas sp. HP72. We also studied how to control the population of plant growth promoting bacteria such as Azorhizobium caulinodans and Azospirillum spp. We revealed that the mechanism of pathogen control by Pseudomonas sp. HP72 is due to the production of Phl. The production of Phl is revealed to be controlled complicatedly by the many genes such as rpsABCDE, rspR, and some other genes. As the rpsABC proteins have transporter-like structure, they considered to be associated with signal transduction pathway leading to the production of Phl. In the next experiment we studied the behavior of Azorhizobium caulinodans ORS 571 on the roots of Arabidopsis thaliana. ORS 571 is a nitrogen fixing bacteriium in the free living condition and exhibited the nitrogen fixing ability on the roots of A. thaliana.. Some A. thaliana strain showed the ability to allow the invasion of the bacterium into the root hairs. In the micro-colonies of A. caulinodans formed on the roots, the NifH activity was observed mainly in the Y shape cells, and the development of cell structure is considered to be related to the nitrogen fixation. We also carried out a screening for plant growth promoting or plant-disease controlling fungi. We finally could isolate several plant-growth promoting and plant-disease controlling fungi. Then, the mechanism of growth promotion and disease control was studied.