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

本研究的目的是创造能够控制植物根际病原体或植物生长促进微生物的植物。研究了植物病原菌假单胞菌（Pseudomonasp.HP72）对植物病原菌的控制机理。我们还研究了如何控制植物生长促进细菌的种群，如Azorhizobium caulinodans和固氮菌。结果表明，假单胞菌HP 72的抑菌机理是产生Phl. Phl的产生受多种基因如rpsABCDE、rspR等的复杂调控。由于rpsABC蛋白具有类似转运蛋白的结构，因此被认为与导致Phl产生的信号转导途径有关。在接下来的实验中，我们研究了Azorhizobium caulinodans ORS 571在拟南芥根部的行为。ORS 571是一株自由生长的固氮菌，在苜蓿根上表现出一定的固氮能力。thaliana..一些A. thaliana菌株显示出允许细菌侵入根毛的能力。在A.茎节细胞在根上形成后，NifH活性主要在Y形细胞中观察到，细胞结构的发育与固氮作用有关。我们还进行了植物生长促进或植物病害控制真菌的筛选。最终分离到几株植物促生和植物病害防治真菌。并对促生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.