Research on the mechanisms involved in pathogenicity and induction of defense reaction by plant pathogenic bacteria.

我们发现PhoP-PhoQ双组分调控系统负责高诱导果胶酸裂解酶，这是主要的毒力因子欧文氏菌subsp. carotovora。这种超诱导的刺激是低pH、低浓度的糖、低浓度的镁和乙酸盐，这些被认为是等同于植物细胞内空间中的环境。这一发现将为抗病作物的构建提供重要的性状。另外，我们还发现avrBs 3/pth基因家族对harpin等普通诱导子诱导的HR具有抑制活性，我们发现燕麦食酸菌对水稻品种的识别需要免疫系统的诱导和III型分泌系统的调节。我们还发现鞭毛结构域位于鞭毛的C末端损伤处。此外，我们还从识别鞭毛的植物蛋白中分离出了功能尚不清楚的FIP 50蛋白，并鉴定了AtBBF 1和AtBBF 2，它们在根癌农杆菌接种的胆囊组织中调节端粒酶的表达。在证实了一种叫做telomestatin的抑制剂能够有效抑制植物端粒酶活性后，我们发现这种抑制剂诱导的细胞凋亡与HR的发生同时出现。AtBI-1是一种凋亡相关基因，在HR发生过程中抑制凋亡的诱导。Bax抑制剂和HC毒素还原酶抑制HR凋亡。

We found that PhoP-PhoQ two component regulatory system is responsible for the hyperinduction of pectate lyase that is the main virulent factor in Erwinia carotovora subsp.carotovora. The stimuli for this hyperinduction were low pH, low concentration of sugars, low concentration of magnesium, and acetate which are thought to be equivalent to the environment in plant intracellular space. This finding will be important traits for the construction of disease resistant crops. Also, we found that avrBs3/pthgene family has suppressor activity on HR induced by general elicitors such as harpin.We found that the induction of immune system and the regulation by type III secretion system are required for the recognition of rice cultivars by Acidovorax avenae. We also found that the domain of flagella resides in C-ending lesion of flagella. Furthermore, we have isolated the protein called FIP50 whose function is not known yet from the search of plant proteins recognizing the flagella.We have identified AtBBF1 and AtBBF2 which regulate the expression of telomerase in the gall tissues inoculated with Agrobacterium tumefaciens. After confirmation of the inhibitor called as telomestatin is effective in inhibiting the plant telomerase activity, we found that this inhibitor induce the apoptosis appearing simultaneously with HR development. The AtBI-1, one of apoptosis-related genes, was found to suppress the induction of apoptosis during HR development. Finally, Bax inhibitor and reducing enzyme of HC toxins inhibit the HR apoptosis.