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Intensification on PAMP triggered immunity by Bacillus strains to control bacterial wilt of tomato

Ting-Hsin Ho: Department of Plant Medicine, National Pingtung University of Science and Technology

<div>Tomato bacterial wilt caused by <em>Ralstonia solanacearum</em> is a devastating disease in tomato production. Currently, there is still no effective chemical to control this disease. To control this disease, reports showed transgenic plants express extracellalar PFLP protein are resistant against bacterial wilt. The mechanism of this resistance is associated with the intensification of harpin-mediafed HR. Therefore, we sought to screen bacterial strains of <em>Bacillus</em> spp. that can enhance harpin-mediated HR and further evaluate their efficacy on controlling bacterial wilt of tomato. Before screening, the harpin from <em>R. solanacearum</em>, PopW, was cloned and expressed in pET system. Results revealed that the HR on tobacco leaves could be induced by PopW. Among 9 rhizosphere <em>Bacillus </em>strains we assayed, <em>B. amyloliquefaciens</em> PMB05 was one strain which could intensify PopW-induced HR. Bacterial suspension of PMB05 applied in the rhizosphere of 2-week old tomato seedlings exhibited strong resistant against bacterial wilt. Finally, we demonstrated that the flg22<sub>RS</sub>-induced ROS generation in tomato roots was intensified by<em> B. amyloliquefaciens</em> strain PMB05. Taken together, we concluded that the PAMP triggered immunity intensified by <em>B.</em> <em>amyloliquefaciens</em> strain PMB05 confers resistance of tomato plants against bacterial wilt disease.</div>