Abstract：
Bacteria are exposed to and tolerate diverse and potentially toxic compounds in the natural environment. While efflux transporters are generally thought to involve bacterial antibiotic resistance in vitro, their contributions to plant bacterial virulence have so far been poorly understood. Pseudomonas cannabina pv. alisalensis (Pcal) is a causal agent of bacterial blight of Brassicaceae. We here demonstrated that NU19, which is mutated in the resistance-nodulation-cell division (RND) transporter encoded gene, showed reduced virulence on cabbage compared to WT, indicating that the RND transporter contributes to Pcal virulence on cabbage. We also demonstrated that brassinin biosynthesis was induced after Pcal infection. Additionally, the RND transporter was involved in resistance to plant-derived antimicrobials and antibiotics, including the cabbage phytoalexin brassinin. These results suggest that the RND transporter extrudes plant-derived antimicrobials and contributes to Pcal virulence. We also found that the RND transporter contributes to Pcal virulence on Brassicaceae and tomato, but not on oat. These results suggest that the RND transporter contributes to Pcal virulence differentially depending on the host-plant species. Lastly, our expression-profile analysis indicated that the type-three secretion system (TTSS), which is essential for pathogenesis, is also involved in suppressing brassinin biosynthesis. Taken together, our results suggest that several Pcal virulence factors are involved in resistance to plant-derived antimicrobials and bacterial survival during infection.
摘要：
细菌在自然环境中暴露于并耐受多种和潜在有毒的化合物。虽然外排转运蛋白通常被认为在体外涉及细菌抗生素抗性，到目前为止，人们对它们对植物细菌毒力的贡献知之甚少。大麻假单胞菌pv。alisalensis（Pcal）是十字花科细菌性疫病的病原体。我们在这里证明了NU19在抗性结瘤细胞分裂（RND）转运蛋白编码基因中突变，与WT相比，对白菜的毒力降低，表明RND转运蛋白有助于Pcal对白菜的毒力。我们还证明了在Pcal感染后诱导了油菜素的生物合成。此外,RND转运蛋白参与了对植物来源的抗微生物剂和抗生素的抗性，包括卷心菜植物抗毒素油菜素.这些结果表明，RND转运蛋白会挤出植物来源的抗菌剂，并有助于Pcal毒力。我们还发现RND转运蛋白有助于Pcal对十字花科和番茄的毒力，但不是在燕麦上。这些结果表明，RND转运蛋白对Pcal毒力的贡献差异取决于宿主植物物种。最后,我们的表达谱分析表明，三型分泌系统（TTSS），这对发病机制至关重要，还参与抑制油菜素的生物合成。一起来看,我们的研究结果表明,几种Pcal毒力因子参与了对植物源性抗菌药物的抗性和感染过程中细菌的存活.
