Ralstonia solanacearum is a soil-borne pathogen that causes bacterial wilt worldwide. The virulence-attenuated mutants were able to combat the soil-borne plant diseases. In this study, we screened the virulence-attenuated mutant PRS-84-4-49 of Ralstonia solanacearum and demonstrated that this strain showed a significant biocontrol effect against patchouli bacterial wilt. Three putative virulence-attenuated mutants obtained in our previous preliminary screen were individually tested for their pathogenicity to patchouli plants. Mutant PRS-84-4-49 showed significantly less virulence to patchouli plants than the other investigated mutants. The virulence-attenuated mutant PRS-84-4-49 was then evaluated for its potential to control patchouli bacterial wilt. The results revealed that the biocontrol treatment significantly reduced disease severity compared with the inoculated control plants, their highest disease incidence were 33% and 63%, respectively, at 5 days post-inoculation. Mutant PRS-84-4-49 exhibited less motility and produced fewer biofilms than the wild-type strain. Therefore, our results demonstrate that virulence-attenuated mutant of Ralstonia solanacearum has potential as biological control agent capable of suppressing patchouli bacterial wilt.

青枯雷尔氏菌是一种土壤传播的病原体，在世界范围内引起细菌性枯萎。毒力减弱的突变体能够抵抗土壤传播的植物病害。在这项研究中，我们筛选了青枯雷尔氏菌的毒性减毒突变体PRS-84-4-49并证明该菌株对广patch香青枯病具有明显的生物防治作用。在我们先前的初步筛选中获得的三个推定的毒力减毒突变体分别测试了它们对广oul香植物的致病性。突变体PRS-84-4-49对广patch香植物的毒力明显低于其他研究突变体。然后评估毒力减弱的突变体PRS-84-4-49防治斑patch细菌枯萎病的潜力。结果表明，与接种的对照植物相比，生物防治处理显着降低了疾病的严重程度，在接种后5天，其最高的发病率分别为33％和63％。与野生型菌株相比，突变体PRS-84-4-49表现出更少的运动性并产生了更少的生物膜。因此，青枯雷尔氏菌具有作为能够抑制广oul香细菌性枯萎的生物防治剂的潜力。