Monosporascus root rot and vine decline (MRVD) of muskmelon, caused by Monosporascus cannonballus, is an economically important disease worldwide. The objectives of this study were to isolate native rhizobacterial strains and to evaluate their ability to promote plant growth and to provide protection against M. cannonballus. Thirty eight native bacterial isolates from the rhizosphere soil of muskmelon and cucumber were screened for their antagonism against M. cannonballus in a dual culture assay. Among them, five isolates viz., Bacillus amyloliquefaciens (B4), Pseudomonas mendocina (B7), Bacillus endophyticus (B10), Pseudomonas resinovorans B11 and P. aeruginosa AT3, identified based on the 16S rRNA gene sequence analysis, showed a significant level of antagonism and the inhibition zone ranged from 5.6 mm to 25.9 mm. Scanning electron microscopic observation of the hyphae of M. cannonballus at the inhibition zone revealed morphological abnormalities including shrinkage, loss of turgidity, pit formation and deformation. These bacterial isolates showed compatibility with one another and with Trichoderma viride. Greenhouse experiments revealed that P. resinovorans B11 was the most effective among the bacterial antagonists in controlling MRVD in melon. When applied as seed treatment and soil application, P. resinovorans B11 reduced the incidence of MRVD by 93.1%, relative to the infected control.

大炮单孢菌引起的甜瓜单孢菌根腐烂和葡萄蔓下降（MRVD）是一种在世界范围内具有重要经济意义的疾病。这项研究的目的是分离天然的根际细菌菌株，并评估其促进植物生长的能力，并提供对炮弹支原体的保护。在双重培养试验中，从甜瓜和黄瓜的根际土壤中分离出了38种天然细菌分离物，以对抗大炮支原体。其中有五个分离株，即解淀粉芽孢杆菌（B4），门氏假单胞菌（B7），内生芽孢杆菌（B10），树脂假单胞菌B11和基于16S rRNA基因序列分析鉴定的铜绿假单胞菌AT3显示出显着的拮抗作用，抑制范围为5.6 mm至25.9 mm。扫描电子显微镜观察大炮支链霉菌菌丝在抑制区的菌丝，发现形态异常，包括收缩，残缺度降低，凹坑形成和变形。这些细菌分离物显示彼此相容，并与木霉相容。温室实验表明，P。resinovorans B11是控制瓜类MRVD的最有效的细菌拮抗剂。当用作种子处理和土壤施用时，P。resinovorans 相对于感染的对照，B11将MRVD的发生率降低了93.1％。