周冬梅 何亮亮 李伟山 冯辉 赵敏 纠敏 魏利辉

摘要： 在根结线虫危害严重的番茄田块采集健康植株的根际，从中分离并筛选对根结线虫病具有防治作用的生防菌株。采用稀释分离法以及离体试验获得16株能显著杀灭南方根结线虫二龄线虫（J2）的菌株，其中菌株MF11对J2的致死率最高。基于生理生化分析、gyrB 和16S rRNA基因碱基序列比对，确定菌株MF11为荧光假单胞菌（Pseudomonas fluorescens）。菌株MF11发酵液浸泡番茄幼苗24 h后，J2在番茄根尖的聚集数量显著减少，侵入番茄根尖的虫量下降80.65%，表明菌株MF11可降低J2对番茄的侵染力。温室试验结果表明， 菌株MF11发酵液处理可以显著降低番茄植株86.53%根结数，以及70.2%的卵块数。田间试验结果表明，菌株MF11发酵液处理降低了根结线虫病的病情指数，其平均防效达66.71%，与10%噻唑膦颗粒剂处理防效相当。综上所述，菌株MF11不仅对根结线虫具有毒杀作用，还能降低根结线虫的侵染、发育和繁殖能力，从而有效防治作物根结线虫病。

关键词： 南方根结线虫;生防菌;荧光假单胞菌;防治效果

中图分类号： S432.4+5  文献标识码： A  文章编号： 1000-4440（2021）02-0326-07

Abstract： Rhizosphere of healthy tomato plants in fields severely infected by root-knot nematode was collected to isolate and screen biocontrol strains with antagonistic effects on diseases caused by Meloidogyne incognita. 16 bacterial strains with significant nematocidal activity on the second-stage larvae （J2） of M. incognita were obtained by separation method of dilution and in vitro experiment. Among them， MF11 strain showed the highest lethality rate to J2. The MF11 strain was identified to be Pseudomonas fluorescens based on physiological， biochemical analysis and gene sequence alignment between gyrB and 16S rRNA. The number of J2 aggregated around the root tips of tomatoes decreased significantly 24 h after the tomato seedlings immersed in the fermentation broth of MF11 strain. The number of root-knot nematode invading the root tips of tomato reduced by 80.65%， indicating that MF11 strain could reduce the infecting effect of J2 to tomato. Experimental results in the greenhouse showed that， tomato plants treated with MF11 strain fermentation broth could decrease the number of root-knots by 86.53% and reduce the egg mass in MF11-treated tomato roots by 70.52% significantly. The results of field experiment showed that， the disease indexes of diseases caused by root-knot nematode in tomato plants treated with MF11 reduced compared with that of water control， with an average control efficacy of 66.71%， which was the same as the treatment by fosthiazate 10% granules. In summary， MF11 strain not only has toxic action on root-knot nematode， but can also decrease the infection， growth and fertility abilities of root-knot nematode to control the diseases caused by root-knot nematode in crops effectively.

Key words： Meloidogyne incognita;biocontrol bacteria;Pseudomonas fluorescens;control efficacy

根结线虫（Meloidogyne spp.）是世界性分布的威胁农业生产的主要土传病原物之一[1]。根结线虫侵染后可导致植物组织发生变化，致使寄主更易受到青枯、枯萎、根腐等病原菌的侵染，造成复合病害，加重这些土传性病害的发生严重度[2]。由于寄主广泛，不同生态环境下根结线虫的发生流行规律存在差异，从而导致作物根结线虫病的防控十分困难[3-4]。在中国对农作物以及……