根系土壤假丝酵母菌Candida sp. YIN9对大丽轮枝菌和全齿复活线虫的抑制作用

目的] 研究黄萎病抗性棉(海 7124)根际土壤中酵母菌株对棉花黄萎病病原真菌大丽轮枝菌和全齿复活线虫的拮抗效果,为生物防治棉花黄萎病和全齿复活线虫提供理论依据。方法] 通过镜检、糖发酵实验、碳源同化实验、26S rRNA测序对菌株的形态、生理生化特征及其系统发育关系进行鉴定,并利用七叶苷筛选、刚果红染色、平皿对峙实验、盆栽实验、平板生测实验测试其产酶活性以及抑制大丽轮枝菌和杀线虫活性。结果] 从大批黄萎病抗性棉(海 7124)根际土壤中筛选出编号为YIN9的酵母菌菌株,分类鉴定结果表明:YIN9菌株属于假丝酵母属Candida。平皿对峙实验结果表明:菌株YIN9对大丽轮枝菌的抑菌率达59%;将菌株YIN9的无菌发酵滤液与大丽轮枝菌孢子共培养12 h后镜检发现,用菌株YIN9处理的实验组,大部分棉花黄萎病病菌孢子不能正常萌发。盆栽实验结果表明:菌株YIN9对棉花黄萎病的平均防治效果为60.02%,可以显著降低感病棉棉花黄萎病的发病率和病情指数。此外,与从黄萎病抗性棉根际土壤中筛选获得的其他酵母菌株相比,菌株YIN9具备较高的杀线虫活性:菌株作用全齿复活线虫48 和60 h后,线虫死亡率分别为90%和100%。将菌株YIN9发酵液煮沸后,其抑制大丽轮枝菌和杀线虫活性均急剧下降,进一步测试发现,该菌株拥有较高的蛋白酶和纤维素酶活性。结论] YIN9中的生防因子可能是热不稳定性物质,具备较高的杀线虫活性,可以显著提高感病棉对黄萎病的抗性。

Study on inhibition effects of Candida sp. YIN9 against Verticillium dahliae and Panagrellus redivivus

Aim] To study the antagonistic effects of strains from the rhizosphere soil of Verticillium wilt-resistant cotton (Hai 7124) against Verticillium dahliae and Panagrellus redivivus, and to provide a model for the biological control of Verticillium wilt and P. redivivus. Method] The strains were identified through microscopic examination, sugar fermentation experiment, carbon source assimilation experiment, 26S rRNA sequencing, morphology, physiological and biochemical characteristics, and phylogenetic analyses. Masculine screening, Congo red staining, plate confrontation experiments, pot experiments, and flat bioassay experiments were used to test the enzyme production activity and inhibition of V. dahliae and nematicidal activity. Result] Yeast strain YIN9 was screened from a large number of rhizosphere soils of Verticillium wilt-resistant cotton (Hai 7124). The results showed that the YIN9 strain belonged to Candida. The plate confrontation experiment showed that the inhibition rate of YIN9 on V. dahliae was up to 59%. After co-cultivating the sterile fermentation filtrate of strain YIN9 with V. dahliae spores for 12 h, the microscopic examination found that in the experimental group treated with strain YIN9, most of the spores of V. dahliae could not germinate normally. Pot experiments indicated that the average control effect of strain YIN9 on cotton Verticillium wilt was 60.02%, which could significantly reduce the incidence and disease index of Verticillium wilt in susceptible cotton. Moreover, compared with other yeast strains isolated from rhizosphere soil of Verticillium wilt-resistant cotton, the strain YIN9 showed comparatively high nematicidal activity: the average mortality of nematodes was 90% and 100% after 48 and 60 h of treatment with YIN9, respectively. After boiling the fermentation broth of strain YIN9, both its nematicidal and inhibitory activities against V. dahliae decreased sharply. Further experiments showed that this strain had high protease and cellulase activities. Conclusion] It was speculated that the biocontrol factor in YIN9 might be a thermally unstable substance, which showed high nematicidal activity and could significantly improve the resistance of susceptible cotton to Verticillium wilt.