贝莱斯芽孢杆菌GDND-2对烟草镰孢根腐病菌生长发育的影响

【背景】尖孢镰孢(Fusariumoxysporum)引起的烟草根腐病在世界烟区普遍发生，严重影响烟草产量和质量，化学农药无法有效防治病害，利用生防菌防治该病成为研究热点。【目的】明确贝莱斯芽孢杆菌(Bacillusvelenzensis)GDND-2对尖孢镰孢生长发育的抑制作用。【方法】制备含10%和20%GDND-2发酵滤液的PDA培养基，涂在玻片上，接种尖孢镰孢分生孢子，观察滤液对尖孢镰孢孢子萌发、菌丝生长、孢子形成和色素产生的影响，应用扫描和透射电镜观察菌体超微结构的变化。【结果】贝莱斯芽孢杆菌GDND-2发酵滤液延迟孢子萌发2h以上，造成芽管膨大畸形，促使菌丝提早分枝，抑制菌丝延伸，使菌丝产生畸形球状结构，10%和20%发酵滤液对菌丝生长抑制率达53.41%和61.58%。滤液延迟病菌产孢，显著抑制产孢量，影响孢子形态，刺激病菌产生色素。10%和20%发酵滤液延迟产孢20h和28h，对产孢量的抑制率为52.11%和78.85%，滤液促使病菌形成小型分生孢子。观察尖孢镰孢的超微结构，部分菌丝膨大、畸形，细胞壁变薄，细胞膜消失，细胞质渗出，胞内呈空腔结构；部分菌丝严重皱缩、扭曲、...

Effect of Bacillus velenzensis GDND-2 on the growth and development of Fusarium oxysporium from tobacco

Background] Root rot caused by Fusarium oxysporum is common in tobacco growing areas worldwide, severely threatening the quality and yield of tobacco. As chemical pesticides fail to effectively control the pathogen, biocontrol strains have attracted the interest of scholars. Objective] To clarify the inhibitory effect of Bacillus velenzensis GDND-2 on the growth and development of F. oxysporium from tobacco. Methods] The PDA containing 10% and 20% fermentation filtrate of GDND-2 was coated on glass slides, and then the conidia of F. oxysporum were inoculated. The effect of the fermentation filtrate on conidial germination, hyphal growth, sporulation, and pigment production of F. oxysporum was investigated, and the ultrastructure of F. oxysporum hyphae was observed by scanning and transmission electron microscopy. Results] After the treatment with fermentation filtrate of GDND-2, the conidial germination was over 2 h late. The fermentation filtrate resulted in the malformation of germ tubes and early branching of hyphae. It inhibited the elongation of hyphae and thus they showed malformed spherical structure. The inhibition rates of hyphal growth by 10% and 20% fermentation filtrate were 53.41% and 61.58%, separately. The fermentation filtrate delayed the sporulation of the pathogen, significantly reduced the spore quantity, affected the conidial morphology, and promoted the pigment production by the pathogen. Under the action of 10% and 20% fermentation filtrate, the sporulation happened 20 h and 28 h late, respectively, and the inhibition rates of spore quantity were 52.11% and 78.85%, separately. The fermentation filtrate stimulated F. oxysporum to form microconidia. As for the ultrastructure of F. oxysporium, some hyphae swelled and malformed, with thinner cell wall, disappearance of cell membrane, cytoplasm exudation, and intracellular cavity structure. Some hyphae shriveled, twisted and thinned, and perforated in severe cases. Some hyphae cells were severely vesiculated and organelle distribution was uneven. In some cells, the number of liposomes increased obviously. Conclusion] The fermentation filtrate of B. velenzensis GDND-2 inhibited the growth and development of F. oxysporum, including conidial germination, hyphal growth, and sporulation.