贝莱斯芽孢杆菌SZAD1对大丽轮枝菌的生物防治效果

Biocontrol Effect of Bacillus velezensis Strain SZAD1 on Verticillium dahliae

【目的】黄萎病是棉花的主要真菌病害,缺乏高抗品种和安全有效的化学杀菌剂。生物防治黄萎病对棉花生产具有重要意义。本研究旨在探讨棉花内生细菌对大丽轮枝菌的拮抗活性和生物防治潜力。【方法】通过16S r DNA与gyr B序列分析,对菌株SZAD1进行鉴定。在平板对峙试验中检测SZAD1对黄萎病菌VD080菌丝生长的抑制能力,通过种子浸泡和灌根检测对黄萎病的防效。制备含羧甲基纤维素或几丁质的琼脂平板培养基来检测菌株能否分泌纤维素酶和几丁质酶,并用二硝基水杨酸试剂法测定酶活性。【结果】SZAD1属于贝莱斯芽孢杆菌(Bacillus velezensis)。SZAD1菌株能显著抑制VD080菌丝生长,种子浸泡法和灌根法处理中SZAD1菌株对棉花黄萎病的防效分别为60.10%和56.00%。SZAD1菌株能产生纤维素酶和几丁质酶,在培养72 h时达到最大酶活性。该菌发酵72 h的上清液抑菌效果最强。加入25 mg·L-1和50 mg·L-1的SZAD1发酵上清液后,液体马铃薯葡萄糖琼脂培养基中的VD080孢子含量分别较对照降低了30.20%和96.53%。【结论】SZAD1菌发酵上清液通过灌根法处理可减少VD080在棉花植株茎部的定植,减轻棉花叶片枯萎程度。SZAD1有作为生防菌控制棉花黄萎病的潜力。

[Objective]Verticillium wilt is the main fungal disease of cotton,lacking high resistant varieties and safe and effective chemical fungicides.Biological control of Verticillium wilt is of great significance to cotton production.The purpose of this study was to analyze the antagonistic activity and biocontrol potential of endophytic bacteria in cotton against Verticillium dahliae.[Method]SZAD1 was identified by 16S rDNA and gyrB sequence analysis.The ability of SZAD1 to inhibit the mycelial growth of V.dahliae strain VD080 was tested by the agar plate test,and the control effect on Verticillium wilt was tested by the seed soaking and root filling method.The agar plate containing carboxy methyl cellulose(CMC)or chitin was prepared to test whether the strain can secrete cellulase and chitinase,and the enzyme activity was determined by the dinitrosalicylic acid reagent method.[Result]SZAD1 belongs to Bacillus velezensis.SZAD1 can significantly inhibit the growth of VD080 mycelium.The control effect of SZAD1 on Verticillium wilt was 60.10%and 56.00%in the seed soaking and root filling experiments respectively.SZAD1 strain can produce cellulase and chitinase with the maximum activity at 72 h after culture.The antibacterial effect of fermented supernatant was the strongest at 72 h after culture.The content of VD080 spores in liquid potato dextrose agar medium decreased by 30.20%and 96.53%compared with the control respectively after adding supernatant with concentrations of 25 mg·L-1 and 50 mg·L-1.[Conclusion]The supernatant of bacteria SZAD1 can reduce the colonization of VD080 in the stem of cotton plant by root filling and decreased the withering degree of cotton leaves.SZAD1 has the potential of controlling cotton Verticillium wilt as a biocontrol bacteria.