魔芋软腐病拮抗菌GZA12的分离鉴定及其防病促生作用

An antagonistic bacterial strain GZA12 against soft rot of konjac:isolation,identification,and application in disease prevention and growth promotion

摘要:

【目的】软腐病是影响魔芋产量和品质的重要病害之一。本研究旨在从魔芋根际土壤中筛选出一株对软腐果胶杆菌(Pectobacteriumaroidearum)具有拮抗作用的菌株，从而为花魔芋软腐病害的生物防治提供种质资源。【方法】通过平板对峙法筛选出一株拮抗菌，并测定该菌株对多种病原真菌的拮抗效果。通过魔芋球茎组织接种、生防和灌根试验验证GZA12对魔芋软腐病的防治效果。同时对该菌株的促生能力进行室内测定，并通过番茄盆栽试验初步验证该菌株促生效果。【结果】筛选出一株具有拮抗能力的菌株GZA12并鉴定为贝莱斯芽孢杆菌(Bacillusvelezensis)，该菌株对软腐果胶杆菌的抑菌圈直径达21.33 mm，对葡萄座腔菌(Botryosphaeria dothidea)、尖孢镰刀菌(Fusarium oxysporum)和茄病镰刀菌(F.solani)的抑菌率分别为58.16%、47.30%和54.53%。在魔芋球茎组织接种试验中，魔芋组织病情指数比单独接种软腐果胶杆菌菌液分别降低了26.67%、33.33%和40.00%；在生防盆栽试验中，与对照组相比，GZA12菌悬液处理组病情指数降低了22.85%，防效达53.31%。在灌根试验中，与清水灌根相比，GZA12发酵液灌根处理后，病情指数降低了4.89%，防效达21.57%。室内促生试验表明菌株GZA12具有固氮、解磷、产铁载体和产吲哚乙酸(indole-3-acetic acid,IAA)的能力，接种GZA12菌悬液能促进番茄幼苗生长，其中高浓度的菌悬液效果更佳。【结论】菌株GZA12对魔芋软腐病病原菌有较好的拮抗效果，并具有促生特性，有进一步开发利用的潜力。

关键词:魔芋;软腐病;芽孢杆菌;根际促生细菌;拮抗;促生

Abstract:

[Objective] Soft rot is one of the major diseases affecting the yield and quality of konjac.This study screened a strain with antagonistic effect on Pectinobacterium aroidearum from the rhizosphere soil of konjac,aiming to provide germplasm resources for the biocontrol of soft rot in konjac.[Methods] An antagonistic strain was screened by the plate confrontation method,and its antagonistic effects on pathogenic fungi were measured.The control effect of GZA12 on soft rot in konjac was examined by the inoculation in konjac corm tissue,pot experiment,and root irrigation.The growth-promoting effect of this strain was tested indoors and preliminarily verified by tomato pot experiments.[Results] A strain GZA12 with antagonistic effect was screened out and identified as Bacillus velezensis.This strain showed the inhibition zone diameter of 21.33 mm against P.aroidearum and the inhibition rates of 58.16%,47.30%,and 54.53% against Botryosphaeria dothidea,Fusarium oxysporum,and F.solani,respectively.Inoculation of GZA12 in konjac corm tissue decreased the disease index by 26.67%,33.33%,and 40.00%,respectively,compared with the inoculation of B.dothidea alone.In the pot experiment,the treatment with GZA12 suspension decreased the disease index by 22.85% compared with the control group and reached the control effect of 53.31%.The results from the root irrigation experiment showed that compared with water irrigation,irrigation with GZA12 fermentation broth reduced the disease index by 4.89% and reached the control effect of 21.57%.Strain GZA12 had the ability to fix nitrogen,solubilize phosphorus,and produce siderophores and indole-3-acetic acid (IAA).Inoculation with GZA12 suspension promoted the growth of tomato seedlings in a concentration-dependent manner.[Conclusion] Strain GZA12 can inhibit the pathogen causing soft rot and promote the growth of konjac,demonstrating the potential for further development and utilization.

Key words:Amorphophallus konjac;soft rot;Bacillus sp.;plant growth-promoting rhizobacteria;antagonism;growth promotion