大豆根腐病生防链霉菌IRHB47的鉴定、生物学特性及防治效果

Identification,Biological Characteristics and Control Efficacy of Streptomyces virginiae IRHB47 Against Soybean Root Rot

【目的】明确1株大豆根际细菌IRHB 47的分类地位及对根腐病的生防潜力,为根腐病防治提供理论依据。【方法】采用平板对峙培养、菌悬液浸种、盆栽接种试验检测IRHB47的抑菌效果、安全性、根腐病防效及环境适应性,通过菌落形态特征及16S rDNA序列分析鉴定其分类地位。【结果】菌株IRHB 47对尖孢镰孢菌Fusarium oxysporum、腐皮镰孢菌F.solani、藤仓镰孢菌F.fujikuroi等5种大豆根腐病致病菌的菌丝生长抑制率达51.04%~70.40%;对大豆白绢病菌Selerotium rolfsii、草莓灰霉病菌Botrytis cinerea、水稻稻瘟病菌Pyricularia oryzae等9种病原真菌拮抗作用显著。盆栽试验发现,IRHB 47菌悬液浸种预防处理和苗期灌根治疗处理均能够显著降低尖孢镰孢菌引起的大豆根腐病病情指数和植株死亡率。经16S rDNA序列分析,IRHB 47被鉴定为弗吉尼亚链霉菌Streptomyces virginiae,为革兰氏阳性菌。生物学特性检测表明,该菌株可在p H 5~10、6.25%LB培养基上生长,具有良好的耐酸碱性和低营养胁迫能力,且能够产生蛋白酶和酪蛋白酶以诱导大豆抗性。【结论】弗吉尼亚链霉菌IRHB 47菌株抑菌谱广,环境适应性强,能够有效缓解根腐病症状。

【Objective】This study aims to uncover the fungal growth inhibition and control efficacy of the strain IRHB 47 from soybean rhizosphere on soybean root rot,and provide some references for the control of root rot.【Method】Plate dual culture method,seed soaking wit bacterial suspension,and pot experi⁃ments were used for detecting the mycelial inhibition effects,application safety,disease control effi⁃ciency and environmental tolerance.Morphologial characteristics of colony combined with phylogenetic analysis based on 16S rDNA sequence were used for clarifying its taxonomy.【Result】The strain IRHB 47 had the fungal growth inhibition effects on five Fusarium species causing soybean root rot including F.oxysporum,F.graminearum,F.asiaticum,F.solani and F.fujikuroi with the inhibition rate of 51.04%-70.40%.And meanwhile it also displayed good antagonistism against nine agricultural pathogenic fungi like Botrytis cinerea,Selerotium rolfsii,Pyricularia oryzae.Pot experiment array showed that IRHB 47 ap⁃plication through either seed soaking or irrigation at the seedling growth significantly decreased the dis⁃ease index of soybean root rot caused by F.oxysporum and promoted its survival of soybean seedlings.Analysis of 16S rDNA sequence showed that IRHB 47 was identified as Streptomyces virginiae and was gram positive bacteria.Furthermore,this strain not only had strong stress tolerance under low nutrients(6.25%LB)and wide pH condition(pH 5-10)but also produced Protease and Caseinase to induce plant immunity.【Conclusion】This study indicates that Streptomyces virginiae IRHB 47 has big poten⁃tial to be explored as one biocontrol bacterium of soybean root rot because of wide fungal growth inhibi⁃tion effects and strong stress tolerance.