Identification and biocontrol evaluation of Streptomyces sp.strain ZH-356 antagonistic to plant pathogenic fungi

Abstract:

[Objective] To identify the laboratory-isolated strain ZH-356 and evaluate its biocontrol effect on plant pathogenic fungi,so as to provide theoretical guidance for the development of biocontrol agents against plant fungal diseases.[Methods] The antimicrobial spectrum of strain ZH-356 and its species were determined by the plate confrontation assay and 16S rRNA gene sequence analysis,respectively.The biocontrol effect of strain ZH-356 was evaluated by the infection prevention test of Valsa malion isolated apple tree branches and the control test of apple valsa canker.[Results]Strain ZH-356 was identified as Streptomyces and had the highest similarity with Streptomyces rectiviolaceus at 99.71%.The antimicrobial spectrum test showed that strain ZH-356 exerted strong inhibitory effect on a variety of plant pathogenic fungi,such as V.mali,Fusarium graminearum,Bipolaris sorokinianumand Alternaria solani,which could lead to the thickening,cross-twisting,infrequent branching and easy fracture of the mycelia of V.mali.In addition,the antimicrobial active substance produced by strain ZH-356 was highly stable to temperature and pH,which only existed in its cells and was secreted in the presence of plant pathogenic fungi to inhibit their growth.In the prevention test of apple valsa canker,strain ZH-356 controlled more than 94% of V.mali infection,and in the control test of apple valsa canker,ZH-356 agents had 100% control of apple valsa canker.[Conclusion] Strain ZH-356 has a wide antimicrobial spectrum and good antagonistic activity against plant pathogenic fungi.It can be used as a biocontrol strain against plant fungal diseases,laying a foundation for the development of ZH-356-based biocontrol agents and the control of plant fungal diseases such as apple valsa canker.