Isolation And Screening Of Antagonistic Bacteria Against Sugarcane Smut Pathogen And Prelimitary Investigation Of Their Effects

Sugarcane(Saccharum spp.L.hybrids)is an important sugar and energy crop mainly grown in tropical and subtropical countries and areas,providing about 80% of the total sugar in the world.Due to long-term of large-scale cultivation,sugarcane has been infected by many diseases,and some of them are getting worse and worse,which decrease the cane yield and quality.Sugarcane rhizosphere soil is rich in microorganisms that have a variety of growth-promoting properties and effects on disease control.It has a great value to use these soil beneficial microorganisms to realize the reduction of fertilizer and chemical application in sugarcane production.In this study,bacteria were isolated from the rhizosphere soil of sugarcane with severe sugarcane smut,and identified and classified by 16 S r RNA.The strains with growth-promoting properties and antagonistic effects on sugarcane smut were screened,and the selected dominant strains were tested preliminarily for their growth-promoting properties and antagonistic ability to smut.The main findings were as follows.1.A total of 68 strains were isolated from the sugarcane soil with severe smut disease in the crop.Through analysis of its 16 S r RNA gene sequence for identification,it is found that the isolated strains mainly belong to the genara Bacillus,Burkholderia,Stenotrophomonas and Enterobacter.The plant growth promoting(PGP)characteristic test results of the strains show that different strains had different growth-promoting properties.The isolates of Burkholderia and Serratia genera had the ability to dissolve iron and phosphorus,and had high activities of protease and ACC deaminase,and high ability to produce chitinase.2.The 68 isolated bacteria were screened by the stand-off method,and 7strains were found to have antagonistic effects on Sporisorium scitamineum,among which Burkholderia strains G1,G10,G23,and Serratia strain G12 showed obviously stronger against sugarcane smut.3.Antagonistic experiments using 6 pathogenic fungi were carried out for the 4 bacterial strains having the strongest smut pathogen antagonistic ability.The results showed that all the Burkholderia isolates G1,G10,and G23 had antagonistic effects on all the pathogenic fungi.4.The results of greenhouse experiments showed that the 4 sugarcane smut pathogen antagonistic strains could reduce the incidence of sugarcane smut disease,indicating their potential as a biocontrol agent.The Burkholderia G23 has significant smut pathogen antagonistic ability and PGP effect on the aboveground and underground parts of sugarcane.The results of the present study have provided a theoretical basis for construction of a resource bank of sugarcane smut-resistant bacteria.