Identification and characterization of sugarcane Sporisorium scitamineum antagonists

Abstract:

Sugarcane smut caused by Sporisorium scitamineum is one of the major diseases affecting the development of China’s sugar industry,and biocontrol is currently the most efficient and safe means,which necessitates the screening of antagonists with strong environmental adaptability and inhibitory effects.[Objective] To isolate and identify the strains with good antagonistic effects against S.scitamineum from soil and provide high-quality biocontrol strain resources for the efficient prevention and control of sugarcane smut.[Methods]The antagonists were isolated by the plate confrontation assay,and their taxonomic status was determined by morphological observation,physiological and biochemical tests,and 16S rRNA gene sequencing.The pot and field experiments were conducted to study the inhibition effects of the antagonists on sugarcane smut.[Results] Three strains of bacteria with significant antagonistic effects were obtained.Strains GB-3 and GH16-3 were identified as Bacillus velezensis and GH16-8 as B.amyloliquefaciens,with the inhibition zone diameters of (30.00±1.07),(44.00±1.21),and (18.00±0.89) mm and the inhibition rates of 16.12%,31.92%,and 5.91%,respectively.The inhibition effects of the three strains against sugarcane smut were 74.33%,76.57%,and 69.07% in pots and 20.08%,55.59%,and 50.08% in fields,respectively.All the three strains had phosphorus-solubilizing ability,tolerance to extreme salt-alkaline environments,and inhibitory effects on a variety of phytopathogenic bacteria and fungi,with the indole-3-acetic acid (IAA) yields of 2.12,1.30,and 1.22 mg/L,respectively.The application of the three strains increased the sugarcane plant height by 28.25%,17.09%,and 23.31%,respectively.[Conclusion] Strain GH16-3 has strong environmental adaptability,growth-promoting effect,and prevention effect against sugarcane smut,demonstrating a promising application prospect.

Key words:sugarcane smut;Sporisorium scitamineum;antagonist;inhibition effects