Evaluation of bioagents and their SynCom inoculants for suppression of Rhizoctonia bataticola and Sclerotium rolfsii in chickpea: In vivo study

The potential of antagonistic isolates was evaluated against the Sclerotium rolfsii and Rhizoctonia bataticola under glasshouse conditions over two seasons. In vitro blotter paper assay against R. bataticola revealed that three isolates (BWA01, RCA08 and RSA02) resulted in no root infection or disease symptoms, while three other isolates (BSA33, RCA5 and BSA17) decreased root infection to < 10% compared to 100% in control. In in vivo biocontrol studies (for two seasons/runs), isolates RSPF04 and BWA01 reduced the S. rolfsii incidence to below 20%, while RCA08 showed lowest disease incidence of 23.4% against R. bataticola . The key antagonistic actinomycetes were identified as Streptomyces spp. except isolate BWA01 as Nesterenkonia aethiopica and bacterial strains as Pseudomonas spp. through 16 s rRNA sequencing. Further, all the synergistic isolates were constructed into six synthetic communities (SynComs) and tested for their efficacy against both the pathogens, S. rolfsii and R. bataticola . SC-6 (SynCom with all potential isolates) treatment led to less prominent symptoms and significantly reduced the disease incidence up to 100% against both the pathogens. The remaining SynComs also significantly reduced the disease incidence. Our findings demonstrate the successful selection of antagonistic microbes including novel species like Nesterenkonia aethiopica and establish that their synergistic application in SynComs confers robust, reproducible protection against soil-borne fungal pathogens in chickpea.