Egyptian Journal of Biological Pest Control (May 2020)
Isolation and efficacy of native chitinolytic rhizobacteria for biocontrol activities against Fusarium wilt and plant growth promotion in pigeon pea (Cajanus cajan L.)
Abstract
Abstract The present study aimed to identify, characterize, and evaluate native chitinolytic rhizobacteria as biocontrol potential against pigeon pea wilt disease, caused by Fusarium udum. A total of 53 isolated rhizobacteria was evaluated for their chitinolytic potential and possession of different antifungal traits. From the successive in vitro experiments and in vivo bioassay, 2 promising bacterial strains (NS-1 and NS-22) that exhibited strong chitinolytic activities and mycolytic action were biochemically characterized and identified as Pseudomonas spp. NS-1 (NCBI GenBank accession number- KT175909) and Bacillus spp. NS-22 (NCBI GenBank accession number-MH425454), using 16S rDNA sequencing. In planta, disease severities for Pseudomonas spp. NS-1- and Bacillus spp. NS-22-treated plants were only about 14.62 and 23.08%, respectively, as compared to pathogen-only control (67.34%) at the end of 4 weeks. Additionally, these bacteria improved plant germination and fresh and dry plant biomasses under pathogen-challenged conditions. Further, both the strains were able to cause a considerable amount of reduction in the fungal biomass, as revealed by bacteria-pathogen interaction studies in liquid culture. Scanning electron microscopy studies also revealed the strong antifungal activities of these 2 chitinolytic bacteria on the pathogen hyphae and mycelia. The curling, bulging, breakdown, and other dysfunctionalities in fungal hyphae were induced by the biocontrol bacteria. In nutshell, the present exclusive investigation demonstrated mycolytic potential and biocontrol prospects of the 2 promising bacteria (Pseudomonas spp. NS-1 and Bacillus spp. NS-22) for the sustainable Fusarium wilt management and as a phytostimulator in pigeon pea.
Keywords
