Characterization of antagonistic‐potential of two Bacillus strains and their biocontrol activity against Rhizoctonia solani in tomato

Abstract

To investigate the biocontrol mechanism of two antagonistic Bacillus strains (Bacillus subtilis MB14 and Bacillus amyloliquefaciens MB101), three in vitro antagonism assays were screened and the results were concluded that both strains inhibited Rhizoctonia solani growth in a similar manner by dual culture assay, but the maximum percent of inhibition only resulted with MB101 by volatile and diffusible metabolite assays. Moreover, cell free supernatant (CFS) of MB101 also showed significant (p > 0.05) growth inhibition as compared to MB14, when 10 and 20% CFS mix with the growth medium of R. solani. After in vitro-validation, both strains were evaluated under greenhouse and the results concluded that strain MB101 had significant biocontrol potential as compared to MB14. Strain MB101 was enhanced the plant height, biomass and chlorophyll content of tomato plant through a higher degree of root colonization. In field trials, strain MB101 showed higher lessening in root rot symptoms with significant fruit yield as compare to strain MB14 and infected control. Next to the field study, the presence of four antibiotic genes (srfAA, fenD, ituC, and bmyB) also concluded the antifungal nature of both Bacillus strains. Phylogenetic analysis of protein sequences revealed a close relatedness of three genes (srfAA, fenD, and ituC) with earlier reported sequences of B. subtilis and B. amyloliquefaciens. However, bmyB showed heterogeneity in among both strains (MB14 and MB101) and it may be concluded that higher degree of antagonism, root colonization and different antibiotic producing genes may play an important role in biocontrol mechanism of strain MB101.

The biocontrol agent Pseudomonas chlororaphis PA23 primes Brassica napus defenses through distinct gene networks

“…In contrast, we observed an increase in relative area dedicated to thylakoid structures in chloroplasts within PA23-treated plants coupled with an increase in total chlorophyll content and repression of CLH1. In other studies, BCA application has been associated with increased chlorophyll in the plant host [60–62]. The lack of overexpression of CLH1 in the PA23-only treatment group is consistent with evidence showing that CLH1 is only induced after cellular collapse, a defense response not elicited by nonpathogenic organisms [63].…”

Stepwise-Selected Bacillus amyloliquefaciens and B. subtilis Strains from Composted Aromatic Plant Waste Able to Control Soil-Borne Diseases

“…In the present study, the most promising bacterial isolates harbor at least two of lipopeptide genes in the genome, as revealed by PCR investigation. This agrees with several authors [9,11,[53][54][55] who described the presence of multiple LP-genes in Bacillus strains exhibiting antagonistic activity. The antifungal properties of lipopeptides have been deeply investigated.…”

Biocontrol Potential of Salt-Tolerant Trichoderma and Hypocrea Isolates for the Management of Tomato Root Rot Under Saline Environment

“…More specifically, PO is involved in the synthesis and modulation of reactive oxygen species (ROS), which could act directly or indirectly to restrict pathogen viability and expansion (Shoresh et al 2010). Similar observations of higher PO and PPO activity in tomato plants fortified with Bacillus amyloliquefaciens MB101 in the presence of R. solani were noticed by Solanki et al (2015). The results of present study indicated that H. lixii and T. asperellum-treated tomato plants develop tolerance toward root rot infections by triggering enzymatic activities of PO, PPO, PAL, and TPC.…”