Biological Control Mechanisms of Bacillus cabrialesii subsp. tritici TSO2T against Fusarium languescens, the Causal Agent of Wilt in Jalapeño Peppers

Abstract

Jalapeño peppers (Capsicum annuum var. Jalapeño) represent one of the most important crops in Mexico. However, many plant diseases, such as wilt caused by strains of the genus Fusarium, reduce its yield. A sustainable alternative to control diseases is the use of biological control agents (BCAs), for example, beneficial microorganisms such as strains of the genus Bacillus. This study aims to analyze the potential use of B. cabrialesii subsp. tritici TSO2T as a BCA and elucidate its potential modes of action against Fusarium strains causing wilt in Jalapeño peppers. For this, symptomatic samples were collected in a commercial field in the Yaqui Valley, Mexico. Six Fusarium isolates were morphologically and molecularly characterized. After pathogenicity tests, F. languescens CE2 was found to be pathogenic. In screening assays for biocontrol bacteria, strain TSO2T, which was isolated from soil in a wheat commercial field under an organic production system and preserved in the Culture Collection of Native Soil and Endophytic Microorganisms (COLMENA), had the best biocontrol effect against CE2, and its cell-free filtrate reduced mycelial growth by 30.95%. Genome mining (antiSMASH) of strain TSO2T allows us to identify gene clusters associated with biocontrol, such as fengycin, surfactin, bacillibactin, bacilysin, bacillaene, subtilosin A, and sporulation killing factor, which codify to antimicrobial metabolites and are associated with swarming motility of the studied beneficial strain. These results demonstrate the effectiveness of B. cabrialesii subsp. tritici TSO2T as a potential BCA for the control of Fusarium wilt, through competition and a complex of antifungal metabolites, which still need to be validated through metabolomic analysis. This study highlights the importance of the use of integrative genomic and bioactivity-guided methodologies in understanding biocontrol pathosystems.

Genomic Insight into a Potential Biological Control Agent for Fusarium-Related Diseases in Potatoes: Bacillus cabrialesii Subsp. cabrialesii Strain PE1

“…Tritici TSO2 T and Bacillus cabrialesii subsp. cabrialesii TE3 T have been reported as biocontrol agents [9,43]. The biocontrol capacity of these biological control strains is largely attributed to their ability to produce extracellular enzymes (cellulase, glucanases, proteases, chitinases, beta-xylosidase, chitin deacetylases, catalase, peroxide dismutase, and peroxidase); and antimicrobial secondary metabolites such as organic compounds (1,2-benzenedicarboxylic acid, 6-undecylamine, 2-methyloctacosane, 9-octadecenoic acid and 1-tetradecanamine, and N,N-dimethyl), lipopeptides (mycosubtilin, fengycin B, iturin A, surfactin A, iturin, bacillomycin, bacilysin, and mersacidin) and siderophores [41,44].…”

“…Fusarium languescens CE2 was obtained from a national microbial culture collection, named COLMENA (Coleccion de Microorganismos Edaficos y Endofitos Nativos, [31]). This is a phytopathogenic strain previously isolated from the Yaqui Valley, Mexico [9]. In this study, the strain CE2 was used as a model for Fusarium.…”

“…In this study, the strain CE2 was used as a model for Fusarium. This assay was carried out following the methods described by Montoya-Martinez et al (2023) [9] and Baard et al (2023) [32], with modifications. Thus, a liquid bacterial culture was prepared by inoculating a 1 × 10 4 CFU of strain PE1 into 20 mL of NB.…”

“…The relative importance of the Fusarium species varies depending on factors such as local climate, agricultural practices, and host susceptibility [8]. For instance, according to Montoya-Martinez and Cota-Barreras [9,10], Fusarium languescens is a significant regional phytopathogen in Sonora, Mexico, that could impact potato production. Currently, new alternative control methods to synthetic fungicides are being considered for sustainable agricultural systems, due to the development of fungicide resistance by Fusarium strains [11][12][13], as well as the negative impact of these synthetic compounds on the environment and health [14].…”