Trichoderma virens Gl006 and Bacillus velezensis Bs006: a compatible interaction controlling Fusarium wilt of cape gooseberry

Abstract

The combination of Trichoderma virens Gl006 and B. velezensis Bs006 as a consortium has high potential to control Fusarium wilt (FW) of cape gooseberry (Physalis peruviana) caused by Fusarium oxysporum f. sp. physali (Foph). However, the interactions between these two microorganisms that influence the biocontrol activity as a consortium have not been studied. Here, we studied the interactions between Gl006 and Bs006 that keep their compatibility under in vitro and greenhouse conditions. Antagonism tests between Gl006 and Bs006 inoculated both individually and in consortium against Foph strain Map5 was carried out on several solid media. The effect of supernatant of each selected microorganism on growth, conidia germination, biofilm formation and antagonistic activity on its partner was also studied. Biocontrol activity by different combinations of cells and supernatants from both microorganisms against Fusarium wilt was evaluated under greenhouse conditions. In vitro antagonism of the consortium against Foph showed a differential response among culture media and showed compatibility among BCA under nutritional conditions close to those of the rhizosphere. The supernatant of Bs006 did not affect the antagonistic activity of Gl006 and vice versa. However, the supernatant of Bs006 promoted the biocontrol activity of Gl006 in a synergistic way under greenhouse, reducing the disease severity by 71%. These results prove the compatibility between T. virens Gl006 and B. velezensis Bs006 as a potential tool to control Fusarium wilt of cape gooseberry.Fusarium oxysporum is the causal agent of Fusarium wilt disease in several species of cultivated plants worldwide. This phytopathogen is in the fifth place within the top ten of the most important plant pathogens due to its effects in crops of economic importance causing severe losses 1 . Fusarium wilt is the main limitation of cape gooseberry (Physalis peruviana) crop in Colombia 2 . Wilt symptoms in field include wilting of top leaves, stunting of plants, lateral yellowing of branches and leaves, some plants present both dry and alive branches. Plants finally become yellow and die, resulting in plant losses and reduced fruit yield. This phytosanitary problem has also caused the migration of cropped areas within the country, but the problem persists in old and new cropped areas 2 . Currently, there are no registered phytosanitary products for the control of this disease in cape gooseberry.In this context, biological control has emerged as an environmentally sustainable alternative. However, classical biological control in which just one biological control agent (BCA) is used has shown high variability among tests. Considering that biocontrol agents are living organisms and they may not be active in all agroecosystems 3 , many of the recent studies have focused on using combinations of BCA to increase the efficacy against phytopathogens. Those combinations are known as consortia. A consortium is a microbial association of two or more microorganisms, which could be archaea, fu...

Microbial Interactions Within Multiple-Strain Biological Control Agents Impact Soil-Borne Plant Disease

“…Vice versa , addition of Trichoderma conidia did not affect viability of B. velezensis suggesting high compatibility of both microbes. Adhesion of B. velezensis spores to the conidia of T. virens without affecting their morphology was observed, supporting compatibility of both soil inhabitants ( Izquierdo-García et al, 2020 ).…”

“…A consortium consisting of Trichoderma asperellum GDFS1009 and Bacillus amyloliquefaciens ACCC1111060 was found to be more efficient against infection by Botrytis cinerea (the agent of gray mold disease) than the individual strains ( Wu et al, 2018 ). Similarly, when Trichoderma virens GI006 was combined with Bacillus velezensis Bs006, efficiency against Fusarium wilt of cape gooseberry was enhanced ( Izquierdo-García et al, 2020 ). A bacterial consortium of Chitionophaga sp.…”

“…Germination of fungal conidiospores and Bacillus endospores, is a critical step in successful colonization of BCAs. The contact of Trichoderma conidia with Bacillus biofilms did not impair the ability of fungal spores to germinate and establish the fungus in soil ( Izquierdo-García et al, 2020 ). The mycelia of Trichoderma can serve as a supporting layer for formation of bacterial biofilms and can aid bacterial migration in the soil.…”

Mixtures of Biological Control Agents and Organic Additives Improve Physiological Behavior in Cape Gooseberry Plants under Vascular Wilt Disease

“…Positive results of the use of BCAs have been reported in the management and protection of various crops [23,24]. Likewise, the use of mixtures of different BCAs has generated interest in the possibility to increase efficacy in the management of plant diseases [25,26]. BCA mixtures can increase the effectiveness in disease control by presenting different biocontrol or action mechanisms.…”

“…BCA mixtures can increase the effectiveness in disease control by presenting different biocontrol or action mechanisms. Synergistic effects have been also observed because of the complementarity of the action mechanisms between BCAs [26,27]. Some of the species of the genera Trichoderma and Bacillus are considered of high interest because they have shown biocontrol potential [28,29].…”