New isolates of Trichoderma antagonistic to Sclerotinia sclerotiorum

Abstract

Forty-nine isolates of Trichoderma from the Brazilian Midwest were evaluated for their antagonistic activity in vitro against Sclerotinia sclerotiorum (causal agent of white mold), which were then identified based on their nuclear ribosomal ITS sequences. Paired culture tests showed that all isolates exhibited some antagonism, with a maximum of 77% mycelial inhibition and complete inhibition of sclerotia production. Two isolates were found to be the most promising biocontrol agents, considering both antagonistic parameters (CEN1253 -T. koningiopsis and CEN1265 -T. brevicompactum). Five different species were identified: T. harzianum (23), T. spirale (9), T. koningiopsis (8), T. brevicompactum (7) and T. asperellum (2). These isolates are stored in the Embrapa Fungi Collection for Biological Control and the information obtained in the experiments will be incorporated into the database of biological assets within the genetic resources information system (Allele) and be made available for further studies. Resumo: Quarenta e nove isolados de Trichoderma obtidos no centro-oeste do Brasil foram avaliados quanto a sua atividade antagônica in vitro contra Sclerotinia sclerotiorum (agente causal do mofo branco) e identificados com base nas sequências ITS do DNA ribossômico nuclear. Os testes de cultivo pareado mostram que todos os isolados exibiram algum antagonismo, com um máximo de 77% de inibiação micelial e inibição total da produção de escleródios. Dois isolados se destacaram como os mais promissores, considerando ambos os parâmetros avaliados (CEN1253 -T. koningiopsis e CEN1265 -T. brevicompactum). Cinco espécies diferentes foram identificadas: T. harzianum (23), T. spirale (9), T. koningiopsis (8), T. brevicompactum (7) and T. asperellum (2). Estes isolados estão armazenados na Coleção de Fungos para Controle Biológico da Embrapa e as informações obtidas nos experimentos serão incorporadas na base de dados de ativos biológicos, no sistema de informações de recursos genéticos, e disponibilizados para estudos futuros. Palavras-chave: Recursos genéticos microbianos, identificação molecular, biocontrole, mofo branco.

Systemic Resistance in Snap Bean (Phaseolus vulgaris L.) Elicited by Some Chemicals and Biotic Inducers Against White Mold Disease Caused by Sclerotinia sclerotiorum

“…Ahmed (2016) recorded that under greenhouse conditions, treated bean seeds with B. subtilis and T. harzianum significantly reduced the incidence of Rhizoctonia solani damping-off, as well as caused a considerable increase in the activity of peroxidase and polyphenoloxidase enzymes. Marques et al (2016) showed that Trichoderma koningiopsis and T. brevicompactum isolates with good antagonistic potential for S. sclerotiorum were considered to be promising for both biocontrol parameters (inhibition of mycelial growth and reduction of sclerotia). Zhang et al (2016) found that T. harzianum increased resistance against S. sclerotiorum infection in soybean seedlings, also, primed pathogenesis-related proteins expression after S. sclerotiorum challenge, increased the activity of the antioxidant enzymes peroxidase PO, superoxide dismutase SOD, and catalase CAT and, improved the contents of chlorophyll and phenolic, indicating that these physiological and molecular mechanisms are involved in the induction of systemic resistance by T. harzianum.…”

Antifungal potential of crude extracts of Trichoderma spp.

“…Since all isolates produced active NVMs against S. sclerotiorum, the results were compared with those obtained in previously performed dual culture tests (Marques et al 2016), and a greater inhibition was observed with the use of the culture filtrates than in the direct comparison between pathogen and antagonist. This fact suggests that the main mechanism of action of these isolates is antibiosis, that is, the production of secondary compounds with antibiotic properties.…”

“…Research Corporate), already characterized and identified in previous studies (Marques et al 2016), were used. According to the study cited, these isolates exhibited antifungal activity in dual culture tests in vitro against S. sclerotiorum, and the identification was performed based on the sequencing of regions ITS1/2 of ribosomal DNA (rDNA).…”

Antagonism and molecular identification of <i>Trichoderma</i> isolated from rhizosphere of medicinal plants

“…These steps are essential because they reveal the mode(s) of action of the antagonists. In addition, a key point in the development of new biopesticides is the discovery of fungal strains with greater activity and more adapted to the agro pathosystems in which these products will be used (Marques et al, 2016;Carvalho et al, 2019).…”

“…Screening of the antagonist potential of Trichoderma isolates has been demonstrated in scientific works for several plant pathogenic fungi, such as Macrophomina phaseolina (El-Benawy et al, 2020, Choudhary et al, 2021, Martínez-Salgado et al, 2021, Paul et al, 2021; Fusarium spp. (Pellan et al, 2020;Kumar et al, 2021;Yassin et al, 2021); Sclerotium rolfsii (Kotasthane et al, 2014;Kamel et al, 2020;Blanco et al, 2021) and Sclerotinia sclerotiorum (Marques et al, 2016;Amaral et al, 2018;Sumida et al, 2018;Carvalho et al, 2019).…”