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Biotechnol Lett ; 43(3): 719-728, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33389271


OBJECTIVE: To evaluate the role of the biocontrol agent Bacillus subtilis CtpxS2-1 in inducing lupin systemic resistance against anthracnose caused by Colletotrichum acutatum by lipopeptide production. RESULTS: First, growth inhibition and thin layer chromatography-bioautography analysis confirmed that CtpxS2-1 cultures and their lipopeptide extracts, specifically fengycin, have strong antifungal activity against C. acutatum. Subsequent microscopic examination of these fungal inhibition zones showed mycelial pathogen deformations. PCR amplification of CtpxS2-1 confirmed the presence of genes encoding fengycins E and C, bacillomycin C, iturin A, and surfactins B and C. Based on this evidence, the effect of CtpxS2-1 and its lipopeptides on the induction of the lupin defence- and growth-related genes PR-1, PR-4, SOD-2, PIN-1 and PIN-3 was evaluated by RT-qPCR. In seedlings from roots treated with CtxpS2-1, a significant increase in the expression of these genes was induced. Efficacy assays showed that CtpxS2-1 treatment completely controlled anthracnose incidence (0.0%) compared with the untreated control. Furthermore, root and shoot growth in treated seedlings with CtpxS2-1 significantly increased due to disease control, as did the synthesis of the defence enzymes catalase, peroxidase and superoxide dismutase. CONCLUSION: B. subtilis CtpxS2-1 is a key factor enhancing Andean lupin health by producing lipopeptides that damage C. acutatum cellular structures and inhibit their growth, as well as by inducing the expression of defence-related genes of lupin plants involved in systemic acquired resistance (SAR) against anthracnose.

Plant Dis ; 97(6): 819-827, 2013 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-30722604


Anthracnose is a serious problem of both Andean lupine and tamarillo in Ecuador. Morphological features, internal transcribed spacer (ITS) sequences, and host specificity were used to characterize Colletotrichum isolates from lupine and tamarillo. Based on phenotypic and molecular characterization, the causal agent of anthracnose on both hosts was Colletotrichum acutatum. All isolates were identified in a C. acutatum-specific polymerase chain reaction assay. Colony diameter, conidia shape, and insensitivity to benomyl also placed isolates from both hosts in the C. acutatum group. However, a detailed analysis of the ITS sequences placed the lupine and tamarillo isolates from the Ecuadorian Andean zone in two clades, with both lupine and tamarillo isolates in each clade. C. acutatum isolates from Andean lupine were distinct from other C. acutatum isolates on lupine around the world. In cross-infection studies, the diameter of lesions produced by isolates from each host was compared on the main stem of two tamarillo and three lupine cultivars. Some isolates produced larger lesions on the host from which they were isolated but others showed similar aggressiveness on their alternate host. Isolates from both hosts were biotrophic on lupine stems, producing little necrosis and abundant sporulation whereas, on tamarillo stems, they produced dark lesions with few conidia. The collection of C. acutatum isolates from lupine and tamarillo provides interesting material for the study quantitative host adaptation.