Biocontrol agents promote growth of potato pathogens, depending on environmental conditions

Autor(es)

Cray, Jonathan A. ; Connor, Mairead C. ; Stevenson, Andrew ; Houghton, Jonathan D. R. ; Rangel, Drauzio E. N. ; Cooke, Louise R. ; Hallsworth, John E.

• Tipo de documento: Artigo Científico
• Fonte: MICROBIAL BIOTECHNOLOGY; v. 9, n. 3, p. 25-pg., 2016-05-01.

Resumo

There is a pressing need to understand and optimize biological control so as to avoid over-reliance on the synthetic chemical pesticides that can damage environmental and human health. This study focused oninteractions between a novel biocontrol-strain, Bacillus sp. JC12GB43, and potato-pathogenic Phytophthora and Fusarium species. In assays carried out in vitro and on the potato tuber, the bacterium was capable of near-complete inhibition of pathogens. This Bacillus was sufficiently xerotolerant (water activity limit for growth=0.928) to out-perform Phytophthora infestans (similar to 0.960) and challenge Fusarium coeruleum (similar to 0.847) and Fusarium sambucinum (similar to 0.860) towards the lower limits of their growth windows. Under some conditions, however, strain JC12GB43 stimulated proliferation of the pathogens: for instance, Fusarium coeruleum growth-rate was increased under chaotropic conditions in vitro (132 mM urea) by >100% and on tubers (2-M glycerol) by up to 570%. Culture-based assays involving macromolecule-stabilizing (kosmotropic) compatible solutes provided proof-of-principle that the Bacillus may provide kosmotropic metabolites to the plant pathogen under conditions that destabilize macromolecular systems of the fungal cell. Whilst unprecedented, this finding is consistent with earlier reports that fungi can utilize metabolites derived from bacterial cells. Unless the antimicrobial activities of candidate biocontrol strains are assayed over a full range of field-relevant parameters, biocontrol agents may promote plant pathogen infections and thereby reduce crop yields. These findings indicate that biocontrol activity, therefore, ought to be regarded as a mode-of-behaviour (dependent on prevailing conditions) rather than an inherent property of a bacterial strain. (AU)

• Processo FAPESP: 10/06374-1 - Luz visível durante o crescimento induz aumento de tolerância de conídios a diferentes condições de estresse em fungos
• Beneficiário: Drauzio Eduardo Naretto Rangel
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 13/50518-6 - Genes relacionados com estresse são induzidos pela luz visível durante o crescimento micelial, resultando em aumento da tolerância de conídios a condições de estresse
• Beneficiário: Drauzio Eduardo Naretto Rangel
• Modalidade de apoio: Auxílio à Pesquisa - Regular