Molecular studies aimed at the identification and biocontrol of plant pathogens

PRINCIPE, ANALÍA; CALIGIORE-GEI, P; LÓPEZ JL; PUCCI GN; PUCHE, RICARDO; MEDEOT, DANIELA; JOFRE, E.

Salta

Congreso; SAIB 2019; 2019

One of the main impacts of climate change on different crops is the outbreak of bacterial diseases that were previously of low incidence. The effects of bacterial diseases include yield loss and impairments of product quality in different plant species, particularly intensive crops like fruit trees and vegetables. The management of these emerging pathogens is mainly based on chemicals derived from copper, a heavy metal that may cause a negative impact on the environment. Hence, biological control emerges as an important alternative for integrated diseases management. This strategy is based on employing live microorganisms to reduce and/or maintain the population of a plant pathogen below the levels, which cause economic loss. Thus, the use of these eco-friendly formulations is an effective tool, useful to avoid the negative effects of the chemical treatments. The evaluation of the effectiveness of bioformulations is commonly performed against reference pathogenic strains, which usually do not respond in the same way as native phytopathogenic strains. For this reason, the main objective of this work was to characterize, at the molecular and genetic level, native pathogenic bacteria as well as to address biocontrol studies using different Bacillus formulations. Eleven bacterial strainswere isolated in the Valle de Uco region, Argentina, where they cause emerging diseases in different crops, including tomato, onion, walnut and garlic. The strains were obtained from diseased plants and confirmed as pathogen following Koch?s postulates. They were later characterized through their fatty acid profiles and bio-typed by MALDI-TOF. In addition, the 16S rRNA gene of each strain, amplified using universal primers rD1 and fD1, was sequenced. Biocontrol tests were performed under in-vitro conditions, challenging the bacterial pathogenic strains against different Bacillus formulations. The results showed that the strains belonged to different species grouped in the Pantoea, Xanthomonas and Pseudomonas genera. The in-vitro biocontrol tests demonstrated that both, the Bacillus strains (ARP2-3, MEP2-18, A6, and A7) and their metabolites, released to the culture medium, showed promising antagonistic activity against the evaluated phytopathogenic strains.