Escrutinio masivo de un banco de germoplasma para obtener microorganismos antagonistas a Fusarium verticillioides

Abstract

Maize crop is one of the most important worldwide. Seven species of Fusarium have been associated to ear, root and stem rot. , from which F. verticillioides is the most important. This study aimed to find new biocontrol techniques to control the disease caused by this phytopathogenic fungus in Sinaloa. Fusarium verticillioides (99% identity at the nucleotide level in the ITS rDNA region) isolates were used to monitor 11,520 isolates corresponding to a germplasm bank using a massive antagonism assay in liquid medium for their antagonist ability against this pathogen. The antagonic activity was monitored on PDB media, in which the phytopathogenic fungi and the bacterial isolates were grown as dual cultures. Fungal biomass was quantified using WGA Alexa Fluor 488. 622 isolates were selected for their ability to decrease at least 60% mycelial growth of F. verticillioides. To confirm their antagonic effect in solid medium, PDA 96-well plates were used and 42 isolates were selected under the criterion that they caused over 45% inhibition of fungal growth in solid media. Most of the 42 selected microorganisms belong to the genus Bacillus, Pseudomonas y Paenibacillus. Hemolysis assays on the 42 selected strains rendered 14 that showed alpha or gamma hemolysis. Three isolates were additionally selected since they exhibited antagonistic potential against F. verticillioides in planta either due to their ability to produce quitinases, auxins or other mechanisms of plant growth promotion.