How siderophore production can influence the biocontrol activity of Aureobasidium pullulans against Monilinia laxa on peaches

In the present study Aureobasidium pullulans strains L1 and L8 were shown both in vitro and in vivo to compete for iron with Monilinia laxa through the secretion of siderophores (1.2 and 1.4 mg ml−1, respectively) and to prevent postharvest fruit decay of peaches. The two strains reduced mycelial growth and conidial germination of M. laxa specially in presence of lower iron concentrations (5 and 10 μg l−1 FeCl3), confirming a better efficacy when nutrients are scarce. In in vivo assay, A. pullulans L1 and L8 strains inhibited pathogen virulence, reducing by 83.5% and 84.4% on average respectively the peach lesion diameter for each tested iron solutions (5, 10, 20 μg l−1 FeCl3,). The highest iron solution slowed down the antagonists’ action and conversely increase the pathogen aggressiveness. Results shows that A. pullulans L1 and L8 strains compete with M. laxa for iron, so revealing new biocontrol aspects. Both strains showed the capability to decrease the accumulation of iron competing with some fungal pathogens and reducing their virulence. These results provide new perspectives for the use of biocontrol agents in agriculture.