Biocontrol of postharvest gray mold of cherry tomatoes with the marine yeast Rhodosporidium paludigenum

The marine yeast Rhodosporidium paludigenum was tested for its biocontrol efficacy in reducing postharvest gray mold of cherry tomatoes caused by Botrytis cinerea in vitro and in vivo tests. A previously unreported gray mold antagonist, R. paludigenum, significantly reduced disease incidence on cherry tomatoes. The results showed that suspensions containing 1 × 108 CFU/ml washed cells of R. paludigenum provided the highest levels of inhibition of gray mold, while the unwashed cell suspension provided less protection against the disease after 5 days at 25 °C. Increasing concentrations of R. paludigenum influenced decay incidence in cherry tomato wounds: the disease incidence decreased as the concentration of R. paludigenum was increased. Moreover, in the small-scale experiment, the incidence of gray mold on cherry tomatoes treated with R. paludigenum was 14.7% and 46.3% of the control at 15 °C after 10 days, respectively. In cherry tomato wounds, the population of R. paludigenum reached peak levels 72 h after inoculation, and then began to decline slowly. In conclusion, our results showed that competition for nutrients may have an important role in biological control of gray mold of cherry tomatoes with R. paludigenum.