Salicylic acid enhances biocontrol efficacy of Rhodotorula glutinis against postharvest Rhizopus rot of strawberries and the possible mechanisms involved

The potential of using Rhodotorula glutinis alone or in combination with salicylic acid (SA) for the control of postharvest Rhizopus rot of strawberries, and their effects on enzyme activities of fruits were investigated. The combination of R. glutinis (1 x 10(8) CFU ml(-1)) with SA (100 mu g ml(-1)) resulted in a significant reduction in the disease incidence and lesion diameter of Rhizopus rot on the strawberry fruits at 20 degrees C and 4 degrees C, and more so than with SA or yeast alone. SA at the concentration of 100-1000 mu g ml(-1) significantly inhibited spore germination of Rhizopus stolonifer. About 100 mu g ml(-1) of SA did not inhibit the growth of the antagonistic yeast, and could significantly increase the population growth of R. glutinis in strawberry wounds at 20 degrees C. SA, combined with R. glutinis, increased the activity of strawberry host defence enzymes (POD) and cell wall lytic enzymes (beta-1,3-glucanase). (C) 2010 Elsevier Ltd. All rights reserved.