Evaluation of Sporidiobolus pararoseus strain YCXT3 as biocontrol agent of Botrytis cinerea on post-harvest strawberry fruits

This study evaluated Sporidiobolus pararoseus (Sp) strain YCXT3 as biocontrol agent of Botrytis cinerea (Bc), the causal agent of strawberry gray mold disease. Efficacy of live yeast cells and volatile organic compounds (VOCs) of Sp in suppression of Bc on strawberry fruits was determined. Results showed that in dual cultures of Sp and Bc on potato dextrose agar at 20 degrees C, Sp did not inhibit mycelial growth of Bc. However, inoculation of the yeast cell suspensions of Sp (1 x 10(5) or 1 x 10(6) yeast cells ml (1)) on strawberry fruits resulted in reducing the disease incidence from 96-100% in the control treatment to 39-50% in the Sp treatment and the disease severity index from 5.1-7.0 in the control treatment to 1.1-1.9 in the Sp treatment. We found that the VOCs from the Sp cultures on yeast extract peptone dextrose agar were highly effective in inhibiting both the conidial germination and the mycelial growth of Bc. A total of 39 VOCs, including 2-ethyl-1-hexanol, were identified in cultures of Sp using GC-MS. Authentic 2-ethyl-1-hexanol was found to have strong anti-fungal activity against Bc with the IC50 values of 1.5 and 5.4 mu l l (1) for conidial germination and mycelial growth, respectively. The VOCs from the Sp cultures were effective in suppression of gray mold disease under the air-tight conditions. This study suggests that the strain YCXT3 of Sp is a promising agent for control of Bc and production of VOCs is a valid biocontrol mechanism for this yeast strain. (C) 2012 Elsevier Inc. All rights reserved.