Yeasts Reduce the Stimulatory Effect of Acetate Esters from Apple on the Germination of Botrytis cinerea Conidia

Abstract

The fungus, Botrytis cinerea, causes decay in apples in postharvest storage. Conidia of B. cinerea on polycarbonate membranes were incubated on filter paper disks saturated with water or suspensions of yeasts (2 × 106 CFU/filter) and then exposed for 24 hr at 22°C to 0–16 μl of ethyl, butyl, or hexyl acetates injected into the headspaces of 500-cc glass jars. Germination of conidia was increased by exposure to 4–16 μl of ethyl acetate compared to the no-ester controls. Conidia were stimulated to germinate by 4 μl of butyl acetate and 8 μl of hexyl acetate, but greater volumes were toxic to germination. The yeasts Cryptococcus laurentii and Sporobolomyces roseus were more effective at reducing the stimulatory effect than Saccharomyces cerevisiae. Acetate esters also stimulated germination of conidia on polycarbonate membranes on apples inside jars. Cryptococcus laurentii or S. roseus suppressed this effect more than S. cerevisiae. Germination of conidia on a membrane on water inside a 3.9-liter jar containing an apple was 2.5-fold greater than the no-apple control. Butyl acetate increased Botrytis infection of apple wounds. Butyl and hexyl acetate were detected by GLC in the headspace of Golden Delicious apples. Results indicated that some acetate esters produced by apple stimulated germination of B. cinerea conidia, and this effect was suppressed by yeasts.