Ethylene production by fruits of zucchini cultivars differing in postharvest fruit quality and tolerance to chilling injury

Zucchini is a non-climacteric fruit that is harvested immature while reaching about 18 cm in length. We have compared the progression of certain postharvest fruit quality parameters with the production of ethylene and the expression of ethylene biosynthesis genes in the fruits of different cultivars stored at 4, 12 and 20 degrees C. Ethylene production remained at very low levels when fruits were stored at 12 or 20 degrees C for a period of 14 days. However, in fruits stored a 4 degrees C for 7 days, and then conditioned at room temperature for a minimum of 4 hours, ethylene production was dramatically induced. This chilling induced ethylene varied among the different cultivars studied, being highest in the fruits of cultivars with lower post-harvest quality and lower tolerance to chilling injury (CI). Chilling induced ethylene does not appear to be responsible for triggering CI, since visible symptoms were evident some days before the burst of ethylene. However, our findings suggest that this chilling induced ethylene may be used as a selection criterion in screening for genotypic differences in shelf life, postharvest fruit quality and tolerance to CI. The expression profiles of CpACS1 and CpACO1 indicated that these genes are induced throughout the period of cold storage.