UV-C treatment on strawberry fruit: effect on gene expression in different tissues

HERNÁN G. ROSLI; MARINA A. POMBO; PEDRO M. CIVELLO; KEVIN FOLTA

Crystal River, Florida (EEUU)

Workshop; XXII Annual PMCB Workshop; 2009

UV-C radiation of fruit has been tested to control postharvest diseases and delay some ripening processes. Nevertheless, there is little information available concerning the mechanism by which beneficial UV-C induced changes occur. This work tests the quality, quantity and duration of treatments, the tissues they affect, and the gene expression programs that are altered by the treatment. Ripe strawberry fruits (cv. Strawberry Festival) were irradiated with UV-C (410 mJ * cm-2). Control fruit received identical treatment with a Plexiglass filter. Samples were taken at different time intervals and the expression of an expansin gene (FaExp2) was analyzed. At 4 h the expression was found to be higher in control fruit, consequently this time point was chosen for further analysis. Fruit were irradiated, but after 4 h of storage different tissues were dissected (deachened epidermis, cortical and medullar tissues) and FaExp2 expression assessed separately. The transcript was detected at higher abundance in cortical tissue of untreated fruit. The UV-C effect may be reversed by white light treatment, so DNA damage could be the first signaling step. Because the effect of UV-C is strongest in the inner tissues, we are currently testing the hypothesis that signals from the epidermis trigger changes in the inner fruit.