Molecular expression of genes involved in parthenocarpic fruit set in tomato

Abstract

To characterize the phenomenon of natural parthenocarpy in tomato (Lycopersicon esculentum Mill.) two different approaches have been followed. At a developmental level, the ovary weights of three non‐parthenocarpic lines and three near‐isogenic parthenocarpic (pat‐2) lines were compared. Four developmental stages were considered: flower bud, preanthesis, anthesis and 4 days after anthesis. The parthenocarpic lines displayed ovary weights higher than their respective non‐parthenocarpic lines from preanthesis to 4 days after anthesis. A molecular approach involved comparison of in vitro translation products from flower RNAs taken from the same developmental stages of non‐parthenocarpic and near‐isogenic parthenocarpic (pat‐2 and pat‐3/pat‐4) lines. Analysis by two‐dimensional polyacrylamide gel electrophoresis showed the differential expression of a 30‐kDa product in parthenocarpic materials from preanthesis to anthesis. These results suggest that the physiological and molecular events responsible for parthenocarpy begin at the preanthesis stage, before the flower is completely mature and receptive to pollination. The differential expression of this in vitro translation product in pat‐2 and pat‐3/pat‐4 genotypes also suggests a common or confluent molecular basis in genetically controlled parthenocarpy.