Biomarkers for selection of parthenocarpic zucchini cultivars

The current cultivars of zucchini (Cucurbita pepo) grown in greenhouses at late seasons (winter), are supplemented with synthetic auxins to induce fruit set, in order to avoid the effect of harsh environmental conditions as low temperatures, inadequate humidity and the inactivity of pollinators. In organic production in greenhouse, to elude the application of synthetic auxins and increase fruit set, the use of parthenocarpic cultivars, with an innate ability to set fruit, should be a useful solution, but unfortunately there are no parthenocarpic cultivars of this crop. Parthenocarpy is the capability of a plant to set seedless fruits in the absence of pollination and fertilization. In Cucurbita pepo crops, parthenocarpy has been related with auxin and ethylene. Synthetic auxins are known to induce parthenocarpic fruit when applied to several horticultural crops out of seasons, and ethylene has been related to ovarian growth in pollinated fruit, and recently has been associated with parthenocarpy. In order to select parthenocarpic cultivars from collections of germplasm, we have tested a method using the population of zucchini mutant lines developed at IFAPA, research centre in Almeria (Spain). The method is based on two biomarkers, phototropism selection (phenotype associated with deregulation in the auxin signalling pathway) and the pattern of ethylene release during early fruit development of C. pepo. Afterward, we evaluated the efficiency of each biomarker to select cultivars useful for organic practices.