Assessing genetic diversity in landraces of Cucurbita spp. using a morphological and molecular approaches

Agriculture can only be considered as sustainable if it includes a suitable system of plant genetic resources conservation. Crop genetic resources conservation is an insurance against risks to food security. The landraces stand important genetic resources for plant breeders due to its genotypic variability. In Portugal, the production of Cucurbita is based in old local cultivars and is mainly for self-consumption (human food or feed) and is sale on local markets. To evaluate the diversity of 54 C. pepo, 32 C. maxima and 21 C. moschata populations collected in Northern and inner center of Portugal, 20 morphological traits from the Minimum Descriptors for Cucurbita spp. and six microsatellites were used. The traits that registered the highest mean values were the fruit length, the skin thickness and the seed weight, in C. pepo, the fruit width and 100 seed weight in C. maxima and the fruit weight and flesh thickness in C. moschata populations. The ANOVA revealed significant differences (P<0.05) for all traits, with exception of skin thickness parameter. The PCA showed that the three most informative PC explained 52.5 % of the total variation and a clear separation of the three species. The molecular analysis with SSR markers revealed a polymorphism of 100%. The Ho and He average were 0.316 and 0.447, respectively. The PIC showed an average of 0.688. The hierarchical analysis revealed a clear separation of the three Curcubita species. The PCoA showed that the three most informative PC explained 66.3 % of the total variation and clearly separated the three species studied. The high genetic diversity found in this Portuguese collection of Cucurbita spp. provides relevant information for the diversity conservation and can be useful for breeding programs. (C) 2015 The Authors. Published by Elsevier B.V.