Genetic diversity of Spanish Cucurbita pepo landraces: an unexploited resource for summer squash breeding

Abstract

Cucurbita pepo is a world-wide cultivated vegetable of American origin. Most of the widely grown comercial types are known as Summer squashes and belong to the elongated forms of C. pepo ssp. pepo (Cocozelle, Vegetable marrow and Zucchini Groups). These forms were developed in Europe after the arrival of the first american landraces through a process of selection and fixation that led to the loss of genetic diversity. Part of the genetic variability included on the first American cultigens remains in diverse landraces, still cultivated for self-consumption and sale in local markets. Using the first colecction of genomic and EST derived microsatellites that has just become available for the species, we compared the natural variation present in a collection of Spanish landraces with that of a set of commercial varieties and hybrids, representing the current Summer squash market offer. A total of 194 alleles allowed us to distinguish all genotypes, even those closely related. In general, Cocozelle and Vegetable marrow, Groups with considerably long histories, were more variable than the Zucchini Group, of more recent origin. We found significant genetic diversity among landraces. Variation present in the local accessions belonging to the Zucchini Group was larger than that of commercial cultivars. Cluster, principal coordinates and population structure results suggested that the variation of the Spanish landraces has not been extensivelly used in breeding. Commercial Summer squashes can then benefit from this underexploited variability, specially from some landraces that already displayed favourable commercial traits.

Genetic diversity in Cucurbita pepo landraces revealed by RAPD and SSR markers

“…The importance of Cucurbita pepo as a vegetable crop has been long recognized worldwide due to its high nutritional and economic value (Formisano et al, 2012;Ghobary and Ibrahim, 2010;Tsivelikas et al, 2009). In South Africa the shoot tips, leaves, flowers, fruits and seeds of C. pepo are cooked to prepare leafy vegetable dishes (Jansen van Voster et al, 2007).…”

Physical and chemical characterization in fruit from 22 summer squash (Cucurbita pepo L.) cultivars

“…The groups differ in geographical distribution and economic importance (Paris, 2010). In general, cocozelle and vegetable marrow groups with considerably long histories, were more variable than the zucchini group, of a more recent origin (Formisano et al, 2012), the nineteenth century (Hern ando-Bermejo & Le on, 1994), and has undergone intensive breeding in the United States and Europe (Paris, 2010). The zucchini group is the most commercially important of morphotypes and is widely grown throughout the Mediterranean basin, especially in Southeastern Spain (Almería), where the production reaches more than 350000 tonnes each year (Consejeria de Agricultura, Pesca y Medio Ambiente de la Junta de Andalucia, 2013).…”

Angolan vegetable crops have unique genotypes of potential value for future breeding programmes

“…Twenty-six microsatellite loci were selected from those previously identified in an in silico screen of an Expressed Sequence Tag (EST) collection of C.pepo. 6 These Simple Sequence Repeats (SSRs) were previously validated in a C.pepo collection, 7 and in the present study were further validated in a wide range of Cucurbita species. First, the amplification of the whole set of SSRs was checked in a subset of 5 accessions belonging to various accessions of the main cultivated species (C.pepo, C.moschata and C.maxima), including the parentals of the C. pepo genetic map from which these SSRs were derived.…”