Germplasm collection, genetic diversity and on-farm conservation of cowpea [Vigna unguiculata (L.) Walp.] landraces from Apulia region (southern Italy)

Cowpea (Vigna unguiculata (L.) Walp.) is a major tropical pulse in a number of countries and especially in sub-Saharan Africa where this species was domesticated. Although as niche product, a remarkable number of cowpea landraces are cultivated in the Mediterranean basin, primarily for human consumption of the grains and fresh pods. In this study, within the frame of a regional project devoted to the safeguard and management of local horticultural genetic resources, some germplasm explorations were carried out in Apulia region (southern Italy) to collect, among other crops, cowpea landraces still present in the area and promote on-farm conservation of this traditional material. A second objective was to investigate the efficiency of SSR markers in detecting genetic polymorphism in cowpea landraces from a restricted geographical area. In total, 13 samples of V. unguiculata were gathered, 12 of cultivar group unguiculata and 1 of cultivar group sesquipedalis. Genetic diversity and phylogenetic relationships among 13 Apulian accessions, 9 samples from various provenances and 1 var. spontanea accession were evaluated using SSR molecular markers. A set of 19 SSR primer pairs successfully identified closely related accessions and were able to separate the different cultivar groups of V. unguiculata.