Abstract

Cowpea is a predominant crop in the small farms of the Brazilian semi-arid region, where several varieties of cowpea with high genetic variability are planted. Due to their genetic diversity, good adaptation to marginal environments and growth in low-input systems, these varieties, often called "landraces," are of great interest for use in breeding and biodiversity conservation programs. The present study describes twelve varieties and three cultivars of cowpea, chosen on the basis of their high frequency of planting by farmers in the Paraíba and Pernambuco States. Total DNA was extracted from the plant seeds. In order to observe the variability of the studied material, four Intersimple sequence repeat (ISSR) markers, the amplified ribosomal DNA restriction analysis (ARDRA) technique using various endonucleases (AluI, HinfI, HpaII, RsaI and NruI), and amplification and sequencing of the ribosomal internal transcribed spacer (ITS1) and ITS2 regions were employed. The results show that two assays, the fingerprinting and the sequencing of the ribosomal ITS1 and ITS2 regions, were sufficient to detect the variability of the cowpea germplasm used by small farmers in the Brazilian semi-arid region. Although the varieties often received the same designation, high diversity may have occurred within a variety, according to the origin of the cowpea seed. This work represents efforts to guide preservation of cowpea biodiversity in semi-arid regions.

Key words: Vigna unguiculata L. (Walp.), coat seeds, intersimple sequence repeat (ISSR), amplified ribosomal DNA restriction analysis (ARDRA), diversity.