Allozyme diversity of cultivated cowpea Vigna unguiculata (L.) Walp.

Publication Type

Journal Article

Journal Name

Theoretical and Applied Genetics

Publication Date

1-1-2000

Abstract

A survey of allozyme variation in cultivargroups of cowpea [Vigna unguiculata (L.) Walp.] was undertaken by examining 21 enzyme systems encoded by 36 loci in 271 accessions representing the five cultivar-groups. Very low levels of variation were found within accessions, which is typical of self- pollinating species. Little variation was also found among accessions. Compared with other legume crops, V. unguiculata is depauperate in allozyme variation. We found an average of 1.61 alleles per locus with 42% of the loci polymorphic and a total heterozygosity of 0.061. Of the variation present, 90% was found within cultivargroups, while 10% was among cultivar-groups. Data analyses revealed continuous variation among cultivargroups and geographic regions with the accessions failing to segregate into discrete morphophysiological or geographic clusters. However, evolved cultivar-groups (cv.-gr. Melanophthalmus and cv.-gr. Sesquipedalis) appear to be less diverse than their putative primitive cultivar-group progenitors. Due to the lack of availability of critical material, no clear center of origin can be established. However, the data presented suggest that Northeast Africa could be a possible center of domestication.

Keywords

Allozymes, Cowpea, Crop evolution, Genetic diversity, Vigna unguiculata

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