Genetic Resources and Crop Evolution

, Volume 39, Issue 2, pp 71–88 | Cite as

Genetic relationships within Vigna unguiculata (L.) Walp. based on isozyme analyses

  • Leonard Panella
  • Paul Gepts


Isozyme analyses of genetic diversity in Vigna unguiculata were performed to determine genetic relationships and level of genetic diversity between wild and cultivated cowpea. Thirty-four cultivated accessions of V. unguiculata, 56 wild accessions of V. unguiculata, and six accessions representing five related wild Vigna species were analyzed. Ten enzyme systems were polymorphic within Vigna unguiculata: AAT, ACO, G6PDH, DIAP, LAP, MUE, ME MDH, PRX, and SOD. Fourteen of 24 putative loci (58%) were polymorphic within wild V. unguiculata, but only one locus (4%) was polymorphic within cultivated cowpea; when five related Vigna species were examined, 21 of the 24 bands of activity showed polymorphisms (88%) adding 33 alleles to the 48 identified within V. unguiculata. In one F2 population of 68 plants (UCDVg 36 × UCDVg 21) a loose linkage was indicated between Diap-2 and G6pd-12 = 15.39; p = 0.004) with an estimated distance of 36.0 cM ± 5.02 (recombination (r) = 0.31). Also in another F2 population of 38 plants (CB 88 × UCDVg 21) a loose linkage was indicated between Lap-1 and Prx (\gC2 = 9.62; p = 0.047) with an estimated distance of 39.8 cM ± 7.0 (r = 0.33). Total genetic diversity (HT) was 0.085 over all of the accessions including the one classified as V. nervosa. Within accession diversity (Hs) approached zero and between accession diversity (Dsi) was responsible for all of the genetic diversity present. Therefore the coefficient of gene differentiation (GST = DSTIIT) approached 1. Absolute gene differentiation (Dm) was 0.087. Two of the nine segregations in this study were skewed. In general, results of this study concurred with the taxonomic classification within V. unguiculata and provided a strong indication that a severe genetic bottleneck occurred during the domestication process of cowpea.

Key words

cowpea crop evolution/domestication genetic diversity isozyme Vigna unguiculata 



aspartate amino-transferase






















glucose-6-phosphate dehydrogenase


glutamate dehydrogenase






isocitrate dehydrogenase








leucine aminopeptidase


malate dehydrogenase


malic enzyme


















ribulose-bisphosphate carboxylase




Sierra Leone


superoxide dismutase






United States of America


xanthine dehydrogenase


South Africa








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Copyright information

© Kluwer Academic Publishers 1992

Authors and Affiliations

  • Leonard Panella
    • 1
  • Paul Gepts
    • 1
  1. 1.Department of Agronomy & Range ScienceUniversity of CaliforniaDavisUSA

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