African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12258

Full Length Research Paper

Genetic variability of indigenous cowpea genotypes as determined using inter-simple sequence repeats markers

R. F. M. Mendes
  • R. F. M. Mendes
  • Universidade Federal do Piaui, Campus Universitario Ministro Petronio Portella, Ininga, 64049-550, Teresina, PI, Brazil.
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F. B. Britto
  • F. B. Britto
  • Universidade Federal do Piaui, Campus Universitario Ministro Petronio Portella, Ininga, 64049-550, Teresina, PI, Brazil.
  • Google Scholar
F. R. Freire Filho
  • F. R. Freire Filho
  • Embrapa Amazonia Oriental, Travessa Dr. Eneas Pinheiro, Caixa Postal 48, 66095-100, Belém, PA, Brazil.
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P. S. C. Lima*
  • P. S. C. Lima*
  • Embrapa Meio-Norte, Avenida Duque de Caxias 5650, Buenos Aires, Caixa Postal 001, 64006-220, Teresina, PI, Brazil.
  • Google Scholar


  •  Received: 24 April 2015
  •  Accepted: 31 August 2015
  •  Published: 24 September 2015

Abstract

Cowpea [Vigna unguiculata (L.) Walp.] is cultivated widely by small farmers in the semiarid region of Northeastern Brazil for subsistence purposes, especially to complement the family income. However, owing to the limited availability of water in this region, there is an urgent need for novel highly productive drought-tolerant cultivars. The aim of the present study was to establish the genetic variability of 14 cowpea populations (60 indigenous genotypes from 13 microregions of Rio Grande do Norte and 4 domesticated cultivars produced by Embrapa) using inter-simple sequence repeats (ISSR) markers. The set of 13 selected primers generated a total of 257 loci, 247 (96.11%) of which were polymorphic, with sizes ranging between 200 and 2000 bp. Genetic similarities between accessions were estimated from Jaccard coefficients and genetic relationships were determined from the dendrogram constructed using the unweighted pair group method with arithmetic average (UPGMA) technique. Bayesian statistics coupled with the Markov chain Monte Carlo technique was applied to determine population structure, while the genetic variability was established by analysis of molecular variance. UPGMA analysis allowed the separation of the genotypes into three groups, but no relationship between the genetic and geographical distances was observed. The fixation index was considered intermediary (FST = 0.0818), the average heterozygosity was low (HS = 0.39) and the coefficient of endogamy was high (f = 92.6%). The results show the presence of genetic diversity among the studied populations and revealed that such variability could be attributed mainly to intra-population variability (91.82%).

 Key words: Vigna unguiculata, genetic diversity, plant improvement, drought stress.