Abstract:
Enzyme electrophoresis was used to estimate the genetic diversity and
population structure of thirteen Vigna unguiculata ssp. unguiculata var. spontanea
populations in Sudan. Plant genotypes were homozygous at most loci and at several
populations. Nine of the twenty-one allozyme loci analysed (42.9%) showed
detectable polymorphism, but only 11.4% of loci were polymorphic within local
populations. Gene diversity at the species level and at the population level was low
(Hes = 0.084; Hep = 0.049, respectively). Analysis of fixation indices, calculated for all
polymorphic loci in each population showed a substantial deficit of heterozygotes
relative to Hardy – Weinberg expectations. This deficit is partly associated with
inbreeding due to self and consanguineous mating. High inbreeding and strong genetic
differentiation coefficients were found. Allele frequency data revealed a low degree
of within population genetic diversity (Hs = 0.049) and a high degree of genetic
heterogeneity among populations (Gst = 0.409). The indirect estimates of gene flow
were calculated based on the level of genetic differentiation between populations and
frequencies of private alleles. These were 0.274 and 0.043 respectively. Genetic and
geographic distances were positively correlated although not significant, indicating
that very little genetic variation is explained by difference in geographic pattern. This
may be a result of inbreeding and genetic drift through a few founders coupled with
limited pollen flow.
