Genetic relationships among annual species of Cicer (Fabaceae) using isozyme variation

In order to determine the pattern of genetic diversity within and among the species of Cicer and to estimate interspecific genetic relationships, allelic variation was assayed for 23 isozyme loci in 63 accessions of 11 species of Cicer using starch gel electrophoresis. The total allozymic variation observed in the genus (H-t) was equal to 0.60. When partitioned (G(st)), 96% of this allelic diversity was found among rather than within species. The allelic diversity among species (D-st) and allelic diversity within species (H-s) were equal to 0.58 and 0.02, respectively. Cicer reticulatum and C. pinnatifidum had the highest proportion of polymorphic loci (17.39%) and the highest mean number of alleles per locus (1.22 and 1.17, respectively). UPGMA cluster analysis of Nei's unbiased genetic distance revealed four genetic groups. One includes C. reticulatum, C. arietinum and C. echinospermum where the first 2 species represent a putative derivative-progenitor pair. A second cluster contains C. bijugum, C. pinnatifidum and C. judaicum. Cicer yamashitae, C. chorassanicum, C. anatolicum and C. songoricum form a third group. Finally, C. cuneatum, which has a very distinct isozyme profile and peculiar morphological features, is the only member of a fourth species group. This species grouping agrees partially with those obtained from crossability and cytogenetic studies. The results suggest that the annual habit arose from perennial progenitors at least twice in the genus Cicer.