GENETICS RELATIONSHIPS AMONG THE ANNUAL CICER L. SPECIES

Rana  I. TAYYAR

Interspecific genetic variation among the nine annual Cicer L. species was investigated using starch gel electrophoresis and C‑banding techniques. The results from the allozyme variation study revealed that Cicer is low in genetic diversity and that most of the variability observed resides among rather than within species. The species clustered in four groups based on Nei's unbiased genetic distance values. Group I included C. reticulatum, C. arietinum and C. echinospermum, where the first two species represented a progenitor‑derivative pair. Group II  contained  C. bijugum, C.  pinnatifidum  and  C. judaicum.  Group III comprised  C. Yamashitae, C. Chorassanicum  and  the  two perennial  species,  C. anatolicum and   C. songoricum. Finally, C. cuneatum which has a very distinct isozyme profile and peculiar morphological characteristics was the sole member of a fourth species group. This species grouping corroborated partially those obtained from crossability studies, seed storage protein analysis and morphological comparisons. In addition, the results suggested that the annual habit arose from perenniality at least twice in Cicer.

Chromosome C‑banding of the annual Cicer species disclosed significant interspecific differences in chromosom length and heterochromatin content. For instance, the haploid chromatin length of the cultivated chickpea, C.arietinum, was 43% higher than its wild relative, C.judaicum.. The species could be divided into two groups based on their heterochromatin content. Group I included C. bijugum and C. cuneatum and group II contained the rest of the annual species. The general C‑banding  pattern was common to all species analyzed. However, some species-specific characteristics were also observed. The various taxa had mostly centromeric bands with occasional intercalary and distal ones. Extended studies are necessary to recognize the specificity of the banding patterns and their possible use in cytogenetic studies and in species recognition in Cicer.

In addition to the investigation of interspecific genetic relationships in Cicer, experiments were conducted to estimate the rate of natural outcrossing in chickpea (C. arientinum). The location of the studies was at the University of California, South Coast Research arid Extension Center, Irvine, CA where high outcrossing rates were observed in different genotypes of the common bean (Phaseolus vulgaris). Although many bumble and honey  bees were observed to visit the open flowers of chickpea, the average rate of natural outcrossing was less than 1% in the lines under investigation.