Construction of a chickpea linkage map and its comparison with maps of pea and lentil

An integrated genetic linkage map of chickpea (Cicer) has been developed that consists of 9 morphological, 27 isozyme, 10 RFLP, and 45 RAPD markers covering 550 cM. The map was made from segregation data from populations of three interspecific crosses of cultivated chickpea (C. arietinum, 2n = 16) and a closely related wild species (C. reticulatum, 2n = 16). The linkage map has 10 linkage groups representing the eight chromosomes of chickpea. Interspecific crosses were chosen for mapping because of the extremely low level of polymorphism found within the cultivated chickpea species. Several regions of the genome were found to be slightly skewed from the expected Mendelian ratios of alleles. The map was compared with published maps for pea (Pisum) and lentil (Lens). Five regions of the chickpea map have gene orders that are similar to those found in the pea genome. The degree of similarity is somewhat less than that found between pea and lentil, which is consistent with the evolutionary distances between these three genera. We have also observed that lentil genomic DNA RFLP probes hybridize poorly to chickpea DNA, indicating considerable divergence of these genomes at the sequence level.