Classical and Molecular Cytogenetics in Arachis

Abstract

The progress that has been achieved in understanding the chromosome complements of peanut and its related wild species is reviewed here. Chromosome markers developed by using fluorescent in situ hybridization (FISH) with rDNA probes and fluorescent banding allowed the construction of the first chromosome map in peanut and in some diploid taxa. They also revealed the existence of different karyotype structures within the section Arachis. Each group of species having different karyotype structure was defined as having different genomes. FISH analysis together with genomic in situ hybridization allowed the differentiation of chromosomes from A. duranensis and A. ipaënsis, the two species involved in the origin of cultivated peanut. The results obtained by these techniques also suggest that the wild tetraploid A. monticola is the direct ancestor of peanut and that the Northwest of Argentina and South of Bolivia are the regions from which the AABB tetraploids of section Arachis have arisen.