Phaseolus Wild Crop Relatives: Genomic and Breeding Resources

The exact number of Phaseolus species currently recognized is not known; however, a reasonable estimate would be 50–60 species. Wild allied species of Phaseolus vulgaris L. was described in most of the countries of Central America and in the western countries of South America. The relationships of P. vulgaris with closer related species are discussed. Domestication of P. vulgaris occurred independently in Mesoamerica and the southern Andes resulting in two gene pools very clearly distinguished. Domesticated P. vulgaris has been submitted to important adaptations such as photoperiod insensitivity and adaptation to acid and low fertility soils. Traits related to the domestication syndrome on common bean as well as possible routes of dispersion of the domesticated P. vulgaris are presented. The advent of new accessible genomic technologies has opened new insights into elucidate aspects related to evolution, genetic diversity, genome organization, and complex traits in common bean. The availability of a growing pool of expressed sequence, quantitative trait loci (QTL) identification, single-nucleotide polymorphism (SNP) discovery, bacterial artificial chromosome libraries, physical maps, and whole-genome sequencing for the P. vulgaris will quickly move toward a realistic goal to link phenotypes to genome target regions that control traits of interest. Taking advantage of biotechnology and, as more genes are discovered, the development of transgenic plants became more accessible and realistic for plant breeding. Systems for genetic transformation have been achieved for both P. vulgaris and P. coccineus and it has been used for introduction of useful traits such as drought tolerance and virus resistance. In addition, efficient plant regeneration systems have been reported for P. lunatus and P. polyanthus .