Genetic Diversity of Lima bean in Relation with Phytogeography in the New World .

Abstract

Phaseolus 1unatus. L., known as Lima bean, is a Neotropical food legume adapted to a wide range of ecologies, including temperate, humid and semi-arid tropical conditions. This adaptation is the consequence of the large distribution of the wild Lima bean populations in the various natural areas of the New World, involving both lowland and highland areas, as well as distinct vegetation types and climates: These wild materials have given rise to landraces of specific ecological properties, according to the origins of the ancestral wild populations in the two main centers of giversity: Mesoamerican and Andean regions. In ord"r to exploit the potential of this food legume, it is essential, first, to know the genetic organization of the diversity of this cultigen at the intra- and inter-specific levels, and, second, to examine the phytogeography of the wild forms and the landraces in the New World. A state of knowledge is given on the taxonomy and the phylogeny of the genus Phaseoltis and Lima bean.. Special attention is devoted to the primary and the ali"n gene pools of P. lunatus. Data on phytogeography on both wild populations and landraces throughout Latin America help in determining the ecological requirements and potentials of this food legume in the traditional farming systems of the tropics. Current results or progress in these areas are useful to preserve the gene pools of this promising, but neglected, species through in situ and ex situ approach, and to develop, on the basis of this diversity, improved and productive cultivars of Lima bean.