Evidence for Introduction Bottleneck and Extensive Inter-Gene Pool (Mesoamerica x Andes) Hybridization in the European Common Bean (Phaseolus vulgaris L.) Germplasm

Abstract

Common bean diversity within and between Mesoamerican and Andean gene pools was compared in 89 landraces from America and 256 landraces from Europe, to elucidate the effects of bottleneck of introduction and selection for adaptation during the expansion of common bean (Phaseolus vulgaris L.) in Europe. Thirteen highly polymorphic nuclear microsatellite markers (nuSSRs) were used to complement chloroplast microsatellite (cpSSRs) and nuclear markers (phaseolin and Pv-shatterproof1) data from previous studies. To verify the extent of the introduction bottleneck, inter-gene pool hybrids were distinguished from “pure” accessions. Hybrids were identified on the basis of recombination of gene pool specific cpSSR, phaseolin and Pv-shatterproof1 markers with a Bayesian assignments based on nuSSRs, and with STRUCTURE admixture analysis. More hybrids were detected than previously, and their frequency was almost four times larger in Europe (40.2%) than in America (12.3%). The genetic bottleneck following the introduction into Europe was not evidenced in the analysis including all the accessions, but it was significant when estimated only with “pure” accessions, and five times larger for Mesoamerican than for Andean germplasm. The extensive inter-gene pool hybridization generated a large amount of genotypic diversity that mitigated the effects of the bottleneck that occurred when common bean was introduced in Europe. The implication for evolution and the advantages for common bean breeding are discussed.

Genomics of Origin, Domestication and Evolution of Phaseolus vulgaris

“…The amplitude of agro-ecological conditions experienced by this crop also dramatically increased, giving new opportunities for both natural and human-mediated selection. Several continents and countries have been proposed as the secondary centers of diversification for P. vulgaris, including Europe (Santalla et al 2002;Angioi et al 2010Angioi et al , 2011Gioia et al in press ), Brazil (Burle et al 2010), central-eastern and southern Africa (Martin and Adams 1987a, b;Asfaw et al 2009;Blair et al 2010) and China (Zhang et al 2008). …”

Genetic Diversity of Croatian Common Bean Landraces

“…Common bean landraces originated from these two gene pools were introduced into Europe at different times. The Mesoamerican common bean landraces probably arrived in Europe through Spain and Portugal in 1,506, and the Andean in the same way in 1,528, after the exploration of Peru by Pizarro (Gioia et al, 2013). Subsequent spread of common bean landraces throughout Europe was very complex with several introductions from various regions of the Americas, combined with frequent exchanges between European and other Mediterranean countries (Papa et al, 2006).…”

Short-Term Local Adaptation of Historical Common Bean (Phaseolus vulgaris L.) Varieties and Implications for In Situ Management of Bean Diversity

“…Upon its introduction onto the Iberian peninsula from the Americas, hybridization of the Andean and Mesoamerican gene pools created novel genetic variation [3,4,5,6] and Europe is considered a secondary center of diversity for common bean [7]. Europe’s landraces and historical varieties of this species constitute a cultural good and a promising resource for plant breeding [6,7]. In general, common bean is a highly variable species and uses are diverse.…”

“…Given a decreasing demand for dry beans on the one hand and the development of modern green bean varieties adapted to African growing environments and to large-scale mechanized agriculture in Europe on the other hand, traditional European bean diversity is at stake. Traditional European bean diversity, landraces and old varieties, show inter- and intra-population diversity [3,4,5,6,7] and were once largely cultivated.…”