Beans (Phaseolus ssp.) as a Model for Understanding Crop Evolution

Abstract

Here, we aim to provide a comprehensive and up-to-date overview of the most significant outcomes in the literature regarding the origin of Phaseolus genus, the geographical distribution of the wild species, the domestication process, and the wide spread out of the centers of origin. Phaseolus can be considered as a unique model for the study of crop evolution, and in particular, for an understanding of the convergent phenotypic evolution that occurred under domestication. The almost unique situation that characterizes the Phaseolus genus is that five of its ∼70 species have been domesticated (i.e., Phaseolus vulgaris, P. coccineus, P. dumosus, P. acutifolius, and P. lunatus), and in addition, for P. vulgaris and P. lunatus, the wild forms are distributed in both Mesoamerica and South America, where at least two independent and isolated episodes of domestication occurred. Thus, at least seven independent domestication events occurred, which provides the possibility to unravel the genetic basis of the domestication process not only among species of the same genus, but also between gene pools within the same species. Along with this, other interesting features makes Phaseolus crops very useful in the study of evolution, including: (i) their recent divergence, and the high level of collinearity and synteny among their genomes; (ii) their different breeding systems and life history traits, from annual and autogamous, to perennial and allogamous; and (iii) their adaptation to different environments, not only in their centers of origin, but also out of the Americas, following their introduction and wide spread through different countries. In particular for P. vulgaris this resulted in the breaking of the spatial isolation of the Mesoamerican and Andean gene pools, which allowed spontaneous hybridization, thus increasing of the possibility of novel genotypes and phenotypes. This knowledge that is associated to the genetic resources that have been conserved ex situ and in situ represents a crucial tool in the hands of researchers, to preserve and evaluate this diversity, and at the same time, to identify the genetic basis of adaptation and to develop new improved varieties to tackle the challenges of climate change, and food security and sustainability.

Pod indehiscence is a domestication and aridity resilience trait in common bean

“…Phaseolus beans are an exceptional experimental system to study domestication and the molecular evolution associated with this process. Humans domesticated members of this genus seven times (Gepts et al, 2008;Bitocchi et al, 2017), which are part of the 41 domestications in the Fabaceae (Harlan, 1992). The common bean (Phaseolus vulgaris L.), a dietary staple for hundreds of millions of people worldwide (Singh, 1999;Gepts et al, 2008), diverged into distinct Middle American and Andean gene pools c. 87 000 yr before present (Ariani et al, 2018), well before the first human migrations into the Americas some 16 000-23 000 yr ago (Moreno-Mayar et al, 2018;Potter et al, 2018).…”

Multi‐tissue integration of transcriptomic and specialized metabolite profiling provides tools for assessing the common bean (Phaseolus vulgaris) metabolome

“…It represents a rich source of protein, vitamins, minerals, and fiber, particularly for poor regions of Africa and Latin America (Broughton et al, 2003;Bitocchi et al, 2016). Phaseolus vulgaris shows a very specific evolutionary history for which it has emerged as a model species to study the phenotypic changes associated with its domestication (Bitocchi et al, 2017). The wild forms of P. vulgaris are distributed over a large area of Latin America, ranging from northern Mexico to northwestern Argentina, with the presence of at least three well differentiated eco-geographical gene pools: the Mesoamerican, the Andean and the Inca gene pool.…”

Adapting legume crops to climate change using genomic approaches

“…The majority of important grain and forage legume species are members of various clades within the Papilionoideae. This includes cool‐season legumes, such as lentil ( Lens culinaris ), chickpea ( Cicer arietinum ), and faba bean ( Vicia faba ; hologalegina clade), and warm‐season legumes, such as soybean ( Glycine max ), common bean ( Phaseolus vulgaris ), cowpea ( Vigna unguiculata ; phaseoloid/millettioid clade), Lupinus (genistoid clade), and Arachis (aeschynomenoid/dalbergioid clade; Bitocchi, Rau, Bellucci, et al, ; Doyle & Luckow, ; Gepts et al, ).…”