Search

Lima bean (Phaseolus lunatus L.) is the second most important domesticated species of Phaseolus in the world and could represent a precious alternative for food security and quality, as well as play a major role for sustainability in the face of climate change in Latin America and worldwide. Currently, many experts on conservation, domestication, genetic improvement, and plant-rhizosphere relationship of Lima bean have been working alone or in small groups. This situation has limited obtaining a greater benefit from their research and strongly prompts the study of the Lima bean worldwide. To increase the collaboration between experts in the study of the Lima bean, we present the Lima Bean International Network (LBIN). The main objectives of LBIN are to deepen the knowledge on this species and to promote its use worldwide. The success of LBIN will depend on the collaboration of the international scientific community interested in the study of Lima bean. Hence, we invite people from different sectors of society (researchers, producers, companies, NGOs, governments) to participate in this initiative. To get more information, you can visit https://www.cicy.mx/sitios/red-internacional-frijol-lima

Tepary bean (Phaseolus acutifolius A. Gray) is more heat and drought tolerant than common bean (P. vulgaris L.). Four hundred mutant lines of two tepary accessions (G40068 and G40159) were generated by ethyl methane sulfonate (EMS) treatment. In preliminary studies of the M5 mutant lines under abiotic stress, three mutant lines (CMT 38, CMT 109, CMT 187) were selected from six mutated lines based on morpho-physiological traits and superior yield and advanced to the M6 generation. The M6 mutant lines were uniform and genetically stable. These mutant lines and their original (M0) parents were evaluated for heat and drought tolerance under greenhouse conditions. Their performance was evaluated for morpho-physiological attributes, seed yield and yield components. Under high temperature and drought conditions, the CMT 38 mutant (M6 line) and its original tepary (M0) accession (G40068) showed greater values of pod biomass, pod number and 100-seed biomass than the other lines tested. The CMT 109 and CMT 187 mutant lines and their G40159 original accession (M0) also showed the highest value of seed number under high temperature and drought conditions. This suggests that the previous screening performed during the population advancement of these mutant lines, based on morphological traits like growth habit, was not detrimental to the yield variables evaluated here. Under combined heat and drought conditions, different parameters could be incorporated into tepary breeding programmes, as selection criteria to screen genotypes for tolerance to heat and drought stress. These parameters included: chlorophyll (SPAD) readings, seed biomass, 100-seed biomass and seed number because they explain the observed variance in the principal component analysis. Two additional traits (root biomass and stem diameter) were also identified as useful attributes, based on univariate analysis. The mutant lines evaluated here offer potential for further improvement of tepary bean to high temperature and drought

Societal Impact Statement Crop wild relatives (CWR) are plant taxa closely related to crops and are a source of high genetic diversity that can help adapt crops to the impacts of global change, particularly to meet increasing consumer demand in the face of the climate crisis. CWR provide vital ecosystem services and are increasingly important for food and nutrition security and sustainable and resilient agriculture. They therefore are of major biological, social, cultural and economic importance. Assessing the extinction risk of CWR is essential to prioritise in situ and ex situ conservation strategies in Mesoamerica to guarantee the long‐term survival and availability of these resources for present and future generations worldwide. Summary Ensuring food security is one of the world's most critical issues as agricultural systems are already being impacted by global change. Crop wild relatives (CWR)—wild plants related to crops—possess genetic variability that can help adapt agriculture to a changing environment and sustainably increase crop yields to meet the food security challenge. Here we report the results of an extinction risk assessment of 224 wild relatives of some of the world's most important crops (i.e. chilli pepper, maize, common bean, avocado, cotton, potato, squash, vanilla and husk tomato) in Mesoamerica—an area of global significance as a centre of crop origin, domestication and of high CWR diversity. We show that 35% of the selected CWR taxa are threatened with extinction according to The International Union for Conservation of Nature (IUCN) Red List demonstrates that these valuable genetic resources are under high anthropogenic threat. The dominant threat processes are land use change for agriculture and farming, invasive and other problematic species (e.g. pests, genetically modified organisms) and use of biological resources, including overcollection and logging. The most significant drivers of extinction relate to smallholder agriculture—given its high incidence and ongoing shifts from traditional agriculture to modern practices (e.g. use of herbicides)—smallholder ranching and housing and urban development and introduced genetic material. There is an urgent need to increase knowledge and research around different aspects of CWR. Policies that support in situ and ex situ conservation of CWR and promote sustainable agriculture are pivotal to secure these resources for the benefit of current and future generations.

This work presents an updated list of the species belonging to the genus Phaseolus following its definition of 1978; it is the outcome of the study of eighty-six herbaria and forty-one explorations in the field in the period 1978–2019. There are currently eighty-one species, all of them native to the Americas, most of them distributed north of Panama (the genus is a migrant into South America), and half of them being known by very few records. They thrive in warm to mild temperate, seasonally dry, open forest, with rains under favorable temperature, from sea level up to 3,000 m. The recent increase in the number of recognized species is due to the endemic ones; this in combination with few unclassified specimens may indicate that the total number of species is not final yet, and that field work will be rewarding.

The CGIAR crop improvement (CI) programs, unlike commercial CI programs, which are mainly geared to profit though meeting farmers’ needs, are charged with meeting multiple objectives with target populations that include both farmers and the community at large. We compiled the opinions from >30 experts in the private and public sector on key strategies, methodologies, and activities that could the help CGIAR meet the challenges of providing farmers with improved varieties while simultaneously meeting the goals of: (i) nutrition, health, and food security; (ii) poverty reduction, livelihoods, and jobs; (iii) gender equality, youth, and inclusion; (iv) climate adaptation and mitigation; and (v) environmental health and biodiversity. We review the crop improvement processes starting with crop choice, moving through to breeding objectives, production of potential new varieties, selection, and finally adoption by farmers. The importance of multidisciplinary teams working towards common objectives is stressed as a key factor to success. The role of the distinct disciplines, actors, and their interactions throughout the process from crop choice through to adoption by farmers is discussed and illustrated., This document arose from the urgent need to join forces (across nations and research disciplines) and stand together to improve the prospects for the most vulnerable population on the globe whose well-being depends on agricultural production. Here, we learn from the past, and draft future strategic guidelines that will facilitate efforts of the CGIAR institutions (https://www.cgiar.org/) to enhance the livelihoods of the less privileged through crop improvement.

Lima bean (Phaseolus lunatus L.), one of the five domesticated Phaseolus bean crops, shows a wide range of ecological adaptations along its distribution range from Mexico to Argentina. These adaptations make it a promising crop for improving food security under predicted scenarios of climate change in Latin America and elsewhere. In this work, we combine long and short read sequencing technologies with a dense genetic map from a biparental population to obtain the chromosome-level genome assembly for Lima bean. Annotation of 28,326 gene models show high diversity among 1917 genes with conserved domains related to disease resistance. Structural comparison across 22,180 orthologs with common bean reveals high genome synteny and five large intrachromosomal rearrangements. Population genomic analyses show that wild Lima bean is organized into six clusters with mostly non-overlapping distributions and that Mesomerican landraces can be further subdivided into three subclusters. RNA-seq data reveal 4275 differentially expressed genes, which can be related to pod dehiscence and seed development. We expect the resources presented here to serve as a solid basis to achieve a comprehensive view of the degree of convergent evolution of Phaseolus species under domestication and provide tools and information for breeding for climate change resiliency., Lima bean is an important crop for improving food security in Latin America and elsewhere. Here, the authors assemble its genome, conduct population genomics analysis using genotyping-by-sequencing data, and identify differentially expressed genes between two pod developmental stages.

Crop landraces have unique local agroecological and societal functions and offer important genetic resources for plant breeding. Recognition of the value of landrace diversity and concern about its erosion on farms have led to sustained efforts to establish ex situ collections worldwide. The degree to which these efforts have succeeded in conserving landraces has not been comprehensively assessed. Here we modelled the potential distributions of eco-geographically distinguishable groups of landraces of 25 cereal, pulse and starchy root/tuber/fruit crops within their geographic regions of diversity. We then analysed the extent to which these landrace groups are represented in genebank collections, using geographic and ecological coverage metrics as a proxy for genetic diversity. We find that ex situ conservation of landrace groups is currently moderately comprehensive on average, with substantial variation among crops; a mean of 63% ± 12.6% of distributions is currently represented in genebanks. Breadfruit, bananas and plantains, lentils, common beans, chickpeas, barley and bread wheat landrace groups are among the most fully represented, whereas the largest conservation gaps persist for pearl millet, yams, finger millet, groundnut, potatoes and peas. Geographic regions prioritized for further collection of landrace groups for ex situ conservation include South Asia, the Mediterranean and West Asia, Mesoamerica, sub-Saharan Africa, the Andean mountains of South America and Central to East Asia. With further progress to fill these gaps, a high degree of representation of landrace group diversity in genebanks is feasible globally, thus fulfilling international targets for their ex situ conservation. ispartof: NATURE PLANTS vol:8 issue:5 pages:491-+ ispartof: location:England status: published

During a search for populations of wild common bean, namely south of the Central Valley of Costa Rica, a new bean species, Phaseolus albicarminus, has been found on the slope of a mountainous range named Cerros Llano Bonito in the western part of Talamanca range, where it appears to be endemic. Its main morphological features are: short pseudoracemes with four small deltoid primary bracts, small early caducous deltoid bracteoles, calyx lobes reduced to two lips, white wings contrasting with carmine purple inner face of standard, and smoothly curved 3–4 seeded pods with prow-shaped beak. The differences with apparently closely related species, P. hygrophilus and P. angucianae, are: in primary bracts (orbicular versus oval acuminate), larger bracteoles (cordate versus rounded), inner face of standard (pale pink to white versus purple), lower calyx lobes (rounded versus triangular), and pod dorsal suture (straight versus sigmoid), respectively. The fact that to date only three populations of P. albicarminus are known from the same small area of Costa Rica, calls for monitoring its conservation status. This new species is tentatively assigned to the section Brevilegumeni which seems well represented in Costa Rica (with five out of six taxa).

AIM: The conservation and effective use of crop genetic diversity are crucial to overcome challenges related to human nutrition and agricultural sustainability. Farmers’ traditional varieties (“landraces”) are major sources of genetic variation. The degree of representation of crop landrace diversity in ex situ conservation is poorly understood, partly due to a lack of methods that can negotiate both the anthropogenic and environmental determinants of their geographic distributions. Here, we describe a novel spatial modelling and ex situ conservation gap analysis modelling framework for crop landraces, using common bean (Phaseolus vulgaris L.) as a case study. LOCATION: The Americas. METHODS: The modelling framework includes five main steps: (a) determining relevant landrace groups using literature to develop and test classification models; (b) modelling the potential geographic distributions of these groups using occurrence (landrace presences) combined with environmental and socioeconomic predictor data; (c) calculating geographic and environmental gap scores for current genebank collections; (d) mapping ex situ conservation gaps; and (e) compiling expert inputs. RESULTS: Modelled distributions and conservation gaps for the two genepools of common bean (Andean and Mesoamerican) were robustly predicted and align well with expert opinions. Both genepools are relatively well conserved, with Andean ex situ collections representing 78.5% and Mesoamerican 98.2% of their predicted geographic distributions. Modelling revealed additional collection priorities for Andean landraces occur primarily in Chile, Peru, Colombia and, to a lesser extent, Venezuela. Mesoamerican landrace collecting priorities are concentrated in Mexico, Belize and Guatemala. CONCLUSIONS: The modelling framework represents an advance in tools that can be deployed to model the geographic distributions of cultivated crop diversity, to assess the comprehensiveness of conservation of this diversity ex situ and to highlight geographic areas where further collecting may be conducted to fill gaps in ex situ conservation.

Phaseolus species are globally important food security crops. Drought and low soil fertility are primary constraints to Phaseolus production in developing nations. Root phenes have important roles in soil resource capture and plant performance. We profiled root phenotypes in 30 wild and seven domesticated Phaseolus taxa in laboratory and greenhouse environments. Our results reveal that substantial variation for root phenotypes exists among and within Phaseolus taxa, notably for phenes such as basal root number, basal root whorl number, root hair length, root hair density, metaxylem vessel number, and total cross-sectional area. Wild taxa display greater genetic variation for root architecture and anatomy and possess desirable phenotypes that are either not found or are not sufficiently expressed in domesticated accessions. Consequently, wild taxa represent an important resource for breeding programs to improve abiotic stress tolerance. Root phenotypes were also associated with the environment in the region of origin, suggesting that they have adaptive value. We speculate that significant variation in root phenotypes across different Phaseolus species is related to their abiotic stress tolerance and are valuable for breeding programs focused on improving edaphic stress tolerance.

A new wild bean found in the mountainous range “Fila Cruces” of southeastern Costa Rica is described. To date, only four populations are known from different sites on the slopes of Cerro Anguciana and “Fila Cruces” where it seems to be endemic. The differences (slender curved racemes, small oval acuminate primary and pedicelar bracts, lilac inner face of standard, white wings) are presented with closely related species such as P. hygrophilus and P. oligospermus of the section Brevilegumeni to which it may belong.

Background and Aims Improved understanding of the secondary gene pools of crops is essential for advancing genetic gain in breeding programmes. Common bean, Phaseolus vulgaris, is a staple crop with several wild relatives in its secondary gene pool. The year-long bean, P. dumosus, an important crop in Guatemala, is considered particularly closely related to P. vulgaris and a potential source of novel variation. However, the genetic diversity and relationship to other Phaseolus species of P. dumosus remain unclear. Methods We conducted the first comprehensive investigation of P. dumosus genetic diversity using both nuclear and chloroplast genome markers. Our nuclear marker set included over 700 markers present within the Phaseolus DArT (Diversity Arrays Technology) array, which we applied to P. dumosus and other relatives of P. vulgaris (including every secondary gene pool species: P. acutifolius, P. albescens, P. coccineus and P. costaricensis). Key Results Phaseolus dumosus arose from hybridization of P. vulgaris and P. coccineus, followed by at least two later hybridizations with sympatric congener populations. Existing P. dumosus collections have low genetic diversity. Conclusions The under-utilized crop P. dumosus has a complex hybrid origin. Further sampling in the region in which it arose may uncover additional germplasm for introgressing favourable traits into crops within the P. vulgaris gene pool.

Background Common bean (Phaseolus vulgaris) is an important grain legume and there has been a recent resurgence in interest in its relative, tepary bean (P. acutifolius), owing to this species’ ability to better withstand abiotic stresses. Genomic resources are scarce for this minor crop species and a better knowledge of the genome-level relationship between these two species would facilitate improvement in both. High-throughput genotyping has facilitated large-scale single nucleotide polymorphism (SNP) identification leading to the development of molecular markers with associated sequence information that can be used to place them in the context of a full genome assembly. Results Transcript-based SNPs were identified from six common bean and two tepary bean accessions and a subset were used to generate a 768-SNP Illumina GoldenGate assay for each species. The tepary bean assay was used to assess diversity in wild and cultivated tepary bean and to generate the first gene-based map of the tepary bean genome. Genotypic analyses of the diversity panel showed a clear separation between domesticated and cultivated tepary beans, two distinct groups within the domesticated types, and P. parvifolius was confirmed to be distinct. The genetic map of tepary bean was compared to the common bean genome assembly to demonstrate high levels of collinearity between the two species with differences limited to a few intra-chromosomal rearrangements. Conclusions The development of the first set of genomic resources specifically for tepary bean has allowed for greater insight into the structure of this species and its relationship to its agriculturally more prominent relative, common bean. These resources will be helpful in the development of efficient breeding strategies for both species and will facilitate the introgression of agriculturally important traits from one crop into the other. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2499-3) contains supplementary material, which is available to authorized users.

This review considers which species of beans were domesticated out of a total of 80 or so species in tropical America, and the morpho- and ecological reasons and other nutritional aspects behind the choices of Amerindians who knew and experimented a lot with the flora. It explains why places of domestication refer to the locations where seeds of wild forms were picked for the last time. It further shows the current discrepancies between the archaeological records and the genetic data. The seven domestication events affecting the genus Phaseolus, five in Mesoamerica and two in the Andes, seem to have happened originally outside the presence of maize and before the wide use of ceramics, with food uses possibly different from the ones known nowadays (like toasting). The bright idea by Amerindians was to combine maize and beans into a performant agronomic and nutritional association that diffused so widely in pre-Columbian America and set the basis for the many brilliant civilizations they left us.

The interspecific breeding line VRW 32 (Reg. No. GP-287, PI 665037) of common bean (Phaseolus vulgaris L.), which is resistant to white mold [caused by Sclerotinia sclerotiorum (Lib.) de Bary], was jointly developed at the University of Idaho Kimberly Research and Extension Center, Kimberly, ID; Colorado State University, Fort Collins, CO; and CIAT, Cali, Colombia. The Idaho Agricultural Experiment Station released VRW 32 on 7 Dec. 2011. VRW 32 is the first white mold-resistant interspecific breeding line derived from P. costaricensis Freytag & Debouck, a member of the secondary gene pool of common bean. VRW 32 was derived from recurrent backcrossing between the small-seeded (100-seed weight < 25 g) tropical black common bean cultivar ICA Pijao and the small-seeded wild P. costaricensis germplasm accession G 40604 (100-seed weight < 19 g). ICA Pijao has an indeterminate upright growth habit Type II, purple flowers, and resistance to Bean common mosaic virus and tolerance to Bean golden mosaic virus. G 40604 has an indeterminate climbing growth habit Type IV and deep reddish-purple magenta flowers. VRW 32 has growth habit Type II, white flowers, grayish-brown seed, and white mold resistance with a score of 2.7 in the fled and 4.3 in the greenhouse in Idaho and 5.5 in the greenhouse in Colorado compared with 5.7, 5.8, and 6.6, respectively, for the recurrent parent, ICA Pijao. VRW 32 matures in approximately 100 d in southern Idaho. VRW 32 may be used to study the interaction between the pathogen and different sources of white mold resistance and for pyramiding resistance from across Phaseolus spp. and introgressing higher levels of resistance into common bean cultivars. © Crop Science Society of America.

The Mesoamerican (MA) gene pool of lima bean (Phaseolus lunatus L.) is widely distributed from northern Mexico to northern Argentina in its wild forms and from the southern United States to the east coast of Brazil in its domesticated forms. This broad distribution and lack of wild accessions of the MA gene pool in many areas of its natural distribution has impeded determining its center of domestication and establishing whether it has a single or multiple centers. To answer these questions, we evaluated 262 accessions of P. lunatus using two intergenic spacers of chloroplast DNA: atpB-rbcL and trnL-trnF. The data were analyzed using a maximum likelihood tree (ML), a haplotype network and two estimators of genetic differentiation (N ST and G ST). Nucleotide diversity (π) and haplotype (Hd) were quantified to estimate the percentage of reduction in genetic diversity (%r) as a founder effect. The ML tree and haplotype network indicated the existence of three groups (AI, MI and MII), which was supported by the high values of N ST (0.61–0.80). Values for %r were high (58.67–60.83 %). Existence of Mesoamerican and Andean gene pools was confirmed, with two genetically and geographically distinct groups (MI and MII) within the MA gene pool. We present the first evidence for multiple origins of domestication for the MA gene pool. For MI, we propose western central Mexico as the domestication area and between Guatemala and Costa Rica for MII. We observed a founder effect in the MA gene pool as a result of domestication.

With 4 figures and 5 tables Abstract Cassava roots are the most important commercial product from this crop. Roots have two major components: the starchy parenchyma and the peel with higher amount of fibre and cyanogenic glucosides. In this study, a sample of 64 clones grown in replicated trials in five locations were evaluated for peel thickness (PT) that ranged from 1.48 to 2.55 mm. Roots from a sample of 33 of these clones were further analysed for the amount of extractable starch. Broad sense heritability for PT was high (0.93) compared with that for yield (0.63). The values obtained demonstrate that there is a very strong genetic component in the expression of PT. Extractable starch depended heavily on dry matter content but also on PT. In an additional evaluation, 1448 accessions from the germplasm collection were evaluated for PT and showed a wide range of variation (from 0.79 to 5.14 mm).

Crop wild relatives that have experienced mul-tiple and independent domestication events provide an excellent model for understanding adaptation processes in crop populations and a fi rst and relevant aspect to investigate is the geographic origin of landraces. The aim of this research was to establish the origin of Meso-american and Andean Lima bean ( Phaseolus lunatus L.) landraces by analyzing chloroplast DNA and ITS polymorphisms in a sample of 59 wild and 50 landrace accessions. Accord-ing to seed size, genetic distance analyses, and haplotype networks, at least two indepen-dent domestication events are proposed. The fi rst one would have taken place in the Andes of southern Ecuador–northwestern Peru and would have given rise to the large-seeded land-races collectively known as the “Big Lima” cul-tivars. The second one would have taken place in central–western Mexico, more likely in the area to the north and northwest of the Isthmus of Tehuantepec. This event, along with post-domestication migrations of landraces in South America, would have given rise to the great vari-ety of small-seeded Mesoamerican landraces that exist today. We did not fi nd any evidence supporting the existence of two discrete groups within Mesoamerican landraces that might cor-respond to the previously proposed “Sieva” and “Potato” cultigroups. A severe reduction in genetic diversity because of domestication, known as the “founder effect”, was detected, which may have implications for the conserva-tion of genetic resources in this species.J.R. Motta-Aldana, M.L. Serrano-Serrano, J. Hernandez-Torres and G. Castillo-Villamizar, Escuela de Biologia, Facultad de Ciencias, Univ. Industrial de Santander-UIS, Cl27 Cra9, Bucaramanga, Colom-bia; D.G. Debouck, Genetic Resources Unit, International Center for Tropical Agriculture (CIAT), Km17 via Cali-Palmira, Colombia; M.I. Chacon S., Facultad de Agronomia, Universidad Nacional de Colom-bia, Cra30 Cl45, Bogota, Colombia. Received 6 Dec. 2009. *Corre-sponding author (michacons@unal.edu.co).

The aims of this research were to assess the genetic structure of wild Phaseolus lunatus L. in the Americas and the hypothesis of a relatively recent Andean origin of the species. For this purpose, nuclear and non-coding chloroplast DNA markers were analyzed in a collection of 59 wild Lima bean accessions and six allied species. Twenty-three chloroplast and 28 nuclear DNA haplotypes were identified and shown to be geographically structured. Three highly divergent wild Lima bean gene pools, AI, MI, and MII, with mostly non-overlapping geographic ranges, are proposed. The results support an Andean origin of wild Lima beans during Pleistocene times and an early divergence of the three gene pools at an age that is posterior to completion of the Isthmus of Panama and major Andean orogeny. Gene pools would have evolved and reached their current geographic distribution mainly in isolation and therefore are of high priority for conservation and breeding programs.

Cassava roots are perceived as having relatively low protein content compared with other sources of energy (such as maize and wheat). This perception is in part due to a deficient screening in protein content levels in different cassava germplasm. For the current article, information on protein content of several cassava clones, gathered for a period of about 10 years, has been consolidated. Roots from a total of 149 accessions from the germplasm collection at the International Center for Tropical Agriculture (CIAT) were analyzed for total crude protein content. For 140 clones the evaluations were based on two different root samples and independent quantifications. Results from eight clones were based on three samples, and only for one clone had four different estimations been made. Large differences in protein content (ranging from 0.95% to 6.42%) were observed in the sample analyzed. Results suggest that a considerable proportion of these differences are genetic in nature and therefore that there are excellent possibilities for exploiting these differences and further increasing them by traditional breeding methods.

Tepary bean (Phaseolus acutifolius A. Gray), a low-rainfall crop from the Sonoran desert, is thought to have low diversity; however, its relationship to its wild relatives is poorly understood. In this study, a total of 147 accessions were evaluated by means of AFLP markers to (i) establish the taxonomic relationships within and between the Acutifolii and other sections and (ii) to understand tepary bean domestication. The structure among the 10 species analyzed corresponded to currently recognized sections: Phaseolus glabelus and Phaseolus lunatus L. were equally distant from the phaseoli and coccinei sections and the rugosi section included Phaseolus angustis-simus, Phaseolus carteri and Phaseolus filiformis. We also compared the gene pool differences for common (Phaseolus vulgaris L.) and lima bean (P. lunatus) with differences observed within the Acutifolii section. The wild relative, Phaseolus parvifolius persistently separated from the bulk of both cultivated and wild tepary, validating its status as a separate species; while within the wild accessions, there was no obvious grouping along the foliar variants. On the basis of our results, one of two Mexican states, Sinaloa or Jalisco, could have been the domestication center, although the hypothesis of multiple domestication events cannot be discarded. Furthermore, domesticated tepary bean was most likely derived from wild genotypes of var. acutifolius rather than genotypes of var. tenuifolius.

A new species of Phaseolus occurs on the eastern slope of Sierra Madre Oriental of Mexico, in the state of Nuevo Leon, at the northeastern corner of the Chihuahuan desert. Because of its coriaceous leaflets, Phaseolus novoleonensis belongs to section Coriacei Freytag. Although morphologically related to P. maculatus subsp. maculatus and subsp. ritensis, it differs by its having trifoliolate leaves at first nodes, small rounded leaflets, few-noded racemes, and flattened cream-colored seeds.

We examined the effects of salinity on four wild (Phaseolus angustissimus, Phaseolus filiformis, P. microcarpus, and P. vulgaris) and two cultivated (P. acutifolius and P. vulgaris L.) Phaseolus species. Relative growth rate (RGR, g g−1 per day), unit leaf rate (ULR, g m−2 per day), leaf area ratio (LAR, m2 g−1), specific leaf area (SLA, m2 g−1), leaf weight ratio (LWR, g leaf g−1), and rate of ion uptake were calculated for the period between 10 and 20 days after planting. Salinity significantly reduced RGR, ULR, LAR, and SLA whereas LWR showed no definite trend. In all species, except in P. filiformis, ULR, but not LAR, was significantly correlated with RGR, indicating that ULR was an important factor underlying the salinity-induced differences in RGR among species. In P. filiformis, high salinity reduced SLA, and consequently LAR. The significant correlation of SLA and LAR with RGR suggested that growth components affecting leaf area expansion were the primary factors explaining the inhibition of growth in this species. Increasing salinity progressively decreased leaf water vapor conductance. The rate of CO2 assimilation decreased gradually with salinity, showing significant reductions only at the highest salt level (80 mM NaCl). Approximately two-thirds of the reduction in CO2 assimilation rate at high salinity was attributable to reduced stomatal conductance. In P. filiformis, however, neither stomatal conductance nor CO2 assimilation were affected by salt stress. Leaf water and osmotic potentials declined significantly as stress intensified. However, osmotic adjustment permitted the maintenance of positive turgor throughout the growth period. Salinity had a significant effect on tissue concentrations of Na+, K+, Ca2+, and Cl− and on the uptake rate of Na+, K+, Ca2+, and Cl−. Thus, in addition to the toxic effects of high concentrations of Na+ and Cl− in plant tissue, saline-induced changes in mineral nutrient uptake likely contributed to the reduction of plant growth. It appears that salt tolerance in P. filiformis is associated with Na+ exclusion and organ Na+ compartmentation in roots and stems as well as sustained K+ concentration in leaves and better stomatal control through osmotic adjustment. All other Phaseolus species are Na+ excluders, and maintained turgor-driven extension growth by accumulating Cl− (osmotic adjustment), but subsequent weight gain reductions suggest that this led to ion toxicity.

The genus Phaseolus includes important cultivated species as well as wild species with diverse ecological adaptations. Characterization of the ecological adaptations of the wild species would be useful for improved understanding, conservation, and utilization of these genetic resources. Salinity tolerance during vegetative growth was evaluated for 132 accessions for 14 wild Phaseolus species (P. acutifolius A. Gray, P. angustissimus A. Gray, P. carteri Freytag & Debouck, P. filiformis Bentham, P. glabellus Piper, P. leptostachyus Bentham, P. lunatus L., P. micranthus Hook & Arnold, P. microcarpus Mart, P. mcvaughii A. Delgado, P. oligospermus Piper, and P. vulgaris L.) and 11 accessions representing five cultivated species (P. acutifolius, P. coccineus L., P. lunatus L., P. polyanthus Greenman, and P. vulgaris) in nutrient solution containing 0 and 180 m M sodium chloride for 21 d. When plants were salinized after the emergence of the first trifoliate leaf, wild accessions of P. acutifolius, P. filiformis, P. lunatus, and P. vulgaris showed a wide range of variation in their salinity tolerance as defined by total dry weight reduction (PR) as a percentage of the unsalinized controls, salt susceptibility index (SSI), and root: shoot ratio (RSR). SSI and PR were correlated positively, indicating either trait could be used to select salt-tolerant accessions. Cluster analysis revealed substantial intraspecific and interspecific variation in salinity tolerance. Salinity tolerance was observed in wild P. micranthus, P. mcvaughii, P. lunatus, cultivated P. coccineus, and several accessions of wild P. filiformis, and P. vulgaris. Of these, P. filiformis was noteworthy in having 9 of 11 accessions rated as highly tolerant. Wild P. vulgaris was more salinity tolerant than the three cultivated P. vulgaris accessions included in the study. Many tolerant accessions originated in arid, coastal, or saline areas. We conclude that the genus Phaseolus has substantial diversity in salinity tolerance.

Interest in bean genetic resources of Central America has resumed because of disease pressures (e.g., web blight, BGMV) and limitations of current bean varieties. As most of the diversity in landraces has been explored, focus is now on the exploration of wild forms of the primary gene pool and wild species of the secondary gene pool. A germplasm collection was carried out in the field and resulted in the collection of 29 wild populations for six Phaseolus species; it complemented field work done in 1987. Nine more populations were found for P. costaricensis, 10 for wild P. lunatus, one for P. oligospermus, one for P. tuerckheimii, four for wild P. vulgaris and four for P. xanthotrichus. Ninety-three herbarium voucher specimens were collected for 19 populations of the six species (deposited at CR). These results confirm the presence of wild P. vulgaris on both slopes of the central valley of Costa Rica, namely in the life zones bh-MB and bmh-P, and of P. costaricensis in the life zone bmh-MB. These life zones of limited range in Costa Rica have been heavily modified, thus fully justifying the germplasm collection for ex situ conservation. For both species the range of distribution in Costa Rica has been almost completely sampled. The life characteristics of each species that are relevant for their conservation in situ are briefly reviewed. Distribution ranges of each wild bean species are compared with the present extension of national parks, protected areas and fauna/flora sanctuaries, and suggestions for expanding such protected areas are made.

The taxonomic classification of the wild Lima bean complex needs to be assessed to select species for use in breeding programs and to identify genetic resources for conservation. The objectives of this study were to determine the genetic relationships among, and the phylogeny of, wild Lima bean (Phaseolus lunatus L.) and related species (P. augusti Harms, P. bolivianus Piper, P. pachyrrhizoides Harms, and P. rosei Piper) from South America and to identify specific genetic reserves for conservation. These relationships were investigated by means of amplified restriction fragment length polymorphism (AFLPs) on total genomic DNA. The 122 accessions formed a cluster that was distant from common bean (P. vulgaris L.), confirming earlier morphology and hybridology data. Two gene pools of wild Lima beans were confirmed. One was widely distributed in neotropical lowlands, while the other was restricted to the western Andes, in Ecuador and northern Peru. The study also revealed the existence of a third group of wild Lima bean distributed in the Departments of Boyaca and Cundinamarca, Colombia. The three species P. augusti, P. bolivianus, and P. pachyrrhizoides differed very little, certainly not sufficiently to merit a separate taxonomic ranking at the species level. The accessions could be grouped instead according to four geographic origins: Ecuador and northern Peru; Department of Junin, Peru; Departments of Cuzco and Apurimac, Peru; and Bolivia and northwestern Argentina. Results from this study should result in a better selection of parental materials in breeding programs and point to areas where germplasm collections and conservation are needed.

Chloroplast DNA (cpDNA) diversity has been examined using PCR-RFLP and RFLP strategies for phylogenetic studies in the genus Phaseolus. Twenty-two species, including 4 of the 5 cultivated species (P. lunatus L., the Lima bean; P. vulgaris L., the common bean; P. coccineus L., the runner bean and P. polyanthus Greenman, the year-bean), represented by 86 accessions were included in the study. Six PCR primers designed from cpDNA and a total cpDNA probe were used for generating markers. Phylogenetic reconstruction using both Wagner parsimony and the neighbor-joining method was applied to the restriction fragment data obtained from each of the molecular approaches. P. vulgaris L. was shown to separate with several species of largely Mesoamerican distribution, including P. coccineus L. and P. polyanthus Greenman, whereas P. lunatus L. forms a complex with 3 Andean species (P. pachyrrhizoides Harms, P. augusti Harms and P. bolivianus Piper) co-evolving with a set of companion species with a Mesoamerican distribution. Andean forms of the Lima bean are found to be more closely related to the 3 Andean wild species than its Mesoamerican forms. An Andean origin of the Lima bean and a double derivative process during the evolution of P. lunatus are suggested. The 3 Andean species are proposed to constitute the secondary gene pool of P. lunatus, while its companion allies of Mesoamerican distribution can be considered as members of its tertiary gene pool. On the basis of these data, an overview on the evolution of the genus Phaseolus is also discussed.

During germplasm explorations carried out in Peru and Colombia, interbreeding complexes of wild and cultivated common bean were observed in both countries, eight in Apurimac and Cusco departments of Peru and eight in Cundinamarca and Boyaca´ departments of Colombia. The existence of complexes was evidenced both by segregation of wild and cultivated morphological traits in certain populations, and by the presence of genetically stabilized weedy types which were assumed to have arisen from past hybridization. Observations on phaseolin seed protein confirmed that genetic exchange was occurring. Phaseolin types introduced from other regions were in incipient stages of introgression into local populations. On the other hand, local phaseolin types were observed in all phases of the complexes from totally wild to fully cultivated beans, suggesting that the complexes had undergone a long evolution. Complexes could be an effective means to generate genetic variability, introgressing genes from wild populations into cultivated types and complementing modern plant breeding programs. The conservation of such complexes depends on the continued existence of the wild, weedy and cultivated beans in close proximity; on the maintenance of a semi-domesticated environment; and on the willingness of farmers to leave weedy types in the field.

The wild, red-flowered Phaseolus glabellus is generally considered either as a species of the P. coccineus complex or as a subspecies of P. coccineus. Biogeographic considerations as well as experimental hybridization, seed storage protein electrophoresis and cpDNA polymorphism point at its isolated taxonomic position and distinctness from P. coccineus. The position of P. glabellus in Phaseolus and its relationships with the remaining taxa of the P. coccineus complex are discussed.

WildPhaseolus vulgaris is distributed between northern Mexico and northern Argentina. Analysis of phaseolin and molecular markers (isozymes, Restriction Fragment Length Polymorphisms or RFLPs) indicate that this gene pool consists of two major groups, Mesoamerican and Andean, and a third intermediate group found in northwestern South America. Previous to this study, only four accessions of wildP. vulgaris beans from Bolivia had been collected and their genetic relationship with other wild beans from Latin America was not known. Due to the problem of intense erosion in some areas of Bolivia, it was our objective to survey and documentPhaseolus spp. in this area before their extinction. We conducted a collection expedition in May 1994 in the departments of Cochabamba, Chuquisaca and Tarija. This resulted in collections of four populations ofP. augusti, two of cultivatedP. lunatus and two mixtures of cultivatedP. vulgaris. The first mixture was made of “k’opurus” or beans consumed after toasting, and represented an addition of 17 accessions to the Bolivian collection. The second mixture was made of “porotos” and resulted in the addition of 10 new accessions. Seven germplasm collections of wildP. vulgaris were found, which allowed us to increase the number of known populations of wild common bean for Bolivia. Another accession was found as a wild-weed-crop complex. Seven of these wildP. vulgaris accessions along with another accession from Bolivia collected previously, and a number of P. vulgaris accessions from Mexico (17), Guatemala (3), Colombia (10), Ecuador (6), Peru (17) and Argentina (16) were analyzed with RAPDs. The use of 14 random primers and one SCAR (Sequence Characterized Amplified Region) resulted in 90 bands, of which 83 were polymorphic. This data was used to construct a dendrogram which shows clear separation into three clusters, corresponding to each of the gene pools and an intermediate group. The Bolivian wild P. vulgaris beans grouped with the accessions of southern Peru and Argentina into the Andean gene pool. RAPD analysis of genetic diversity correlated well with genetic diversity obtained with other markers. Moreover, the ease of analysis allowed us to obtain a large number of bands which was conducive to greater sensitivity and identification of geographic subgroups and accessions of hybrid origin.

The lima bean,Phaseolus lunatus L., is a bean species with a broad distribution in the Americas that rivals that of common bean (P. vulgaris). In order to better understand the organization of genetic diversity and the pattern of domestication in lima bean, a review was conducted of the available information on the geographic distribution of wild and cultivated forms of this species. In addition, one-dimensional SDS polyacrylamide gel electrophoresis of seed proteins was also conducted on a sample of 84 wild, 6 weedy, and 426 cultivated forms. Results show that wild forms can be divided into two groups, one with smaller seeds and a very extensive distribution that includes Mexico, Central America, and the eastern slope of the Andes, and the other with a more circumscribed distribution on the western slope of the Andes in Ecuador and northern Peru. Electrophoretic analyses of seed proteins confirmed this subdivision and, additionally, showed that the large-seeded cultivars had been domesticated from the large-seeded wild lima beans in western South America. For the small-seeded lima bean cultivars, it was not possible to determine a domestication center as the most abundant protein pattern in the cultivars also had a widespread distribution in the small-seeded wild progenitor. Electrophoretic analyses showed, however, that domestication led to a reduction of genetic diversity in the small-seeded, Mesoamerican group, but not in the large-seeded group. The latter may be due to insufficient sampling of the larger-seeded, wild germplasm.

Common bean (Phaseolus vulgaris) consists of two major geographic gene pools, one distributed in Mexico, Central America, and Colombia and the other in the southern Andes (southern Peru, Bolivia, and Argentina). Amplification and sequencing of members of the multigene family coding for phaseolin, the major seed storage protein of the common bean, provide evidence for accumulation of tandem direct repeats in both introns and exons during evolution of the multigene family in this species. The presumed ancestral phaseolin sequences, without tandem repeats, were found in recently discovered but nearly extinct wild common bean populations of Ecuador and northern Peru that are intermediate between the two major gene pools of the species based on geographical and molecular arguments. Our results illustrate the usefulness of tandem direct repeats in establishing the polarity of DNA sequence divergence and therefore in proposing phylogenies.

Nunas are a group of common bean (Phaseolus vulgaris, Fabaceae) varieties, whose grains are consumed after toasting in their original Andean habitats. Nowadays, these varieties are restricted to certain parts of the highlands of Peru and Bolivia. Linguistic, ethnobotanical, and archaeological data suggest that they were grown in that zone duringpre-Hispanic times. SDS-PAGE electrophoresis shows a wide range ofphaseolin types amongnunas, many of which are present in sympatric wild forms. This paper discusses the possibility thatnunas resulted from an early and widely applied selection pressure during bean domestication in the Andes.

† Background and Aims The actual number of domestications of a crop is one of the key questions in domestication studies. Answers to this question have generally been based on relationships between wild progenitors and domesticated descendants determined with anonymous molecular markers. In this study, this question was investigated by determining the number of instances a domestication phenotype had been selected in a crop species. One of the traits that appeared during domestication of common bean (Phaseolus vulgaris) is determinacy, in which stems end with a terminal inflorescence. It has been shown earlier that a homologue of the arabidopsis TFL1 gene ‐ PvTFL1y ‐ controls determinacy in a naturally occurring variation of common bean. † Methods Sequence variation was analysed for PvTFL1y in a sample of 46 wild and domesticated accessions that included determinate and indeterminate accessions. † Key Results Indeterminate types ‐ wild and domesticated ‐ showed only synonymous nucleotide substitutions. Determinate types ‐ observed only among domesticated accessions ‐ showed, in addition to synonymous substitutions, non-synonymous substitutions, indels, a putative intron-splicing failure, a retrotransposon insertion and a deletion of the entire locus. The retrotransposon insertion was observed in 70 % of determinate cultivars, in the Americas and elsewhere. Other determinate mutants had a more restricted distribution in the Americas only, either in the Andean or in the Mesoamerican gene pool of common bean. † Conclusions Although each of the determinacy haplotypes probably does not represent distinct domestication events, they are consistent with the multiple (seven) domestication pattern in the genus Phaseolus. The predominance of determinacy in the Andean gene pool may reflect domestication of common bean prior to maize introduction in the Andes.

International audience; Grain legumes contribute significantly to total world food production. Legumes are the primary source of dietary proteins in many developing countries, where protein hunger and malnutrition are widespread. Grain legumes germplasm constitute similar to 15% of the 7.4 M accessions preserved globally. Nearly, 78% of the CGIAR's, 0.217 M accessions, have been characterized, compared to 34% of national genebank collections. Interestingly, limited data on grain quality are available as the primary focus has been on morpho-agronomic traits. Clearly, more resources should be targeted on biochemical evaluation to identify nutritionally rich and genetically diverse germplasm. The formation of core and mini core collections has provided crop breeders with a systematic yet manageable entry point into global germplasm resources. These subsets have been reported for most legumes and have proved useful in identifying new sources of variation. They may however not eliminate the need to evaluate entire collections, particularly for very rare traits. Molecular characterization and association mapping will further aid to insights into the structure of legume diversity and facilitate greater use of collections. The use of high resolution elevational climate models has greatly improved our capacity to characterize plant habitats and species' adaptive responses to stresses. Evidence suggests that there has been increased use of wild relatives as well as new resources resulting from mutagenesis to enhance the genetic base of legume cultigens.

The genetic variability of seven Phaseolus taxa has been evaluated on the basis of molecular data and the results have used to clarify the phyletic relationships between several taxa of the P. coccineus L. complex. Chloroplast DNA (cpDNA) from 33 populations was digested with six restriction endonucleases, revealing some polymorphisms that made it possible to divide most of the taxa into two main groups: the subspecies of P. coccineus on the one hand, and P. vulgaris L., P. polyanthus Greenman and P. costaricensis (Freytag and Debouck) on the other hand. P. polyanthus is closer to P. vulgaris than the other taxa of the second group and should be considered as a separate species. The position of the wild species P. costaricensis is intermediate between P. coccineus and P. polyanthus. P. glabellus shows sufficient polymorphisms at the cpDNA level to be recognized as a separate species, as previously suggested from total seed-protein electrophoretic studies. These results favour the hypothesis of a common phylogeny for P. vulgaris, P. polyanthus, P. costaricensis and P. coccineus from a single wild ancestor. Although cpDNA is generally known to be uniform at the intraspecific level, some additional polymorphisms were also detected within P. vulgaris, P. polyanthus and P. coccineus. Further studies are required to understand the significance of the latter.

Our goal was to investigate in more detail wild and cultivated common bean (Phaseolus vulgaris) accessions from northwestern South America (Colombia, Ecuador, and northern Peru) because prior research had shown this region to be the meeting place of the two major gene pools (Middle American and Andean) of common bean. Explorations were conducted in these countries to collect additional materials not represented in germplasm collections. It was possible to identify wild common bean populations in Ecuador and northern Peru, where they had never been described before. In addition, we were able to extend the distribution of wild common bean in Colombia beyond what was known prior to this study. In all areas, the wild common bean habitat had suffered severely from destruction of natural vegetation. In Colombia, wild common beans were found on the Eastern slope of the Andes (in continuation of its distribution in Venezuela), whereas in Ecuador and northern Peru they were found on the western slope of this mountain range. This geographic distribution was correlated with an ecological distribution in relatively dry environments with intermediate temperatures (known as “dry mountain forest”). Isozyme andphaseolin seed protein analyses of the northern Peruvian and Ecuadoran wild populations showed that they were intermediate between the Middle American and Andean gene pools of the species. Phaseolin analyses conducted on landraces of the Upper Magdalena Valley in Colombia showed that Andean domesticates were grown at a higher altitude than Middle American domesticates suggesting that the former are adapted to cooler temperatures. Our observations and results have the following consequences for the understanding and conservation of genetic diversity in common bean and other crops: 1) Our understanding of the distribution of the wild relative of common bean (and other crops) is imperfect and further explorations are needed to more precisely identify and rescue wild ancestral populations; 2) For crops for which the wild ancestor has not yet been identified, it may be worthwhile to conduct additional explorations in conjunction with genetic diversity studies at the molecular level to guide the explorations; 3) Our study shows the benefit for more efficient germplasm conservation which can be derived from the dynamic interplay between field explorations (and other conservation operations) and molecular analyses to determine genetic distances and diversities; 4) The intermediate materials identified in northern Peru and Ecuador may have basic importance to understand the origin of the common bean and an applied role as a bridge between the Middle American and Andean gene pools; and 5) The differential adaptation to temperature of the two major cultivated gene pools may help breeders select genotypes based at least partially on their evolutionary origin.