The Domestication of Phaseolus vulgaris L Taxonomic Overview Family Fabaceae Leguminosae Subfamily Papilionoideae Tribe Phaseolae Phaseolus is a monophyletic genus Diploid 2n 22 x 11 Predominantly selfpollinating due to papilionaceous cleistogamous flower structure some bees The genus Phaseolus is strictly New World in tropical and subtropical locales Documenting Domestication reports range as from Mexico to Argentina However two species P sinuatus Nuttall ex T G and P polystachios L BSP are found throughout the Southeastern U S A Radford 1964 Importance to Humans Fabaceae is one of the most important plant families has been for millenia Includes other domesticates such as Cicer arietinum L Chick pea Arachis hypogaea L Peanut Lathyrus odoratus L Sweet pea Phaseolae also includes Glycine max L Merr soybean Vigna unguiculata L Walp 4 ssps Cowpea Black eyed pea Yardlong bean Catjang Phaseolus includes 5 domesticated species P vulgaris L P lunatis L lima bean P acutifolius A Gray tepary bean P coccineus L runner bean P polyanthus Greenman Of these Phaseolus vulgaris L is the most important vegetable protein source for humans Diversity History Native to Central South Americas Arrived in Spain Portugal from Central America in 1506 after the discovery of the New World Accessions from the Andes started arriving in Europe after 1532 Reached Germany by at least 1543 as evidenced by a description in a German herbal Mystery of Domestication Role of introgressive hybridization of P vulgaris and P coccineus in Mexico bumblebees Domesticated twice How many species are we dealing with here Role of Hybridization Discussed in article at some length hybridization b t P coccineus and P vulgaris resulting in P polyanthus Also proposed by Freytag in 1955 that gene flow from P coccineus could be responsible for the larger seed size in Mesoamerican varieties as opposed to Andean varieties Gepts and Khairallah both report the Andean varieties to have larger seeds Domesticated Twice Archaeological Evidence Molecular Evidence Archaeological Evidence Supports two events of domestication because 1 Domesticates appear before evidence for cultural contact b t Meso Andean America occurred 2000 1000 yrs BPE Gepts et al 1986 2 Distinct varieties matching varieties today found in sites 3 Wild P vulgaris grows in both regions Kaplan 1980 Earliest evidence in Mesoamerica found in Coxcatlan Cave of Tehuacan Valley dating to 5 5007 000 yrs BPE Earliest evidence in Andes dates to 8 000 yrs BPE found in Guitarrero Wild remains were found in Mesoamerica but not in Andes all sites located outside of natural growth of wild P vulgaris Molecular Evidence Wealth of evidence Focus mainly on 1 Phaseolin types protein markers 2 RFLP diversity 3 mtDNA analysis for you Phil Following table is from Gepts 1996 Phaseolin Types Authoritative article on this subject is Gepts et al 1986 Analyzes phaseolin variations b t Andean Mesoamerican wild plants as well as landraces using 1 D SDSPAGE and 2 D IEF SDS PAGE on 106 wild forms and 99 landraces Condensed Results from Gepts 1986 on Phaseolin Distribution Wild forms Mexico M S nearly all M Guatemala same as Mexico Peru S T mainly T Brazil Argentina T Domesticated Mexico S 2 T Colombia Guatemala Costa Rica S 1 T Ecuador S T C 1 C Peru few S lots T 2 C 2 H 1 A Bolivia Chile Argentina T C few S 2 H RFLP Diversity Looked at Velasquez Gepts 1994 Digested genomic DNA four ways one time each with three different restriction enzymes EcoRI EcoRV and HindIII and one time with all three Generated diagrams based on Nei s distances Nei s Distance Diagrams Velasquez Gepts 1994 Mitochondrial DNA Analysis Khairallah et al 1990 Examined 23 Malawian landraces Digested mtDNA with 8 restriction endonucleases HaeIII BamHI DraI EcoRI HindIII PstI SalI XhoI 2 distinct mtDNA groups were discovered corresponding to the two nuclear DNA groups However a high level of mt genome homogeneity Demonstrates divergence before domestication How Many Species Are We Dealing with Here Evidence supports that P vulgaris is at least in the process of speciation Two divergent gene pools repeatedly identified Gepts Bliss 1985 demonstrated F1 hybrid lethality b t Meso and Andean American varieties 3 gene pools Islam et al 2002 Map of Type Distribution of Wild Phaseolus vulgaris Gepts 1996 Condensed Results from Gepts 1986 on Phaseolin Distribution Wild forms Mexico M S nearly all M Guatemala same as Mexico Peru S T mainly T Brazil Argentina T Domesticated Mexico S 2 T Colombia Guatemala Costa Rica S 1 T Ecuador S T C 1 C Peru few S lots T 2 C 2 H 1 A Bolivia Chile Argentina T C few S 2 H Nei s Distance Diagrams Velasquez Gepts 1994 Sources Freytag G F 1955 Variation of the common bean in Central America Unpublished thesis Henry Shaw School of Botany Washington Univ St Louis MO Gepts Paul 1996 Origin and evolution of cultivated Phaseolus species In B Pickersgill and J M Lock eds Advances in Legume Systematics 8 Legumes of Econoic Importance pp 65 74 Royal Botanic Gardens Kew Islam F M A et al 2002 Genetic variability in cultivated common bean beyond the two major gene pools Gen Res Crop Evol 49 271 283 Kaplan Lawrence 1981 What is the Origin of the Common Bean Khairallah M M et al 1990 Mitochondrial DNA polymorphisms of Malawian bean lines further evidence for two major gene pools Theor Appl Genet 80 753 761 Velasquez Viviana L Becerra and Paul Gepts 1994 RFLP diversity of common bean Phaseolus vulgaris in its centres of origin Genome 37 256 263
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