Tracing Back the Origin of Pumpkins (cucurbita Pepossp.pepol.) in Mexico

Cucurbita pepois an economically important crop, which consists of cultivatedC. pepossp.pepo, and two wild taxa (C. pepossp.fraternaandC. pepossp.ovifera).We aimed at understanding the domestication and the diversity ofC. pepoin Mexico. We used two chloroplast regions and nine nuclear microsatellite loci to assess the levels of genetic variation and structure forC. pepossp.pepo's landraces sampled in 13 locations in Mexico, five improved varieties, oneC. pepossp.fraternapopulation and ornamentalC. pepossp.ovifera. We tested four hypotheses regarding the origin ofC. pepossp.pepo's ancestor through approximate Bayesian computation:C. pepossp.oviferaas the ancestor;C. pepossp.fraternaas the ancestor; an unknown extinct lineage as the ancestor; andC. pepossp.pepoas hybrid fromC. pepossp.oviferaandC. pepossp.fraternaancestors.Cucurbita pepossp.peposhowed high genetic variation and low genetic differentiation.Cucurbita pepossp.fraternaandC. pepossp.peposhared two chloroplast haplotypes. The three subspecies were well differentiated for microsatellite loci.Cucurbita pepossp.fraternawas probablyC. pepossp.pepo's wild ancestor, but subsequent hybridization between taxa complicate definingC. pepossp.pepo's ancestor.