Abstract Detail



Crops and Wild Relatives

Aguirre-Dugua, Xitlali [1], Gasca-Pineda, Jaime [2], Barrera-Redondo, Josué [3], Vázquez-Lobo, Alejandra  [4], Sánchez-de la Vega, Guillermo [3], Monterrubio, Brenda [3], Castellanos-Morales, Gabriela [5], Scheinvar, Enrique [3], Aguirre-Planter, Erika [3], Montes-Hernández, Salvador [6], Lira-Saade, Rafael [7], Eguiarte, Luis [8].

Gene flow patterns and population genomics of the highland cucurbits, the chilacayote (Cucurbita ficifolia) and its wild relatives.

The figleaf gourd or chilacayote (Cucurbita ficifolia), is a domesticated species cultivated at high elevations (1000-3000 m asl) in mountain ranges in the Americas from Mexico to Chile and Argentina. Its origins are debated, since no direct wild ancestor has been identified, and it represents an isolated lineage in the phylogeny of the genus. Hybridization experiments have shown reproductive isolation with other domesticated taxa, while having a limited reproductive compatibility with wild Cucurbita found in the Mexican highlands, especially C. pedatifolia (which therefore would represent the secondary gene pool of C. ficifolia in terms of genetic resources). C. ficifolia also coexists with wild C. radicans, C. foetidissima and C. x scabridifolia. This study evaluates potential gene flow between C. ficifolia and its wild relatives based on GBS data (Illumina 100 bp Single End) from 142 individual samples of 58 localities across their distribution range in Mexico. We also generated a high-quality genome assembly for C. ficifolia with chromosome-level scaffolds to aid in the identification of genetic variation across the genome. Reference-guided mapping of reads on the newly assembled C. ficifolia genome generated a matrix of 6,292 quality-filtered biallelic single nucleotide polymorphisms (SNPs). The ancestral and derived states of the SNPs were polarized using C. cordata as an outgroup. Bayesian assignation (Structure) and principal coordinate analyses showed that the five taxa are clearly distinguishable entities. Small amounts of gene flow were detected between C. ficifolia and C. x scabridifolia based on an ABBA-BABA test. Demographic model selection (with coalescent-based FastSimCoal) supports rapid population growth from a small ancestral effective population size in C. ficifolia from Mexico, in agreement with low levels of genetic diversity (Ho=0.0125) and low genetic structure among populations (FST=0.04). Demographic models also support the hybrid origin of C. x scabridifolia from C. foetidissima and C. pedatifolia. Our results further support that C. ficifolia is a highly reproductively isolated species, which agrees with its isolated phylogenetic position. Future studies should include samples from South America to test for possible domestication scenarios of C. ficifolia across the continent.


1 - Colegio De Postgraduados, Posgrado En Botnica, Km 36.5 Carretera Federal Mxico-Texcoco, Montecillo, MEX, 56230, Mexico
2 - Instituto De Ecologa, UNAM, Ecologa Evolutiva, Apartado Postal 70-275 Ciudad Universitaria, D.F., Circuito Exterior S/n Anexo, UNAM 04510 Mxico, , Mexico City, 04510, Mexico
3 - Universidad Nacional Autónoma de México, Instituto de Ecología, Circuito Exterior s/n Anexo al Jardín Botánico, Ciudad Universitaria, Coyoacán, Ciudad de Mexico, Ciudad de Mexico, 04510, México
4 - Universidad Autónoma del Estado de Morelos, Centro de Investigaciones en Biodiversidad y Conservación, Av. Universidad 1001 Col. Chamilpa, Cuernavaca, Morelos, 62209, México
5 - El Colegio de la Frontera Sur Unidad Villahermosa, Departamento de Conservación de la Biodiversidad, Carretera Villahermosa-Reforma km 15.5, Ranchería El Guineo 2a sección, Villahermosa, Tabasco, 86280, México
6 - Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuari, Campo Experimental Bajío, km 6.5 carretera federal Celaya-San Miguel de Allende, Celaya, Guanajuato, 38110, México
7 - Facultad de Estudios Superiores Iztacala, Universidad Nacional Autóno, Unidad de Biotecnología y Prototipos, Av. de los Barrios 1, Col. Los Reyes Iztacala, Tlalnepantla, Estado de Mexico, 54090, México
8 - Universidad Nacional Autnoma De Mxico, Instituto De Ecologa, C.U., UNAM, Apartado Postal 70-275, C.U., Coyoacn, Mxico, DIF, C.P. 04510, Mexico

Keywords:
Crop wild relatives
domestication
genetic resources
cucurbits
Mesoamerica.

Presentation Type: Oral Paper
Number:
Abstract ID:688
Candidate for Awards:None


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