title: Pollen-Mediated Gene Flow in Maize: Implications for Isolation Requirements and Coexistence in Mexico, the Center of Origin of Maize.
abstract: Mexico, the center of origin of maize (Zea mays L.), has taken actions to preserve the identity and diversity of maize landraces and wild relatives. Historically, spatial isolation has been used in seed production to maintain seed purity. Spatial isolation can also be a key component for a strategy to minimize pollen-mediated gene flow in Mexico between transgenic maize and sexually compatible plants of maize conventional hybrids, landraces, and wild relatives. The objective of this research was to generate field maize-to-maize outcrossing data to help guide coexistence discussions in Mexico. In this study, outcrossing rates were determined and modeled from eight locations in six northern states, which represent the most economically important areas for the cultivation of hybrid maize in Mexico. At each site, pollen source plots were planted with a yellow-kernel maize hybrid and surrounded by plots with a white-kernel conventional maize hybrid (pollen recipient) of the same maturity. Outcrossing rates were then quantified by assessing the number of yellow kernels harvested from white-kernel hybrid plots. The highest outcrossing values were observed near the pollen source (12.9% at 1 m distance). The outcrossing levels declined sharply to 4.6, 2.7, 1.4, 1.0, 0.9, 0.5, and 0.5% as the distance from the pollen source increased to 2, 4, 8, 12, 16, 20, and 25 m, respectively. At distances beyond 20 m outcrossing values at all locations were below 1%. These trends are consistent with studies conducted in other world regions. The results suggest that coexistence measures that have been implemented in other geographies, such as spatial isolation, would be successful in Mexico to minimize transgenic maize pollen flow to conventional maize hybrids, landraces and wild relatives.
authors.affiliation: Monsanto Company, 800 North Lindbergh Blvd, St. Louis, Missouri, 63167, United States of America.
authors.forename: Baltazar M
authors.initials: BM
authors.lastname: Baltazar
authors.affiliation: Instituto Tecnológico de Sonora, Dirección de Recursos Naturales, 5 de Febrero 818 Sur, Colonia Centro Cd. Obregón, Sonora, C.P. 85000, México.
authors.forename: Luciano
authors.initials: L
authors.lastname: Castro Espinoza
authors.affiliation: Universidad Autónoma Agraria Antonio Narro, Unidad Laguna, Periférico Raúl López Sánchez y Carretera Santa Fe, Col. Valle Verde, Torreón, Coahuila, C.P. 27059, México.
authors.forename: Armando
authors.initials: A
authors.lastname: Espinoza Banda
authors.affiliation: Monsanto Comercial, Park Plaza Torre II, piso 1. Ave. Javier Barros Sierra #504, Col. Santa Fe, Del. Álvaro Obregón, México D.F., CP 01210, México.
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: de la Fuente Martínez
authors.affiliation: Universidad Autónoma de Sinaloa, Facultad de Ciencias Químico Biológicas, Ave. Las Américas y Josefa Ortiz, S/N Culiacán, Sinaloa, C.P. 80000, México.
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Garzón Tiznado
authors.affiliation: Universidad Autónoma de Chihuahua, Facultad de Ciencias Agrícolas y Forestales, Km. 2.5 Carr. Delicias-Rosales, Cd. Delicias, Chihuahua, C.P. 33000, México.
authors.forename: Juvencio
authors.initials: J
authors.lastname: González García
authors.affiliation: Instituto Tecnológico de Sonora, Dirección de Recursos Naturales, 5 de Febrero 818 Sur, Colonia Centro Cd. Obregón, Sonora, C.P. 85000, México.
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Gutiérrez
authors.affiliation: Universidad Autónoma de Nuevo León, Facultad de Agronomía, Av. Francisco Villa S/N, Col. Ex Hacienda "El Canadá," Escobedo, Nuevo León, C.P. 66050, México.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Guzmán Rodríguez
authors.affiliation: Monsanto Comercial, Park Plaza Torre II, piso 1. Ave. Javier Barros Sierra #504, Col. Santa Fe, Del. Álvaro Obregón, México D.F., CP 01210, México.
authors.forename: Oscar
authors.initials: O
authors.lastname: Heredia Díaz
authors.affiliation: Monsanto Company, 800 North Lindbergh Blvd, St. Louis, Missouri, 63167, United States of America.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Horak
authors.affiliation: Universidad Autónoma de Sinaloa, Facultad de Ciencias Químico Biológicas, Ave. Las Américas y Josefa Ortiz, S/N Culiacán, Sinaloa, C.P. 80000, México.
authors.forename: Jesús Ignacio
authors.initials: JI
authors.lastname: Madueño Martínez
authors.affiliation: Monsanto Company, 800 North Lindbergh Blvd, St. Louis, Missouri, 63167, United States of America.
authors.forename: Adam W
authors.initials: AW
authors.lastname: Schapaugh
authors.affiliation: Monsanto Company, 800 North Lindbergh Blvd, St. Louis, Missouri, 63167, United States of America.
authors.forename: Duška
authors.initials: D
authors.lastname: Stojšin
authors.affiliation: Universidad Autónoma de Chihuahua, Facultad de Ciencias Agrícolas y Forestales, Km. 2.5 Carr. Delicias-Rosales, Cd. Delicias, Chihuahua, C.P. 33000, México.
authors.forename: Hugo Raúl
authors.initials: HR
authors.lastname: Uribe Montes
authors.affiliation: Universidad Autónoma de Nuevo León, Facultad de Agronomía, Av. Francisco Villa S/N, Col. Ex Hacienda "El Canadá," Escobedo, Nuevo León, C.P. 66050, México.
authors.forename: Francisco
authors.initials: F
authors.lastname: Zavala García
mesh_terms: D000465:Algorithms; D018556:Crops, Agricultural / Q000235:genetics / Q000254:growth & development; D003433:Crosses, Genetic; D051456:Gene Flow; D017343:Genes, Plant / Q000235:genetics*; D014644:Genetic Variation; D005828:Genetics, Population; D005843:Geography; D006813:Humidity; D006824:Hybridization, Genetic; D008800:Mexico; D008957:Models, Genetic; D030821:Plants, Genetically Modified / Q000235:genetics; D011058:Pollen / Q000235:genetics*; D054817:Pollination / Q000235:genetics; D011157:Population Dynamics; D011891:Rain; D012639:Seeds / Q000235:genetics / Q000254:growth & development; D013696:Temperature; D014919:Wind; D003313:Zea mays / Q000235:genetics* / Q000254:growth & development