title: Dissecting maize diversity in lowland South America: genetic structure and geographic distribution models.
abstract: Maize landraces from South America have traditionally been assigned to two main categories: Andean and Tropical Lowland germplasm. However, the genetic structure and affiliations of the lowland gene pools have been difficult to assess due to limited sampling and the lack of comparative analysis. Here, we examined SSR and Adh2 sequence variation in a diverse sample of maize landraces from lowland middle South America, and performed a comprehensive integrative analysis of population structure and diversity including already published data of archaeological and extant specimens from the Americas. Geographic distribution models were used to explore the relationship between environmental factors and the observed genetic structure.
  
  
  
  Bayesian and multivariate analyses of population structure showed the existence of two previously overlooked lowland gene pools associated with Guaraní indigenous communities of middle South America. The singularity of this germplasm was also evidenced by the frequency distribution of microsatellite repeat motifs of the Adh2 locus and the distinct spatial pattern inferred from geographic distribution models.
  
  
  
  Our results challenge the prevailing view that lowland middle South America is just a contact zone between Andean and Tropical Lowland germplasm and highlight the occurrence of a unique, locally adapted gene pool. This information is relevant for the conservation and utilization of maize genetic resources, as well as for a better understanding of environment-genotype associations.
authors: Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes y Costanera Norte s/n, 4to, Piso, Pabellón II, Ciudad Universitaria, C1428EHA, Ciudad Autónoma de Buenos Aires, Argentina.|Escuela de Ciencias Agrarias, Naturales y Ambientales, Universidad Nacional del Noroeste de la Provincia de Buenos Aires, Av. Pte. Dr. Arturo Frondizi, N° 2650, Pergamino, Buenos Aires, Argentina.
authors: Mariana
authors: M
authors: Bracco
authors: Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes y Costanera Norte s/n, 4to, Piso, Pabellón II, Ciudad Universitaria, C1428EHA, Ciudad Autónoma de Buenos Aires, Argentina.|Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires, Argentina.
authors: Jimena
authors: J
authors: Cascales
authors: Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martín 4453, C1417DSE, Ciudad Autónoma de Buenos Aires, Argentina.
authors: Julián Cámara
authors: JC
authors: Hernández
authors: Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes y Costanera Norte s/n, 4to, Piso, Pabellón II, Ciudad Universitaria, C1428EHA, Ciudad Autónoma de Buenos Aires, Argentina.|Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires, Argentina.
authors: Lidia
authors: L
authors: Poggio
authors: Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes y Costanera Norte s/n, 4to, Piso, Pabellón II, Ciudad Universitaria, C1428EHA, Ciudad Autónoma de Buenos Aires, Argentina.|Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires, Argentina.
authors: Alexandra M
authors: AM
authors: Gottlieb
authors: Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes y Costanera Norte s/n, 4to, Piso, Pabellón II, Ciudad Universitaria, C1428EHA, Ciudad Autónoma de Buenos Aires, Argentina. lia.veronica@inta.gob.ar.|Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires, Argentina. lia.veronica@inta.gob.ar.|Instituto de Biotecnología, CICVyA, INTA, N. Repetto y De las Cabañas s/n 1686, Hurlingham, Buenos Aires, Argentina. lia.veronica@inta.gob.ar.
authors: Verónica V
authors: VV
authors: Lia
mesh_terms: D001499:Bayes Theorem; D014644:Genetic Variation; D005838:Genotype; D018895:Microsatellite Repeats; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics; D013020:South America; D003313:Zea mays / Q000145:classification / Q000235:genetics*
chemical_list: D010940:Plant Proteins
keywords: Genetic diversity; Geographic distribution models; Guaraní communities; Lowland South America; Maize landraces