title: Genetic Vulnerability and the Relationship of Commercial Germplasms of Maize in Brazil with the Nested Association Mapping Parents.
abstract: A few breeding companies dominate the maize (Zea mays L.) hybrid market in Brazil: Monsanto® (35%), DuPont Pioneer® (30%), Dow Agrosciences® (15%), Syngenta® (10%) and Helix Sementes (4%). Therefore, it is important to monitor the genetic diversity in commercial germplasms as breeding practices, registration and marketing of new cultivars can lead to a significant reduction of the genetic diversity. Reduced genetic variation may lead to crop vulnerabilities, food insecurity and limited genetic gains following selection. The aim of this study was to evaluate the genetic vulnerability risk by examining the relationship between the commercial Brazilian maize germplasms and the Nested Association Mapping (NAM) Parents. For this purpose, we used the commercial hybrids with the largest market share in Brazil and the NAM parents. The hybrids were genotyped for 768 single nucleotide polymorphisms (SNPs), using the Illumina Goldengate® platform. The NAM parent genomic data, comprising 1,536 SNPs for each line, were obtained from the Panzea data bank. The population structure, genetic diversity and the correlation between allele frequencies were analyzed. Based on the estimated effective population size and genetic variability, it was found that there is a low risk of genetic vulnerability in the commercial Brazilian maize germplasms. However, the genetic diversity is lower than those found in the NAM parents. Furthermore, the Brazilian germplasms presented no close relations with most NAM parents, except B73. This indicates that B73, or its heterotic group (Iowa Stiff Stalk Synthetic), contributed to the development of the commercial Brazilian germplasms.
authors: Plants Science Department, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil.
authors: Luciano Rogério Braatz de
authors: http://orcid.org/0000-0003-4752-1164
authors: LR
authors: Andrade
authors: Genetics Department, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, São Paulo, Brazil.
authors: Roberto
authors: R
authors: Fritsche Neto
authors: Genetics Department, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, São Paulo, Brazil.
authors: Ítalo Stefanine Correia
authors: ÍS
authors: Granato
authors: Systèmes biologiques, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Montpellier, Languedoc-Roussillo, France.
authors: Gustavo César
authors: GC
authors: Sant'Ana
authors: Plants Science Department, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil.
authors: Pedro Patric Pinho
authors: PP
authors: Morais
authors: Plants Science Department, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil.
authors: Aluízio
authors: A
authors: Borém
mesh_terms: D001938:Brazil; D002874:Chromosome Mapping; D005787:Gene Frequency; D060005:Genotyping Techniques / Q000379:methods*; D010802:Phylogeny; D000069600:Plant Breeding; D020641:Polymorphism, Single Nucleotide; D012639:Seeds / Q000235:genetics*; D003313:Zea mays / Q000235:genetics*