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Universidade de Sao Paulo (2016)

Multi-environment-multi-locus association mapping for drought tolerance in maize

Anoni, Carina de Oliveira

Titre : Multi-environment-multi-locus association mapping for drought tolerance in maize

Mapeamento associativo para múltiplos ambientes e múltiplos locos, visando tolerância à seca em milho

Auteur : Anoni, Carina de Oliveira

Université de soutenance : Universidade de Sao Paulo

Grade : Doctorat 2016

Drought is a severe stress factor in maize production and causes significant reduction in grain yield. Genetic architecture of drought tolerance is complex and a better understanding of this trait is required. Association mapping studies are useful to explore quantitative traits and simultaneously account for genetic backgrounds including genotype, environment and genotype-by-environment (G × E) interactions. By accounting for G × E into association mapping models it is possible to identify regions associated with specific environment and conditions. The main goal of this study was detect significant associations related to drought tolerance in maize via multi-environment-multi- locus association mapping model, distinguishing information about specific-environment effects from main and association-by-environment (QEI) effects. Our association panel was composed by 190 inbred lines classified according to heterotic groups. The panel was genotyped with ∼500K SNPs. Two inbred lines (L228-3 and L3) were used as common testers and testcrosses were assessed in two locations (Janaúba-MG e Teresina-PI), two years (2010 and 2011), under two treatment conditions (well-watered and water-stressed). A total of six traits were evaluated including grain yield, anthesis-silking interval, female and male flowering time, plant and ear height. Two mapping groups were considered, grouped by common testers. SNPs were used to test significant association along the maize genome and also to account for population structure and relatedness coefficient. Our mapping model detected a total of 179 associations and the highest number of associations were related to the flowering time measures. The most associations (168) showed significant QEI and the size and magnitude of those effects were distinguished by environment conditions. Only female flowering trait did not show stable effects across all environments. Mapped associations in nearby positions indicate plausible pleiotropy effects. Some associations were co-located in maize genome regions related to metabolic pathway factors. Our study support the detection of significant associations along the maize genome and contributes for understanding of the genetic basis of drought tolerance in maize.

Mots clés  : G×E - Zea mays - GWAS - Tolerância à seca - Drought tolerance


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