Genome-Wide Association Studies for nitrogen use efficiency and its components in tropical maize lines

Abstract

To meet the global demand for food a significant portion of maize crops will occur in environmental conditions that restrict the full development of culture. In Brazil, this is already happening on a large scale, where which much of our crop production migrated to the season called "safrinha" and for areas of the Cerrado. In these areas it is common the low availability of nutrients in the soil, especially nitrogen (N). Additionally, this second season is characterized by low investment by the farmers in fertilizer. Thus, it becomes important to develop cultivars with nitrogen use efficient use (NUE) and well suited to these culture conditions. In this sense, the identification of QTLs associated with NUE can help the selection process of superior genotypes for these conditions. Given the above, this project aims to identify QTLs associated with nitrogen use efficiency and its components in tropical maize inbred lines. For this, 64 inbred lines contrasting for NUE will be evaluated in low and high soil nitrogen availability, in three different growth stages and in two cultivation sites in the region of Piracicaba-SP. The 64 lines will be genotyped by the Illumina Maize Platform SNP50 DNA Analysis Kit, with approximately 56,000 SNP. The phenotyping will be made for NUE and its components, leaf chlorophyll content, photosynthetic rate, agronomic traits and length and morphology of roots. The data of phenotypic traits will be analyzed using the mixed model equations. The relationships between phenotypic characters will be made by path analysis. For the identification of QTLs the data of molecular markers with the phenotypic together will be analyzed by the method of Genome-wide Association Studies (GWAS). From the results to be obtained by this study, it is expected to find molecular markers in linkage disequilibrium with the characters that control the NUE, thereby aiding the development of maize cultivars adapted to growing conditions of this abiotic stress. (AU)