Association mapping for traits related to nitrogen use efficiency in tropical maize lines under field conditions

Abstract

Nitrogen deficiency is one of the most critical abiotic stresses for maize (Zea mays) cultivation worldwide. For a productive and sustainable scenario, developing genotypes more efficient in nitrogen use is essential. This study aimed to identify single nucleotide polymorphism (SNP) markers associated with nitrogen use efficiency (NUE) traits under field conditions and candidate genes related to these markers by genome-wide association study (GWAS). Sixty-four tropical maize inbred lines were evaluated in ideal and low nitrogen conditions for total root length (TRL) and low nitrogen tolerance index (LNTI). GWAS was performed using a fixed and random model circulating probability unification method, with marker-based principal components to correct for population stratification. Genotypic values were predicted using mixed model equations. Seven significant markers were identified. Among the primary biological processes, candidate genes are related to transcription control and regulation, detected to all evaluated traits, and the synthesis of Guanosine Monophosphate Synthetase, enzyme directly involved in the provision and recycling of nitrogen. GWAS analysis revealed genomic regions in tropical maize associated with NUE under field conditions. The main biological process identified as related to these markers/regions evidence cellular processes and functions associated with different process of nitrogen synthesis and recycling.