Identification of QTL associated with nitrogen metabolism in a maize (Zea mays L. ssp. mays) testcross population

Maize is a widely cultivated crop in the world and its production relies heavily on nitrogen (N) fertilization. N is an essential mineral nutrient for plant growth and development. However, during the last decades excessive quantities of N have been applied by farmers, a surplus to what maize plants can uptake, and several problems have arisen, such as pollution of the ecosystem and an economic loss to farmers. Breeding maize hybrids that are more efficient in the use of N is a long term goal for plant breeders. Nonetheless, previous to breeding, the genetic basis of N-metabolism in maize would need to be elucidated. Herein, maize testcrosses (TC), derived from the IBMSyn10-DH crossed by an elite inbred, were: 1) Grown in hydroponic condition and several physiological traits related to N-metabolism were assessed on leaf and root tissues. After performing statistical analyses, quantitative trait loci (QTL) were identified; 2) Grown in field conditions under low and high N, several agronomic traits were determined, and statistical and QTL analyses were implemented. A novel statistical approach was implemented to differentiate experimental errors from truthful phenotypic records in order to remove them for further genetic analysis. This automated method for outlier determination helped to focus the analysis on real data and obtain more reliable QTL mapping results. Several QTL associated with N-metabolism were determined and numerous candidate genes underlying QTL genomic regions are proposed for further analysis. At least one rich QTL region, presenting three or more overlapping confidence intervals for QTL, were determined at each of the ten chromosomes. These genomic regions may be valuable in the determination of N-metabolism in maize TC