Association Mapping for Components of Reaction Norms to Environmental Covariates in Public Tropical Maize (<scp><i>Zea mays</i></scp>) Panel Under Water Stress

ABSTRACT Using reaction norm components instead of traditional phenotypic data in genetic association studies (GWAS) may allow the identification of genomic regions that are more influenced by environmental variables in terms of tolerance and responsiveness to water stress. To test this hypothesis, we used a public genetic diversity panel of tropical maize inbred lines, evaluated in eight environments, four in well‐watered (WW) and four in water stress (WS) conditions. Most SNPs explained at least 40% of the genetic variability, and some reached 67%. The identified genes and genomic regions revealed physiological responses and direct or indirect molecular mechanisms related to water deficit tolerance and responsiveness. This information will enable more assertive selections and subsidize breeding programs aimed at obtaining cultivars for water deficit conditions while reducing the costs of the evaluation processes of reaction standards.