Genetic architecture of phosphorus use efficiency across diverse environmental conditions: insights from maize elite and landrace lines

Phosphorus is an essential nutrient for all crops. Thus, a better understanding of the genetic control of phosphorus use efficiency evident in physiological, developmental, and morphological traits and its environmental plasticity is required to establish the basis for maintaining or enhancing yield while making agriculture more sustainable. In this study, we utilized a diverse panel of maize (Zea mays L.), including 398 elite and landrace lines, phenotyped across three environments and two phosphorus fertilization treatments. We performed genome-wide association mapping for 13 traits, including phosphorus uptake and allocation, that showed a strong environment dependency in their expression. Our results highlight the complex genetic architecture of phosphorus use efficiency as well as the substantial differences between the evaluated genetic backgrounds. Despite harboring more of the identified quantitative trait loci, almost all of the favorable alleles from landraces were found to be present in at least one of the two elite heterotic groups. Notably, we also observed trait-specific genetic control even among biologically related characteristics, as well as a substantial plasticity of the genetic architecture of several traits in response to the environment and phosphorus fertilization. Collectively, our work illustrates the difficulties in improving phosphorus use efficiency, but also presents possible solutions for the future contribution of plant breeding to improve the phosphorus cycle.