The Genetic Architecture of Maize Nodal Root Number during Domestication

Maize nodal root system plays a crucial role in the development of the above-ground plant parts and determines the yield via water and nutrient uptake for mature plants in the field. However, the genetic basis of maize nodal root system remains unknown and it has become the darkest matter of the maize domestication process. Here, through a large teosinte-maize population, our high-resolution mapping revealed that 61 out from 132 quantitative trait loci (QTLs), accounting for approximately half of the total genetic variations of nodal root number, were co-localized with the flowering time QTLs. Genome-wide association study, fine mapping and a transgenic complementation analysis further validated that 5 flowering time genes controlled nodal root number. These results suggested that maize nodal root number buried in the soil has been generally and indirectly reshaped by the selection exerted on the above-ground trait flowering time during domestication. In addition, our results supported that few but long crown roots were favored during maize domestication.