Plasticity and domestication of root anatomy in maize-teosinte derived population.

Maize (Zea mays L.) underwent profound changes during domestication in root anatomy for environmental adaptation. However, the genetic mechanism of maize root anatomy domestication and plasticity remains unclear. In this study, a high-resolution mapping was performed for nine root anatomical traits using a maize-teosinte population (mexicana × Mo17) across three environments. Large genetic variations were detected for different root anatomical traits. The cortex area, stele area, aerenchyma area, xylem vessels number and cortical cell number had large variations across three environments, indicating high plasticity. Sixteen quantitative trait loci (QTL) were identified, including seven QTL with QTL × Environment interaction (EIQTL) for high plastic traits and nine QTL without QTL × Environment interaction (SQTL). Most of the root loci were consistent with shoot QTL depicting domestication signals. Combining transcriptome and genome-wide association study (GWAS) revealed that ZmPILS4 serve as a candidate gene underlying a major QTL of xylem traits. The near-isogenic lines (NILs) with lower expression of ZmPILS4 had 18-24% more IAA concentration in the root tip and 8-15% more xylem vessels. Significant domestication signal in promoter region suggested that ZmPILS4 was involved in maize domestication and adaptation. These results divulged the potential genetic basis of root anatomy plasticity and domestication.