R2R3 MYB transcription factor AtDIV1 regulates root growth through regulation of PIN5 expression in Arabidopsis

Key message The R2R3 MYB transcription factor AtDIV1 negatively regulates PIN5 expression to modulate primary root growth. As a crucial organ for nutrient uptake, the root plays a vital role in plant growth and development, a process regulated by multiple factors including phytohormones and transcriptional mechanisms. In this study, we identify AtDIV1, a R2R3-MYB transcription factor, as the key regulator of root development. Loss of function of AtDIV1 led to significantly shortened primary roots, accompanied by reductions in both cell number and cell length compared to the wild type. Pharmacological experiments demonstrated that exogenous IAA application partially rescued the root length defect in atdiv1 mutant, restoring cell number in both meristem and elongation zones. Notably, PIN5 expression was significantly upregulated in atdiv1 roots and the root developmental defects observed in atdiv1 mutants were fully rescued in atdiv1 pin5 double mutants. Collectively, our findings establish that AtDIV1 negatively regulates PIN5 expression to modulate primary root growth.