Summary R2R3 MYB transcription factors, such as MYB16 and MYB106 (MYB16/106) in Arabidopsis thaliana , are recognized for their role in conical cell specification. However, the mechanism by which MYB16/106 orchestrate the morphogenesis of conical cells remains poorly understood. Here, we combined genetic analysis, transcriptomics, metabolomics, and live‐cell imaging to clarify the MYB16/106‐mediated conical cell development in Arabidopsis. Genetic characterization revealed that the myb16 myb106 double mutant exhibited flattened adaxial petal epidermal cells, having lost the wild‐type conical shape, and displayed significantly disrupted cuticle nanoridge formation. Transcriptomic (RNA‐seq) and chromatin immunoprecipitation‐quantitative PCR (ChIP‐qPCR) analyses identified the direct transcriptional targets of MYB16/106, which include CYP86A7 , CUS2 , RXF26 , and ABCB13 . These genes encode pivotal regulators of cuticular wax and cutin biosynthesis, as well as lipid transport. Metabolomic profiling further validated that MYB16/106 coordinately modulate metabolic pathways associated with cuticle formation, consistent with their transcriptional regulation of cuticle‐related targets. Furthermore, the myb16 and myb106 mutants exhibited physiological and cytoskeletal alterations, including an elevated apoplastic pH and disrupted cortical microtubule (CMT) organization. Collectively, our findings establish a hierarchical regulatory framework in which MYB16/106 act as central coordinators, integrating three cellular processes – cuticle biosynthesis, apoplastic pH balance, and CMT organization – to regulate conical cell morphogenesis.
Zhu et al. (Fri,) studied this question.