Characterization of Proteins Involved in MYB Transcription Factor Complexes that Regulate Suberin Deposition in Arabidopsis thaliana

Terrestrial plants deposit cell wall-associated, glycerolipid-based polymeric barriers in specific tissue layers to help protect themselves from various environmental stresses. One of these layers, suberin, influences water uptake and retention, ion transport, and gas exchange within roots. A set of myeloblastosis (MYB)-type transcription factors (TFs) have been found to regulate suberin production. The main focus of this study was to characterize protein-protein interactions involving MYB TFs that regulate suberin deposition in root endodermis. Results indicate that: 1) MYB92 and MYB93 interact directly with bHLH111 (a basic helix-loop-helix TF); 2) expression pattern of the bHLH111 gene was consistent with a role in regulating suberin deposition; and 3) knock-out mutations of bHLH111 and the related bHLH112 gene were found to have reduced levels of suberin in Arabidopsis roots. Altogether, these findings provide evidence for bHLH proteins working together with MYB TFs to regulate suberin production in the root endodermis of Arabidopsis.