Members of the MYB68 subclade orchestrate cork differentiation by regulating stem cell proliferation and suberin deposition

Plants have developed specialized barriers to isolate the inner tissues from the environment. The periderm is a dynamic barrier comprising a stem-cell niche, the cork cambium, which produces the cork. Cork cells have a unique cell wall impregnated with hydrophobic polymers such as suberin and lignin, which are essential for the barrier function. Despite its importance, the cork differentiation network remains largely unknown. Here, we identify MYB68 subclade transcription factors as activators of suberin biosynthesis and polymerization, as well as repressors of cork cambium proliferation. We further show that suberin deposition in the cork is also regulated by MYBs from other subclades. However, only MYB68 subclade members suppress cell proliferation, revealing both shared and distinct roles of MYB transcription factors. These findings have broad applicability, as tissue-specific manipulation of MYB activity has the potential to improve the traits of biotechnological interest, such as thicker periderms and more suberized cork layers. To investigate how MYB68 and MYB86 control suberin deposition, w performed RNA seq with WT and myb68 my84 roots. We collected only the 2 uppermost cm of 18-day-old roots (plants were grown in vitro 1/2 MS in continuous light at 22C). 3 biological replicates. Each biological is from at least 40 plants