Molecular mechanisms underlying cork barrier differentiation: the role of MYBs transcription factors

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Like our skin, the outermost tissues of the plant body, evolved to protect the plant against biotic and abiotic agents and to control loss of water and gas exchanges. The periderm, is the outer tissue that covers and protects the vasculature during secondary growth. It originates from the cork cambium, which divides and produces inward the phelloderm and outward the cork. The barrier properties of the periderm are conferred by the cork, which accumulates high amount of suberin and lignin in the cell walls. Despite the economic and agronomical importance of the cork, few regulators of periderm formation and cork differentiation are known. Based on periderm/cork transcript-profiling of several species, we identified a set of closely related MYB transcription factors (TFs), which are conserved among species and specifically expressed in the periderm/cork. Our preliminary results, exploiting the Arabidopsis root, as a model, suggest a dual function in cork differentiation for these MYBs. On one hand, they promote suberin accumulation and on the other hand they repress cork cambium activity. Here, exploiting tools and resources in which TFs expression in the periderm can be induced in a precisely defined spatiotemporal context, we aim to further dissect their role during cork differentiation, to identify their targets and thus establish the first cork regulatory network. In addition, we will focus on their function during abiotic stresses, paving the way for breeding programs targeting root barriers.