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bioRxiv · 10.1101/2019.12.21.885863

OBERON3 and SUPPRESSOR OF MAX2 1-LIKE proteins form a regulatory module specifying phloem identity

Wallner, E.-S.·Tonn, N.·Wanke, F.·Lopez-Salmeron, V.·Gebert, M.·Wenzl, C.·Lohmann, J. U.·Harter, K.·Greb, T.
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Abstract

Spatial specificity of cell fate decisions is central for organismal development. The phloem tissue mediates long-distance transport of energy metabolites along plant bodies and is characterized by an exceptional degree of cellular specialization. How a phloem-specific developmental program is implemented is, however, unknown. Here we reveal that the ubiquitously expressed PHD-finger protein OBE3 forms a central module with the phloem- specific SMXL5 protein for establishing phloem identity in Arabidopsis thaliana. By protein interaction studies and phloem-specific ATAC-seq analyses, we show that OBE3 and SMXL5 proteins form a complex in nuclei of phloem stem cells where they establish a phloem-specific chromatin profile. This profile allows expression of OPS, BRX, BAM3, and CVP2 genes acting as mediators of phloem differentiation. Our findings demonstrate that OBE3/SMXL5 protein complexes establish nuclear features essential for determining phloem cell fate and highlight how a combination of ubiquitous and local regulators generate specificity of developmental decisions in plants.

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Wallner, E.-S., Tonn, N., Wanke, F., Lopez-Salmeron, V., Gebert, M., Wenzl, C., Lohmann, J. U., Harter, K., Greb, T.. 2019-12-23. OBERON3 and SUPPRESSOR OF MAX2 1-LIKE proteins form a regulatory module specifying phloem identity. https://doi.org/10.1101/2019.12.21.885863

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