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.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
In comparison to the first version, data on smxl4;smxl5;bam5 triple mutant and phloem-specific ATAC-seq data comparing wild type, smxl5, smxl4;smxl5 and smxl5;obe3 plants were added.
https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE184344