Plants have the remarkable potential for indeterminate post-embryonic growth. Following their specification in the early embryo, tissue-specific precursor cells first establish tissues, and later maintain these for indeterminate, post-embryonic development. Despite their importance, mechanisms underlying tissue establishment and indeterminacy are virtually unknown. Recently, we defined local control of oriented, periclinal cell division (PCD) as the mechanism underlying both establishment and indeterminacy of the vascular tissue, one of the three major plant tissues. We identified an auxin-regulated bHLH transcription factor dimer as a critical regulator of PCD in vascular cells that is sufficient for triggering these ectopically (Figure on right side). We showed that this dimer operates independently of tissue identity, but is restricted to a small vascular domain by integrating the overlapping transcription patterns of the interacting bHLH proteins (Figure below). Our work reveals a common mechanism for tissue establishment and indeterminacy in vascular development, and provides a conceptual frame-work for developmental control of local cell divisions in plants. Our future work will focus on understanding how the TMO5/LHW dimer controls PCD through analysis of downstream targets. Moreover, as correct positioning of the TMO5/LHW dimer is crucial for normal vascular development, we also want to know how the exact location of the dimer is restricted.
Techniques used: to tackle these problems, we use a combination of genetics, transcriptomics, proteomics (including IP-MS, FRET-FLIM) and advanced confocal imaging.
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