Novel repressors of cambium activity in Arabidopsis
Wang, X.; Han, J.; Turley, E. K.; Mäkilä, R.; Bagman, A.-M.; Kraus, J. M.; He, Q.; Alhowty, H.; Edwards, J.; Li, Y.; Blasciuc, R.; Fatz, W.; Wei, W.; de Lucas, M.; Brady, S. M.; Zheng, S.; Chen, C.; Mähönen, A. P.; Etchells, J. P.
Show abstract
Wood is the greatest reservoir of terrestrial biomass and an essential carbon sink. Formed of xylem, it is derived from the cambium, a meristematic zone within plant stems from which phloem also forms. In Arabidopsis, cell division within the cambium is promoted by three major factors: auxin, cytokinin, and the TDIF-PXY ligand-receptor pair. Meristems and other stem cell populations are typically regulated by a balance between cell division-promoting factors and those that repress cell division to control meristem size, however few factors with cambium-repressing activity are known. Here we combined transcriptomics and transcriptional network analysis, which led to identification of related homeodomain zinc-finger transcription factors, ATHB23, ATHB30, and ATHB34, that repress cambium activity. These factors inhibit cambium activity by directly binding of promoters from a subset of auxin, cytokinin and TDIF-PXY transcriptional target genes, resulting in attenuation of their transcription. Our findings thus reveal a new mechanism underpinning balanced cambium activity.
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