Resumen de Modulation of primary meristem activity by gibberellins through DELLA-TCP interaction in Arabidopsis
Plant development is an iterative process of organ formation from the primary meristems of the plant. Meristem activity is driven by dynamic transcriptional programs that determine cell fate and identity as cells are displaced trough the meristematic tissue to initiate organ primordia. This regulatory network includes members of the TCP and KNOX family of transcription factors, and integrates external and intrinsic cues to efficiently adapt meristem activity to an ever-changing environment. However, how this integration occurs is not clear yet.
DELLA proteins have been proposed to modulate transcriptional circuits in plants in response to environmental signals. Although they do not show DNA binding capacity, DELLAs regulate transcription through physical interaction with a large number of DNA-binding transcription factors and other transcriptional regulators. Given the observed interaction between DELLAs and several members of the TCP family of transcription factors, we have explored the relevance of this interaction in the regulation of primary meristems. We have confirmed that DELLAs interact with members of both Class I and Class II TCPs, and prevent their ability to regulate downstream targets. In the embryonic roots, DELLAs maintain a dormant meristem by impairing TCP14/15-dependent activation of cell-cycle genes. On the other hand, DELLAs participate in the establishment of the shoot apical meristem domain that keeps an indeterminate fate, through the control of KNAT1 gene expression by the TCP2/4-AS1 regulatory module. In summary, this Thesis provides a mechanistic framework to eventually explain environmental regulation of meristem activity.
