title: The APC/C E3 ligase remains active in most post-mitotic Arabidopsis cells and is required for proper vasculature development and organization.
abstract: Selective protein degradation via the ubiquitin-26S proteasome is a major mechanism underlying DNA replication and cell division in all eukaryotes. In particular, the APC/C (anaphase promoting complex or cyclosome) is a master ubiquitin protein ligase (E3) that targets PDS1/SECURIN and cyclin B for degradation allowing sister chromatid separation and exit from mitosis, respectively. Interestingly, it has been found that the APC/C remains active in differentiated neurons in which the E3 ligase regulates axon growth, neuronal survival and synaptic functions. However, despite these recent findings, the role of APC/C in differentiated cells and the regulation of its activity beyond cell division is still poorly understood. Here, we investigate the activity and function of APC/C in the model plant Arabidopsis thaliana. We used cyclin reporter constructs to follow APC/C activity during plant development and found that this E3 ligase remains active in most post-mitotic plant cells. Strikingly, hypomorphic mutant lines, in which the APC/C activity is reduced, exhibited several developmental abnormalities, including defects in cotyledon vein patterning and internode elongation leading to a characteristic broomhead-like phenotype. Histological analyses revealed an increased amount of vascular tissue, most notably xylem and lignified sclerenchyma, indicating a role for APC/C in plant vasculature development and organization.
authors.affiliation: Institut de Biologie Moléculaire des Plantes du CNRS, 67084 Strasbourg Cedex, France.
authors.forename: Katia
authors.initials: K
authors.lastname: Marrocco
authors.forename: Alexis
authors.initials: A
authors.lastname: Thomann
authors.forename: Yves
authors.initials: Y
authors.lastname: Parmentier
authors.forename: Pascal
authors.initials: P
authors.lastname: Genschik
authors.forename: Marie Claire
authors.initials: MC
authors.lastname: Criqui