Complementary and dose‐dependent action of AtCCS52A isoforms in endoreduplication and plant size control

Abstract

SummaryThe dimension of organs depends on the number and the size of their component cells. Formation of polyploid cells by endoreduplication cycles is predominantly associated with increases in the cell size and implicated in organ growth. In plants, the CCS52A proteins play a major role in the switch from mitotic to endoreduplication cycles controlling thus the number of mitotic cells and the endoreduplication events in the differentiating cells.Arabidopsis has two CCS52A isoforms; AtCCS52A1 and AtCCS52A2. Here we focused on their roles in endoreduplication and cell size control during plant development.We demonstrate their complementary and dose-dependent actions that are dependent on their expression patterns. Moreover, the impact of CCS52A overexpression on organ size in transgenic plants was dependent on the expression level; while enhanced expression of the CCS52A genes positively correlated with the ploidy levels, organ sizes were negatively affected by strong overexpression whereas milder overexpression resulted in a significant increase in the organ sizes.Taken together, these finding support both complementary and dose-dependent actions for the Arabidopsis CCS52A isoforms in plant development and demonstrate that elevated ectopic CCS52A expression positively correlates with organ size, opening a route to higher biomass production.

Tissue-Specific Control of the Endocycle by the Anaphase Promoting Complex/Cyclosome Inhibitors UVI4 and DEL1

“…Because ccs52a1-1 ccs52a2-1 double mutants are not viable (Vanstraelen et al, 2009;Baloban et al, 2013), we generated a ccs52a1-1 DEL1 OE double mutant, which lacks a functional CCS52A1 and displays reduced CCS52A2 expression, owing to increased activity of the DEL1 transcriptional repressor (Lammens et al, 2008). Using flow cytometry, we confirmed the previously observed reduced DNA ploidy levels of the ccs52a1-1 and DEL1 OE single mutant leaves compared to the wild type (Vlieghe et al, 2005;Vanstraelen et al, 2009;Baloban et al, 2013;Fig.…”

“…CCS52A1 has been predominantly implicated in controlling trichome branching and root ploidy levels (Vanstraelen et al, 2009;Kasili et al, 2010), whereas CCS52A2 has been demonstrated to control the proliferation status of the root QC stem cells (Vanstraelen et al, 2009) and shoot apical meristem maintenance (Liu et al, 2012). Although CCS52A1 and CCS52A2 control different developmental processes, functional redundancy is expected, as plants being deficient for both CCS52A genes are not viable (Baloban et al, 2013). Indeed, endoreplication onset in leaves is ensured by both CCS52A-type proteins.…”

“…In leaves, both CCS52A1-and CCS52A2-activated APC/C complexes control endocycle onset, as mutation of either results in reduced DNA ploidy levels (Lammens et al, 2008). Functional redundancy between CCS52A1 and CCS52A2 is additionally suggested by the observation that no viable double mutant plants can be obtained (Baloban et al, 2013).…”

UBIQUITIN-SPECIFIC PROTEASE 14 interacts with ULTRAVIOLET-B INSENSITIVE 4 to regulate endoreduplication and cell and organ growth in Arabidopsis

“…Therefore, UBP14 influences the abundance of the CDKB1;1-CYCA2;3 complex, which is crucial for the regulation of endoreduplication . UBP14, UVI4, CCS52A1, CYCA2;3, and CDKB1;1 showed overlapping expression in aboveground organs in Arabidopsis ( Figures 3A to 3F) (Boudolf et al, 2004;Hase et al, 2006;Imai et al, 2006;Baloban et al, 2013), supporting their genetic and biochemical relationships. However, it is noteworthy that their expression patterns in roots were not similar.…”

Endoreduplication-mediated initiation of symbiotic organ development in Lotus japonicus

“…In plants, CCS52A isoforms are necessary and sufficient for the progress of endocycling (Cebolla et al, 1999;Larson-Rabin et al, 2009;Mathieu-Rivet et al, 2010;Baloban et al, 2013), which skips the mitotic phase and re-enters the S phase without cytokinesis, resulting in the duplication of the nuclear DNA content. In M. truncatula, MtCCS52A is shown to be expressed before endoreduplication and to regulate endoreduplication of infected cells within nodules (Vinardell et al, 2003).…”