SCL28 promotes endoreplication and cell expansion in Arabidopsis by activating a group of SIAMESE-RELATED cyclin-dependent kinase inhibitors

BARRERA, VIRGINIA; GOLDY, CAMILA; BUCHESKY, CELESTE; VENA, RODRIGO; RODRIGUEZ VIRASORO, RAMIRO ESTEBAN

Congreso; XXXIII Argentinian meeting of Plant Physiology; 2021

SAFV

Plant organ growth initiates with proliferating cells generated by the mitotic cell cycle (MCC). Then, cells enter a expansion and differentiation program. During the later stage, cells often switch to an alternative cell cycle named endoreplication (ER), in which cells replicate their DNA without progressing through mitosis nor cytokinesis.The transition from MCC to ER involves regulatory mechanisms that specifically inhibit mitotic cyclin/cyclin-dependent kinase (CDKs) complexes causing cells to oscillate between S and G1 phases for a defined period. One of these regulatory mechanisms involves a family of CDKs inhibitors named SIAMESE-RELATED (SMR). These proteins have been reported to trigger the transition from the MCC to ER by its association with specific CDKs.SCL28 is a transcription factor that is expressed preferentially in G2/M cells in the root meristem and promotes progression through these phases of the cell cycle. From a transcriptome analysis of SCL28 mutants we found that several SMRs genes were downregulated in the mutant. In this work we characterize the regulation of SMRs by SCL28 and its role in promoting MCC to ER transition, cell expansion and differentiation.