Arabidopsis TCP20 links regulation of growth and cell division control pathways

Abstract

During postembryonic plant development, cell division is coupled to cell growth. There is a stringent requirement to couple these processes in shoot and root meristems. As cells pass through meristems, they transit through zones with high rates of cell growth and proliferation during organogenesis. This transition implies a need for coordinate regulation of genes underpinning these two fundamental cell functions. Here, we report a mechanism for coregulation of cell division control genes and cell growth effectors. We identified a GCCCR motif necessary and sufficient for high-level cyclin CYCB1;1 expression at G 2/M. This motif is overrepresented in many ribosomal protein gene promoters and is required for high-level expression of the S27 and L24 ribosomal subunit genes we examined. p33 TCP20 , encoded by the Arabidopsis TCP20 gene, binds to the GCCCR element in the promoters of cyclin CYCB1;1 and ribosomal protein genes in vitro and in vivo. We propose a model in which organ growth rates, and possibly shape in aerial organs, are regulated by the balance of positively and negatively acting teosinte-branched, cycloidea, PCNA factor (TCP) genes in the distal meristem boundary zone where cells become mitotically quiescent before expansion and differentiation.

Longitudinal zonation pattern inArabidopsisroot tip defined by a multiple structural change algorithm

“…The distribution of molecular markers for the G2-to-M transition, CycB1;1 DB :GUS or CycB1;1 DB :GFP, has been used as a marker for the PD of the RAM (Colon-Carmona et al, 1999;Hauser and Bauer, 2000;Aida et al, 2004;Ticconi et al, 2004;Li et al, 2005;Cruz-Ramırez et al, 2012).…”

PEAPOD regulates lamina size and curvature in Arabidopsis

“…I propose a model in which there are two separate cell-cycle arrest fronts progressing from the tip to the base during leaf development: a primary front that determines arrest of general cell division in the primordium, followed by a secondary front that involves PPD and arrests DMC proliferation. The shape and progression of the primary arrest front is known to be influenced by class II TCP genes, CIN in Antirrhinium (19) or TCP2 and TCP4 in Arabidopsis (20), and it has been suggested that the extent of cell proliferation in the primordium may be regulated by a balance between the antagonistic activities of class I and II TCP genes on the expression of cyclin and ribosomal protein genes (28). Other genes, such as ANT, ARGOS, AN3, GRF5, JAG, SMP, and SWP, which promote cell division during leaf development, also seem to act on proliferation in the primordium (8)(9)(10)(11)(12)(13)(14)(15)(16).…”

Hormonal Regulation of Branching in Grasses

“…TB1 is expressed in organs that are suppressed in both maize and teosinte (Hubbard et al, 2002). In maize, there is an increase in the expression of TB1 relative to teosinte, causing buds to be suppressed, perhaps by affecting the cell cycle (Kosugi and Ohashi, 1997;Hubbard et al, 2002;Li et al, 2005). The increase in expression is proposed to be due to selection at a distant enhancer upstream of the TB1 locus (Clark et al, 2004(Clark et al, , 2006.…”