CINCINNATA Controls Both Cell Differentiation and Growth in Petal Lobes and Leaves of Antirrhinum

Abstract

To understand how differentiation and growth may be coordinated during development, we have studied the action of the CINCINNATA (CIN) gene of Antirrhinum. We show that in addition to affecting leaf lamina growth, CIN affects epidermal cell differentiation and growth of petal lobes. Strong alleles of cin give smaller petal lobes with flat instead of conical cells, correlating with lobe-specific expression of CIN in the wild type. Moreover, conical cells at the leaf margins are replaced by flatter cells, indicating that CIN has a role in cell differentiation of leaves as well as petals. A weak semidominant cin allele affects cell types mainly in the petal but does not affect leaf development, indicating these two effects can be separated. Expression of CIN correlates with expression of cell division markers, suggesting that CIN may influence petal growth, directly or indirectly, through effects on cell proliferation. For both leaves and petals, CIN affects growth and differentiation of the more distal and broadly extended domains (leaf lamina and petal lobe). However, while CIN promotes growth in petals, it promotes growth arrest in leaves, possibly because of different patterns of growth control in these systems.Development involves coordination of two interconnected processes: growth and cellular differentiation. The genetic control of each of these processes has been studied extensively in plants. For example, genes affecting leaf growth or epidermal cell fate have been isolated and analyzed (Masucci et al., 1996;Tsuge et al., 1996;Gu et al., 1998;Kim et al., 1998;Mizukami and Fischer, 2000;Kim et al., 2002). However, the way that growth and differentiation are coupled through the action of genes has been less well studied. To help address this, we have investigated the effects of the CINCINNATA (CIN) gene on growth and cell differentiation in Antirrhinum.CIN encodes a TCP transcription factor that promotes growth arrest, particularly in leaf margins (Nath et al., 2003). In cin mutants, leaves are larger and have an undulating edge due to excessive growth in marginal regions. In addition to these effects on leaf growth, cin mutants also show alterations in petal shape and cell types. This suggests that the CIN transcription factor may have targets involved in both growth and differentiation pathways. To determine how these pathways may be affected, we have analyzed the role of CIN in petal growth and differentiation.Flowers of Antirrhinum have five petals, which are united in their proximal region to form a corolla tube.The distal region of each petal forms a lobe, which itself can be subdivided into a more proximal region, termed the lip, and a more distal region ( Fig. 1A; Keck et al., 2003). The flowers exhibit dorsoventral asymmetry and comprise two dorsal petals, two lateral petals, and one ventral petal. The lateral and ventral petal lobes form a platform for bees to land on and pry open the flower. A variety of cell types can be recognized in the flower, forming characteristic patterns along the proximo...

TCP transcription factor, BRANCH ANGLE DEFECTIVE 1 (BAD1), is required for normal tassel branch angle formation in maize

“…CYC and the related DICH gene prevent cell division in specific floral organs, and cyc/dich mutants have reduced floral bilateral symmetry (11,19). CIN genes restrict cell proliferation at the margins of the developing leaf primordial, and cin mutants have crinkly leaves showing excessive proliferation at the leaf margin (13,21). TB1, the only maize TCP gene characterized so far, is reported to repress axillary meristem development, consistent with tb1 mutants having excessive vegetative lateral branches (10).…”

A TCP domain transcription factor controls flower type specification along the radial axis of the Gerbera (Asteraceae) inflorescence

“…The decreased leaf size in these plants was due to reduction in both cell proliferation and cell expansion, whereas enlarged petals resulted from increased cell expansion (26). Furthermore, the class II TCP factor CIN reduces growth in Antirrhinum leaves but promotes the growth of petals (20).…”

“…The expression of CYC and DICH is restricted to the dorsal domain of the flowers to establish bilateral petal symmetry and to arrest the development of the dorsalmost stamen (12,13). CIN arrests the growth of Antirrhinum leaf margins but also affects differentiation of epidermal cells and growth of petal lobes through effects on cell proliferation (20).…”

Impact of InMIR319 and light on the expression of InTCP4 gene involved in the development of Ipomoea nil plants

“…This TCP domain is most similar to the domain present in CIN A. majus (data not shown), which indicates that InTCP4 may take part in the regulation of similar processes. The CIN gene is responsible for regulating the growth of the leaf blade and influencing the morphogenesis of flower petals (Crawford et al 2004). Similar functions are also played by another gene with high similarity to the nucleotide sequence InTCP4 of I. nil, namely LA from S. melongena.…”

“…TCP4 and miR319a, A. thaliana regulate the normal development of stamens and petals (Schommer et al 2008;Nag et al 2009). Analysis of cin mutants in Antirrhinum showed that the miRNA-regulated TCP gene, CIN, affects petal lobe development by controlling epidermal cell differentiation and growth (Crawford et al 2004).…”