Bracteomania, an inflorescence anomaly, is caused by the loss of function of the MADS-box gene squamosa in Antirrhinum majus.

Abstract

Anomalous flowering of the Antirrhinum majus mutant squamosa (squa) is characterized by excessive formation of bracts and the production of relatively few and often malformed or incomplete flowers. To study the function of squamosa in the commitment of an inflorescence lateral meristem to floral development, the gene was cloned and its genomic structure, a well as that of four mutant alleles, was determined. SQUA is a member of a family of transcription factors which contain the MADS‐box, a conserved DNA binding domain. In addition, we analysed the temporal and spatial expression pattern of the squa gene. Low transcriptional activity of squa is detectable in bracts and in the leaves immediately below the inflorescence. High squa transcript levels are seen in the inflorescence lateral meristems as soon as they are formed in the axils of bracts. Squa transcriptional activity persists through later stages of floral morphogenesis, with the exception of stamen differentiation. Although necessary for shaping a normal racemose inflorescence, the squa function is not absolutely essential for flower development. We discuss the function of the gene during flowering, its likely functional redundancy and its possible interaction with other genes participating in the genetic control of flower formation in Antirrhinum.

Identification and Characterization of Four Chrysanthemum MADS-Box Genes, Belonging to the APETALA1/FRUITFULL and SEPALLATA3 Subfamilies

“…A striking difference in CDM41 expression level was observed between petals from ray and disc flowers, indicating that these petals are clearly distinct from each other. CDM111 transcript levels are high in mature inflorescence bracts and petals of both types of florets, which correspond with expression data from the SQUA-like genes (Huijser et al, 1992). CDM44 expression is predominantly in young florets present in small inflorescence buds, but diminishes in the floral organs upon maturity.…”

“…Moreover, AP1 specifies the identity of sepals and petals, thereby representing the A function in Arabidopsis (Mandel et al, 1992). The expression pattern of CDM111 is very similar to that described for AP1 and for its ortholog in Antirrhinum SQUA (Bowman et al, 1989;Gustafson-Brown et al, 1994;Huijser et al, 1992), although CDM111 is expressed at earlier stages in bracts and inflorescence meristems, while AP1 fails to show expression in these tissues. Furthermore, expression of CDM111 in Arabidopsis plants caused a similar early flowering phenotype as was observed with ectopic expression of AP1 (Mandel and Yanofsky, 1995).…”

“…Equal loading of RNA was demonstrated by staining a representative gel with radiant red before blotting (rRNA). development has been reported for the Antirrhinum gene SQUA (Huijser et al, 1992) and the petunia gene PFG (Immink et al, 1999).…”

“…In addition, the MADS box gene FRUITFULL (FUL) acts in a redundant manner with AP1 to control inflorescence architecture and floral meristem identity (Ferrándiz et al, 2000b). Genes belonging to the AP1/FUL clade have been identified from many other plant species (Theissen et al, 2000) and functional analysis studies using gain-or loss-offunction mutants revealed that putative orthologs have slightly diverged over evolution with respect to redundancy and gene function (Huijser et al, 1992;Immink et al, 1999;Prasad et al, 2001).…”

Snakin-1, a Peptide from Potato That Is Active Against Plant Pathogens

“…Previously described procedures were used (Huijser et al 1992). The tissue was fixed in a mixture of 2% formaldehyde, 5%> acetic acid, and 60% ethanol for 48 h at 4°C.…”