Control of Arabidopsis Flower and Seed Development by the Homeotic Gene APETALA2

Abstract

APETALA2 (AP2) plays a central role in the establishment of the floral meristem, the specification of floral organ identity, and the regulation of floral homeotic gene expression in Arabidopsis. We show here that in addition to its functions during flower development, AP2 activity is also required during seed development. We isolated the AP2 gene and found that it encodes a putative nuclear protein that is distinguished by an essential 68-amino acid repeated motif, the AP2 domain. Consistent with its genetic functions, we determined that AP2 is expressed at the RNA level in all four types of floral organs--sepals, petals, stamens, and carpels--and in developing ovules. Thus, AP2 gene transcription does not appear to be spatially restricted by the floral homeotic gene AGAMOUS as predicted by previous studies. We also found that AP2 is expressed at the RNA level in the inflorescence meristem and in nonfloral organs, including leaf and stem. Taken together, our results suggest that AP2 represents a new class of plant regulatory proteins that may play a general role in the control of Arabidopsis development.

Heterologous expression of the BABY BOOM AP2/ERF transcription factor enhances the regeneration capacity of tobacco (Nicotiana tabacum L.)

“…The Arabidopsis AP2/ERF family comprises a large class of 144 transcription factors with diverse roles throughout the plant life cycle. The members of this class of regulatory proteins all contain the conserved AP2/ERF domain, a 60-70 amino acid region that is thought to mediate DNA binding and protein-protein interactions (Jofuku et al 1994;Okamura et al 1997). The AP2/ERF family has been organized into Wve phylogenetically distinct subfamilies that diVer in the number of AP2/ERF domains, as well as the amino acid similarity between these domains (Sakuma et al 2002).…”

“…The AP2/ERF family has been organized into Wve phylogenetically distinct subfamilies that diVer in the number of AP2/ERF domains, as well as the amino acid similarity between these domains (Sakuma et al 2002). Genes belonging to two of these subfamilies have been shown to enhance in vitro regeneration (Banno et al 2001;Boutilier et al 2002), while others play a role in related processes controlling meristem cell fate and organ development (Jofuku et al 1994;Elliot et al 1996;Chuck et al 1998;van der GraaV et al 2000). One of these genes, ENHANCER OF SHOOT REGENERA-TION1 (ESR1), was identiWed in an over-expression screen for Arabidopsis genes that promote adventitious shoot formation from callus both in the absence and presence of cytokinins (Banno et al 2001).…”

The whorl‐specific action of a petunia class B floral homeotic gene

“…In Arabidopsis and Antirrhinum, genes class A, B and C have been identi®ed (Yanofsky et al 1990;Sommer et al 1990;Jack et al 1992;Mandel et al 1992;Trobner et al 1992;Bradley et al 1993;Goto & Meyerowitz 1994;Jofuku et al 1994). Most of these genes encode proteins with a conserved DNA-binding domain, the MADS box.…”

Photo and hormonal control of meristem identity in the Arabidopsis flower mutants apetala2 and apetala1.

“…We chose ap2-7 for this analysis because it has been well characterized both phenotypically and at the molecular leve1 (Bowman et al, 1989(Bowman et al, , 1991bJofuku et al, 1994). As shown in Figure l A , under LD conditions, ap2-7 mutant flowers are characterized by the homeotic transformation of first-whorl sepals into leaves that are distinguished by the presence of branched or stellate trichomes.…”