PoppyAPETALA1/FRUITFULLOrthologs Control Flowering Time, Branching, Perianth Identity, and Fruit Development    

Abstract

Several MADS box gene lineages involved in flower development have undergone duplications that correlate with the diversification of large groups of flowering plants. In the APETALA1 gene lineage, a major duplication coincides with the origin of the core eudicots, resulting in the euFUL and the euAP1 clades. Arabidopsis FRUITFULL (FUL) and APETALA1 (AP1) function redundantly in specifying floral meristem identity but function independently in sepal and petal identity (AP1) and in proper fruit development and determinacy (FUL). Many of these functions are largely conserved in other core eudicot euAP1 and euFUL genes, but notably, the role of APETALA1 as an "A-function" (sepal and petal identity) gene is thought to be Brassicaceae specific. Understanding how functional divergence of the core eudicot duplicates occurred requires a careful examination of the function of preduplication (FUL-like) genes. Using virus-induced gene silencing, we show that FUL-like genes in opium poppy (Papaver somniferum) and California poppy (Eschscholzia californica) function in axillary meristem growth and in floral meristem and sepal identity and that they also play a key role in fruit development. Interestingly, in opium poppy, these genes also control flowering time and petal identity, suggesting that AP1/FUL homologs might have been independently recruited in petal identity. Because the FUL-like gene functional repertoire encompasses all roles previously described for the core eudicot euAP1 and euFUL genes, we postulate subfunctionalization as the functional outcome after the major AP1/FUL gene lineage duplication event.

Developmental and evolutionary diversity of plant MADS-domain factors: insights from recent studies

“…The A class is the most debated and apparently least evolutionarily conserved homeotic function (Causier et al, 2010). Recent analysis of the function of SQUA subfamily genes from basal eudicots suggests that the 'Afunction' evolved via subfunctionalization after gene duplication(s) at the base of core eudicots from a more broad action of SQUA subfamily members in floral meristem specification, floral organ specification and fruit development [see Pabón-Mora et al (Pabón-Mora et al, 2012) and references therein]. Interestingly, the E function appears to be exerted not only by genes from the SEP subfamily, but also by the closely related AGL6 subfamily, at least in some flowering plant species such as petunia (Vandenbussche et al, 2003b;Rijpkema et al, 2009), rice (Ohmori et al, 2009;Cui et al, 2010;Gao et al, 2010;Li et al, 2011) and maize (Thompson et al, 2009).…”

“…The MC protein interacts with JOINTLESS (J), a member of the STMADS11 subfamily and a regulator of fruit abscission, to form a functionally active transcription factor complex (Nakano et al, 2012). The multiple roles of SQUA subfamily members in floral transition, axillary meristem growth, perianth identity and fruit development are already evident in the basal eudicot species California poppy and opium poppy (Pabón-Mora et al, 2012). …”

TheseirenaB Class Floral Homeotic Mutant of California Poppy (Eschscholzia californica) Reveals a Function of the Enigmatic PI Motif in the Formation of Specific Multimeric MADS Domain Protein Complexes

“…However, the A function is thought to be Brassicaceae specific, and in the asterids petunia and snapdragon, C gene expression is excluded from the perianth by the action of microRNA genes BLIND and FISTULATA, respectively (Cartolano et al, 2007). Interestingly, recent experiments by Pabón-Mora et al (2012) have revealed that expression of the opium poppy AG homolog and reproductive organ identity are expanded when AP1/FUL-like genes are downregulated by VIGS. However, downregulation of the AP1/ FUL-like genes in California poppy had no effect on floral organ identity, indicating that spatial regulation of AG homolog expression is variable among angiosperms (Pabón-Mora et al, 2012).…”

“…Interestingly, recent experiments by Pabón-Mora et al (2012) have revealed that expression of the opium poppy AG homolog and reproductive organ identity are expanded when AP1/FUL-like genes are downregulated by VIGS. However, downregulation of the AP1/ FUL-like genes in California poppy had no effect on floral organ identity, indicating that spatial regulation of AG homolog expression is variable among angiosperms (Pabón-Mora et al, 2012).…”

The Tomato FRUITFULL Homologs TDR4/FUL1 and MBP7/FUL2 Regulate Ethylene-Independent Aspects of Fruit Ripening

“…The recent discovery that a FUL homolog regulates anthocyanin accumulation in the nonclimacteric fruits of bilberry (Jaakola et al, 2010) provides strong evidence for the wide conservation of ripening regulators. The role of FUL in fruits may be even more widely conserved, since the gene is also essential for dry fruit development in Arabidopsis (Ferrándiz et al, 2000) and the basal eudicot poppy (Eschscholzia californica; Pabón-Mora et al, 2012). In this context, it will also be very interesting to determine the regulatory network involved in fruit ripening in Solanaceae species that bear dry capsular fruits, like petunia (Petunia hybrida) and tobacco (Nicotiana tabacum).…”