Silencing ofEcFLO, AFLORICAULA/LEAFYGene of the California Poppy (Eschscholzia californica), Affects Flower Specification in a Perigynous Flower Context

Abstract

Flowers are reproductive shoots produced by determinate floral meristems. The role of FLORICAULA/ LEAPY-like genes in the specification of flowers varies between lineages and has not been characterized in a basal eudicot species. Here we report the phenotypic effects of virus-induced silencing of EcFLO, a FLORICAULA/LEAFY homologue in the California poppy Eschscholzia californica. EcFLO silencing resulted in repeated sepal and petal whorl formation and internodes between calyxes. A subset of silenced flowers showed reduced petal and stamen numbers and mosaic identities of floral organs. We also provide expression data of other floral regulator genes and conclude that EcFLO contributes to certain aspects of flower development, reflecting both functional conservation and differentiation among basal eudicots, core eudicots, and monocot grasses. EcFLO is involved in stamen and petal initiation, floral organ identity delimitation, suppression of internodes, and limitation of the number of perianth whorls. Further, silencing of EcFLO allows insights into perigynous flower development in Eschscholzia. We demonstrate that receptacle cup formation, by which the perianth and the androecium are elevated above the gynoecium late in flower development, responds to the initiation of the synsepalous calyx.

LEAFY maintains apical stem cell activity during shoot development in the fern Ceratopteris richardii

“… All citations included in reference list of main article ( Bradley et al, 1996 ; Blázquez et al, 1997 ; Bradley et al, 1997 ; Kyozuka et al, 1998 ; Pnueli et al, 1998 ; Ratcliffe et al, 1999 ; Gourlay et al, 2000 ; Bomblies et al, 2003 ; Becker et al, 2005 ; Meng et al, 2007 ; Souer et al, 2008 ; Wreath et al, 2013 ). …”

Homologs of LEAFY and UNUSUAL FLORAL ORGANS Promote the Transition From Inflorescence to Floral Meristem Identity in the Cymose Aquilegia coerulea

“…Setting aside these caveats, it remains the case that none of our silenced phenotypes resemble the strong loss of FM identity that is observed in most core eudicot LFY or cymose UFO mutants. Notably, the Aquilegia phenotypes are reminiscent of what Wreath et al observed when they silenced EcFLO , a LFY ortholog in Eschscholzia californica (Wreath et al, 2013). Eschscholzia is a member of the Papaveraceae, which is deeply diverged from Aquilegia ’s family, the Ranunculaceae, within the order Ranunculales (Becker et al, 2005).…”

“…By contrast, in Aquilegia , aqlfy still retains substantial FM identity, so AqUFO function in stamen (and possibly petal) initiation could be independent of AqLFY . It is interestingly to note in this regard that EscFLO silencing in Eschscholzia also results in reduced organ number in some flowers, particularly the stamens (Wreath et al, 2013). This observation, combined with the fact that we see reduced AqLFY expression in the aqufo flowers and have confirmed the ability of AqLFY to interact with at least AqUFO1, makes us hesitant to assert that the organ loss phenotype is definitively independent of AqLFY .…”

“…Eschscholzia is a member of the Papaveraceae, which is deeply diverged from Aquilegia ’s family, the Ranunculaceae, within the order Ranunculales (Becker et al, 2005). Wreath et al (2013) observed the repeated production of sepal whorls, including some instances of internodal elongation between the early whorls, before the meristems finally transitioned to the production of the other floral organs. This is closely analogous to our phenotype of sepal-like organs arising with variable phyllotaxy and degrees of internodal elongation.…”

The ontogenetic bases for variation in ovary position in Melastomataceae

“…However, what we observed is that this structure originates from an intercalary meristem in the floral apex (Leins, 1972) and that during anthesis it preserves characteristics similar to those of surrounding organs such as the same indumentum of the sepals. Some ontogenetic processes can be controlled and shared by both sepal and hypanthium formation, since proper sepal development is necessary to initiate the perigynous hypanthium in Eschscholzia (Papaveraceae, Wreath et al, 2013).…”