Non-cell-autonomous regulation of petal initiation in Arabidopsis thaliana

Abstract

In many flowering plants, petals initiate in alternate positions from first whorl sepals, suggesting possible signaling between sepal boundaries and petal initiation sites. PETAL LOSS (PTL) and RABBIT EARS (RBE) regulate petal initiation in Arabidopsis thaliana, and their transcripts are expressed in sepal boundary and petal initiation sites, respectively, suggesting that PTL acts in a non-cell-autonomous manner. Here, we determined that cells expressing PTL and RBE fusion proteins did not overlap but were adjacent, confirming the non-cell-autonomous function of PTL. Genetic ablation of inter-sepal cells by expressing the diphtheria toxin-A chain gene driven by the PTL promoter resulted in flowers lacking petals, suggesting these cells are required for petal initiation. Transcriptome analysis combined with a PTL induction system revealed 42 genes that were upregulated under PTL activation, including UNUSUAL FLORAL ORGANS (UFO), which likely plays an important role in petal initiation. These findings suggest a molecular mechanism in which PTL indirectly regulates petal initiation, where UFO mediates positional signaling between the sepal boundary and petal initiation sites.

Transcriptional dissection of petty spurge (Euphorbia peplusL.) reproductive structures supports theEuphorbiacyathium as an inflorescence rather than a complete flower

“…The involucre-upregulated gene with the highest p-value, Ep_chr5_g16200, is in an orthogroup with AT5G03680, PETAL LOSS (PTL), which generally represses tissue growth by limiting cell division. (Despite its name, PTL does not regulate petal organ identity, and its expression is not limited to petals– ptl mutants’ lack of petals may be due to indirect effects of tissue overgrowth disrupting auxin maxima (O’Brien et al, 2015; Takeda et al, 2022). ) This gene is upregulated in filiform structures, young pistillate flowers, mature pistillate flowers, nectaries, and both stages of primordia as compared with cyathophylls, suggesting functions in patterning across multiple cyathium components.…”

“…not elongated) staminate flowers aren't yet mature transcriptomically compared with pistillate flowers. As UFO functions in the development of individual perianth organs as well as in the broader activation of the B class genes (Takeda et al, 2022), some of the changes in UFO expression and sequence in Euphorbia could be related to the suppression of perianth development in addition to potential functions in defining the floral meristem.…”

Thinking outside the F‐box: how UFO controls angiosperm development

“…In some species, LFY is an UFO activator (see below). Then, during flower development, AP3 and PETAL LOSS positively regulate UFO expression in Arabidopsis (Wuest et al, 2012;Takeda et al, 2022) AP1 ortholog SQUA likely activates FIM in snapdragon (Simon et al, 1994). Overall, precisely understanding the regulation of UFO in time and space will require more work and the identification of additional regulators.…”

“…In some species, LFY is an UFO activator (see below). Then, during flower development, AP3 and PETAL LOSS positively regulate UFO expression in Arabidopsis (Wuest et al ., 2012; Takeda et al ., 2022), and AP1 is required for late UFO expression (Lee et al ., 1997; Ng & Yanofsky, 2001). Similarly, the AP1 ortholog SQUA likely activates FIM in snapdragon (Simon et al ., 1994).…”

MeGT2.6 increases cellulose synthesis and active gibberellin content to promote cell enlargement in cassava

“…GT TFs are mainly involved in regulating plant development and responding to stress (Gao et al., 2009). Arabidopsis PETAL LOSS (PTL) is regarded as a member of GT2 family, and its mutant exhibits dwarf, rolled leaves and male sterility (O'Brien et al., 2015; Takeda et al., 2022). When soybean ( Glycine max (L.) Merr.)…”