Elaboration of B Gene Function to Include the Identity of Novel Floral Organs in the Lower Eudicot Aquilegia

Guo

Proc. Natl. Acad. Sci. U.S.A.

et al. 2013

Self Cite

Absence of petals, or being apetalous, is usually one of the most important features that characterizes a group of flowering plants at high taxonomic ranks (i.e., family and above). The apetalous condition, however, appears to be the result of parallel or convergent evolution with unknown genetic causes. Here we show that within the buttercup family (Ranunculaceae), apetalous genera in at least seven different lineages were all derived from petalous ancestors, indicative of parallel petal losses. We also show that independent petal losses within this family were strongly associated with decreased or eliminated expression of a single floral organ identity gene, APETALA3-3 ( AP3-3 ) , apparently owing to species-specific molecular lesions. In an apetalous mutant of Nigella , insertion of a transposable element into the second intron has led to silencing of the gene and transformation of petals into sepals. In several naturally occurring apetalous genera, such as Thalictrum , Beesia , and Enemion , the gene has either been lost altogether or disrupted by deletions in coding or regulatory regions. In Clematis , a large genus in which petalous species evolved secondarily from apetalous ones, the gene exhibits hallmarks of a pseudogene. These results suggest that, as a petal identity gene, AP3-3 has been silenced or down-regulated by different mechanisms in different evolutionary lineages. This also suggests that petal identity did not evolve many times independently across the Ranunculaceae but was lost in numerous instances. The genetic mechanisms underlying the independent petal losses, however, may be complex, with disruption of AP3-3 being either cause or effect.

Section: Ap3-3 Orthologs In Clematismentioning

confidence: 99%

Disruption of the petal identity gene APETALA3-3 is highly correlated with loss of petals within the buttercup family (Ranunculaceae)

Guo

Proc. Natl. Acad. Sci. U.S.A.

et al. 2013

Self Cite

“…Although evidence for a causal role of gene duplication in morphological novelty remains limited, data are beginning to accumulate in support of a functional link. For example, differential expression patterns of three paralogues of AP3 coupled with PI control petaloidy in Aquilegia (Ranunculales) and appear to be responsible for the novel features of columbine flowers [90,136]. Duplications of entire genomes allow more complex intergenic interactions, involving multiple paralogues of all genes in the genome, with potentially greater morphological effect than duplications of single genes.…”

Section: Implications Of Gamma Palaeohexaploidymentioning

confidence: 99%

Evolution of floral diversity: genomics, genes andgamma

Chanderbali

Berger

Howarth

et al. 2017

Phil. Trans. R. Soc. B

One contribution of 17 to a theme issue 'Evo-devo in the genomics era, and the origins of morphological diversity'. A salient feature of flowering plant diversification is the emergence of a novel suite of floral features coinciding with the origin of the most species-rich lineage, Pentapetalae. Advances in phylogenetics, developmental genetics and genomics, including new analyses presented here, are helping to reconstruct the specific evolutionary steps involved in the evolution of this clade. The enormous floral diversity among Pentapetalae appears to be built on a highly conserved ground plan of five-parted (pentamerous) flowers with whorled phyllotaxis. By contrast, lability in the number and arrangement of component parts of the flower characterize the early-diverging eudicot lineages subtending Pentapetalae. The diversification of Pentapetalae also coincides closely with ancient hexaploidy, referred to as the gamma whole-genome triplication, for which the phylogenetic timing, mechanistic details and molecular evolutionary consequences are as yet not fully resolved. Transcription factors regulating floral development often persist in duplicate or triplicate in gamma-derived genomes, and both individual genes and whole transcriptional programmes exhibit a shift from broadly overlapping to tightly defined expression domains in Pentapetalae flowers. Investigations of these changes associated with the origin of Pentapetalae can lead to a more comprehensive understanding of what is arguably one of the most important evolutionary diversification events within terrestrial plants.This article is part of the themed issue 'Evo-devo in the genomics era, and the origins of morphological diversity'.

“…It is optimized for use with paraformaldehyde fixed, paraffin-embedded sections, which give excellent preservation of histology, and DIG-labeled probes that are visualized by immuno-detection and alkaline-phosphatase colorimetric reaction. This protocol has been successfully applied to a number of tissues from a wide range of plant species, and can be used to analyze expression of mRNAs as well as small RNAs [8][9][10][11][12][13][14] .…”

mentioning

confidence: 99%

<em>In Situ</em> Hybridization for the Precise Localization of Transcripts in Plants

Javelle

Marco

Timmermans

2011

JoVE

With the advances in genomics research of the past decade, plant biology has seen numerous studies presenting large-scale quantitative analyses of gene expression. Microarray and next generation sequencing approaches are being used to investigate developmental, physiological and stress response processes, dissect epigenetic and small RNA pathways, and build large gene regulatory networks [1][2][3]