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Genetic analysis of floral symmetry in Van Gogh's sunflowers reveals independent recruitment of CYCLOIDEA genes in the Asteraceae.

Genetic analysis of floral symmetry in Van Gogh's sunflowers reveals independent recruitment of CYCLOIDEA genes in the Asteraceae.
Genetic analysis of floral symmetry in Van Gogh's sunflowers reveals independent recruitment of CYCLOIDEA genes in the Asteraceae.
The genetic basis of floral symmetry is a topic of great interest because of its effect on pollinator behavior and, consequently, plant diversification. The Asteraceae, which is the largest family of flowering plants, is an ideal system in which to study this trait, as many species within the family exhibit a compound inflorescence containing both bilaterally symmetric (i.e., zygomorphic) and radially symmetric (i.e., actinomorphic) florets. In sunflower and related species, the inflorescence is composed of a single whorl of ray florets surrounding multiple whorls of disc florets. We show that in double-flowered (dbl) sunflower mutants (in which disc florets develop bilateral symmetry), such as those captured by Vincent van Gogh in his famous nineteenth-century sunflower paintings, an insertion into the promoter region of a CYCLOIDEA (CYC)-like gene (HaCYC2c) that is normally expressed specifically in WT rays is instead expressed throughout the inflorescence, presumably resulting in the observed loss of actinomorphy. This same gene is mutated in two independent tubular-rayed (tub) mutants, though these mutations involve apparently recent transposon insertions, resulting in little or no expression and radialization of the normally zygomorphic ray florets. Interestingly, a phylogenetic analysis of CYC-like genes from across the family suggests that different paralogs of this fascinating gene family have been independently recruited to specify zygomorphy in different species within the Asteraceae.
1553-7390
e1002628
Chapman, Mark A
8bac4a92-bfa7-4c3c-af29-9af852ef6383
Tang, Shunxue
71c2474e-92b9-4814-bcbf-e7b8dec812a5
Draeger, Dörthe
00b49d8f-1435-4595-b61f-4df61c9bc0e8
Nambeesan, Savithri
20362abd-9ce1-4331-ac7f-9b07625aba0f
Shaffer, Hunter
0bf99f1c-07dc-44d9-8807-37596b00b81c
Barb, Jessica G
b469ada2-efde-4e9c-a15b-5a36cb280857
Knapp, Steven J
425ed499-965e-4a12-b852-8643c19246d0
Burke, John M
2b408ed2-1c92-4e50-bf32-9dd739a5022e
Chapman, Mark A
8bac4a92-bfa7-4c3c-af29-9af852ef6383
Tang, Shunxue
71c2474e-92b9-4814-bcbf-e7b8dec812a5
Draeger, Dörthe
00b49d8f-1435-4595-b61f-4df61c9bc0e8
Nambeesan, Savithri
20362abd-9ce1-4331-ac7f-9b07625aba0f
Shaffer, Hunter
0bf99f1c-07dc-44d9-8807-37596b00b81c
Barb, Jessica G
b469ada2-efde-4e9c-a15b-5a36cb280857
Knapp, Steven J
425ed499-965e-4a12-b852-8643c19246d0
Burke, John M
2b408ed2-1c92-4e50-bf32-9dd739a5022e

Chapman, Mark A, Tang, Shunxue, Draeger, Dörthe, Nambeesan, Savithri, Shaffer, Hunter, Barb, Jessica G, Knapp, Steven J and Burke, John M (2012) Genetic analysis of floral symmetry in Van Gogh's sunflowers reveals independent recruitment of CYCLOIDEA genes in the Asteraceae. PLoS Genetics, 8 (3), e1002628. (doi:10.1371/journal.pgen.1002628). (PMID:22479210)

Record type: Article

Abstract

The genetic basis of floral symmetry is a topic of great interest because of its effect on pollinator behavior and, consequently, plant diversification. The Asteraceae, which is the largest family of flowering plants, is an ideal system in which to study this trait, as many species within the family exhibit a compound inflorescence containing both bilaterally symmetric (i.e., zygomorphic) and radially symmetric (i.e., actinomorphic) florets. In sunflower and related species, the inflorescence is composed of a single whorl of ray florets surrounding multiple whorls of disc florets. We show that in double-flowered (dbl) sunflower mutants (in which disc florets develop bilateral symmetry), such as those captured by Vincent van Gogh in his famous nineteenth-century sunflower paintings, an insertion into the promoter region of a CYCLOIDEA (CYC)-like gene (HaCYC2c) that is normally expressed specifically in WT rays is instead expressed throughout the inflorescence, presumably resulting in the observed loss of actinomorphy. This same gene is mutated in two independent tubular-rayed (tub) mutants, though these mutations involve apparently recent transposon insertions, resulting in little or no expression and radialization of the normally zygomorphic ray florets. Interestingly, a phylogenetic analysis of CYC-like genes from across the family suggests that different paralogs of this fascinating gene family have been independently recruited to specify zygomorphy in different species within the Asteraceae.

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Published date: March 2012
Organisations: Faculty of Natural and Environmental Sciences, Centre for Biological Sciences

Identifiers

Local EPrints ID: 350272
URI: https://eprints.soton.ac.uk/id/eprint/350272
ISSN: 1553-7390
PURE UUID: 2a1c327e-31ef-4d4e-87de-e69ed1a0eb60
ORCID for Mark A Chapman: ORCID iD orcid.org/0000-0002-7151-723X

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Date deposited: 25 Mar 2013 09:56
Last modified: 29 Oct 2019 01:38

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