Evolutionary Developmental Biology (Evo-Devo)
Chou, Shao-Pei , Möller, Michael , Wang, Chun-Neng .
Unveiling the genetic control of floral shape: the role of the floral symmetry genes in pollination syndrome evolution.
The evolution of bilaterally symmetric (zygomorphic) flower is the most important trend in facilitating pollination of the flowering plants. Changes in flower symmetry and shape are often linked to changes in their pollination syndromes. Candidate genes such as CYCLOIDEA (CYC), RADIALIS (RAD), DIVARICATA (DIV) and MIXTA have been suggested to function not only in creating zygomorphy but also in altering corolla shape. However, no genetic analysis on the phenotypic effects of these genes relating to flower shape evolution has ever been carried out. Species of the genus Streptocarpus (Cape Primrose, Gesneriaceae) exhibit flowers with pollination syndromes ranging from butterfly flowers with keyhole type corollas, fly flowers with open tube corollas to bird flowers with narrow tube, red corollas. We produced F1 and F2 plants between the open tube flowered S. rexii and the keyhole flowered S. johannis. Segregation analysis among 119 F2 individuals revealed that CYC and MIXTA genotype variation significantly correlated to traits related to the height and width in the distal, dilated part of the corolla tube, the ‘insect visiting chamber’ (accounting for 25% of the phenotypic variation). RAD genotype variation evidently correlated to the length of the corolla tube and filaments. Moreover, CYC and MIXTA genotypes were strongly linked, while RAD and DIV formed another linkage group. This study is the first report that implies that floral symmetry genes play important roles in corolla shape variations, thus represent the genetic links in the evolution of pollination syndromes.
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Presenting author's homepage
1 - National Taiwan University, Institute of Ecology and Evolutionary Biology, No.1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan
2 - Royal Botanic Garden Edinburgh, Gesneriaceae Research Group, 20A Inverleith Row, Edinburgh, Scotland, EH3 5LR, UK
3 - National Taiwan University, Department of Life Science, Institute of Ecology and Evolutionary Biology, No.1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan
Presentation Type: Oral Paper:Papers for Topics
Date: Wednesday, July 30th, 2008
Time: 9:15 AM