Evolution of bract development and B-class MADS box gene expression in petaloid bracts of Cornus s. l. (Cornaceae)
Article first published online: 16 AUG 2012
© 2012 The Authors. New Phytologist © 2012 New Phytologist Trust
Volume 196, Issue 2, pages 631–643, October 2012
How to Cite
Feng, C.-M., Liu, X., Yu, Y., Xie, D., Franks, R. G. and Xiang, Q.-Y. (2012), Evolution of bract development and B-class MADS box gene expression in petaloid bracts of Cornus s. l. (Cornaceae). New Phytologist, 196: 631–643. doi: 10.1111/j.1469-8137.2012.04255.x
- Issue published online: 17 SEP 2012
- Article first published online: 16 AUG 2012
- Received: 21 May 2012, Accepted: 27 June 2012
- B-class gene expression;
- evolution of petaloid bracts;
- heterotopic petaloidy;
- •Despite increasing interest in the molecular mechanisms of floral diversity, few studies have investigated the developmental and genetic bases of petaloid bracts. This study examined morphological patterns of bract initiation and expression patterns of B-class MADS-box genes in bracts of several Cornus species. We suggest that petaloid bracts in this genus may not share a single evolutionary origin.
- •Developmental pathways of bracts and spatiotemporal expression of B-class genes in bracts and flowers were examined for four closely related dogwood species.
- •Divergent morphological progressions and gene expression patterns were found in the two sister lineages with petaloid bracts, represented by Cornus florida and Cornus canadensis. Phylogeny-based analysis identified developmental and gene expression changes that are correlated with the evolution of petaloid bracts in C. florida and C. canadensis.
- •Our data support the existence of independent evolutionary origins of petaloid bracts in C. canadensis and C. florida. Additionally, we suggest that functional transference within B-class gene families may have contributed to the origin of bract petaloidy in C. florida. However, the underlying mechanisms of petaloid bract development likely differ between C. florida and C. canadensis. In the future this hypothesis can be tested by functional analyses of Cornus B-class genes.