Abstract Detail

Developmental and Structural Section

Xiang, Qiu-Yun(Jenny) [1], Feng, Chunmiao [2], Liu, Xiang [3], Franks, Robert G. [4].

Floral and petaloid bract development in dogwoods (Cornus, Cornaceae) – testing the role of B-class genes.

Evolution of morphology cannot be fully understood without an understanding of the development and genetic controls. Recent studies found many deviations from the ABC (or ABCE) model of floral genetics and suggested that no single model applies to all angiosperms. The B-class genes (PI and AP3 homologs) are known to determine petal and stamen identities in many plant lineages and were suggested to be likely responsible for bract petaloidy via ectopic expression in novel locations in some lineages. We investigated the floral and petaloid bract development in dogwood and examined the expression pattern of the B-class genes in several species to determine if their functions in floral development are conserved in the dogwoods. Furthermore, we are interested in if bract petaloidy in dogwood species is due to transference of a conserved petal identity program (homeoheterotopy). Our analyses using SEM, qRT-PCR, and in-situ hybridization revealed divergent development pathways and temporal differences of the B-class gene expressions among different bract types displayed by evolutionary divergence lineages. Both PI and AP3 were expressed in petal and stamens during their initiation and early developmental stages. The results obtained so far suggested functional conservation of B-class genes in dogwood floral development and that PI may not be necessary in bract petaloidy of C. canadensis, but AP3 is. The results futher suggested that bract petaloidy in dogwoods may be controlled by homeoheterotopy with modification of the program in C. canadensis.

Broader Impacts:
The study will not only enhance our understanding of the developmental and molecular basis of floral and bract evolution in angisperms, but also hold a promise in breeding and bioengineering of dogwoods. Biotechnological improvement of Cornus species in display, holds tremendous industrial potential. Thus the results of this study will interesting to the scientific, biotechnolgical, and industrial communities.

1 - North Carolina State University, Department of Plant Biology, Campus Box 7612, Raleigh, NC, 27695-7612, USA
2 - North Carolina State University, Department of Plant Biology, Campus Box 7612, Raleigh, North Carolina, 27695-7612, USA
3 - North Carolina State University, Plant Biology, Raleigh, NC, 27695-7612, USA
4 - North Carolina State University, Genetics, Raleigh, NC, 27695, USA

Keywords:
Floral development
Bract petaloidy
genetics
Cornus.

Presentation Type: Oral Paper:Papers for Sections
Session: 29
Location: 551A/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 9:00 AM
Number: 29004
Abstract ID:413