Smart, M , Roden, Laura C. , Cramer, MD .
Gene expression profiles of photoperiodic responsive genes and their role in determination of meristem identity in Proteaceae.
Proteaceae of South Africa flower mostly in the months leading up to and including summer, although variation in flowering time exists within and between the genera. The Protea, Leucadendron and Leucospermum genera have been extensively cultivated for the cut flower industry and these show divergent flowering times within the hybrid groups as well as between the hybrids and their parental species. As photoperiod regulates flowering in many plants we tested whether floral initiation is responsive to photoperiod in the Proteaceae. Floral responses to photoperiod in Arabidopsis thaliana are mediated at the molecular level through CONSTANS (CO) which activates the expression of the floral integrator FLOWERING LOCUS T (FT) which ultimately activates the expression of the floral meristem identity gene, LEAFY. Proteaceae CO and FT homologues were identified and changes in their diurnal expression profiles determined from autumn (April) to summer (November). We also identified a homologue of the A. thaliana meristem identity gene LEAFY in Proteaceae (PROFL). PROFL has a multicopy nature in Protea hybrids, with at least three copies confirmed by Southern analysis. PROFL was found to be expressed in both the floral meristem and vegetative leaves during shoot and flower development. PROFL transcript abundance increases in the meristem during floral induction and development as expected for a floral meristem identity gene. This study has identified some of the floral responses to environmental cues, especially photoperiod, in a fairly unexplored group of plants. Further characterisation of the floral response in Proteaceae should allow for manipulation of flowering time with light or plant growth regulators.
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1 - University of Cape Town, Molecular and Cell Biology, Private Bag X3, Rondebosch, 7701, South Africa
2 - University of Cape Town, Molecular and Cell Biology
3 - University of Cape Town, Botany
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM