Browsing by Subject "flower development"

Sort by: Order: Results:

Now showing items 1-4 of 4
  • Shiradhonkar, Rohan (Helsingin yliopisto, 2019)
    The complex inflorescence architecture in Asteraceae is characterized by the presence of morphologically distinct flowers having specialized functions. In gerbera, the presence of three different flower types (ray, trans and disc), intricate inflorescence organization and an underlying complex molecular control makes it an excellent target for research on functional genomics, flower development and evolution. The genes governing flower development have been shown to have undergone sub- and neo-functionalization in gerbera leading to morphological features that are not present in the conventional model plant species. The genes encoding the CYC2 subclade of CYC/TB1-like TCP domain transcription factors are known to regulate the flower type identity in gerbera inflorescence. Although most genes of the CYC2 subclade have demonstrated functional redundancy, one such gene, GhCYC5, was found to have diverged function in regulating rate of initiation of flowers. This study aimed at investigating and affirming the function of GhCYC5 by studying two RNAi lines. Phenotypic analysis of the RNAi inflorescences showed that the length of ray ligules was significantly decreased along with the number of disc flowers and the number of involucral bracts. However, gene expression analysis could not confirm the downregulation of GhCYC5 in the RNAi lines mainly due to low endogenous expression of the gene. However, GhCYC3, another CYC2 clade gene was found to be downregulated due to the off-target silencing effect of the RNAi product and the observed phenotype was associated with suppression of GhCYC3. Further, the role of GhCYC5 in regulating the rate of involucral bract and flower initiation was unclear based on the SEM imaging and expression analysis of the inflorescence meristem, and still requires further studies.
  • Zhao, Yafei (Helsingfors universitet, 2013)
    The transition from vegetative growth to flower formation is especially crucial for the reproduction of flowering plants. This transition is controlled through the regulatory activities of a group of genes named as floral meristem identity genes, of which LEAFY (LFY) is thought as the most important one. As a plant-specific transcription factor, LFY controls flower formation and floral patterning, which has been most intensively studied in the model annual plant Arabidopsis. In contrast to the plant architecture and flower morphology in Arabidopsis, Gerbera (Gerbera hybrida), belonging to the large sunflower family (Asteraceae), processes head-like inflorescences with different types of flowers distinct in floral morphs, sex and sometimes coloration. Within the last decades, a number of MADS-box and TCP transcription factor genes have been functionally characterized using stable transgenic plants. Recently, another functional assessment method using virus-induced gene silencing (VIGS) has been developed in Gerbera hybrida. In this study, the expression pattern of GhLFY was analyzed in wild-type Gerbera and TRV-based GhLFY silencing was conducted in two Gerbera cultivars – Terra Regina and Grizzly. It could be concluded that the activity of GhLFY is involved in regulating flower development. In VIGS:GhLFY lines, leaf-like organs emerged in disc flowers and the identity of stamen and carpel was interrupted. However, further VIGS trials are needed verify the observed phenotypes. At the same time, two potential lfy mutants – Pingpong and Marimbo were analyzed in both phenotype and genotype. These cultivars show phenotypic alteration in inflorescence development and floral organ structures that were distinct from WT Gerbera. Although the expression level of GhLFY did not change among these cultivars, but the GhLFY sequences contained amino acids mutation sites and four missing proline amino acids in Marimbo were detected. The role of these mutation sites need to be further analyzed in later experimental steps.
  • Juntheikki-Palovaara, Inka; Tahtiharju, Sari; Lan, Tianying; Broholm, Suvi K.; Rijpkema, Anneke S.; Ruonala, Raili; Kale, Liga; Albert, Victor A.; Teeri, Teemu H.; Elomaa, Paula (2014)
  • Titov, Soubir (Helsingfors universitet, 2010)
    Protein-protein interactions (PPIs) regulate many different cellular processes including transcription, translation, cell division, signal transduction, and oncogenic transformation. It is therefore important to develop sensitive and versatile techniques for the detection of these protein-protein interactions in order to fully understand protein functions. The most commonly used and traditional technique, the yeast two-/three hybrid (Y2H/Y3H) method, often results in false positives and false negatives, and other widely used techniques, such as bioluminescence resonance energy transfer (BRET), fluorescence resonance energy transfer (FRET), and bimolecular fluorescence complementation (BiFC) require extensive instrumentation. When compared with other PPI detection methods, the luciferase-based complementation assay specially split luciferase is believed to deliver the most sensitive and highest dynamic range, making it ideal for large-scale analysis. Therefore, for testing PPIs in planta, split Renilla luciferase complementation assay was chosen. In order to conduct this experiment, a series of plasmid constructs were made to enable the transient expression of fusion proteins. A well known protein pair, Arabidopsis nuclear Histone 2A and 2B, was tested initially as a proof of concept, and then three more proteins of the Gerbera MADS-box B class were investigated. For Arabidopsis Histone 2A and 2B, the intensity in all combinations was on average 9.4-fold higher in Relative Luminescence Units (RLUs) than the mock treated protoplasts. Moreover, in the case of Gerbera MADS-box B class proteins, the protein pairs GDEF1-GDEF2, GDEF1-GGLO1, and GDEF2-GGLO1 showed 8.4-19.4, 9.5-15.8, and 8.3-9.1-fold higher signals than the mock treated protoplasts. These results suggest that various complexes formed from different combinations of these three B class MADS-box proteins may increase the complexity of their regulatory functions, thus specifying the molecular basis of whorl morphogenesis and combinatorial interactions of floral organ identity genes in Gerbera. Finally, it was concluded that split Renilla luciferase can be a simple, reliable, fast, and effective method for examining PPIs in planta.