Skip to main content
Login | Suomeksi | På svenska | In English

Browsing by Subject "Calendula officinalis"

Sort by: Order: Results:

  • Development of tissue culture and virus-induced gene silencing for Calendula officinalis 
    Liu, Yanbo (2011)
    Calendula officinalis is grown widely as an ornamental plant across Europe. It belongs to the large. Asteraceae family. In this study, the aim was to explore the possibilities to use Calendula officinalis as a new model organism for flower development and secondary mechanism studies in Asteraceae. Tissue culture of Calendula officinalis was established using nine different cultivars. Murashige & Skoog (MS) medium with four different combinations of plant growth regulators were tested. Of all these combinations, the medium containing 1mg/l BAP, 0.1 mg/l IAA, and 1mg/l Zeatin achieved highest frequency of adventitious shoot regeneration from hypocotyl and cotyledon explants. Virus-induced gene silencing is a recent developed genetic tool for charactering the gene functions in plants, and extends the range of host plants that are not accessible for Agrobacterium transformation. Here, tobacco rattle virus (TRV)-based VIGS technique was tested in calendula (cv. Single Orange). We used TRV carrying Gerbera hybrid phytoene desaturase (PDS) gene fragment to induce PDS silencing in calendula. Vacuum infiltration and syringe infiltration methods both resulted in photo-bleaching phenotypes in leaves, bracts and petals. Loss-of-function phenotypes occurred on calendula 13 days post-infiltration. In conclusion, the data indicates that calendula explants can be regenerated through tissue culture which is a prerequisite for development of stable transformation methods. However, further optimization is still needed to improve the frequency. In addition, VIGS was applied to silence PDS marker gene expression indicating that this method has potential for gene functional studies in future.
  • Optimization of VIGS and functional analysis of Gerbera hybrida TCP genes in Calendula officinalis 
    Zhang, Yao (2012)
    The evolution of floral novelties involves activities of several transcription factors. The large Asteraceae plant family has inflorescences consisting of different types of flowers. TCP transcription factors have recently been reported to regulate this complex structure. Gerbera hybrida, a common ornamental crop, has been used as a model plant for flower developmental studies in Asteraceae. It can be genetically transformed; however, transformation is laborious and time-consuming. Calendula officinalis also belongs to the Asteraceae plant family. It has working micropropagation methods, and it grows and flowers faster than Gerbera hybrida. In addition, Calendula officinalis genes possess high sequence similarity to Gerbera hybrida genes and thus provide an opportunity for functional testing of large numbers of genes. For functional assessment, virus induced gene silencing (VIGS) is a rapid approach, as it circumvents the need to establish stable transgenic lines that requires efficient tissue culture and time-consuming whole-plant regeneration steps. In this study, twelve Calendula officinalis cultivars were tested for VIGS. Calendula showed potential as a new model for the Asteraceae plant family as all twelve different cultivars could be infected by tobacco rattle virus (TRV) via observing the fluorescence caused by pTRV2: GFP; and they all showed photobleaching silencing phenotype caused by PHYTOENE DESATURASE (GhPDS) gene from gerbera. Especially the cultivars „Touch of Red/Orange? and „Princess Orange? turned out to be the most efficient in silencing. Virus dynamics was successfully traced by fluorescence encoded by pTRV2: GFP construct. However, using the construct pTRV2: GFP: PDS, it was observed that the GFP gene could not be applied as a marker gene to indicate the silencing area, because fluorescence could not be observed in photobleaching area. The calendula PDS was also tested. More similar sequence corresponding to the plant?s endogenous gene could cause more visible silencing symptom, but quantitative polymerase chain reaction results showed no statistically significant difference on gene silencing efficiency between GhPDS and CoPDS fragments. VIGS was also tested for silencing of TCP domain transcription factor genes using gerbera specific gene fragments. It was observed that the VIGS approach was not suitable for functional testing of CYCLOIDEA-clade genes in Calendula officinalis as identification of the putative phenotypes was highly disturbed by variable inflorescence phenotype of the tested cultivar.

Yhteystiedot

HELSINGIN YLIOPISTO