Evolutionary Developmental Biology (Evo-Devo)
Boyden, Geraldine S. , Hardej, Diane , Howarth, Dianella G. .
Virus-induced gene silencing of Cycloidea-like genes in Fedia cornucopiae.
Bilateral symmetry (zygomorphy, monosymmetry) in flowers has been associated with the evolution of Angiosperms. Studies that focused on the evolutionary changes of flower patterns and Evo-Devo genetics of floral symmetry, pointed to the independent evolution of zygomorphic clades from actinomorphic ancestors in angiosperms. Shifts in symmetry of flowers between radial and bilateral symmetry have been common among angiosperms and have been the subject of intense studies in the genetic model organism, Antirrhinum majus. Specific transcription factors such as CYCLOIDEA (CYC), DICHOTOMA (DICH), RADIALIS (RAD) and DIVARICATA (DIV) are recruited and implicated in dorsoventral asymmetry of flowers in angiosperms. Virus-induced gene silencing (VIGS) is a powerful, high throughput reverse genetic tool used to study the function of genes in plants and has been used to silence a number of genes encoding proteins that are implicated in metabolic pathways, developmental processes and plant defense against pathogens. A number of Solanaceous plant species and basal core eudicots have been silenced by TRV-based VIGS techniques. In this study, we show that VIGS can be applied to species in the campanulid Asteridae clade, specifically Fedia cornucopiae (Dipsacales). We have focused our studies on the effects of silencing a copy of the CYC gene (CYC2A) involved in floral symmetry (dorsoventral asymmetry). Orthologs of CYC2 genes in other organisms are expressed in dorsal regions of the flower, and mutants have resulted in the shifts in symmetry patterns. In Fedia the knocked down phenotype showed marked variation in development compared to the wildtype, where flower buds were opened prematurely displaying green petals with prominent underdeveloped anthers. The green flowers developed while opened (splayed petals) and did not attain the customary pink color until maturity (the later stages of development). Therefore, CYC2A appears to play a role in maintaining bud closure in developing Fedia flowers.
VIGS, a form of post-transcriptional gene silencing strategy (RNAi), which involves the degradation and subsequent down-regulation of gene expression in plants, can contribute to advancing our knowledge on the function of floral symmetry genes. In addition, the approach to using RNAi explores new possibilities for therapeutic interventions (gene therapy) leading to treatment of diseases for which vaccines or therapy is currently unavailable.
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1 - St. John's University, Biological Sciences, 8000 Utopia Parkway, SAH RM 257, Jamaica, NY, 11439, USA
2 - St. John's University, Toxicology, 8000 Utopia Parkway, Jamaica, NY, 11439, USA
Presentation Type: Poster:Posters for Topics
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM