title: Reverse genetics of floral scent: application of tobacco rattle virus-based gene silencing in Petunia.
abstract: Floral fragrance is responsible for attracting pollinators as well as repelling pathogens and pests. As such, it is of immense biological importance. Molecular dissection of the mechanisms underlying scent production would benefit from the use of model plant systems with big floral organs that generate an array of volatiles and that are amenable to methods of forward and reverse genetics. One candidate is petunia (Petunia hybrida), which has emerged as a convenient model system, and both RNAi and overexpression approaches using transgenes have been harnessed for the study of floral volatiles. Virus-induced gene silencing (VIGS) is characterized by a simple inoculation procedure and rapid results relative to transgenesis. Here, we demonstrate the applicability of the tobacco rattle virus-based VIGS system to studies of floral scent. Suppression of the anthocyanin pathway via chalcone synthase silencing was used as a reporter, allowing easy visual identification of anthocyaninless silenced flowers/tissues with no effect on the level of volatile emissions. Use of tobacco rattle virus constructs containing target genes involved in phenylpropanoid volatile production, fused to the chalcone synthase reporter, allowed simple identification of flowers with suppressed activity of the target genes. The applicability of VIGS was exemplified with genes encoding S-adenosyl-l-methionine:benzoic acid/salicylic acid carboxyl methyltransferase, phenylacetaldehyde synthase, and the myb transcription factor ODORANT1. Because this high-throughput reverse-genetics approach was applicable to both structural and regulatory genes responsible for volatile production, it is expected to be highly instrumental for large-scale scanning and functional characterization of novel scent genes.
authors.affiliation: Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture , Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Ben
authors.initials: B
authors.lastname: Spitzer
authors.forename: Michal Moyal Ben
authors.initials: MM
authors.lastname: Zvi
authors.forename: Marianna
authors.initials: M
authors.lastname: Ovadis
authors.forename: Elena
authors.initials: E
authors.lastname: Marhevka
authors.forename: Oren
authors.initials: O
authors.lastname: Barkai
authors.forename: Orit
authors.initials: O
authors.lastname: Edelbaum
authors.forename: Ira
authors.initials: I
authors.lastname: Marton
authors.forename: Tania
authors.initials: T
authors.lastname: Masci
authors.forename: Michal
authors.initials: M
authors.lastname: Alon
authors.forename: Shai
authors.initials: S
authors.lastname: Morin
authors.forename: Ilana
authors.initials: I
authors.lastname: Rogachev
authors.forename: Asaph
authors.initials: A
authors.lastname: Aharoni
authors.forename: Alexander
authors.initials: A
authors.lastname: Vainstein
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D000872:Anthocyanins / Q000378:metabolism; D035264:Flowers / Q000378:metabolism*; D020868:Gene Silencing; D005818:Genetic Engineering; D009812:Odorants; D032306:Petunia / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D010942:Plant Viruses
chemical_list: D000872:Anthocyanins; D000217:Acyltransferases; C020141:flavanone synthetase