title: Pollinator choice in Petunia depends on two major genetic Loci for floral scent production.
abstract: BACKGROUND
  Differences in floral traits, such as petal color, scent, morphology, or nectar quality and quantity, can lead to specific interactions with pollinators and may thereby cause reproductive isolation. Petunia provides an attractive model system to study the role of floral characters in reproductive isolation and speciation. The night-active hawkmoth pollinator Manduca sexta relies on olfactory cues provided by Petunia axillaris. In contrast, Petunia exserta, which displays a typical hummingbird pollination syndrome, is devoid of scent. The two species can easily be crossed in the laboratory, which makes it possible to study the genetic basis of the evolution of scent production and the importance of scent for pollinator behavior.
  
  
  RESULTS
  In an F2 population derived from an interspecific cross between P. axillaris and P. exserta, we identified two quantitative trait loci (QTL) that define the difference between the two species' ability to produce benzenoid volatiles. One of these loci was identified as the MYB transcription factor ODORANT1. Reciprocal introgressions of scent QTL were used for choice experiments under controlled conditions. These experiments demonstrated that the hawkmoth M. sexta prefers scented plants and that scent determines choice at a short distance. When exposed to conflicting cues of color versus scent, the insects display no preference, indicating that color and scent are equivalent cues.
  
  
  CONCLUSIONS
  Our results show that scent is an important flower trait that defines plant-pollinator interactions at the level of individual plants. The genetic basis underlying such a major phenotypic difference appears to be relatively simple and may enable rapid loss or gain of scent through hybridization.
authors.affiliation: Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Klahre
authors.forename: Alexandre
authors.initials: A
authors.lastname: Gurba
authors.forename: Katrin
authors.initials: K
authors.lastname: Hermann
authors.forename: Moritz
authors.initials: M
authors.lastname: Saxenhofer
authors.forename: Eligio
authors.initials: E
authors.lastname: Bossolini
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Guerin
authors.forename: Cris
authors.initials: C
authors.lastname: Kuhlemeier
mesh_terms: D000818:Animals; D001070:Appetitive Behavior / Q000502:physiology; D002849:Chromatography, Gas; D003433:Crosses, Genetic; D035264:Flowers / Q000737:chemistry* / Q000235:genetics; D049810:Genetic Speciation; D005828:Genetics, Population; D018402:Manduca / Q000502:physiology*; D013058:Mass Spectrometry; D009812:Odorants / Q000032:analysis*; D032306:Petunia / Q000235:genetics* / Q000502:physiology; D054817:Pollination / Q000235:genetics / Q000502:physiology*; D040641:Quantitative Trait Loci / Q000235:genetics*; D013045:Species Specificity; D014157:Transcription Factors / Q000235:genetics; D055549:Volatile Organic Compounds / Q000032:analysis
chemical_list: D014157:Transcription Factors; D055549:Volatile Organic Compounds