title: Natural variation in floral nectar proteins of two Nicotiana attenuata accessions.
abstract: BACKGROUND
  Floral nectar (FN) contains not only energy-rich compounds to attract pollinators, but also defense chemicals and several proteins. However, proteomic analysis of FN has been hampered by the lack of publically available sequence information from nectar-producing plants. Here we used next-generation sequencing and advanced proteomics to profile FN proteins in the opportunistic outcrossing wild tobacco, Nicotiana attenuata.
  
  
  RESULTS
  We constructed a transcriptome database of N. attenuata and characterized its nectar proteome using LC-MS/MS. The FN proteins of N. attenuata included nectarins, sugar-cleaving enzymes (glucosidase, galactosidase, and xylosidase), RNases, pathogen-related proteins, and lipid transfer proteins. Natural variation in FN proteins of eleven N. attenuata accessions revealed a negative relationship between the accumulation of two abundant proteins, nectarin1b and nectarin5. In addition, microarray analysis of nectary tissues revealed that protein accumulation in FN is not simply correlated with the accumulation of transcripts encoding FN proteins and identified a group of genes that were specifically expressed in the nectary.
  
  
  CONCLUSIONS
  Natural variation of identified FN proteins in the ecological model plant N. attenuata suggests that nectar chemistry may have a complex function in plant-pollinator-microbe interactions.
authors.affiliation: Department of Chemistry, Chonbuk National University, Jeonju 561-756, Korea.
authors.forename: Pil Joon
authors.initials: PJ
authors.lastname: Seo
authors.forename: Natalie
authors.initials: N
authors.lastname: Wielsch
authors.forename: Danny
authors.initials: D
authors.lastname: Kessler
authors.forename: Ales
authors.initials: A
authors.lastname: Svatos
authors.forename: Chung-Mo
authors.initials: CM
authors.lastname: Park
authors.forename: Ian T
authors.initials: IT
authors.lastname: Baldwin
authors.forename: Sang-Gyu
authors.initials: SG
authors.lastname: Kim
mesh_terms: D015180:Electrophoresis, Gel, Two-Dimensional; D035264:Flowers / Q000737:chemistry / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D014644:Genetic Variation; D013058:Mass Spectrometry; D010802:Phylogeny; D057048:Plant Nectar / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D057048:Plant Nectar; D010940:Plant Proteins