title: Thiamine modulates metabolism of the phenylpropanoid pathway leading to enhanced resistance to Plasmopara viticola in grapevine.
abstract: BACKGROUND
  Previously, we have reported the ability of thiamine (vitamin B1) to induce resistance against Plasmopara viticola in a susceptible grapevine cv. Chardonnay. However, mechanisms underlying vitamins, especially, thiamine-induced disease resistance in grapevine are still largely unknown. Here, we assessed whether thiamine could modulate phenylpropanoid pathway-derived phytoalexins in grapevine plants, as well as, the role of such secondary metabolites in thiamine-induced resistance process to P. viticola.
  
  
  RESULTS
  Our data show that thiamine treatment elicited the expression of phenylpropanoid pathway genes in grapevine plants. The expression of these genes correlated with an accumulation of stilbenes, phenolic compounds, flavonoids and lignin. Furthermore, the total anti-oxidant potential of thiamine-treaded plants was increased by 3.5-fold higher level as compared with untreated-control plants. Four phenolic compounds are responsible of 97% of the total anti-oxidant potential of thiamine-treated plants. Among these compounds, is the caftaric acid, belonging to the hydroxy-cinnamic acids family. This element contributed, by its own, by 20% of this total anti-oxidant potential. Epifluorescence microscopy analysis revealed a concomitant presence of unbranched-altered P. viticola mycelia and stilbenes production in the leaf mesophyll of thiamine-treated inoculated plants, suggesting that stilbenes are an important component of thiamine-induced resistance in grapevine.
  
  
  CONCLUSIONS
  This work is the first to show the role of thiamine, as a vitamin, in the modulation of grapevine plant secondary metabolism contributing to an enhanced resistance to P. viticola, the most destructive fungal disease in vineyards.
authors: Laboratoire de Physiologie Moléculaire des Plantes, Centre de Biotechnologie de Borj-Cédria, 2050, Hammam Lif, Tunisie. hatem.boubakri@cbbc.rnrt.tn
authors: Hatem
authors: H
authors: Boubakri
authors: Anne
authors: A
authors: Poutaraud
authors: Mohamed Ali
authors: MA
authors: Wahab
authors: Celine
authors: C
authors: Clayeux
authors: Raymonde
authors: R
authors: Baltenweck-Guyot
authors: Damien
authors: D
authors: Steyer
authors: Christophe
authors: C
authors: Marcic
authors: Ahmed
authors: A
authors: Mliki
authors: Isabelle
authors: I
authors: Soustre-Gacougnolle
mesh_terms: D002851:Chromatography, High Pressure Liquid; D060467:Disease Resistance; D005419:Flavonoids / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008031:Lignin / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009868:Oomycetes / Q000472:pathogenicity*; D060888:Real-Time Polymerase Chain Reaction; D013267:Stilbenes / Q000378:metabolism; D013831:Thiamine / Q000494:pharmacology*; D027843:Vitis / Q000378:metabolism* / Q000382:microbiology*
chemical_list: D005419:Flavonoids; D013267:Stilbenes; D008031:Lignin; D013831:Thiamine