title: WAX INDUCER1 (HvWIN1) transcription factor regulates free fatty acid biosynthetic genes to reinforce cuticle to resist Fusarium head blight in barley spikelets.
abstract: Fusarium head blight (FHB), caused by Fusarium graminearum, is one of the most devastating diseases of wheat and barley. Resistance to FHB is highly complex and quantitative in nature, and is most often classified as resistance to spikelet infection and resistance to spread of pathogen through the rachis. In the present study, a resistant (CI9831) and a susceptible (H106-371) two-row barley genotypes, with contrasting levels of spikelet resistance to FHB, pathogen or mock-inoculated, were profiled for metabolites based on liquid chromatography and high resolution mass spectrometry. The key resistance-related (RR) metabolites belonging to fatty acids, phenylpropanoids, flavonoids and terpenoid biosynthetic pathways were identified. The free fatty acids (FFAs) linoleic and palmitic acids were among the highest fold change RR induced (RRI) metabolites. These FFAs are deposited as cutin monomers and oligomers to reinforce the cuticle, which acts as a barrier to pathogen entry. Quantitative real-time PCR studies revealed higher expressions of KAS2, CYP86A2, CYP89A2, LACS2 and WAX INDUCER1 (HvWIN1) transcription factor in the pathogen-inoculated resistant genotype than in the susceptible genotype. Knockdown of HvWIN1 by virus-induced genes silencing (VIGS) in resistant genotype upon pathogen inoculation increased the disease severity and fungal biomass, and decreased the abundance of FFAs like linoleic and palmitic acids. Notably, the expression of CYP86A2, CYP89A2 and LAC2 genes was also suppressed, proving the link of HvWIN1 in regulating these genes in cuticle biosynthesis as a defense response.
authors.affiliation: Plant Science Department, McGill University, Sainte-Anne-de-Bellevue, QC H9X3V9, Canada.
authors.forename: Arun
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Plant Science Department, McGill University, Sainte-Anne-de-Bellevue, QC H9X3V9, Canada.
authors.forename: Kalenahalli N
authors.initials: KN
authors.lastname: Yogendra
authors.affiliation: Plant Science Department, McGill University, Sainte-Anne-de-Bellevue, QC H9X3V9, Canada.
authors.forename: Shailesh
authors.initials: S
authors.lastname: Karre
authors.affiliation: Plant Science Department, McGill University, Sainte-Anne-de-Bellevue, QC H9X3V9, Canada ajjamada.kushalappa@mcgill.ca.
authors.forename: Ajjamada C
authors.initials: AC
authors.lastname: Kushalappa
authors.affiliation: Centre de Recherché sur les Grains Inc., 740, chemin Trudeau, Saint-Mathieu-de-Beloeil, QC J3G0E2, Canada.
authors.forename: Yves
authors.initials: Y
authors.lastname: Dion
authors.affiliation: Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Ave., Ottawa, ON K1A0C6, Canada.
authors.forename: Thin M
authors.initials: TM
authors.lastname: Choo
mesh_terms: D060467:Disease Resistance / Q000235:genetics / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000096:biosynthesis* / Q000502:physiology; D060585:Fusariosis / Q000378:metabolism; D005670:Fusarium / Q000472:pathogenicity*; D055785:Gene Knockdown Techniques; D017343:Genes, Plant / Q000235:genetics / Q000502:physiology*; D001467:Hordeum / Q000235:genetics / Q000382:microbiology* / Q000502:physiology; D018514:Plant Structures; D060888:Real-Time Polymerase Chain Reaction; D014157:Transcription Factors / Q000502:physiology*; D014885:Waxes / Q000378:metabolism*
chemical_list: D005230:Fatty Acids, Nonesterified; D014157:Transcription Factors; D014885:Waxes
keywords: Cuticle reinforcement; Fusarium head blight; free fatty acids; quantitative resistance; resistance-related metabolites; transcription factors.