title: Transcription factor StWRKY1 regulates phenylpropanoid metabolites conferring late blight resistance in potato.
abstract: Quantitative resistance is polygenically controlled and durable, but the underlying molecular and biochemical mechanisms are poorly understood. Secondary cell wall thickening is a critical process in quantitative resistance, regulated by transcriptional networks. This paper provides compelling evidence on the functionality of StWRKY1 transcription factor, in a compatible interaction of potato-Phytophthora infestans, to extend our knowledge on the regulation of the metabolic pathway genes leading to strengthening the secondary cell wall. A metabolomics approach was used to identify resistance-related metabolites belonging to the phenylpropanoid pathway and their biosynthetic genes regulated by StWRKY1. The StWRKY1 gene in resistant potato was silenced to decipher its role in the regulation of phenylpropanoid pathway genes to strengthen the secondary cell wall. Sequencing of the promoter region of StWRKY1 in susceptible genotypes revealed the absence of heat shock elements (HSEs). Simultaneous induction of both the heat shock protein (sHSP17.8) and StWRKY1 following pathogen invasion enables functioning of the latter to interact with the HSE present in the resistant StWRKY1 promoter region. EMSA and luciferase transient expression assays further revealed direct binding of StWRKY1 to promoters of hydroxycinnamic acid amide (HCAA) biosynthetic genes encoding 4-coumarate:CoA ligase and tyramine hydroxycinnamoyl transferase. Silencing of the StWRKY1 gene was associated with signs of reduced late blight resistance by significantly increasing the pathogen biomass and decreasing the abundance of HCAAs. This study provides convincing evidence on the role of StWRKY1 in the regulation of downstream genes to biosynthesize HCAAs, which are deposited to reinforce secondary cell walls.
authors.affiliation: Department of Plant Science, McGill University, Ste Anne de Bellevue, Quebec, Canada.
authors.forename: Kalenahalli N
authors.initials: KN
authors.lastname: Yogendra
authors.affiliation: Department of Plant Science, McGill University, Ste Anne de Bellevue, Quebec, Canada.
authors.forename: Arun
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Department of Plant Science, McGill University, Ste Anne de Bellevue, Quebec, Canada.
authors.forename: Kobir
authors.initials: K
authors.lastname: Sarkar
authors.affiliation: Department of Plant Science, McGill University, Ste Anne de Bellevue, Quebec, Canada.
authors.forename: Yunliang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Plant Science, McGill University, Ste Anne de Bellevue, Quebec, Canada.
authors.forename: Doddaraju
authors.initials: D
authors.lastname: Pushpa
authors.affiliation: Department of Plant Science, McGill University, Ste Anne de Bellevue, Quebec, Canada.
authors.forename: Kareem A
authors.initials: KA
authors.lastname: Mosa
authors.affiliation: Department of Animal Science, McGill University, Ste Anne de Bellevue, Quebec, Canada.
authors.forename: Raj
authors.initials: R
authors.lastname: Duggavathi
authors.affiliation: Department of Plant Science, McGill University, Ste Anne de Bellevue, Quebec, Canada ajjamada.kushalappa@mcgill.ca.
authors.forename: Ajjamada C
authors.initials: AC
authors.lastname: Kushalappa
mesh_terms: D002473:Cell Wall / Q000378:metabolism / Q000382:microbiology; D003373:Coumaric Acids / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006360:Heat-Shock Proteins / Q000378:metabolism; D053858:Metabolic Networks and Pathways / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D055750:Phytophthora infestans; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D010940:Plant Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011198:Solanum tuberosum / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D003373:Coumaric Acids; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D014157:Transcription Factors; D020928:Mitogen-Activated Protein Kinases
keywords: Hydroxycinnamic acid amides; Phytophthora infestans; quantitative resistance; secondary cell wall thickening; transcription factors