title: Quantitative resistance in potato leaves to late blight associated with induced hydroxycinnamic acid amides.
abstract: Late blight is a serious economic threat to potato crop, sometimes leading to complete crop loss. The resistance in potato to late blight can be qualitative or quantitative in nature. Qualitative resistance is not durable. Though quantitative resistance is durable, the breeding is challenging due to polygenic inheritance. Several quantitative trait loci (QTLs) have been identified, but the mechanisms of resistance are largely unknown. A nontargeted metabolomics approach was used to identify resistance-related (RR) metabolites in a resistant genotype (F06025), as compared to a susceptible (Shepody) genotype, mock- or pathogen-inoculated. The RR metabolites, which had high fold change in abundance, mainly belonged to phenylpropanoid, flavonoid, fatty acid, and alkaloid chemical groups. The most important phenylpropanoids identified were hydroxycinnamic acid amides, the polyaromatic domain of suberin that is known to be associated with cell wall reinforcement. These metabolites were mapped on to the potato metabolic pathways, and the candidate enzymes and their coding genes were identified. A quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay revealed a higher upregulation of 4-coumarate: CoA ligase (4-CL), tyrosine decarboxylase (TyDC), and tyramine hydroxycinnamoyl transferase (THT) in the pathogen-inoculated resistant genotype than in susceptible. These genes were sequenced in both resistant and susceptible genotypes, and nonsynonymous single-nucleotide polymorphisms (nsSNPs) were found. The application of these genes in potato resistance improvement, following validation, is discussed.
authors.affiliation: Plant Science Department, McGill University, Ste.-Anne-de-Bellevue, Quebec, H9X 3V9, Canada.
authors.forename: Kalenahalli N
authors.initials: KN
authors.lastname: Yogendra
authors.forename: Doddaraju
authors.initials: D
authors.lastname: Pushpa
authors.forename: Kareem A
authors.initials: KA
authors.lastname: Mosa
authors.forename: Ajjamada C
authors.initials: AC
authors.lastname: Kushalappa
authors.forename: Agnes
authors.initials: A
authors.lastname: Murphy
authors.forename: Teresa
authors.initials: T
authors.lastname: Mosquera
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D000577:Amides; D000595:Amino Acid Sequence; D003066:Coenzyme A Ligases / Q000235:genetics / Q000378:metabolism; D003373:Coumaric Acids / Q000276:immunology* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000276:immunology*; D005838:Genotype; D053858:Metabolic Networks and Pathways; D008969:Molecular Sequence Data; D055750:Phytophthora infestans / Q000472:pathogenicity / Q000502:physiology; D010935:Plant Diseases / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D057865:Plant Immunity / Q000235:genetics; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D016415:Sequence Alignment; D011198:Solanum tuberosum / Q000201:enzymology / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D014445:Tyrosine Decarboxylase / Q000235:genetics / Q000378:metabolism
chemical_list: D000577:Amides; D003373:Coumaric Acids; D010940:Plant Proteins; D000217:Acyltransferases; C108168:hydroxycinnamoyl-CoA-tyramine N-(hydroxycinnamoyl)transferase; D014445:Tyrosine Decarboxylase; D003066:Coenzyme A Ligases