title: Homoserine and asparagine are host signals that trigger in planta expression of a pathogenesis gene in Nectria haematococca.
abstract: Some pathogenesis-related genes are expressed in fungi only when the pathogen is in the host, but the host signals that trigger these gene expressions have not been identified. Virulent Nectria haematococca infects pea plants and requires either pelA, which is induced by pectin, or pelD, which is induced only in planta. However, the host signal(s) that trigger pelD expression was unknown. Here we report the isolation of the host signals and identify homoserine and asparagine, two free amino acids found in uniquely high levels in pea seedlings, as the pelD-inducing signals. N. haematococca has evolved a mechanism to sense the host tissue environment by using the high levels of two free amino acids in this plant, thereby triggering the expression of pelD to assist the pathogenic process.
authors.affiliation: Biomolecular Science Center and Department of Molecular Biology and Microbiology, Burnett College of Biomedical Sciences, University of Central Florida, Orlando, FL 32816, USA.
authors.forename: Zhennai
authors.initials: Z
authors.lastname: Yang
authors.forename: Linda M
authors.initials: LM
authors.lastname: Rogers
authors.forename: Yuanda
authors.initials: Y
authors.lastname: Song
authors.forename: Wenjin
authors.initials: W
authors.lastname: Guo
authors.forename: P E
authors.initials: PE
authors.lastname: Kolattukudy
mesh_terms: D001216:Asparagine / Q000378:metabolism*; D005658:Fungi / Q000201:enzymology / Q000235:genetics / Q000472:pathogenicity*; D006714:Homoserine / Q000378:metabolism*; D006790:Host-Parasite Interactions / Q000235:genetics / Q000502:physiology; D030781:Organisms, Genetically Modified; D018532:Pisum sativum / Q000378:metabolism / Q000382:microbiology*; D011133:Polysaccharide-Lyases / Q000096:biosynthesis / Q000235:genetics*; D011401:Promoter Regions, Genetic; D036226:Seedlings / Q000378:metabolism / Q000382:microbiology
chemical_list: D006714:Homoserine; D001216:Asparagine; D011133:Polysaccharide-Lyases; C023911:pectate lyase