title: Unveiling the phytoalexin biosynthetic puzzle in salt cress: unprecedented incorporation of glucobrassicin into wasalexins A and B.
abstract: Salt cress (Thellungiella salsuginea also known as T. halophila) is a wild cruciferous extremophile highly resistant to salt, drought, and cold. The recent discovery that salt cress produces the phytoalexins wasalexins A and B, and the phytoanticipins 1-methoxyglucobrassicin and 4-methoxyglucobrassicin in relatively higher amounts than other cruciferous species, prompted investigation of their biosynthetic relationships. Toward this end, perdeuterated 1-methoxybrassinin, l-Trp, glucobrassicin, 1-methoxyindolyl-3-acetaldoxime, brassinin, and methionine, as well as the corresponding natural abundance compounds, were administered to salt cress plants previously irradiated with UV-light (λ(max) 254 nm). Remarkably, administration of hexadeuterated glucobrassicin led to incorporation of several deuterium atoms into wasalexins A and B, 1-methoxyglucobrassicin and 4-methoxyglucobrassicin. This unprecedented discovery suggests that glucobrassicin is a biosynthetic precursor of wasalexins and methoxylated glucosinolates in salt cress.
authors.affiliation: Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada. s.pedras@usask.ca
authors.forename: M Soledade C
authors.initials: MS
authors.lastname: Pedras
authors.forename: Estifanos E
authors.initials: EE
authors.lastname: Yaya
authors.forename: Sajjad
authors.initials: S
authors.lastname: Hossain
mesh_terms: D019607:Brassicaceae / Q000378:metabolism* / Q000528:radiation effects; D003903:Deuterium / Q000378:metabolism; D005961:Glucosinolates / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D007211:Indoles / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism / Q000528:radiation effects; D012717:Sesquiterpenes / Q000737:chemistry / Q000378:metabolism*; D013440:Sulfides / Q000737:chemistry / Q000378:metabolism*; D013859:Thiocarbamates / Q000737:chemistry / Q000378:metabolism; D014466:Ultraviolet Rays; D000094162:Phytoalexins
chemical_list: D005961:Glucosinolates; D007211:Indoles; D012717:Sesquiterpenes; D013440:Sulfides; D013859:Thiocarbamates; C401941:wasalexin A; C089020:brassinin; D003903:Deuterium; C048308:glucobrassicin; D000094162:Phytoalexins