Local and systemic effects of oxylipins on powdery mildew infection in barley.
Treatment of the first leaves of barley seedlings with the oxylipin colneleic acid, or the two trihydroxy oxylipins 9,12,13-trihydroxy-11(E)-octadecenoic acid and 9,12,13-trihydroxy-10(E)-octadecenoic acid, reduced infection of that leaf by the powdery mildew fungus Blumeria graminis Speer f sp hordei Marchal. When applied to first leaves, etheroleic acid and colneleic acid, as well as the trihydroxy oxylipin 9,12,13-trihydroxy-10(E),15(Z)-octadecadienoic acid, also reduced mildew infection in second leaves. In all cases where local and systemic effects against mildew were observed, activity of the defence-related enzyme phenylalanine ammonia lyase (PAL) was increased, but only following challenge inoculation with powdery mildew. Peroxidase activity was not affected by oxylipin treatment or mildew inoculation. Whether the effects observed were due to the oxylipins or to breakdown products is not known, since no information is available on the stability of these particular oxylipins on leaf surfaces. Nevertheless, these data represent the first report of systemic effects against pathogen infection following pre-treatment with oxylipins.
Cowley
Tracy
T
Crop & Soil Research Group, Scottish Agricultural College, King's Buildings, West Mains Road, Edinburgh EH9 3JG, UK.
Walters
Dale
D
D001203:Ascomycota / Q000187:drug effects*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D005659:Fungicides, Industrial / Q000494:pharmacology*; D001467:Hordeum / Q000187:drug effects* / Q000382:microbiology*; D018515:Plant Leaves / Q000187:drug effects / Q000382:microbiology
D005231:Fatty Acids, Unsaturated; D005659:Fungicides, Industrial; C095608:etheroleic acid; C002946:colneleic acid