UPLC-ESI-TOF-MS Profiling of Metabolome Alterations in Barley (Hordeum vulgare L.) Leaves Induced by Bipolaris sorokiniana

Spot blotch of barley (Hordeum vulgare L.), caused by Bipolaris sorokiniana, is responsible for major losses in crop yield. Breeding-resistant barley varieties have proven to be an effective countermeasure for protecting agricultural production. Plants react to pathogen attacks by up-regulating secondary metabolites. Marker compounds for a B. sorokiniana infection are examined by untargeted UPLC-TOF-MS metabolomics and lipidomics techniques. Through the analysis of nine quantitatively resistant and susceptible barley genotypes, derived from the nested association mapping population HEB-25, followed by structure identification experiments and spore germination assays, 57 metabolites are identified. In addition to previously known metabolites, the unknown compounds 5-carboxydidehydroblumenol C-9-O-ß-d-glucoside (46) and grasshopper ketone 3-sulfate (47) were elucidated. 5-Carboxyblumenol C-9-O-ß-d-glucoside (45) was described for the first time in barley leaves. Pheophytin derivatives, oxylipins, linolenate-conjugated lipids, and flavone glycosides were described for the first time in connection with infections by phytopathogenic fungi or resistance in barley.