Resistance in Triticeae to fusarium head blight (FHB) is quantitatively inherited. Metabolomics as a tool was used to better understand the mechanisms of resistance and to identify potential FHB resistance biomarker metabolites in barley. Five FHB-resistant two-row barley genotypes (CIho 4196, Zhedar-1, Zhedar-2, Fredrickson, and Harbin-2r) and one FHB-susceptible genotype (CH 9520–30) were each inoculated with either pathogen-suspension or mock-solution. Disease severity, quantified as the proportion of spikelets diseased, varied among genotypes, being the greatest in CH 9520–30. Spikelets were sampled, metabolites extracted with aqueous methanol, and analyzed using an LC-ESI-LTQ-Orbitrap system. A pair wise, resistant vs. susceptible, t-test identified 1774 significant treatment peaks. Canonical discriminant analysis of peak abundance allowed the genotypes to be sorted into three clusters: (i) CH9520-30, (ii) Harbin-2r, (iii) the remaining four genotypes. The t-test was further used to identify resistance-related (RR) and pathogenesis-related (PR) metabolites. The pathogen-produced virulence factor deoxynivalenol (DON), and its detoxification product, DON-3-O-glucoside (D3G) were designated as resistance indicator (RI) metabolites. Metabolites (RR, PR, or RI) occurring in at least two resistant genotypes, showing a two-fold or greater abundance in resistant vs. susceptible lines, and also known to have plant defense functions were selected as potential FHB resistance biomarker metabolites. These included phenylalanine, p-coumaric acid, jasmonate, linolenic acid, total DON produced (TDP), and the proportion of DON converted to D3G (PDC). Total DON was the lowest in CIho 4196, while PDC was the highest in Zhedar-2. The application of RR, PR, and RI metabolites as potential biomarkers to enhance resistance is discussed.
Fusarium graminearumGibberella zeaeBiomarkers Metabolomics Functional genomics Barley FHB DON
Supplementary Table S1Phenylpropanoid, flavonoid and fatty acid RR metabolites identified in five Fusarium head blight (FHB) resistant barley genotypes, as compared to susceptible CH 9520–30 (DOC 80 kb)
Figure S1DON and its adduct, DON + CH3COO−, 3ADON and its adduct 3ADON + CH3COO−, and DON-3-O-glucoside (D3G) and and its adduct, D3G + CH3COO-, each of the three at one retention time (RT) (PPT 677 kb)
Figure S2Abundances of DON, D3G, and 3ADON and their adducts in barley based on LC-LTQ-Orbitrap: a) Abundances of DON and DON + CH3COO−; b) Abundances of D3G and D3G + CH3COO−; c) Abundances of 3−ADON and 3-ADON + CH3COO− in lemma + palea of six barley genotypes inoculated with F. graminearum under greenhouse conditions, based on LC-ESI-LTQ-Orbitrap analysis (PPT 130 kb)