Abstract:
Metabolic changes in sorghum seedlings in response to Paenibacillus alvei (NAS-6G6)-induced systemic resistance against Fusarium pseudograminearum crown rot were investigated by means of untargeted ultra-high performance liquid chromatography-high definition mass spectrometry (UHPLC-HDMS). Treatment of seedlings with the plant growth-promoting rhizobacterium P. alvei at a concentration of 1 × 108 colony forming units mL- 1 prior to inoculation with F. pseudograminearum lowered crown rot disease severity significantly at the highest inoculum dose of 1 × 106 spores mL-1. Intracellular metabolites were subsequently methanol-extracted from treated and untreated sorghum roots, stems and leaves at 1, 4 and 7 days post inoculation (d.p.i.) with F. pseudograminearum. The extracts were analysed on an UHPLC-HDMS platform, and the data chemometrically processed to determine metabolic profiles and signatures related to priming and induced resistance. Significant treatment-related differences in primary and secondary metabolism post inoculation with F. pseudograminearum were observed between P. alvei-primed versus naïve S. bicolor seedlings. The differential metabolic reprogramming in primed plants comprised of a quicker and/or enhanced upregulation of amino acid-, phytohormone-, phenylpropanoid-, flavonoid- and lipid metabolites in response to inoculation with F. pseudograminearum.
Description:
Supplementary Materials: Figure S1. (A) Microscopic identification of F. pseudograminearum at 400 × magnification.
(B) Conidial morphology of F. pseudograminearum taken from Aoki et al. [65]. Figure S2. UHPLC-HDMS BPI
chromatograms of ESI-positive data indicating the metabolomic profiles of untreated (black), naïve infected (blue)
and primed infected (green) stems obtained at 1 d.p.i. with F. pseudograminearum. Figure S3. UHPLC-HDMS BPI
chromatograms of ESI-positive data indicating the metabolomic profiles of untreated (black), naïve infected (blue)
and primed infected (green) leaves obtained at 1 d.p.i. with F. pseudograminearum. Figure S4. PCA score/scatter plot
of stem samples computed from ESI-positive data. Figure S5. PCA score/scatter plot of leaf samples computed from
ESI-positive data. Figure S6. PCA score/scatter plot of root samples computed from ESI-negative data. Figure S7.
PCA score/scatter plot of stems samples computed from ESI-negative data. Figure S8. PCA score/scatter plot of
leaves samples computed from ESI-negative data. Figure S9. OPLS-DA modelling and variable/feature selection
ESI-positive data (stem samples). Figure S10. OPLS-DA modelling and variable/feature selection ESI-positive
data (leaf samples). Table S1. Summary of the description and validation of all the generated OPLS-DA models
separating naïve versus primed S. bicolor plants. Figure S11. Summary of pathway analysis with MetPA. Figure S12.
Venn diagram comparing the number of metabolites shown in Table 2 that were significantly upregulated at 1 d.p.i.
(blue), 4 d.p.i. (yellow) and 7 d.p.i. (green) with F. pseudograminearum in primed versus naïve S. bicolor seedlings.
