Primary Metabolomic Profiling Associated with Rice Blast Resistance

Abstract

 This research aimed to apply metabolomics technology to investigate changes in rice metabolites in response to infection by the rice blast pathogen Pyricularia oryzae. The blast-resistant rice varieties (Hangyee 71 and RD59) and blast-susceptible rice varieties (KDML 105 and PTT1) were used. The thirty-day-old rice plants were inoculated with a spore suspension of P. oryzae at a concentration of 5×10⁴ spores×mL^-1. The leaf samples were collected 8 and 12 hours, and 1–7 days after inoculation. Metabolite profiling was performed using comprehensive two-dimensional gas chromatography with      a time-of-flight mass spectrometer (GCxGC-TOFMS). The results revealed distinct metabolic profiles between the blast-resistant and blast-susceptible rice varieties. In the resistant rice varieties,  a significant increase (p≤0.1) in phenylalanine, citrulline, and shikimic acid was detected three days after inoculation, whereas in the susceptible cultivars these metabolites were observed, starting five days after inoculation. These compounds are key precursors in the phenylpropanoid and shikimate pathways, which are associated with plant defense mechanisms. In addition, the resistant rice varieties showed the presence of methoxyflavone, an antioxidant compound, and salicylic acid, a plant hormone involved in defense induction. These findings provide insights into the metabolic mechanisms underlying rice blast resistance.