Integrative Transcriptome and Metabolome Analyses of the Interaction of Oat–Oat Stem Rust

Abstract

Stem rust, caused by Puccinia graminis f. sp. avenae (Pga) Eriks. and E. Henn., is a worldwide and harmful disease of oat (Avena sativa L.). Currently, no resistant varieties are used in production as the molecular resistance mechanism of oat to stem rust remains unclear. Here, oat plants were inoculated with Pga pathogens, and the metabolome and transcriptome of leaves were detected to investigate the molecular and physiological changes. Our results showed that Pga inoculation increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and phenylalnine ammonialyase (PAL), which triggered defense responses. The transcriptomic and metabolomic analyses were performed to detect the key genes and metabolites of oat interacting with Pga. We identified 1814 upregulated and 1955 downregulated genes in Pga infected leaves. These genes were mainly involved in the ‘phenylpropanoid biosynthesis’, ‘flavonoid biosynthesis’, and ‘photosynthesis-antenna proteins’. We also detected 162 differential metabolites between Pga-infected and non-infected leaves, including flavonoids and derivatives, amino acids, organic acids, and carbohydrates. The integrated analysis revealed four pathways, including the ‘citrate cycle’, ‘cysteine and methionine metabolism’, ‘tryptophan metabolism’, and ‘glyoxylate and dicarboxylate metabolism’. The networks for these pathways were subsequently constructed. Overall, the results suggested that oat plants fight against Pga by activating the metabolism of amino acids, organic acids, and flavonoids. This study provides valuable molecular information about the response of oat to Pga infection.