Abstract
Epichloë endophytes enhance tolerance to metal stress in various cool-season grasses, but the mechanism of Epichloë-associated grasses responding to different concentrations of Na(2)SeO(3) are still unclear. After Festuca sinensis infected with (EI) or without (EF) Epichloë sinensis were grown for 90 days, the physiochemical and transcriptional profiling of glutathione metabolism in both shoots and roots over a period of 3 days was investigated in pot trials supplied with 0, 20, and 50 mg/L Na(2)SeO(3) using high-throughput RNA sequencing technology. Results of the study showed that Epichloë endophytes increased the glutathione reductase (GR) levels in shoots and roots and reduced the glutathione (GSH) and GSH/GSSG ratio in shoots. Treatment with 20 mg/L Na(2)SeO(3) resulted in elevated levels of GR and GSSG in both shoots and roots of EI and EF plants. In line with the accumulation of GSH in plant tissues, the endophyte enhanced the expression of GCLC (glutamate-cysteine ligase catalytic subunit), GR, APX (ascorbate peroxidase), and 5-OPase (5-oxoprolinase) in shoots in response to 20 mg/L Se, and Grx (glutaredoxin) on day 2 in the presence of Se, while reducing most GST (glutathione S-transferase) genes. Under selenium treatment, the expression of most GST and GR genes was upregulated in shoots of both EI and EF plants, with a higher accumulation of GST genes observed in roots. Our findings suggest that the Epichloë endophyte differentially activated plant glutathione metabolism depending on treatment duration under Se application and could represent a promising strategy for enhancing Se tolerance in F. sinensis.