Epichloë Endophyte Improves Ergot Disease Resistance of Host (Achnatherum inebrians) by Regulating Leaf Senescence and Photosynthetic Capacity

Epichloë gansuensis and Claviceps purpurea are common species of Clavicipitaceae on drunken horse grass (Achnatherum inebrians). We conducted an inoculation test by spraying a spore suspension of C. purpurea during the flowering stage of drunken horse grass. The disease incidence, disease index, chlorophyll content, leaf senescence characteristics, and photosynthetic indexes of symbiotic (E +) and non-symbiotic (E-) drunken horse grass were measured 15 days after inoculation. A. inebrians-endophyte symbionts showed, which delayed the senescence of leaves, increased the activity of superoxide dismutase, peroxidase, catalase, and proline content, reduced malondialdehyde content, and increased leaf chlorophyll content and photosynthetic rate. Epichloë endophyte significantly (P < 0.05) reduced the incidence and disease index of ergot disease. The structural equation models showed that endophyte indirectly reduced the incidence of ergot disease by affecting malondialdehyde content. It was the first time to successfully inoculate ergot pathogen into the grass-endophyte symbionts. Epichloë endophyte reduced the colonization of the grass by C. purpurea.