Endophytic Fungi Activated Similar Defense Strategies of Achnatherum sibiricum Host to Different Trophic Types of Pathogens

It is well documented that endophytes can enhance the resistance of grasses to herbivory. However, reports on resistance to pathogenic fungi are limited, and their conclusions are variable. In this study, we chose pathogenic fungi with different trophic types, namely, the biotrophic pathogen species and the necrotrophic pathogen , to test the effects of on the pathogen resistance of . The results showed that, compared to species, caused a higher degree of damage and lower photochemical efficiency ( ) in endophyte-free (E-) leaves. Endophytes significantly alleviated the damage caused by these two pathogens. The leaf damaged area and of endophyte-infected (E+) leaves were similar between the two pathogen treatments, indicating that the beneficial effects of endophytes were more significant when hosts were exposed to than when they were exposed to species. We found that initiated jasmonic acid (JA)-related pathways to resist but salicylic acid (SA)-related pathways to resist species. Endophytic fungi had no effect on the content of SA but increased the content of JA and total phenolic compounds, which suggest that endophyte infection might enhance the resistance of to these two different trophic types of pathogens through similar pathways.