Plants, fungi, and culture conditions
Seeds ofA.
sibiricum were collected from the experimental field of the Inner
Mongolia Grassland Ecosystem Research Station of the Chinese Academy of
Sciences (43° 38′ N, 116° 42′ E).
We separately prepared E. sibiricum -infected seeds and
endophyte-free seeds according to the methods reported in a previous
article (Shi et al ., 2020). Plump surface-sterilized seeds of EI
and EF plants were sown in square pots (length × width × height was
10×10×12 cm; one seed was sown in one pot) filled with vermiculite.
After 30 days of cultivation, the endophytic infection status of each
plant was inspected by trypan blue staining (Latch and Christensen,
1985). The endophytic infection rate in the EF plants was 0, and that in
the EI plants was 100%. Identical sizes of EF and EI seedlings were
selected and cultured for subsequent tests.
C.
lunata was provided by the
Agricultural Culture Collection of
China (ACCC) and cultured on potato dextrose agar (PDA) culture medium
at 25 °C for 15 days. To obtain a spore suspension of the pathogen, the
hyphae of the pathogenic fungus were washed with sterile water
(containing 0.02% Tween 20) and filtered through a double layer of
sterile gauze. The concentration of the pathogen spore suspension
quantified with a hemocytometer was 1.2 × 105spores/mL, and the spore germination rate was 80%.