2.2 Inoculation of T. controversa and T. laevis
For inoculation, wheat seeds were sterilized with 30% sodium hypochlorite for 5 min, rinsed 5 times in water, and germinated for 30 days in incubator (AUCMA, Qing Dao, China) to vernalize. Then seedlings were grown in a 1:2 mixture of organic matter (peat moss, Beijing, China) and soil (Beijing, China) in pots. Seedlings for the T. controversa experiment were grown in a 14 h light/10 h dark at 5 °C while for the T. laevis experiment at 15 °C to the tillering stage and both at 25 °C at the boot stage. At the early boot stage, the spikes were injected with 1 ml inoculum suspensions of T. controversa or T. laevis when the young tassels of wheat were still wrapped by leaf sheaths. The suspension contained infectious hyphae at the concentration of 106 cfu/ml with the OD600 of 0.15. Inoculation was repeated 5 times with one day interval. Plants injected with sterilized ddH2O were grown under the same conditions for use as the control treatment.