Fungal Growth and Phytoalexin Assay

Botrytis cinerea strain AI18 (Kuroyanagi et al., 2022 (link)), Epichloë festucae strain Fl1 (Young et al., 2005 (link)) and their transformants used in this study are listed in Supplementary Table 1. They were grown on potato dextrose agar (PDA) at 23°C. For the incubation in phytoalexins, mycelia plugs (approx.1 mm³) were excised from the growing edge of the colony using a dissection microscope (Stemi DV4 Stereo Microscope, Carl Zeiss, Oberkochen, Germany) and submerged in 50 μl of water or indicated phytoalexin in a sealed 96 well clear plate. The plate was incubated at 23°C for the indicated time.
Capsidiol was purified from Nicotiana tabacum as previously reported (Matsukawa et al., 2013 (link)) and synthesized rishitin (Murai et al., 1975 (link)) was provided by former Prof. Akira Murai (Hokkaido University, Japan). Resveratrol and brassinin were obtained from Sigma-Aldrich (Burlington, MA, USA). Glyceollin (glyceollin I) was obtained from Wako pure chemical (Osaka, Japan). Medicarpin was obtained from MedChemExpress (Monmouth Junction, NJ, USA).