A putative transcription factor Gf.BMR1 in Grifola frondosa, the homolog of BMR1 in Bipolaris oryzae, was strongly induced by near-ultraviolet light and blue light

• Near-ultraviolet light can forcefully darken and expand Grifola frondosa pilei.
• A putative transcription factor Gf.BMR1 was induced by near-ultraviolet light and blue light.
• Gf.BMR1 contains two Cys2His2 zinc fingers and a Zn(II)2Cys6 binuclear cluster.
• Pileus darkening and expansion in G. frondosa is not regulated solely by Gf.BMR1.

Near-ultraviolet (NUV) light and blue light have different effects on fungal fruiting body development. However, while blue light signaling has been well studied, the process of NUV-induced signals transduction remains unclear. In this study, we found that NUV light caused the pileus of Grifola frondosa to darken in color and double in expansion compared to when it was exposed to blue light, suggesting that G. frondosa distinguishes between NUV light and blue light. We then sought a putative transcription factor expressed under NUV light and identified Gf.BMR1, which has the same two Cys2His2 zinc finger domains and one Zn(II)2Cys6 binuclear cluster in the N-terminus as the melanin biosynthesis regulation protein, BMR1, in Bipolaris oryzae. However, the level of expression induced by both NUV light and blue light was the same. This result suggested that pileus darkening and expansion in G. frondosa are not regulated solely by Gf.BMR1.