Transcription factors FfMYB9 and FfMYB13 jointly activate the expression of hydrophobin gene FfHyd19 to mediate fruiting body morphogemesis in Flammulina filiformis.

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Citation abstract

Hydrophobins (Hyds) are small cysteine-rich proteins secreted by fungi. Hydrophobin-encoding genes have been demonstrated to play important physiological roles in the fruiting process of macro-fungi. However, a systematic study on the Hyd genes of Flammulina filiformis and its transcriptional regulation mechanism remains limited. In this study, 19 F. filiformis Hyd (FfHyd) genes were identified and unevenly distributed on 6 chromosomes with molecular weights ranging from 10.4 to 14.72 kDa. Phylogenetic analysis indicated that 19 FfHyds showed low homology with those of Lentinula edodes. Expression analysis revealed that FfHyd19 showed a significantly up-regulated expression in primordium and fruiting body stage. Overexpression of FfHyd19 could promote mycelial growth and primordium formation, as well as enhance stipe elongation. Consistent with this, RNAi-FfHyd19 exhibited opposite results. Furthermore, we found that the expression patterns of FfMYB9 and FfMYB13 were similar to the trend of FfHyd19. The result of EMSA and dual luciferase reporter experiments demonstrated that both FfMYB9 and FfMYB13 could activate the FfHyd19 promoter by recognizing the MYB element. Collectively, these findings provides comprehensive information for FfHyd gene family and shed new insights for understanding the functional research and transcription regulatory mechanism of these macrofungus hydrophobic proteins.