Heat shock protein 9 mRNA expression increases during fruiting body differentiation in Grifola frondosa and other edible mushrooms

•We have isolated HSP9 from G. frondosa, P. eryngii, H. marmoreus, and L. edodes.•The predicted tertiary structures of these HSP9s showed all the same structure.•The expression of HSP9s increased in a fruiting body differentiation-dependent manner.•These results suggest HSP9 is associated with the fruiting body differentiation.

We isolated a homolog of Schizosaccharomyces pombe HSP9 from Grifola frondosa and designated it Gf.HSP9. The Gf.HSP9 gene consisted of four exons and three introns and encoded 84 amino acid residues. We have also identified related HSP9 genes from Pleurotus eryngii (Pe.HSP9), Hypsizygus marmoreus (Hm.HSP9), and Lentinula edodes (Le.HSP9). The predicted tertiary structures of these HSP9s were the same. In addition, the expression pattern of their mRNA increased during fruiting body in a differentiation-dependent manner. These results suggested that HSP9 was associated with the fruiting body differentiation in these four edible mushrooms.