Genetic analyses of causal genes of albinism (white fruiting body) in Grifola frondosa

Nobuhisa Kawaguchi,Takeshi Yamaguchi,Mirai Hayashi,Fu-Chia Chen,Norihiro Shimomura,Tadanori Aimi

doi:10.1186/s10086-019-1811-7

Abstract

The tyrosinase 2 gene (tyr2) from two compatible strains of Grifola frondosa, the albino-type monokaryon strain IM-WM1-25 and the wild-type monokaryon strain IM-BM11-P21, were amplified and characterized (designated tyr2−Δ25 and tyr2+, respectively). A single base deletion in the coding region of tyr2−Δ25 from IM-WM1-25 was discovered, and this mutation is predicted to cause a frame-shift in translation, yielding inactive protein tyrosinase protein 2 (TYR2). Polymerase chain reaction (PCR) primer pairs were designed to detect normal tyr2+ and mutant tyr2−Δ25, and then the tyr2 genotype of F1 progenies, which was obtained from basidiospore isolation of IM-BM11-P21 × IM-WM1-25 (tyr+ × tyr2−Δ25) strain, was analyzed. Back-crossing (F1 progenies × IM-WM1-25) was performed and fruiting body colors of the crossed strains were analyzed. The fruiting bodies of all crossed strains were white and beige, and the corresponding genotypes were tyr2−Δ25 × tyr2−Δ25 and tyr+ × tyr2−Δ25. These results suggest that the causal gene of the albino mutation is tyr2 and this study provides a new strategy for the breeding of albino mushrooms belonging to G. frondosa.

Highlights

Grifola frondosa is a polyporous basidiomycete that grows on decaying wood and an economically important edible mushroom called ‘‘Maitake’’ [1]
Amplification deoxyribonucleic acid (DNA) sequence of tyrosinase protein 2 (TYR2) from G. frondosa In a previous study, we showed that TYR2 is closely related to the fruiting body color and melanin production [3]
Comparison of tyr2 in wild‐type and albino‐type strains Tyr2 from wild-type monokaryotic strain IM-BM11-P21 is designated tyr2+, with a nucleotide sequence from the initial ATG to the stop codon of the coding region consisting of 1866 bp and encoding 621 amino acids

Summary

Introduction

Grifola frondosa is a polyporous basidiomycete that grows on decaying wood and an economically important edible mushroom called ‘‘Maitake’’ [1]. Due to recent advances in bottle or plastic bag cultivation technology in Japan, this mushroom is available in domestic markets throughout the year. In 2016, Japanese annual production of Maitake was 48,523 ton [2]. Maitake is a delicious mushroom but dark brown pigment was extracted from fruiting body into supernatant. The fruiting body of G. frondosa consists of a dark brown cap that is colored with visible dark and white stripes. This mushroom exhibits pigmentation from the primordia stage until mature fruiting body formation.

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