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

Kawaguchi, Nobuhisa, Hayashi, Mirai, Chen, Fu-Chia, Shimomura, Norihiro, Yamaguchi, Takeshi, Aimi, Tadanori
Journal of wood science 2019 v.65 no.1 pp. 32
Grifola frondosa, albino, backcrossing, color, enzymes, frameshift mutation, fruiting bodies, genes, genetic analysis, genotype, mushrooms, mutants, oligodeoxyribonucleotides, polymerase chain reaction, translation (genetics)
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.