Morphological and genetical studies on the geographical variants of shiitake

1998 Fiscal Year Final Research Report Summary

• Project/Area Number: 08640904
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 系統・分類
• Research Institution: The Japan Kinoko Research Center Foundation
• Principal Investigator: HASEBE Kozaburo The Japan Kinoko Res.Ctr.Foundation, The Tottori Mycological Institute, Research Scientist, 研究員 (10124330)
• Co-Investigator(Kenkyū-buntansha): SHIMOMURA Norihiro The Japan Kinoko Res.Ctr.Foundation, The Tottori Mycological Institute, Research, 研究員 (00250093)
• Project Period (FY): 1996 – 1998
• Keywords: F_1 hybrid / genetics / geographical strains / morphology / physiology / shiitake / taxonomy

Research Abstract

Pegler (1983) suggested that Shiitake (Lentinula edodes) contained three distinct species based on geographycal and morphological distinctions, They are L.lateritia from Papua New Guinea (PNG), L.novaezelandieae from New Zealand (NG) and L.edodes from Japan (JPN). We studied morphological and physiological characteristics of two strains each of the three variants together with F_1 hybrids between the component monokaryons of these six strains. The three variants are characterized by producing fruiting bodies with reddish brown pilei in PNG, with dark brown pilei and reddish brown fibrillose squamules on the stipes in NZ, and with medium brown pilei in JPN.Sizes and thickness of the pilei and stipes among and between the three variants were not consistent. From morphological characteristics shown in the F_1 hybrids, it seemed that the size and thickness in the pileus were under the control of many genes which individually exert a slight effect on the phenotypes. The F_1 hybrids of NZ X PNG and NG X JPN produced fruiting bodies with dark brown pilei. In the F_1 hybrids of JPN X PNG, two crosses between JPN and a certain component monokaryon of PNG produced fruiting bodies with medium brown pilei, and others produced with reddish brown. These results led to the assumption that the shades of brown would be expressed by additive effects of the dominant genes. The range of physiological variations such as the rates of spore germination and colony formation among the basidiospore progenies of the F_1 hybrids were about the same as those among the basidiospore progenies of the geographical variants tested, and the F_2 progenies were established without showing any abnormal mating response. All the F_2 populations, except one, exhibited a decrease in their mycelial growth resulting from inbreeding, and the extent of inbreeding depression expressed by the F_2 progenies was not so deviated from that by inbreeding progenies of geographical variants. These results indicate that Asia-Australasian shiitake variants that were divided into three distinct species based on morphological characters and geographical distribution (Pegler, 1983) are conspecific and belong to one morphologically variable spesies, i.e. Lentinula edodes.