Shiitake mushrooms and molecular clocks: historical biogeography of Lentinula

Abstract

Aim Fungi make up a large, ecologically important group of eukaryotes that has been neglected in historical biogeography. In this study, molecular phylogenies and molecular clock dating were used to infer historical biogeography of the shiitake genus, Lentinula Earle, which occurs in both the Old World and New World. The major goals of this study were to determine if the Old World and New World groups are monophyletic, and whether the Old World/New World disjunction is the result of vicariance or long distance dispersal. Location Collections studied are from Asia, Australasia, the Gulf Coast region of North America, the Caribbean, Central America, and northern South America. Methods Phylogenetic trees were inferred with nuclear large subunit (nuc‐Isu) ribosomal DNA (rDNA) and internal transcribed spacer (ITS) sequences. Molecular clock dating was performed using trees derived from nuc‐Isu rDNA and mitochondrial small‐subunit (mt‐ssu) rDNA sequences. Rate constancy was tested with maximum likelihood, and clocks were calibrated using evidence from fossils or other molecular clock studies, or according to expected ages under different historical biogeographic scenarios. Results Analyses of ITS and nuc‐Isu rDNA sequences suggest that there are seven species of Lentinula worldwide, which occur in two main clades, one in the New World the other in the Old World. Rate constancy cannot be rejected in nuc‐Isu rDNA, but can be rejected in mt‐ssu rDNA. Both genes suggest that the Old World/New World disjunction could be due to fragmentation of an ancient Laurasian range. An alternative Gondwanan hypothesis is not supported by the molecular clock age estimates. Main conclusions Only one long distance dispersal event must be invoked in Lentinula, that being between Australia and New Zealand. Despite having airborne spores, it appears that long distance dispersal is rare in Lentinula. This may also be true in other fungi, which are therefore excellent candidates for historical biogeographic studies using molecular characters.

The biogeographical speciations of shiitake Lentinula edodes and a new species Lentinula platinedodes sp. nov. found in Cat Tien, South Vietnam

“…(1998) [5], Hibbett (2001) [6], TrÞnh Tam KiÖt (1981) [8], Mata & Petersen (2000, 2001 [9,10], kÕt hîp tra cøu vµ so s¸nh trªn internet.…”

“…Nh− vËy, cã thÓ cho r»ng L. edodes lµ loµi trung t©m, gÇn nhÊt víi nhãm tae tiªn cña Lentinula, khi ph¸t t¸n sang c¸c vïng nhiÖt ®íi ® ph©n hãa m¹nh, cã lÏ nh¸nh ph¸t t¸n sang ch©u Mü còng tõ L. edodes qua ch©u ¢u vµ qua eo biÓn Berrhing tõ h¬n 34 triÖu n¨m vÒ tr−íc [6]. Sù ph©n hãa tiÕp tôc ® dÉn ®Õn sù h×nh thµnh c¸c loµi kh¸c nh− L. aciculospora, L. boryana vµ L. raphanica.…”

“…(1995Hibbett vµ nnk. ( , 1998 [4,5] vµ Hibbett (1992Hibbett ( , 2001 , lowerland of Dong Nai province, particularly among which the last one is showing high similarity in morphological characters with both Amarica's Shiitake -type species, Lentinula boryana and L. edodes, due to the forms at different stages of development of fruitbodies, collected in the wild. This new species showed some phenotypte forms similar to each others in their early stages of morphological genesis of young fruitbodies in nature and in cultivations.…”

“…VÊn ®Ò lµ cÇn chØ ra ®−îc nh÷ng dÉn chøng cho thÊy nhãm ë T©y b¸n cÇu còng cã quan hÖ trùc tiÕp víi nhãm ë §«ng b¸n cÇu, v× trªn thùc tÕ chóng rÊt bÊt t−¬ng hîp [2,9]. NhiÒu dÉn liÖu thùc nghiÖm vÒ gi ¶i tr×nh tù nhiÒu gene (kÓ c ¶ gene tubulin, gene ty thÓ) còng ®−îc ¸p dông chøng tá qu¸ tr×nh ph©n hãa vµ mèi quan hÖ chAEt chÏ nµy [6,10,13,22]. HiÖn vÉn chØ lµ gi ¶ thiÕt r»ng chóng cã tae tiªn chung mµ ch−a cã dÉn liÖu thuyÕt phôc vÒ kh ¶ n¨ng quan hÖ trùc tiÕp.…”

“…NhËn ®Þnh cña Hibbett vµ nnk. (1998) [5], Hibbett (2001) [6] cho r»ng tae tiªn cña c¸c loµi Lentinula cã thÓ lµ vïng T©y Nam Th¸i b×nh d−¬ng dùa trªn ý kiÕn vÒ c¸c ®¹i diÖn cã tÝnh nguyªn s¬ nh− L. lateritia vµ L. boryana. Thùc ra, chÝnh Pegler (1983) [15] cho r»ng, ®¹i diÖn nguyªn s¬ L. lateritia chØ lµ d¹ng ph©n hãa nhiÖt ®íi cña L. edodes, nghÜa lµ chóng thø sinh.…”