Sporocarp Ontogeny in Panus (Basidiomycotina): Evolution and Classification David S. Hibbett; Shigeyuki Murakami; Akihiko Tsuneda American Journal of Botany, Vol. 80, No. 11. (Nov., 1993), pp. 1336-1348. Stable URL: http://links.jstor.org/sici?sici=0002-9122%28199311%2980%3A11%3C1336%3ASOIP%28E%3E2.0.CO%3B2-M American Journal of Botany is currently published by Botanical Society of America. Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at http://www.jstor.org/about/terms.html. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at http://www.jstor.org/journals/botsam.html. 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HIBBETTSHIGEYUKI,~ MURAKAMI, AN D AKIHIKOTSUNEDA Tottori Mycological Institute, 21 1 Kokoge, Tottori 689-1 1 Japan Ontogenies of cultured Panus conchatus, P. rudis, and P. fulvus sporocarps were observed macroscopically and with scanning electron microscopy. Hymenophore differentiation in Panus involves periclinal growth of context hyphae below a closed surface palisade of hymenial elements, resulting in a cantharelloid appearance and radiate trama. This pattern is qualitatively different from that in Lentinus s. str., which suggests that lamellae of Panus and Lentinus are not homologous. Panus conchatus and P. rudis sporocarps have short stipes, develop directly from the mycelium, and mature in 5-10 d. Panus fulvus sporocarps have an elongate stipe, develop from a pseudosclerotium, and mature in about 3 wk, the first approximately 15 d of which involve apical elongation of a stipelike primordium that is able to dedifferentiate and regenerate cut apices. Panus conchatus and P. rudis sporocarps lacked regeneration ability. Panus conchatus sporocarps developed an ephemeral partial veil that was obliterated during sporocarp expansion. Outgroup comparison suggests that evolutionary changes in developmental programs in Panus have included: 1) delay in offset of primordium growth, with a corresponding increase in primordium size and time to maturation (hypermorphosis); 2) insertion of the pseudosclerotial stage in ontogeny; 3) gain of ability for dedifferentiation and regeneration; and 4) nonterminal gain or loss of veil tissue. The generic limits and phylogenetic relationships of chemistries. In basidiomycetes, two major classes ofwood Panus Fr. and Lentinus Fr. are controversial (Corner, decay type are recognized: 1) white rot, in which both 1981; Hibbett and Vilgalys, 1993; Pegler, 1983). Both lignin and cellulose are degraded; and 2) brown rot, in genera include wood-decaying basidiomycetes that have which lignin is not appreciably degraded. In 1985, Red- a tough dimitic construction, decurrent lamellae, and cy- head and Ginns segregated the brown rot species of Panus lindric to ellipsoid hyaline spores. Panus and Lentinus and Lentinus as Neolentinus Redhead and Ginns and are found on all continents except Antarctica, and reach Heliocybe Redhead and Ginns. Neolentinus and Heliocybe their greatest density and species diversity in the tropics correspond to parts of Lentinus subg. Panus sensu Pegler, (Corner, 198 1; Pegler, 1983). Panus sensu Corner, and Lentinus sensu Singer and Kiihner Major treatments for Panus and Lentinus include those (this distribution illustrates the conflict between the pre- of Corner (1 98 1), Kuhner (1 980), Pegler (1 983), and Sing- vious classifications). er (1 986). Each is unique in its delimitation of Panus and Recently, molecular characters have been applied to Lentinus. Pegler and Corner both strongly emphasized systematics of Panus and Lentinus (Hibbett and Vilgalys, the system of sporocarp hyphal analysis that was devel- 199 1, 1993). These studies included distance-based anal- oped by Corner (1932). Pegler (1983) included Panus as yses of restriction fragment length polymorphisms in ri- a subgenus ofLentinuswhereas Corner (198 1) maintained bosomal DNA (rDNA, Hibbett and Vilgalys, 199 l), and Panus as a distinct genus, but their classifications are cladistic analyses of rDNA sequence data, alone or in otherwise essentially parallel. In contrast, Singer (1986) conjunction with morphological characters (Hibbett and and Kuhner (1980) emphasized the anatomy of the hy- Vilgalys, 1993). The rDNA data supported the monophyly menophoral trama and the number of nuclei per spore in of Lentinus sensu Corner (1981), Neolentinus (in large their treatments of Panus, Lentinus, and other lentinoid- part), and a restricted concept of Panus. In the cladistic pleurotoid fungi. Consequently, even though there are analyses of rDNA sequence data, Panus s. str. was rep- significant differences between the Singer and Kuhner resented by P. conchatus (Bull.: Fr.) Fr., which is the type classifications, they are more similar to each other than species of Panus (Corner, 198 1; Pegler, 1983), P. rudis either is to the Pegler or Corner classifications. The dis- Fr., and P. fulvus (Berk.) Pegler and Rayner. The mono- crepancies between the Corner-Pegler and Singer-Kuhner phyly of the clade containing these species was strongly treatments are exacerbated by disagreements about the supported by both bootstrap (Felsenstein, 1985) and de- type species of Panus and Lentinus. cay index (Mishler, Donoghue, and Albert, 1991) mea- The Corner, Kuhner, Pegler, and Singer classifications sures of topological robustness. were constructed without consideration of wood decay Some polypores and bracket fungi are anatomically similar to Panusand Lentinus (Corner, 198 1; Pegler, 1983). Consequently, some authors place Panus and Lentinus in I Received for publication 16 March 1993; revision accepted 1 June 1993. the Polyporaceae, despite the fact that Panusand Lentinus The authors thank their colleagues at the Tottori Mycological Institute are gilled mushrooms (e.g., Singer, 1986). The rDNA stud- for assistance; Harold H. Burdsall, Jr., Orson K. Miller, Jr., and Rytas ies supported the view that Lentinus s. str. is derived from Vilgalys for donating fungal isolates; and Wilma L. Lingle and Scott Polyporus Fr., but did not indicate that Panus is derived Redhead for comments on the manuscript. This research was supported from polypore fungi. This suggests that the lamellae of by a Science and Technology Agency of Japan Postdoctoral Research Panus and Lentinus are not homologous, but rather are Fellowship to DSH. Paper number 279 of the Tottori Mycological In- stitute. products of convergent evolution. Author for correspondence, current address: Harvard University We have previously investigated ontogeny of the Len- Ferbaria, 22 Divinity Avenue, Cambridge, MA 02138. tinus s. str. hymenophore using scanning electron mi- November 19931 HIBBETTET AL. -PANUSONTOGENY 1337 croscopy (SEM) of cultured sporocarps (Hibbett, Muraka- TABLE1. Panus isolates used in this study. mi, and Tsuneda, 1993). In the present paper, we report developmental observations of three species of Panus s. Species Isolate number8 Country of origin str. Our primary objective in this work was to determine P. conchatus VT- 1502 USA if there are developmental differences between the pu- TMI- 1293 Japan tatively convergent Panus and Lentinus hymenophores. TMI- 1294 Japan TMI- 1295 Japan Such differences would corroborate our previous molec- P. rudis VT-9 15 USA ular phylogenetic hypotheses, and support the taxonomic VT-340 USA segregation of Panus and Lentinus. D-743 USA We were also interested in comparing sporocarp on- TMI- 183 Japan togenies within Panus. Panus conchatus and P. rudis have P. fulvus FPL-4 147 USA short lateral to excentric (occasionally central) stipes, but a VT isolates were provided by Dr. Orson K. Miller, Jr., Virginia P.fulvus has a slender, elongate central stipe whose length Polytechnic Institute, Blacksburg, Virginia. FPL isolate was provided far exceeds pileus diameter. In addition, P. fulvus spo- by Dr. Harold H. Burdsall, Jr., USDA Forest Products Laboratory, rocarps develop from a pseudosclerotium (Petch, 19 15; Madison, Wisconsin. D isolate was provided by Dr. Rytas Vilgalys, Corner, 198 1; Pegler, 1983) that is lacking in P. conchatus Department of Botany, Duke University, Durham, North Carolina. TMI isolates are from culture collection of Tottori Mycological Institute. and P. rudis. (Pseudosclerotia are composed of wood sub- All isolates are deposited at TMI. strates infiltrated by hyphae, whereas true sclerotia are composed only of hyphae.) Our second objective was therefore to understand