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Heterothallism in the Microascaceae Demonstrated by Three Species in the Scopulariopsis Brevicaulis Series Author(S): Sean P

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Heterothallism in the Microascaceae Demonstrated by Three Species in the Scopulariopsis Brevicaulis Series Author(S): Sean P Mycological Society of America Heterothallism in the Microascaceae Demonstrated by Three Species in the Scopulariopsis brevicaulis Series Author(s): Sean P. Abbott and Lynne Sigler Source: Mycologia, Vol. 93, No. 6 (Nov. - Dec., 2001), pp. 1211-1220 Published by: Mycological Society of America Stable URL: http://www.jstor.org/stable/3761682 Accessed: 30/09/2008 15:49 Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at http://www.jstor.org/page/info/about/policies/terms.jsp. 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. 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Mycological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Mycologia. http://www.jstor.org Mycologia, 93(6), 2001, pp. 1211-1220. ? 2001 by The Mycological Society of America, Lawrence, KS 66044-8897 Heterothallism in the Microascaceae demonstrated by three species in the Scopulariopsis brevicaulis series Sean P. Abbott' strata (soil, plant litter, wood, dung, animal remains), Lynne Sigler and have a worldwide distribution in tropical, tem- University of Alberta Microfungus Collection and perate and polar regions (Barron et al 1961, Morton Herbarium, Devonian Botanic Garden, Edmonton, and Smith 1963, Domsch et al 1993, Abbott 2000). Alberta, Canada T6G 2E1 The genus Microascus was established by Zukal in 1885, but the Microascaceae were not united at the family level until 1951 (Luttrell 1951, Malloch 1970). Abstract: Scopulariopsis anamorphs are known for Axenic culture studies first provided evidence of con- many species of the genus Microascus (Ascomycota, nections between the anamorphic genus Scopulariop- Microascaceae), but teleomorph connections for ana- sis and teleomorphs within Microascus (Emmons and morphic species within the brevicaulis 'Scopulariopsis Dodge 1931, Barron et al 1961, Morton and Smith series' are tenuous or lacking. Microascus brevicaulis 1963), but many Scopulariopsisspecies remain uncon- was recently described as the teleomorph of the type nected or tenuously connected to teleomorphs. and commonest species, S. brevicaulis, but only a few Most species of the Microascus have been isolates yielded fertile perithecia. To investigate thought to be homothallic (Barron et al 1961), but the mat- whether paucity of sexual reproduction was the result behavior has been Emmons of heterothallism, mating experiments were conduct- ing rarely investigated. and showed that 20 ed among isolates representing the species S. brevi- Dodge (1931) single ascospore isolates of M. trigonosporusEmmons & Dodge devel- caulis, S. candida, S. asperula, S. fusca and S. konin- fertile In 1998, we demonstrated gii. Results demonstrated heterothallism within three oped perithecia. sexual species and confirmed that two taxa could be re- reproduction in five isolates of Scopulariopsis brevicaulis duced to synonymy. Three holomorph species, M. (Sacc.) Bainier and described the teleo- M. brevicaulis S.P. Abbott. This es- brevicaulis, M. manginii, and M. niger,are recognized morph discovery to include anamorphs S. brevicaulis (synonym S. kon- tablished a definitive link between the type species of the and the ingii), S. candida, and S. asperula (synonyms S. ar- anamorph genus Scopulariopsis Microas- noldii, S. bestae, S. fusca, and S. roseola), respectively. caceae (Abbott et al 1998), but raised the question as to the sexual of such Microascus niger is redescribed and a neotype pro- why stage a well known spe- posed. The three species are most readily recognized cies had hitherto been unreported. Scopulariopsis by colony color (sandy tan to avellaneous in M. brev- brevicaulis has been known since 1881 and is the icaulis, white to cream in M. manginii, and medium commonest Scopulariopsis species worldwide. To ad- to dark fuscous brown in M. niger). These colonial dress this question, we investigated the possibility of distinctions correlate generally with conidia that are heterothallism in this and other taxa within the 'Sco- coarsely roughened, smooth, or finely roughened, re- pulariopsis brevicaulis series' in which sterile, perithe- spectively. However, conidium ornamentation, previ- cium-like structures devoid of ascospores had been ously considered a reliable taxonomic character, is occasionally reported (Morton and Smith 1963). shown to be variable. The 'Scopulariopsis brevicaulis series' includes spe- Key Words: anamorph-teleomorph connections, cies having large, subglobose, smooth or ornament- Ascomycota, holomorph, hyphomycetes, Microascus ed, white to brown conidia, produced from highly branched conidiophores bearing annellides that are broad at the apex (3 (Lm) and not abruptly swollen INTRODUCTION at the base (Morton and Smith 1963). Species in- cluded are S. brevicaulis, S. asperula (Sacc.) S. Members of the Microascaceae are ascomycete family Hughes, S. flava (Sopp) Morton & G. Smith, S. can- found on cellulosic and sub- primarily protein-rich dida Vuillemin, S. koningii (Oudemans) Vuillemin, and S. fusca Castellani. Connections to teleomorphs, Accepted for publication May 3, 2001. where known, are tenuous. Many isolates of S. can- 1 Corresponding author, current address: Environmental Microbi- ology Laboratory, Inc., 1800 Sullivan Ave., Suite 209, Daly City, CA dida produce sterile perithecia-like structures (Ab- 94015, USA; Email: [email protected] bott et al 1998), and this species has been connected 1211 1212 MYCOLOGIA to M. manginii (Loub.) Curzi based on conidial sim- pared for each of the 9 single ascospore isolates. Self-self ilarity (Morton and Smith 1963). Morton and Smith crosses and crosses in all combinations were made by pi- tentatively accepted a connection between S. asperula peting one drop of suspension onto the center of an OAT and with a from a second strain. Plates and M. niger (Sopp) Curzi, but recommended that plate mixing drop were incubated at 22 C, examined after 7 wk and periodi- the teleomorph described as Acaulium nigrum Sopp cally for 14 mo. Plates were examined macroscopically for (Sopp 1912) be disregarded since there was no ex- the presence of submerged ascomata around the edge of tant material and the had not been seen type species the plate. Plates were examined also with a dissecting mi- since the original description. croscope but because heavy conidial growth often obscured To test the hypothesis of heterothallism and to clar- ascomata forming at the agar surface, some of the surface ify holomorph concepts, mating trials among strains growth in the central areas was removed prior to exami- of 5 of 6 species in the 'S. brevicaulis series' were nation. Microscopic mounts of developing perithecia were performed. Scopulariopsis flava was not included be- made periodically to monitor for ascospore production. cause of the lack of available authentic material (see Two single ascospore isolates that yielded a fertile cross were as (UAMH 9090) and minus (UAMH Morton and Smith 1963). Disposition of S. flava is designated plus 9092) These were mated with six nonascocar- the topic of a separate paper. The status of S. koningii mating types. pic wild-type strains of S. brevicaulis examined in Abbott et and S. fusca as distinct species was questioned be- al (1998) and with two strains originally received as S. kon- cause of morphological similarities to S. brevicaulis ingii and one as S. flava. Conidia of each strain were sus- and S. Authentic material of asperula, respectively. pended in semisolid detergent agar (SSD; Pitt 1973). Each these species was included in mating trials to aid in test strain was streaked onto one half of an OAT plate op- the evaluation of their taxonomic status. Neither has posite to the mating type streak, allowing for a central zone previously been connected to a sexual state. The mat- of contact as the isolates grew. Plates were incubated at 22 ing tests provided experimental evidence for a reap- C and monitored after 6 wk and periodically thereafter for praisal of accepted species within the 'S. brevicaulis 12 mo for development of ascomata within the central zone. series' and for their connections to species of Mi- Scopulariopsiscandida.-Nine wild-type strains of S. candida croascus. were crossed in all possible combinations (including self- self pairings). Conidia were suspended in SSD and streaked MATERIALSAND METHODS onto OAT as described above. Plates were examined over 19 mo. Strains were chosen to represent the broad range Morphology.-Living cultures and herbarium material of of variation observed among the 35 strains held at UAMH, wild-type strains, single ascospore isolates, and mated pairs and included a strain that routinely exhibited
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