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Note on the basidium in the Tilletiaceae
Short Communications
387
Note on the basidium in the Tilletiaceae C. T. I N G O L D 11
Buckner's Close, Benson, Oxford OX9 6LR, U.K.
Note on the basidium in the Tilletiaceae. MycologicaI Research 93 (3): 387-389 (1989). The structure of the aerial, unicellular basidium in the Tilletiaceae is discussed by reference to Tilletia, Urocystis and Melanotaenium. An illustrated account is given of the basidium in Urocystis violae. Comparison is made with Ustilago and Anthracoidea.
Key words: Ballistospore, Basidium, Tilletia, Urocystis, Melanotaenium. Having studied germination of teliospores in Tillefia trifici (Bjerk.) R. Wolff, Urocystis anemones (Pers.) Winter, U. violae (Sow.) A. Fischer v. Waldheim and Melanotaenium endogenum (Unger) deBary I have developed a view of the basidium that may be of interest. The basidium of T. frifici, resulting from germination of the teliospore (which might better be termed a probasidium) has certain features (Fig. 1A). First, it is an aerial structure. This was stressed by Buller & Vanterpool(1933) who showed how the germ-tube, which initially tends to grow on the surface of the medium, eventually turns away from it due, apparently, to negative hydrotropism. Secondly, basal vacuolation pushes the visible contents forward, and the seemingly empty region is periodically walled off by retraction-septa (retaining walls). There are no true septa. In species of Usfilago and its close allies, by way of contrast, basal vacuolation rarely occurs and the cross-walls are true septa (Fig. 1E). Thirdly, the apex of the basidium is lobed. Fourthly, the filamentous basidiospores are readily detachable. Fifthly, ballistospores are sometimes produced either from a single basidiospore or, more usually, from one of a pair united by a conjugation-tube often while still attached to the basidium. It is noteworthy that on nutrient agar both basidiospores and ballistospores give rise to branched mycelia on which both ballistospores and filamentous sedentary blastospores, closely resembling the basidiospores, are produced. It has been argued (Ingold, 1987a) that basidiospores, ballistospores and filamentous blastospores are homologous. The basidium of Urocystis violae (Fig. 1B) is structurally similar to that of T . trifici except that the proportions of its various parts are rather different. I was able to study this spec:es in June 1988 on Viola riviniana Rchb. at Hetchell Wood, West Yorkshire, England. When spore balls were streaked on 0.2 % malt agar (MA) the teliospores germinated after 2 d at room temperature. The metabasidium derived from a teliospore consisted of a straight stalk (usually 15-20 x 3-4 pm) growing up into the air and crowned by a cluster of 3-8 (usually 4 or 5) narrowly ovate or finger-like lobes (8-12 x 2.5-3.5 um) (Fig. 2). The lower part of the stalk often became cut off by a retraction-septum as a compartment visibly free from contents. Normally, each lobe narrowed apically into a spiculum from the tip of which a fusiform basidiospore (15-20 x 2-3 pm) developed symmetrically.
Occasionally, instead of producing a basidiospore, a lobe grew out as an unbranched hypha (Fig. 2H). Mounting in water usually led to the immediate release of any fully formed basidiospores. Most of the visible material of the metabasidial lobes had passed into these, giving finely granular contents in each spore, except for a tiny clearer region apparently corresponding to the nucleus (Fig. 21). This account of the basidium of U . violae agrees in all essentials with that of Brefeld (1895). Each metabasidial lobe together with its spiculum may be equated with a sterigma, a point made by Buller & Vanterpool (1933), who remarked 'the basidial apparatus of this species reminds one of the basidia in Tulasnella'. However, the fundamental difference between the basidium of U. violae and that of Tulasnella spp. is that, in the latter, the basidiospores are ballistospores. In possessing a basidium with aerial basidiospores which are not ballistospores but are, nevertheless, delicately poised, apparently ready for immediate liberation into the air, this smut is similar to Anfhracoidea inclusa Brefeld (Ingold, 1989). It is a most unusual situation for a basidiomycete. Although the filamentous basidiospores of Tillefia frifici separate readily from the basidiurn, they are not so easily set free as are those of U . violae and A. inclwa. In Urocysfisanemones (Fig. 1C ) germination of the teliospore gives a metabasidium with 2-4 (usually 3) apical lobes (Ingold, 1987b). However, these fail to form basidiospores, but, apparently following a process of dikaryotization, hyphae grow out apically from two of them. Some mycologists have regarded the metabasidial lobes as the equivalent of the filamentous basidiospores of Tillefia frifici. However, they do not become detached and comparison with U . violae suggests that interpretation is invalid. They might better be compared with the apical metabasidial lobes in T . trifici in spite of the differences in size and form. In Melanotaenium endogenum (Fig. I D ) (Ingold, 1988), the aerial metabasidium has 2-9 apical lobes as in Urocysfis spp. However, ballistospores are produced, which may be formed on spicula arising directly from the lobes, or on hyphae growing from them. Those ballistospores formed on the lobes may reasonably be termed basidiospores, and they seem to be the only ballistosporic basidiospores so far reported in smuts. Most mycologists do not accept the somewhat obscure
Short Communications
388
Fig. IA-F. Realistic diagram of some smut basidia. A. Tillefia tritici; B, Urocystis violae; C, Urocystis anemones; D, Melanofaenium endogenurn; E, Usfilago avenae; F, Anfhracoidea inclusa. H, Horizontal axes; V, vertical axis; horizontal plane shaded.
argument of Buller & Vanterpool (1933) that the ballistospores borne on the filamentous spores of Tilletia trifici are the true basidiospores, and that the filamentous structures are no than primary sterigmata. Discharged ballistos~oresin M. endogenurngeminate On MA give a myce1ium bearing further ballistospores. However, unlike the situation i T. fritici, no other spores are produced. The view expressed here is that the basidium in the Tilletiaceae is both unicellular and aerial in contrast with that in the Ustilaginaceae which is both septate and prostrate. The position of Anfhracoidea (Fig. 1F) calls for brief comment. With its aerial, septate basidiurn it is not readily allocated to either family gngold, 1989), neither is it easy to envisage this genus as intermediate between the two accepted families. (Received for publication 14 December 1988)
REFERENCES BREFELD, 0. (1895). Unfersuchungen aus dem Gesammtgebiete der Mykologie 11, Miinster. BULLER, A, H. R. & VANTERPOOL, T, C. (1933). The violent discharge of basidiospores (secondary conidia) of Tillefia frifici. In ~~~~~~~h~~ on ~~~~i 5, pp, 2 0 b 2 7 8 , ~ ~ u,K,: ~L d ~ Green & CO. INGOLD, C. T. (1987a). Ballistospores and blastic conidia of Tillefia ayresii, and comparison with those of T. frifici and Enfylomaficariae. Transactions of the British Mycological Society 88. 75-82. INGOLD, C. T. (1987 b). Germination of teliospores in certain smuts.
Trawacfiom of the British Mycological Society 88, 355-363. INGOLD, C. T. (1988). Ballistospores in Melanofaenium endogenurn. Transacfions of the British Mycological Society 91, 712-714. INGOLD, C. T. (1989). The basidium of Anthracoidea inclusa in relation to smut taxonomy. Mycological Research 92, 245-246.
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Short Communications
389
Fig. 2. Urocysfis violae. A-D, Metabasidia each with a crown of lobes; E-G, basidia with attached basidiospores; in G one has just become free; H, apical part of a basidium; one metabasidial lobe has given rise to a hypha; from another a basidios~orehas just become free; I, liberated basidiospores.
An Australian species of Chaetocalathus J. A. SIMPSON Pathology Section, Wood Technology and Forest Research Division, Forestry Commission N.S.W., P.O. Box 100, Beecroff 2119, Australia
C. A. G R G U R I N O V I C 51 Vardys Rd, Kings Lungley 2147, Australia
An Australian species of Chaefocalafhus.Mycological Research 93 (3):389-391 (1989).
Pleurotus cheelii is transferred to the genus Ckaetocalathw. The fungus is redescribed from the type and other collections. Key words: Chaetocalafkus cheelii, Pleurotus, Australia.
Re-examination of the holotype collection and available authentic material of Pleurofus cheelii Massee has indicated the species would be better placed in Chaefocalafhw Singer, a genus not previously reported from Australia. The species is therefore redescribed.
Chaetocalathus cheelii (Massee) Simpson & Grgurinovic, comb. nov. (Fig. I) Pleurofus cheelii Massee, Bull. Misc. Inf. b 1907: 122 (1907). Basidiome small, white, cyphelloid-pleurotoid. Pilew membranaceous, dimidiate, conchate, 2-3 mm long, 3-4 rnrn wide,
387
Note on the basidium in the Tilletiaceae C. T. I N G O L D 11
Buckner's Close, Benson, Oxford OX9 6LR, U.K.
Note on the basidium in the Tilletiaceae. MycologicaI Research 93 (3): 387-389 (1989). The structure of the aerial, unicellular basidium in the Tilletiaceae is discussed by reference to Tilletia, Urocystis and Melanotaenium. An illustrated account is given of the basidium in Urocystis violae. Comparison is made with Ustilago and Anthracoidea.
Key words: Ballistospore, Basidium, Tilletia, Urocystis, Melanotaenium. Having studied germination of teliospores in Tillefia trifici (Bjerk.) R. Wolff, Urocystis anemones (Pers.) Winter, U. violae (Sow.) A. Fischer v. Waldheim and Melanotaenium endogenum (Unger) deBary I have developed a view of the basidium that may be of interest. The basidium of T. frifici, resulting from germination of the teliospore (which might better be termed a probasidium) has certain features (Fig. 1A). First, it is an aerial structure. This was stressed by Buller & Vanterpool(1933) who showed how the germ-tube, which initially tends to grow on the surface of the medium, eventually turns away from it due, apparently, to negative hydrotropism. Secondly, basal vacuolation pushes the visible contents forward, and the seemingly empty region is periodically walled off by retraction-septa (retaining walls). There are no true septa. In species of Usfilago and its close allies, by way of contrast, basal vacuolation rarely occurs and the cross-walls are true septa (Fig. 1E). Thirdly, the apex of the basidium is lobed. Fourthly, the filamentous basidiospores are readily detachable. Fifthly, ballistospores are sometimes produced either from a single basidiospore or, more usually, from one of a pair united by a conjugation-tube often while still attached to the basidium. It is noteworthy that on nutrient agar both basidiospores and ballistospores give rise to branched mycelia on which both ballistospores and filamentous sedentary blastospores, closely resembling the basidiospores, are produced. It has been argued (Ingold, 1987a) that basidiospores, ballistospores and filamentous blastospores are homologous. The basidium of Urocystis violae (Fig. 1B) is structurally similar to that of T . trifici except that the proportions of its various parts are rather different. I was able to study this spec:es in June 1988 on Viola riviniana Rchb. at Hetchell Wood, West Yorkshire, England. When spore balls were streaked on 0.2 % malt agar (MA) the teliospores germinated after 2 d at room temperature. The metabasidium derived from a teliospore consisted of a straight stalk (usually 15-20 x 3-4 pm) growing up into the air and crowned by a cluster of 3-8 (usually 4 or 5) narrowly ovate or finger-like lobes (8-12 x 2.5-3.5 um) (Fig. 2). The lower part of the stalk often became cut off by a retraction-septum as a compartment visibly free from contents. Normally, each lobe narrowed apically into a spiculum from the tip of which a fusiform basidiospore (15-20 x 2-3 pm) developed symmetrically.
Occasionally, instead of producing a basidiospore, a lobe grew out as an unbranched hypha (Fig. 2H). Mounting in water usually led to the immediate release of any fully formed basidiospores. Most of the visible material of the metabasidial lobes had passed into these, giving finely granular contents in each spore, except for a tiny clearer region apparently corresponding to the nucleus (Fig. 21). This account of the basidium of U . violae agrees in all essentials with that of Brefeld (1895). Each metabasidial lobe together with its spiculum may be equated with a sterigma, a point made by Buller & Vanterpool (1933), who remarked 'the basidial apparatus of this species reminds one of the basidia in Tulasnella'. However, the fundamental difference between the basidium of U. violae and that of Tulasnella spp. is that, in the latter, the basidiospores are ballistospores. In possessing a basidium with aerial basidiospores which are not ballistospores but are, nevertheless, delicately poised, apparently ready for immediate liberation into the air, this smut is similar to Anfhracoidea inclusa Brefeld (Ingold, 1989). It is a most unusual situation for a basidiomycete. Although the filamentous basidiospores of Tillefia frifici separate readily from the basidiurn, they are not so easily set free as are those of U . violae and A. inclwa. In Urocysfisanemones (Fig. 1C ) germination of the teliospore gives a metabasidium with 2-4 (usually 3) apical lobes (Ingold, 1987b). However, these fail to form basidiospores, but, apparently following a process of dikaryotization, hyphae grow out apically from two of them. Some mycologists have regarded the metabasidial lobes as the equivalent of the filamentous basidiospores of Tillefia frifici. However, they do not become detached and comparison with U . violae suggests that interpretation is invalid. They might better be compared with the apical metabasidial lobes in T . trifici in spite of the differences in size and form. In Melanotaenium endogenum (Fig. I D ) (Ingold, 1988), the aerial metabasidium has 2-9 apical lobes as in Urocysfis spp. However, ballistospores are produced, which may be formed on spicula arising directly from the lobes, or on hyphae growing from them. Those ballistospores formed on the lobes may reasonably be termed basidiospores, and they seem to be the only ballistosporic basidiospores so far reported in smuts. Most mycologists do not accept the somewhat obscure
Short Communications
388
Fig. IA-F. Realistic diagram of some smut basidia. A. Tillefia tritici; B, Urocystis violae; C, Urocystis anemones; D, Melanofaenium endogenurn; E, Usfilago avenae; F, Anfhracoidea inclusa. H, Horizontal axes; V, vertical axis; horizontal plane shaded.
argument of Buller & Vanterpool (1933) that the ballistospores borne on the filamentous spores of Tilletia trifici are the true basidiospores, and that the filamentous structures are no than primary sterigmata. Discharged ballistos~oresin M. endogenurngeminate On MA give a myce1ium bearing further ballistospores. However, unlike the situation i T. fritici, no other spores are produced. The view expressed here is that the basidium in the Tilletiaceae is both unicellular and aerial in contrast with that in the Ustilaginaceae which is both septate and prostrate. The position of Anfhracoidea (Fig. 1F) calls for brief comment. With its aerial, septate basidiurn it is not readily allocated to either family gngold, 1989), neither is it easy to envisage this genus as intermediate between the two accepted families. (Received for publication 14 December 1988)
REFERENCES BREFELD, 0. (1895). Unfersuchungen aus dem Gesammtgebiete der Mykologie 11, Miinster. BULLER, A, H. R. & VANTERPOOL, T, C. (1933). The violent discharge of basidiospores (secondary conidia) of Tillefia frifici. In ~~~~~~~h~~ on ~~~~i 5, pp, 2 0 b 2 7 8 , ~ ~ u,K,: ~L d ~ Green & CO. INGOLD, C. T. (1987a). Ballistospores and blastic conidia of Tillefia ayresii, and comparison with those of T. frifici and Enfylomaficariae. Transactions of the British Mycological Society 88. 75-82. INGOLD, C. T. (1987 b). Germination of teliospores in certain smuts.
Trawacfiom of the British Mycological Society 88, 355-363. INGOLD, C. T. (1988). Ballistospores in Melanofaenium endogenurn. Transacfions of the British Mycological Society 91, 712-714. INGOLD, C. T. (1989). The basidium of Anthracoidea inclusa in relation to smut taxonomy. Mycological Research 92, 245-246.
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Short Communications
389
Fig. 2. Urocysfis violae. A-D, Metabasidia each with a crown of lobes; E-G, basidia with attached basidiospores; in G one has just become free; H, apical part of a basidium; one metabasidial lobe has given rise to a hypha; from another a basidios~orehas just become free; I, liberated basidiospores.
An Australian species of Chaetocalathus J. A. SIMPSON Pathology Section, Wood Technology and Forest Research Division, Forestry Commission N.S.W., P.O. Box 100, Beecroff 2119, Australia
C. A. G R G U R I N O V I C 51 Vardys Rd, Kings Lungley 2147, Australia
An Australian species of Chaefocalafhus.Mycological Research 93 (3):389-391 (1989).
Pleurotus cheelii is transferred to the genus Ckaetocalathw. The fungus is redescribed from the type and other collections. Key words: Chaetocalafkus cheelii, Pleurotus, Australia.
Re-examination of the holotype collection and available authentic material of Pleurofus cheelii Massee has indicated the species would be better placed in Chaefocalafhw Singer, a genus not previously reported from Australia. The species is therefore redescribed.
Chaetocalathus cheelii (Massee) Simpson & Grgurinovic, comb. nov. (Fig. I) Pleurofus cheelii Massee, Bull. Misc. Inf. b 1907: 122 (1907). Basidiome small, white, cyphelloid-pleurotoid. Pilew membranaceous, dimidiate, conchate, 2-3 mm long, 3-4 rnrn wide,