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Note on abnormal spores in Podospora minuta
186
NOTE ON ABNORMAL SPORES IN
PODOSPORA MINUTA By WINIFRED M. PAGE, M.Sc. (W ith 5 Text-figures) PODOSPORA MIN UTA occurs commonly on rabbit pellets. It appears early in the succession of fungi, usually fruiting at the same time as Ascophanus carneus and other Discomycetes. The spores germinate readily and single-spore cultures are easily obtained.
a
b
c
\l
g
Fig.
I.
h
k
m
Types of asci showing variation in number of spores and abnormal spores. x 200.
The normal asci contain four spores, each of which is capable of producing a mycelium giving rise to fruits (Fig. If). In perithecia grown in culture and also in those growing on rabbit pellets collected
Note on Abnormal Spores in Podospora minuta
187
from various sources, asci with abnormal spores sometimes occur. From one to seven spores which, apart from size, are normal in appearance have been observed (Fig. r a-i). In addition irregular spores, some of which never completely darken, are occasionally 1
3
4
5
1
3 4
5 2 6 7
•• •• • •• • • •• •
2
6
7
•• • •• •• •• • ••
Fig. 2. Table showing results of crossing mycelia from A and B spores.
Fig. 3. Diagram from photograph of culture from A and B spores. Points of inoculation indicated by x. The fine dots show abortive perithecia and the broken lines the limits of the mycelia.
seen (Fig. rj-m). Of asci with other than four spores, the one giant and two normal is the most common variety (Fig. r c-e). Asci with two dwarf and three normal spores are not so frequent, but a number of the dwarf spores have been isolated and germinated (Fig. r g). As in Sordaria fimicola (four-spored form) the perithecium initials in
188
Transactions British Mycological Society
the mycelia from these spores never mature. When the spherical stage is reached no further development takes place (4, 5, 6). The mycelia from the se dwarf spores were found to be of two different, but complementary, strains. A number of crosses were
o Q.
8 Fig. 4. Sections of young four- and five-spored asci showing nuclei. x 400.
Fig. 5. Form ation of small colourless spores. x
1600.
made and the results are shown in the table (Fig. 2). The details of the results agree with those of Sordaria fimicola (6) . The normal spores contain two nuclei and the dwarf spores one nucleus each (Fig. 4.). The eight-spored form of this fungus is not common; I have found it only once in many years of collecting. It was, however, cultured . .Each of the eight spores is uninucleate and capable of producing mycelia which fruit.
Note on Abnormal Spores in Podospora minuta
189
In the four-spored variety very tiny colourless spores are produced, being cut off from flask-shaped outgrowths (Fig. 5). These have been seen in normal cultures and also in those from dwarf spores. Work on these spores is now in progress, and up to the present there has been no indi cation that they possess the functions predicated for the "micro-conidia" by Ames in Podospora (Pleurage) anserinaii, 2, 3). The perithecium initials, whether normal or abortive, early send out branches to form secondary mycelia, but there is no evidence that any of these can be described as a trichogyne. It is interesting to note that Winter in 1873 figured an ascus with two spores in Sordaria (Podospora) anserina in, REFERENCES (I) AMES, L. M. "A study of some homothallic and heterothallic Ascomycetes." Mycologia, xx (1930), 318. (2) - - "An hermaphroditic self-sterile bu t cross-fertile condition in Pleurage anserine:" Bull. Torrey bot. Gl. LIX (1932), 34 1. (3) - - "Hermaphroditism involving self-sterility and cross-fertility in the Ascomycete Pleurage anserina." My cologia, XXVI ( 1934), 5. (4) DOWDING, E. SILVER. "The sexuality of the normal, giant, and dwarf spores of Pleurage anserina (Ces.) Kunze. " Ann. Bot. XLV (1931), J. (5) - - "Gelasinospora, a new genus of Pyrenomycetes with pitted spores. " Ganad.]. Res. IX (1933), 294. (6) PAGE, W. M. "A contribution to the life history of Sordariafimicola (four-spored form) with special reference to th e abnormal spores." Trans. Brit. mycol. Soc. XVII (1932), 296. (7) WINTER, G. "Die deutschen Sordarien." Abh. naturf. Ges. Halle, XIII (1873).
NOTE ON ABNORMAL SPORES IN
PODOSPORA MINUTA By WINIFRED M. PAGE, M.Sc. (W ith 5 Text-figures) PODOSPORA MIN UTA occurs commonly on rabbit pellets. It appears early in the succession of fungi, usually fruiting at the same time as Ascophanus carneus and other Discomycetes. The spores germinate readily and single-spore cultures are easily obtained.
a
b
c
\l
g
Fig.
I.
h
k
m
Types of asci showing variation in number of spores and abnormal spores. x 200.
The normal asci contain four spores, each of which is capable of producing a mycelium giving rise to fruits (Fig. If). In perithecia grown in culture and also in those growing on rabbit pellets collected
Note on Abnormal Spores in Podospora minuta
187
from various sources, asci with abnormal spores sometimes occur. From one to seven spores which, apart from size, are normal in appearance have been observed (Fig. r a-i). In addition irregular spores, some of which never completely darken, are occasionally 1
3
4
5
1
3 4
5 2 6 7
•• •• • •• • • •• •
2
6
7
•• • •• •• •• • ••
Fig. 2. Table showing results of crossing mycelia from A and B spores.
Fig. 3. Diagram from photograph of culture from A and B spores. Points of inoculation indicated by x. The fine dots show abortive perithecia and the broken lines the limits of the mycelia.
seen (Fig. rj-m). Of asci with other than four spores, the one giant and two normal is the most common variety (Fig. r c-e). Asci with two dwarf and three normal spores are not so frequent, but a number of the dwarf spores have been isolated and germinated (Fig. r g). As in Sordaria fimicola (four-spored form) the perithecium initials in
188
Transactions British Mycological Society
the mycelia from these spores never mature. When the spherical stage is reached no further development takes place (4, 5, 6). The mycelia from the se dwarf spores were found to be of two different, but complementary, strains. A number of crosses were
o Q.
8 Fig. 4. Sections of young four- and five-spored asci showing nuclei. x 400.
Fig. 5. Form ation of small colourless spores. x
1600.
made and the results are shown in the table (Fig. 2). The details of the results agree with those of Sordaria fimicola (6) . The normal spores contain two nuclei and the dwarf spores one nucleus each (Fig. 4.). The eight-spored form of this fungus is not common; I have found it only once in many years of collecting. It was, however, cultured . .Each of the eight spores is uninucleate and capable of producing mycelia which fruit.
Note on Abnormal Spores in Podospora minuta
189
In the four-spored variety very tiny colourless spores are produced, being cut off from flask-shaped outgrowths (Fig. 5). These have been seen in normal cultures and also in those from dwarf spores. Work on these spores is now in progress, and up to the present there has been no indi cation that they possess the functions predicated for the "micro-conidia" by Ames in Podospora (Pleurage) anserinaii, 2, 3). The perithecium initials, whether normal or abortive, early send out branches to form secondary mycelia, but there is no evidence that any of these can be described as a trichogyne. It is interesting to note that Winter in 1873 figured an ascus with two spores in Sordaria (Podospora) anserina in, REFERENCES (I) AMES, L. M. "A study of some homothallic and heterothallic Ascomycetes." Mycologia, xx (1930), 318. (2) - - "An hermaphroditic self-sterile bu t cross-fertile condition in Pleurage anserine:" Bull. Torrey bot. Gl. LIX (1932), 34 1. (3) - - "Hermaphroditism involving self-sterility and cross-fertility in the Ascomycete Pleurage anserina." My cologia, XXVI ( 1934), 5. (4) DOWDING, E. SILVER. "The sexuality of the normal, giant, and dwarf spores of Pleurage anserina (Ces.) Kunze. " Ann. Bot. XLV (1931), J. (5) - - "Gelasinospora, a new genus of Pyrenomycetes with pitted spores. " Ganad.]. Res. IX (1933), 294. (6) PAGE, W. M. "A contribution to the life history of Sordariafimicola (four-spored form) with special reference to th e abnormal spores." Trans. Brit. mycol. Soc. XVII (1932), 296. (7) WINTER, G. "Die deutschen Sordarien." Abh. naturf. Ges. Halle, XIII (1873).