New Zealand Forest Service Reprint No. 1012 ODe 181 352
Notes and brief articles
SEPEDONIUM SP. PARASITIC ON FRUITING BODIES OF RHIZOPOGON SP. AND SUILLUS SP. IN NEW ZEALAND MYRA CHU-CHOU AND LYNETTE J. GRACE Forest Researck Institute, New Zealand Forest Service, Rotorua
In January 1976, fruiting bodies of mycorrhizal fungi of Pinus radiata D. Don were collected in the nursery area of the Forest Research Institute, Rotorua. It was found that 90 % of the fruiting bodies of a Rhizopogon species collected were infected by Sepedonium. In addition, nearly every fruiting body of Suillus collected beneath a 15year-old Pinus radiata stand was infected by this parasitic fungus. Infection of species of Agaricus and Boletus by Sepedonium is commonly known in many parts of the world (Tulasne & Tulasne, 186o; Howell, 1939; Damon, 1952; Hawker, 1955; Tubaki, 1955), and infection of Rhizopogon provincialis Tul. by this fungus in Great Britain was reported by Hawker (1955). In New Zealand Boletus parasitized by Hypomyces chrysospermum Tul. (perfect stage of Sepedonium chrysospermum (Bull.) Fr.) was reported by Dingley (1951) but, to the authors' knowledge, Sepedonium infection of Rhizopogon has not been reported. The first visible sign of infection on fruiting bodies of Rhizopogon was a thin, small, white colony on the surface. Dissection of the affected part showed that the underlying glebal tissue was darker in colour. As the surface colony continued to enlarge, becoming whiter, thicker, and more fluffy, the darker tissue of the gleba also enlarged into a distinct fan-shaped region with alternate darker and lighter zones. At this stage immature, white conidia could be seen occupying all the cavities of the infected gleba. Later, the glebal
tissue was filled and the surface of the fruiting body became covered with a thick layer of golden yellow powder indicating the maturation ofconidia. Infection caused a noticeable reduction in the size of the fruiting body. Totally collapsed fruiting bodies of Rhizopogon were commonly seen, their presence being indicated by the golden yellow conidial mass of Sepedonium on the soil surface. Two kinds of conidia, namely phialospores and blastospores are produced by Sepedonium. The phialospores are single-celled and hyaline; both bottle-shaped and ovoid forms are seen (Fig. 1). The blastospores are globose, rough-tuberculate, and golden yellow when mature. Sepedonium was isolated from both infected Rhizopogon (Isolate 1, IMI203032) and Suillus (Isolate 2, IMI 203033) fruiting bodies. The type species of this genus, Sepedonium chrysospermum (Bull.) Fr., reported to be parasitic on boleti and other higher basidiomycetes, produces only ovoid phialospores. Our two isolates produce ovoid as well as bottle-shaped phialospores, a character regarded by Damon (1952) as important enough to propose a new species, Sepedoniumampullosporum. However, compared with Sepedonium ampullosporum our two isolates have larger blastospores (Table 1). The two isolates also differ from each other in spore size (Table 1), in cultural characteristics (Fig. 2), in sporulation capacity as tested on different media (Table 2), and in the ratio of bottle-shaped and ovoid phialospores on fruiting bodies (being 8o: 20 for Isolate 2 parasitic on
Table 1. Spore measurement of the two isolates as compared with Sepedonium chrysospermum and S. ampullosporum Phialospores C/J,m) Blastospores Species S. chrysospermum (Howell, 1939) S. ampullosporum (Damon, 1952) S. ampullosporum (Tubaki, 1955) Isolate 1 from Rhizopogon In nature In culture Isolate 2 from Suillus In nature In culture Trans. Br. mycol. Soc. 68 (3) (1977)
Ovoid 8-11 x 5-6 No record 8'5-20 X 4-8
Bottle-shaped No record 10-20 x 5-7'5 17-18'2 x 4'8-7'0
Cllm)
14-16 (10-)13- 18(-22) 12-20
15-19 x 6-8 14-19 x 6-8
15-16 x 6-"7 16-19 x 6-8
(17-)19-22(-27) (15-)17-20(-27)
14-17 x 5-7 14-17 x 5-7
17-21 x 5-7 16-19 x 5-7
(15-)22-2SH1)
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(15-)1!)-22Ho)
Notes and briefarticles
474
A
D
Fig. 1. Phialospores and blastospores of Isolate 1 (A-C) and Isolate 2 (D-F). x 650. Suillus, and 20: 80 for Isolate
1
parasitic on Rhizo-
pogon). The two isolates are therefore tentatively considered as two separate strains of Sepedonium
ampullosporum. Trans. Br. mycol. Soc. 68 (3) (1977)
Both Rhizopogon and Suillus are important mycorrhizal fungi of P. radiata in New Zealand. The destruction of their fruiting bodies means a reduction of mycorrhizal inoculum, but how this
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Notes and brief articles
Fig.
2.
475
Cultural characteristic differences between Isolate 1 (A) and Isolate 2 (B) on three media (L to R - malt agar (Difco), PDA, and Hagem agar).
Table 2. Differences in sporulation capacity of
the two isolates on different media Ovoid
Bottle-shaped
~~
Isolate Isolate Isolate Isolate Media Hagem, PDA Peptone Sucrose, V-8 Modified Melin-Norkrans PDA+Malt
1
+ + + +
2
1
2
+ +
+ + +
+
affects mycorrhizal formation in nature is unknown. Further investigation is required to gauge the full economic significance of these observations. Thanks are due to Professors J. H. Western and and Dr J. A. Butcher for reading and commenting on the manuscript.
J. Colhoun
Trans. Br. mycol. Soc. 68 (3) (1977)
REFERENCES
DAMON, S. C. (1952). Two noteworthy species of Sepedonium. Mycologia 44, 86-96. DINGLEY, J. M. (1951). The Hypocreales of New Zealand. Transactions of the Royal Society of New Zealand 79, 55-61, HAWKER, L. E. (1955). Hypogeous fungi. IV and V. Transactions of the British Mycological Society 38, 73-n HOWELL, A. (1939). Studies on Histoplasma capsulatum and similar form species. I. Morphology and development. Mycologia 31, 191-216. TUBAKI, K. (1955). Studies on the Japanese hyphomycetes. II. Fungicolous group. Nagaoa 5, 11-39. TULASNE, L. R. & TULASNE, C. (1860). De quelques spheries fongicoles Ii propos d'un memoire de M. Antoine de Bary sur les Nyctalis. Annales des Sciences Naturelles (Botanique) IV, 13, 5-19.
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