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Two aquatic hyphomycetes as endophytes in Alnus glutinosaroots
P. J. FISHERDepartment of Biological Sciences, University of Exeter, EX4 4PS, UK
Mikrobiologisches Institut, ETH-Zentrum, CH-8092 Zurich, Switzerland
Two aquatic hyphomycetes as endophytes in Alnus glutinosa roots. Mycological Research 92 (3): 367-368 (1989).
The aquatic hyphomycetes Tricladium splendens and Campylospora parvula have been isolated from surface-sterilized roots of Alnusglutinosa.
Key words: Alnus glutinosa, Aquatic hyphomycetes, Endophytic fungi.
Aquatic hyphomycetes have been found in abundance ondecaying leaves and twigs of deciduous trees in unpollutedstreams. The use of the term aquatic implies that such fungilive in water, but evidence is accumulating that they can alsobe found in terrestrial situations.
Bandoni (1981) has summarized the occurrences of aquatichyphomycetes from non-aquatic habitats. It is of interest that.of the 34 examples cited, only 3 refer to the roots of plants.Waid (1954) isolated Varicosporium e10deae Kegel from theroot surfaces of beech seedlings grown in beechwood soil, andNemec (1969) isolated Anguillospora longissima (Sacc. & Syd.)Ingold and Tetracladium marchalianum de Wild. from the rootsof diseased strawberry plants.
In a study of endophytic fungi in the bark and xylem ofAlnus glutinosa (L.) Gaertner, we have demonstrated colon-ization of the bark of roots by the aquatic hyphomycetesTricladium splendens Ingold and Campylospora parvula Kuzula(Fig. 1). The latter fungus may have once previously beenrecorded in Britain from a stream in Kent (Ingold, 1975),whilst T. spendens can be found in most streams containingsuitable substrates. It is also one of the few aquatichyphomycetes that will form spores when its mycelium isexposed to the atmosphere.
Roots of Alnus glutinosa were sampled from 3 trees
standing on the bank of the Exeter Canal, Grid ReferenceSY 925915. The roots were scrubbed clean of all surface soiland subjected to surface-sterilization by the method of Fisher,Anson & Petrini (1986). Then the bark was stripped off witha sterile scalpel and cut into 1 em lengths before being placedin groups of 5 onto 1'5 % malt (MEA) extract. Plates wereincubated at ambient temperature (ca 20C) for 5-14 ddepending on the growth rate of the fungi. Isolation was bytransfer of mycelium to 2 % MEA. After 4 wk incubation at20, strips 1 em wide were cut from each culture andsubmerged in sterile distilled water and further incubated at10 in diffuse daylight. After 4--0 d, spores of T. splendens andC. parvula were formed. This is the first record of aquatichyphomycetes as endophytes in the roots of a plant. Only1'6 % of the 300 pieces of bark sampled grew T. splendens and0'7% C. parvula, compared with the most common rootendophyte, Cylindrocarpon destructans (Zins.) Scholten, whichcolonized 19 % of all bark fragments. The infrequent occurrenceof T. splendens and C. parvula suggests that these species mayonly be able to establish themselves as marginal endophytesin the roots of certain trees which grow near streams.
Specimens (dried sporulating cultures and microscope slides)have been preserved as HME 4353 C. parvula, HME 4354T. splendens. Cultures of C. parvula have been deposited at
Short Communications 368
Fig. 1. A, Conidium of Tricladium splendens; B, conidium development of Campylospora parvula; C and 0, mature spores. Bar scale =20 IJm.
CAB International Mycological Institute (1MI 327408), and atthe Czechoslovak Collection of Microorganisms, 662 43 Brno,Accession Number CCM 8044.
We are indebted to Dr Ludmila Marvanova for confirmingthe identification of C. parvu/a.
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