Sj. Hendry et al., INTERACTIONS BETWEEN CALLUS-CULTURES OF EUROPEAN BEECH, INDIGENOUS ASCOMYCETES AND DERIVED FUNGAL EXTRACTS, New phytologist, 123(3), 1993, pp. 421-428
Ascomycete fungi from the Xylariaceae and Diatrypaceae responded in th
ree distinct ways when grown in dual culture with callus material of b
eech (Fagus sylvatica L.). Growth of the putative weak pathogens Bisco
gniauxia nummularia (Bull.) 0. Kuntze and Eutypa spinosa (Pers.) Tul.
& C. Tul. was stimulated whilst the saprotrophs Ustulina deusta (Hoffm
.) Lind. and Xylaria polymorpha (Pers.) Grev. were unaffected by the p
resence of callus. Sapwood-colonizing fungi displayed a range of respo
nses, with Diatrype stigma (Hoffm.) Fr. being unaffected, Diatrype dis
ciformis (Hoffm.) Fr. stimulated, and Hypoxylon fragiforme (Pers.: Fr.
) Kickx and 'Hypoxylon purpureum' inhibited by the presence of callus.
Changes in morphology were evident in many of the fungi during intera
ctions, with yeast-like forms being produced by those members of the X
ylariaceae which have been recognized as endophytes. Reciprocally, hig
h concentrations of cell free extracts of some of the Xylariaceous fun
gi resulted in necrosis or inhibition of callus growth, while at sub-l
ethal concentrations marked stimulation of growth was evident. The imp
ortance of these results with respect to pathogenicity testing and elu
cidation of the biology of tree-fungus interactions is discussed.