ATTEMPTED ISOLATION AND SUCCESS IN THE CULTURING OF A BROAD-SPECTRUM OF LICHEN-FORMING AND LICHENICOLOUS FUNGI

Isolation into pure culture was attempted on 1183 species (2238 specim ens) of lichen-forming and lichenicolous fungi from diverse ecosystems and systematic groups (covering 14 ascomycete orders, 77 families and 280 general, in 20 countries. Four hundred and ninety three species ( 42 %) were successfully isolated either from ascospores (or basidiospo res, or conidia) or photobiont-free fragments from thallus macerates. Of the total number of isolation attempts from ascospores (1609) and t hallus fragments (719), 30 % and 32 % respectively were successful. Th e reasons for failure to isolate from ascospores were: ascospores did not germinate (43 %) > ascospores were not discharged (30 %) > ascospo res germinated but growth was not sustained (19 %) > discharged spores were heavily contaminated (8 %). 59 % of isolation failures with frag ments were due to lack of growth and 41 % were due to contamination. T he orders from which mycobionts were most readily isolated were the Os tropales (70 % of species attempted were isolated), Dothideales (63 %) , Pertusariales (53 %) and Lecanorales (45 %); those orders least read ily yielding isolates were Verrucaviales (10 %), Gyalectales (20 %), A rthoniales (30%), Lichinales (29 %) and Peltigerales (27 %). Members o f the Lecanorales comprised c. 60 % of species collected of which Porp idiaceae (80% of species successfully isolated), Cladoniaceae (69%), L ecideaceae (67%), Rhizocarpaceae (62%), Umbilicariaceae (60 %), Ramali naceae (60 %) and Lecanoraceae (54 %) were comparatively successful fa milies and Alectoviaceas (18%), Catillariaceae (8 %), Pannariaceae (8 %) Collemataceae (7 %), and Micareaceae (6 %) were least successful. O f those species containing a cyanobacterium (either as the primary pho tobiont or in cephalodia), only 22 % yielded isolates compared with 46 % and 43 % of lichens containing only a chlorococcoid photobiont or T rentepohlia, respectively. Success was even lower (17 %) in species co ntaining a cyanobacterium as the primary photobiont. Among non-cyanoba cterial lichens, isolation of mycobionts was achieved in 56 % of fruti cose species collected compared with 43 % and 40 % for crustose/squamu lose and foliose taxa respectively. Mycobionts of fruticose lichens cu ltured particularly readily from fragments, with 56 % of green algal s pecies to which this method was applied coming into culture compared t o 37 % of non-cyanobacterial foliose species. Lichenicolous fungi cult ured less readily, with only 31 % of species yielding isolates. In man y species viability of ascospores varied between collections. Weather conditions at the time of collection, environmental conditions during transportation, and developmental stage of ascomata of pyrenocarpous l ichens might partly explain this variation.