Review article. Use of RAPD-PCR DNA fingerprinting and vegetative incompatibility tests to investigate genetic variation within lichen-forming fungi

The use of the DNA fingerprinting technique randomly amplified polymorphic DNA (RAPD) analysis to investigate genetic variation in lichen-forming fung i is reviewed. Particular thermostable enzymes are recommended for RAPD-PCR together with the use of DNA extracted from axenic cultures of the mycobio nt, thereby overcoming the problem of amplification of non-target contamina ting DNA. The use of RAPD-PCR in phylogenetic reconstruction is described, with certain similarity coefficients and a resampling technique (bootstrapp ing or jackknifing) advocated. Investigations with a variety of lichen spec ies have revealed genetic diversity values comparable with those detected i n populations of free-living fungi. RAPD-PCR has also been used to investig ate other aspects of lichen biology. Studies of breeding systems revealed h omothallism in model species. Studies of thallus 'individuality' revealed t hat thalli may be composed of more than one genotype. The use of vegetative incompatibility tests to detect variation in lichen-forming fungi was also assessed using axenic cultures of Graphis scripta and Phaeographis dendrit ica. Pigmentation was observed at boundaries between colonies of different genotype unlike control tests. However, overall vegetative compatibility gr ouping results were inconclusive.