Intraspecific aluminium response in Suillus luteus (L.) s.f. gray., an ectomycorrhizal symbiont of scots pine
Ten isolates of the ectomycorrhizal fungus <i>Suillus luteus</i> have been cultured on an aluminium containing growth medium in order to determine their <i>in vitro</i> aluminium tolerance. Five isolates originated from a site heavily polluted by acid rain with a high availability of aluminium in the soil. Five others were collected from a site free from direct pollution. Aluminium content in the sporocarps of <i>S. luteus</i> differed according to the site of origin and did not reveal symptoms of bioconcentration, although such phenomena were found when mycelium isolated from the sporocarps was submited to 100 mg/L Al in liquid culture. A clear relationship between Al accumulation <i>in vitro</i> and the site of origin of the isolate was not observed, although the highest amount of Al was found in the mycelium derived from the polluted soil. In a second experiment all isolates were grown in agar media containing 10, 100, 500 and 1000 mg/L<sup>-1</sup> Al and the colony diameter during culture and the final colony dry weight determined.<i> S. luteus</i> appeared to be very tolerant to the presence of Al in the medium. Each of the parameters used to measure the metal tolerance of the fungus ranked the isolates in a slightly different order, but those originating from the polluted area showed some superiority over the others. In polluted soils this species seems to have been submitted to a selection for higher aluminium tolerance. The results are discussed with reference to the possibilities of transformating in vitro studies to situation in the forest ecosystem.