Intraspecific aluminium response in Suillus luteus (L.) s.f. gray., an ectomycorrhizal symbiont of scots pine

Abstract

Ten isolates of the ectomycorrhizal fungus Suillus luteus have been cultured on an aluminium containing growth medium in order to determine their in vitro 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 S. luteus 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 in vitro 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-1 Al and the colony diameter during culture and the final colony dry weight determined. S. luteus 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.

Keywords

• aluminium toxicity
• ectomycorrhiza
• intraspecific variation
• Pinus sylvestris