Responses of pine needle endophytes to air pollution

Summary The effects of heavy metals and sulphuric acid on pine needle endophytes were studied using gradient analyses, an experimental field study and an in vitro laboratory experiment. Gradient analyses were carried out near factory complexes at Harjavalta (southern Finland) and Monchegorsk (Kola peninsula, Russia); both factories emit heavy metals and sulphur. The experimental field plots had received copper (Cu) and nickel (Ni) treatment, sulphuric acid treatment, or a combination of the two, for 3 yr before sampling. Endophyute strains isolated 1 and 8 km from the factory were studied for their mental tolerance in the laboratory. The total number of needles infected with endophytes and also the number of needles infected with a specific endophyte, Cenangium ferrucinosum Fr.:Fr., were significantly lower near factories than at the control area. The frequency of the endophyte Hormonema sp., on the other hand, was not correlated with distance from the factory. In the experimental field study, the total number of endophyte‐infected needles was not affected by the treatments. The number of needles infected with Hormonema sp., however, was significantly lower in the Cu and Ni treated trees than in irrigated controls. Hormonema sp., strains isolated near the Harjavalta factory were more tolerant of Cu and Ni in vitro than were those isolated 8 km from the factory.