Biochemical and cytological responses of ectomycorrhizae in Pinus massoniana to artificial acid rain

The effects of artificial acid rain on the formation, development, and the activity of enzyme in ectomycorrhizae of Pinus massoniana were investigated. The comparison of the fungi, roots of plant and ectomycorrhizal roots suggested that infection with ectomycorrhizal fungi could stimulate the activities of acid phosphatase and nitrate reductase in roots of plant. Light acid rain (pH 4.5) stimulated the occurrence of ectomycorrhizae. Serious acid rain (pH lower than 3.0) inhibited the activities of enzyme and disturbed the cytological structure though the enzymes showed higher activity in ectomycorrhizae compared with that in nonectomycorrhizae. In contrast, lower pH stimulated the activity of superoxide dismutase and it showed the highest activity in non-mycorrhizae at pH 2.2. Furthermore, the enzyme activity in the root infected with mixed mycelia of three fungal species had a stronger response to acid rain than that in the root infected with single specie. The probable mechanisms of the resistance and response of ectomycorrhizae to acid rain were discussed.