DYNAMICS OF CYTOSKELETAL PROTEINS IN DEVELOPING PINE ECTOMYCORRHIZA

Mycorrhizal short roots of Pinus contorta Dougl. ex Loud colonized by Suillus variegatus (Sow. ex Fr.) O. Kuntze or Paxillus involutus (Bats ch) Fr. were collected 1->60 days after fungal contact. The proteins o f the inoculated roots were extracted, electrophoretically separated, blotted and immunostained for alpha-tubulin and actin. The development of the mycorrhiza was also followed microscopically. The signal of pl ant alpha-tubulin was stronger than the signal of fungal alpha-tubulin during the first 5 days in S. variegatus mycorrhiza and was then exce eded by fungal alpha-tubulin. This correlated well with the increase o f fungal mycelium in the mycorrhiza. A transient drop in both plant an d fungal alpha-tubulin signals was observed 20 days after fungal conta ct, suggesting a change in the metabolism of the mycorrhiza. The signa ls for plant and fungal actins in the mycorrhiza increased steadily du ring early infection and then remained at a high level as the mycorrhi za matured. Similar trends were observed in P. contorta-P. involutus m ycorrhiza. The data from P. contorta-S. variegatus mycorrhizas suggest s that alpha-tubulin is a growth-related protein, subject to changes, while the amount of actin reflects the general metabolic activity of t he mycorrhiza. In both mycorrhizal systems clear alpha-tubulin and act in signals were detected 60 days after colonization, which indicates t hat the mycorrhizas were metabolically active in spite of their wither ed appearance.