SYMBIOSIS-RELATED POLYPEPTIDES ASSOCIATED WITH THE EARLY STAGES OF ECTOMYCORRHIZA ORGANOGENESIS IN BIRCH (BETULA-PENDULA ROTH)

As a preliminary step towards elucidation of the molecular basis of ectomycorrhiza differentiation, polypeptide changes at different stages of mycorrhiza development were analyzed in birch (Betula pendula Roth). Time-sequencing of the stages in the infection process of clonal plants inoculated with a compatible isolate of Paxillus involutus Batsch revealed that by 8 d mature ectomycorrhizas were obtained. Total phenol-extracted proteins of roots during the 'mycorrhiza formation stage' (2-8 d post-inoculation) were separated by two-dimensional polyacrylamide gel electrophoresis and the resulting patterns compared with non-mycorrhizal roots and mycelium. Alteration in the concentration of polypeptides from the host plant roots was limited even after 8 d of contact between the symbionts. However, seven novel polypeptides were detected 4 d after inoculation, three of them being already present in 2-d-old ectomycorrhizas. These findings demonstrate that symbiosis-related polypeptides accumulate in ectomycorrhizal roots prior to any of the morphological changes characterizing the symbiotic state.