VARIATIONS IN NITROGENASE ACTIVITY AMONG PURE‐CULTURED <i>FRANKIA</i> STRAINS TESTED ON ACTINORHIZAL PLANTS AS AN INDICATION OF SYMBIOTIC COMPATIBILITY

Abstract

SUMMARY Frankia strains ArI5, AvcIl, AvsI2, CpI1 and MpI1, previously isolated from nodules of actinorhizal plants, were tested in association with various actinorhizal plants to determine differences in nitrogen‐fixing effectiveness. Alnus incana ssp. rugosa, Alnus rubra, Alnus viridis ssp. crispa, Comptonia peregrina and Myrica gale plants, grown in nitrogen‐free water culture, were inoculated with the cultured Frankia strains. Significant differences in rates of acetylene reduction were found among strains which suggested that endophytes were not fully compatible with some or all of the host plants tested. A pattern of compatibilities among hosts and endophytes was developed to explain differences in rates of acetylene reduction.