Influence of host (Alnus and Myrica) genotype on infectivity, N fixation, spore formation and hydrogenase activity in Frankia.

Nine species of Alnus, two of them represented by several provenances, and Myrica gale were inoculated with a 'local source' of Frankia. The inoculum is an effective (N -fixing), spore-Forming type of Frankia that lacks H, uptake (hydrogenase) activity in symbiosis with A. incana. Despite their wide geographical origin (Europe, China, North America) and their various taxonomie grouping within the genus, all Alnus species/provenances formed Infixing nodules. In all studied nodules Frankia had the phenotype Spore . None of the studied symbioses had hydrogenase activity. The Frankia inoculum was infective also on M. gale, and gave effective nodules without hydrogenase activity. Unlike some other spore-forming types of symbiotic Frankia, all studied symbiotic phenotypes of the 'local source' of Frankia were thus stable characters not influenced by the various host genotypes included in the study.