Mycorrhizal associations of some actinomycete nodulated nitrogen-fixing plants

Abstract

Flowering plants that fix atmospheric nitrogen in actinomycete-induced nodules were sampled for mycorrhizal associates. Twenty-five species from seven families (Betulaceae, Casuarinaceae, Myricaceae, Rhamnaceae, Rosaceae, Elaeagnaceae, and Datiscaceae) were examined. Samples included were from the United States, Japan, and England.Both mycorrhizae and actinomycete-induced nitrogen-fixing nodules were present on: (i) four species of Alnus, (ii) two species of Casuarina, (iii) eight species of Ceanothus, (iv) four species of Myrica, (v) and one species each of Shepherdia, Hippophae, Cercocarpus, Dryas, Purshia, Comptonia, and Datisca. Soil sieving revealed species of the following genera of vesicular–arbuscular (VA) mycorrhizal fungi: Gigaspora, Glomus, Acaulospora, Entrophospora, and three undescribed taxa soon to be described. Spores of species in the first three genera of fungi were found most frequently from soil sievings. The VA mycorrhizal fungi exhibited distinct distributional patterns when associated with nonleguminous nitrogen-fixing hosts in different habitats. The ectomycorrhizae were not characterized.