The root nodules of the Podocarpaceae harbour arbuscular mycorrhizal fungi

Abstract

Here we present the ultrastructure and molecular identification of the fungi in the mycorrhizal nodules of four species of Podocarpaceae endemic to New Zealand. Podocarps form a major component of the rain forest of New Zealand, where they grow on soils poor in extractable phosphate and high in organic matter. Histological studies showed that the mycorrhizal nodules develop as modified lateral roots, and are colonised by an endophytic fungus. Scanning and transmission electron microscopy showed the fungus to contain intracellular coils and arbuscules typical of the order Glomales. DNA was extracted and amplified using PCR to identify mycorrhizal fungi. Several different lineages of arbuscular mycorrhizal fungi colonising the nodules were identified. Individual nodules contained more than one fungal lineage. This study is the first to indicate species of Glomales present in the New Zealand rain forest. It is likely that many of the taxa sampled are new to science because there has been little taxonomic work on Australasian Glomales. © New Phytologist (2002).