Abstract:
Africa hosts numerous endemic actinorhizal plants from the genus Morella, but
the diversity of their Frankia endosymbionts has never been explored. The diversity
of Frankia in root nodules collected from natural stands of six Morella species within
the Cape flora of South Africa was investigated. The diversity of Frankia in root
nodules collected from natural stands of six Morella species within the Cape flora of
South Africa was investigated by comparative nitrogenase (nifH) gene sequence
analysis. Gene sequences assigned nodular strains to both cluster I (Alnus hostinfection
group) and cluster III (Elaeagnus host-infection group), with sequences
from both groups recovered from three hosts: M. intergra, M. diversifolia and M.
quercifolia. Cluster I sequences were found in nodules from acidic soils exclusively.
Frankia strains representing both groups were isolated and characterized by 16S
rRNA and nifH analysis. This study is the first to investigate the diversity of Frankia
associated with endemic African actinorhizal species in their natural habitats, and to
report isolation of Frankia strains from African Morella.
