Identification of a nodD-like gene in Frankia by direct complementation of a Rhizobium nodD-mutant

Clones from a Frankia At4 gene bank were pooled into groups and mass conjugated into a nodD mutant of Rhizobium leguminosarum bv. viciae by triparental matings. When peas were inoculated with the pooled transconjugants, nodulation was observed. A plasmid, pAt2GX containing Frankia DNA, was isolated from bacteria recovered from these nodules. This plasmid was shown to complement a nodD mutant of R. leguminosarum bv. viciae. Thus pAt2GX contains a Frankia gene that is functionally equivalent to nodD of R. leguminosarum bv. viciae.