High-frequency induction of nodulation and nitrogen fixation mutants of Rhizobium japonicum.

AUTOR(ES)

Skogen-Hagenson, M J

RESUMO

More than 50 symbiotic mutants of Rhizobium japonicum were isolated by purported plasmid-curing techniques. Wild-type R. japonicum strains were grown in liquid culture at 28 or 36 degrees C in different concentrations of acridine orange, ethidium bromide, or sodium dodecyl sulfate for selection of mutants. The symbiotic traits of 133 isolates from nine treatment groups were determined. Forty-two isolates were Nod- Nif+, seven were Nod+ Nif-, and two were Nod- Nif-. The nifDH genes were deleted in three mutants and consequently showed no hybridization to a nifDH probe. None of these mutants showed any detectable loss of plasmid DNA.

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