Antibiotic Resistant Mutants of Solanum Nigrum

Abstract

Recently, an efficient system for expanding the number and range of plastome encoded antibiotic resistant mutants in Solanaceous species was reported (1,2). This involved mutagenesis of leaf strips, derived from axenic shoot cultures, with the plastome targetted mutagen, nitroso-methylurea, followed by incubation on medium normally associated with adventitious shoot initiation, but containing levels of antibiotics suppressing morphogenesis and causing bleaching of the explant. Resistant mutants appear as green nodules which develop into adventitious shoots. The previous report (1) concentrated on selection of streptomycin resistant mutants and demonstrated that while the technique could be used for several solanaceous species, Solanum nigrum was particularly responsive. Maternal inheritance of streptomycin resistance was demonstrated for three of the S. nigrum mutants and evidence was also found for occasional paternal inheritance in one of them. The present report extends this investigation to include the selection of additional antibiotic resistance markers both on the plastome (lincomycin and spectinomycin resistance) and nuclear genome (kanamycin resistance) using the leaf strip system for mutagenesis and Agrobacterium — mediated transformation respectively.