A system has been developed for rapid selection
of streptomycin resistant mutants, as adventitious shoots
arising from explants of several Solanaceous species. Efficient
mutagenesis was achieved by incubating shoot culturederived
leaf strips with 1 or 5 mM nitroso-methylurea, for
90 or 120 min. In Nicotiana tabacum and Lycopersicon peruvianum
these treatments resulted in white or variegated adventitious
shoots from up to 3.5% of explants placed on
medium promoting shoot regeneration. Chlorophyll deficiencies
were only observed very rarely in Solanum nigrum.
Streptomycin resistant shoots were obtained from leaf explants
placed on medium containing 500 mg 1- 1 streptomycin
sulphate, under which conditions ex plants are bleached
and adventitious shoot development suppressed. Green adventitious
shoots appeared at a frequency dependent both
on the mutagenic treatment and on the species. The best
response was with S. nigrwn where > 70% of the ex plants
produced streptomycin resistant shoots, most of which retained
their resistance on subsequent testing. Maternal inheritance
of streptomycin resistance has been confirmed for
several N. tabacum and S. nigrum mutants, and there is
also evidence for paternal transmission in the latter species.
The procedure h3.s been successfully extended to other species,
including N. s_vlvestris and N. plumbagin (fOlia, and also
to obtain spectinomycin resistant mutants
