Restriction endonuclease analysis of chloroplast DNA from streptomycin-resistant mutants of Nicotiana plumbaginifolia.

Chloroplast DNA isolated from wild-type Nicotiana plumbaginifolia and 12 maternally inherited streptomycin-resistant mutants was digested with various restriction enzymes and the resultant patterns were compared. No gross structural alterations of the chloroplast genome were detected in any mutants; however, variant patterns owing to the gain or loss of a restriction site were found in three mutants, SR1007, SR1019, and SR1022. The variant patterns in SR1019 and SR1022 are identical and are the results of mutation in the psbG gene coding for a chloroplast membrane protein G, and that in SR1007 is due to mutation in the 16S rRNA gene. Inheritance of the variant patterns in mutants SR1007 and SR1019 was studied. The results showed that the variant patterns and streptomycin resistance were co-transmitted in reciprocal crosses.