Maternal inheritance of cytochrome f in interspecific Nicotiana hybrids

Cytochrome f has been purified to homogeneity, as judged by polyacrylamide gel electrophoresis, from the leaves of Nicotiana tabacum, Nicotiana glutinosa and their reciprocal hybrids. The cytochrome was extracted from chloroplast membranes by sonication in 2% Triton X-100 and 4M urea and was subsequently purified by acetone precipitation and chromatography on Ultrogel AcA 22 in the presence of cholate and on Sephadex G-200 in the presence of sodium dodecylsulphate. The purified cytochrome had a molecular weight of 32,700 determined by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulphate. A difference in the primary structure of cytochrome f from N. tabacum and N. glutinosa was detected by ion-exchange chromatography of the products of trypsin hydrolysis. Cytochrome f from N. tabacum contained an additional peptide not present in the cytochrome fom N. glutinosa. This additional peptide was present in the cytochrome from N. tabacum female x N. glutinosa male, but not in the cytochrome from N. glutinosa female x N. tabacum male, indicating a maternal mode of inheritance of the primary structure of cytochrome f. This suggests an extranuclear, probably chloroplast, location for the genetic information for cytochrome f.