title: Heteroplasmy of the chloroplast genome of Medicago sativa L. cv 'Regen S'' confirmed by sequence analysis.
abstract: The heteroplasmy of chloroplast DNA (cpDNA) observed in Medicago sativa L., which involves the presence (type B) or absence (type A) of an Xba I restriction site, was examined using closed fragments covering the variable XbaI site from type-A and type-B cpDNA. The 6.2-kb PstI fragment of DNA from type-A cpDNA (-XbaI) and from type-B cpDNA (+XbaI) was cloned into pUC19 plasmids. EcoRI fragments bearing the variable XbaI site from the type-A and type-B 6.2-kb PstI fragments were subcloned into pUC19. DNA sequences of both types of the 696-bp EcoRI fragments were determined and computer-assisted analysis of the sequence data carried out. Type-A cpDNA was found to differ from type-B cpDNA by 1 base, a G to T conversion, which results in a non-recognition site for XbaI in the type-A cpDNA. The sequence difference was in a non-coding region. Cloning and sequencing of the fragments verified the individual identity of the type-A and type-B cpDNA.
authors.affiliation: Department of Biological Sciences, University of Newcastle, 2308, New South Wales, Australia.
authors.forename: J T
authors.initials: JT
authors.lastname: Fitter
authors.forename: M R
authors.initials: MR
authors.lastname: Thomas
authors.forename: R J
authors.initials: RJ
authors.lastname: Rose
authors.forename: N
authors.initials: N
authors.lastname: Steele-Scott