Mitochondrial DNA amplification in albino plants of rye (Secale cereale L.) regenerated in vitro

Abstract

Somaclonal variation has been intensively studied by using various molecular markers, however, very little information has been published concerning the nature of the changes and the mutational events involved in the appearance of the marker pattern modifications. Albino plants appeared with a high frequency among the regenerated plants of rye. When RAPDs were performed using the OpF13 primer, all the albino plants presented a very conspicuous band, the ScF13c amplicon, which was very faint or imperceptible in the green plants. We investigated the reasons for the differential amplification of this sequence. IPCR and Southern data indicated that the ScF13c sequence is located in the mitochondrial DNA. The appearance of this band seemed to be related with the amplification of the mitochondrial genome in the albino plants, as the real time PCR data proved. We also observed an increase in the number of mitochondria per cell in these plants that could explain the rise in the copy number of the mitochondrial sequences studied. We observed a very high rate of mutation in a nuclear locus because the same recessive mutation involved in albinism appeared independently in three different cell lines, as the progeny study revealed. This very high rate of mutation in a nuclear locus has been rarely reported. The albino plants of these progenies also showed an increase in the mitochondrial DNA, and in the number of mitochondria.