Intersectional cytoplasmic hybrids in Nicotiana : Identification of plastomes and chondriomes in N. sylvestris + N. rustica cybrids having N. sylvestris nuclear genomes.

Cybrid plants having the nuclear genomes of one species and either or both plastomes and chondriomes of another species were obtained by fusing protoplasts of Nicotiana sylvestris, as "recipients", with X-irradiated protoplasts of N. rustica as "donors" of chloroplasts and mitochondria. Forty-nine flowering plants, derived from 28 calli, were analysed. As expected, they all had N. sylvestris (i.e. "recipients") morphology. Chloroplast DNA restriction patterns indicated that 8 and 41 plants had N. rustica and N. sylvestris plastomes, respectively. Some of the plants with either type of plastomes produced sterile pollen but none showed anther malformation typical to alloplasmic male sterility. Chondriome identification by mitochondrial DNA restriction analysis of cybrid plants revealed only restriction patterns which were either similar or identical to those of N. sylvestris while no cybrids with N. rustica restriction patterns were detected.