Protoplast Fusion-Mediated Transfer of Male Sterility and Other Plasmone-Controlled Traits

Summary

Genetic and biochemical evidence indicates that cytoplasmic male sterility (CMS) in Gramineae and Solanaceae crop species is controlled by nuclear genome–chondriome (mitochondrial genome) interactions. This evidence is especially strong for maize, tobacco and petunia. We introduced the chondriome or some of its components from an alien donor species into a target cultivar by the donor–recipient protoplast fusion procedure and showed that CMS can be induced in a given tobacco cultivar by organelle transfer. This procedure has been used successfully in several laboratories to combine CMS with plastome-controlled atrazine tolerance in cultivars of Brussica, in order to establish desirable ‘seed parents’ for F1 hybrid seed production. In recent studies with Nicotiana we investigated pre-fusion treatments and plastome mutants as means by which to control organelle transfer from donor protoplasts to target plants. Such treatments have been used to produce male sterile potato cultivars. CMS cultivars should be very useful as seed parents for the production of F1 hybrid true potato seeds, which at present are produced by laborious manual emasculation and pollination.