The effects of different mutagens on self-incompatibility in Nicotiana alata Link and Otto: II. Acute irradiations with X-rays and fast neutrons

Pollen mother cells of Nicotiana alata were exposed to acute doses of X-rays or fast neutrons and, at anthesis, the pollen produced was used to pollinate unirradiated plants of the same clone. The results indicate that fast neutrons are slightly more effective than X-rays for inducing self-compatible pollen-part mutations but that neither fast neutrons nor X-rays have the capacity to generate new self-incompatibility alleles. An unexpectedly high fraction of the self-compatibility mutations induced does not display the centric fragment which usually characterises such mutations. The ratio of fragment to non-fragment self-compatibility mutations of fast neutrons is identical to that of X-rays. The possible use of permanent self-compatibility mutations for production of F1 hybrid seed is discussed.