The combined use of leaf irradiation and of the adventitious bud technique for inducing and detecting polyploidy, marker mutations and self-compatibility in clonal populations of Nicotiana alata Link and Otto

Summary

The method of vegetative propagation by adventitious bud formation on detached leaves has been used, in combination with radiation treatment, for obtaining self-compatibility mutations and marker mutations in two clonal populations derived from single S ₂S₃plants of Nicotiana alata. Out of in all 345 individuals arisen from leaves exposed to various dosages of X-rays, 3 self-compatible and 3 marker mutants were selected, which maintain their phenotypes after several cycles of vegetative propagation. These results demonstrate that it is possible to recover, in a self-incompatible clone, mutant individuals which are characterized by the same genetic background as the mother plant and which are, consequently, free of the inbreeding effects usually resulting from the conventional methods of mutation induction and detection.

In addition to these six mutants, a number of plants originated from both control and irradiated leaves were found to be tetraploid and self-compatible. Whereas the occurrence of tetraploidy is taken as an indication that some of the initial cells from which the plantlets originated were polyploid, the fact that no cytochimeras were detected, is considered to present a further demonstration of the ‘one cell-one plant’ theory. Self-compatibility in the tetraploid plants is ascribed to a competition effect in heterogenic pollen.

Attempts are now in progress to obtain more mutant individuals and to use the marker-mutations available for mapping the S-locus. A biochemical comparison of self-compatible and self-incompatible plants with almost identical genetic backgrounds will be initiated.