The role of temperature and growth regulators on the expression of the solanifolium mutation has been examined.
Solanifolium (sf) is a recessive mutation which affects the development of both leaves and flowers (Rick and Harrison, 1959, J. Hered. 50:90-98). The leaves of the mutant possess an entire margin in contrast to the lobed margin of the normal plants. Under our growth conditions, the f lowers produced laterally-free sepals, petals, stamens and a split gynoecium often with exposed ovules. However, the stamens and the gynoecium were both fertile.
The normal (cv. Pearson) and the solanifolium mutant plants grown under different temperature regimes showed that under relatively high temperatures, mutant plants produced normal-looking flowers i.e. with laterally fused stamens and intact gynoecium. On the other hand, normal plants grown under relatively low temperatures produced flowers with some mutant-like features, i.e. with laterally-free stamens and frequently split gynoecium. The sepals and petals of mutant and normal plants were, however, unaffected by different temperature conditions. Similarly, different temperature regimes had no effect on the leaf shape of either the normal or the mutant plants.
Experiments with growth regulators showed that normal plants treated with gibberellic acid (GA3) produced leaves which resembled the leaves of the solanifolium mutant. Similarly, mutant plants treated with chlorocholine chloride (CCC), an inhibitor of gibberellin synthesis, produced some lobed leaves. The CCC treatment also caused the fusion of stamens in mutant flowers.
These experiments show that the expression of the solanifolium mutation can be altered by temperature and growth regulators. Details on these experiments and a further discussion of these findings will be published elsewhere.