P uzzle box , a tobacco line with flowers that mix floral and inflorescence characteristics

Abstract

We characterized the development of a tobacco morphological mutant, puzzle box, previously obtained by selection for resistance to an inhibitor of an enzyme in the polyamine biosynthetic pathway. Puzzle box plants are shorter than wild type with smaller leaves and an irregular leaf plastochron. The diameter and shape of the puzzle box shoot apex are similar to wild type. In puzzle box plants, the terminal flower develops but not the cymose inflorescence. This flower has a variable phenotype with more than five sepals, five petals, and five stamens. The organs in the fourth whorl are produced by carpellike primordia and contain tissue biochemically similar to wild type transmitting tissue. These organs form a cylinder within which additional floral organs are produced. Some cultures of puzzle box buds and excised cylinders produce additional floral organs. The inflorescence and floral programs may be expressed together in puzzle box.