Morphology and inheritance of double floweredness in catharanthus roseus

Abstract

A double-flowered periwinkle [Catharanthus roseus (L.) G. Don.] mutant TYV1 wasidentifiedandthemorphologyandinheritanceofthedouble-floweredphenotypewas studied. TYV1 has an outer salverform whorl of petals and an additional inner funnel-shaped whorl of petals originating from the apex of the corolla. The apex of corolla tube forms a narrow opening. There are hairs under the opening at the apex. The stigma in this mutant is set below the anthers. The overlap between the top end of the pistil and bottom ends of anthers in TYV1 flowers at 1 to 2 days after anthesis is 0.56 ± 0.01 mm. TYV1couldbeusedaseitherthemaleorfemaleparentincrossing.Self-pollinatedTYV1 produced all double-flowered progeny compared with self-pollinated single-flowered cultivars Little Pinkie and Titan Burgundy, which produced all single-flowered progeny. F1 plants between TYV1 and'Little Pinkie 'or' Titan Burgundy' wereallsingle.Three F2 populations segregated into 3 single: 1 double ratio. Backcrossing F1 to seed parents also indicated that a double-flowered form was controlled by a recessive allele. A single dominant gene expressed in the homozygous or heterozygous state resulted in the single-floweredphenotype.Alltheyoungseedlingsofself-pollinated TYV1anddouble-flowered progeny had distorted leaves before the sixth pair of leaves emerged.