Inheritance of functional male sterility in the medicinal plant, periwinkle

Abstract

Periwinkle [Catharanthus roseus (L) G. Don], an ever blooming tropical plant, is the source of anti-cancer (vincristine and vinblastine) and anti-hypertension (ajmalicine) alkaloids, which are found in its leaves and roots, respectively. Levy et al. [1] reported heterosis for leaf and root yields while Sevestre-Rigouzzo et al. [2] reported heterosis for the content of alkaloids in leaves and roots. Automatic intra-flower self-pollination does not occur in periwinkle and pollination is brought about mainly by butterflies. Periwinkle produces fairly large number of flowers per plant per day, and pollinating butterflies have been found to bring about geitonogamous self-pollination as well as phenotypic assortative mating for flower colour [3]. Therefore, although periwinkle is a crosspollinating species, the availability of male sterility is an essential pre-requisite for exploiting heterosis. A mutant (EMS 1-10) with indehiscent anthers (functional male sterility) was isolated following an induced mutagenesis programme, which was taken up with an objective of inducing mutants with high content of alkaloids in a dieback resistant variety, Nirmal [4]. The mutant appeared to be similar to another mutant, wavy leaf margin (NEU 1-7), except for indehiscent anthers. The mutant was phenotypically normal for other morphological traits. The mutant had smaller anthers (Fig. 1) with lesser number of pollen grains than parental variety, Nirmal. Pollen grains of the mutant were fertile, and good fruit- and seed-set was obtained on artificial selfing (Table 1).