Leaf Color Variants from Coleus Shoot Cultures

Abstract

Nuclear-controlled leaf variegation was studied among Coleus × hybridus Voss (formerly C. blumei Benth.) cultivars propagated by seed and as shoot cultures on Murashige and Skoog (MS) medium + 1 to 3 mg BA/liter. Cultivars tested possessed pattern chlorophyll variegation and either pattern or nonpattern anthocyanin variegation. The gene controlling an albino midrib region appears to be fairly stable, with only 2% of the micropropagated plantlets having a solid-green leaf characteristic, a characteristic that was always inherited following selfing. Pattern anthocyanin variegation (PAV) was fairly stable, while nonpattern anthocyanin variegation (NAV) was very unstable. In addition, variants from pattern-variegated phenotypes produced offspring identical to their parent following selfing. In contrast, variants of nonpattern cultivars, when selfed, yielded offspring identical to the original cultivar, identical to the variant, or novel phenotypes. When variants were returned to culture, those derived from cultivars with PAV were more stable than those derived from nonpattern cultivars. In Coleus, micropropagation may induce epigenetic and/or heritable changes in leaf variegation. Cultivars with NAV are less stable than cultivars with PAV. Chemical names used; N-(phenylmethyl)-lH-purine-6-amine [benzyladenine (BA)].