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- Author or Editor: Michael Marcotrigiano x
- Journal of the American Society for Horticultural Science x
A two-stage micropropagation system was devised for cranberries (Vaccinium macrocarpon Ait.). Shoot-tip explants taken from four cultivars of greenhouse-grown plants were placed on media composed of Anderson's major salts, Murashige and Skoog's (MS) minor salts and organics, plus various concentrations of 2iP, IBA, and GA3. In other experiments, explant source, salt formulations for media, and rooting treatments were studied. Optimal multiplication and shoot quality occurred when nodal explants taken from greenhouse-grown or micropropagated plants were placed on medium containing 150 μm 2iP, 1.0 μm IBA, and no GA3. Histological examination revealed that the initial response of nodes to culture is axillary bud proliferation, but adventitious shoot formation occurred after 4 to 6 weeks. Cultures that contained only axillary shoots were not evident unless low levels of 2iP were used, at which point only axillary buds present on the explants were released. Proliferated shoots could be rooted ex vitro without auxin treatment. Optimal rooting occurred under high-light conditions. Plants were transplanted to the field for comparison to conventionally propagated material. Chemical names used: gibberellic acid (GA3), N-(3-methyl-2-butenyl)-1H-purin-6-amine (2iP), 1H-indole-3-butanoic acid (IBA).
Investigations were performed to determine the influence of gibberellic acid (GA3) on intact plants and cultured phylloclades of `Crimson Giant' Easter cactus [Rhipsalidopsis gaertneri (Regel) Moran]. Responses of intact plants depended on GA3 concentration, number of spray applications, and application time. Single GA3 applications delayed flowering and reduced the percentage of apical phylloclades flowering and number of flower buds per plant when applied before floral primordia formation [from 20 days before to the start of long days (LDs)], but hastened flowering and did not affect the percentage of apical phylloclades flowering or number of flower buds per plant when applied during floral bud development (20 days after the start of LDs). When sprays were applied at or before the start of LDs, increasing the GA, concentration resulted in fewer plants flowering, longer flowering delays, and further decreases in the number of flower buds per plant. Multiple GA3 applications were more inhibitory to flowering than single applications. Whole plants and cultured phylloclades exhibited similar reactions to GA3, but cultured phylloclades were more responsive to GA3 than intact plants. Intact plants and cultured phylloclades generally produced more new phylloclades as GA3 concentration increased. Spine growth also increased when phylloclades were cultured in a GA3-containing medium. Flowering was accelerated by ≈55 days when GA, was applied to intact plants with 1- to 2-mm-long flower buds. GA, may be horticulturally useful for Easter cactus crop scheduling.
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)].
Abstract
A phenotypic and sexual analysis of Fragaria vesca ‘Albo-Marginata’ determined that the leaf variegation was of chimeral origin. Stable periclinal chimeras were established in vitro from runner tips. Plants were transferred to proliferation media containing 0.5 μm IBA, 0.3 μm GA3, and BA at either 0, 1.3, 4.4, or 13.2 μm. Whereas the histogens of field-grown runner plants remained stable, more than 90% of the plantlets propagated in vitro varied from the original explants. Most variants were albino or were green, but some were mericlinal chimeras. Histological evidence indicated that many shoots were adventitious, arising from basal callus tissue or petioles. Chemical names used: 1H-indole-3-butanoic acid (IBA); gibberellic acid (GA3); N-(phenylmethyl)-1H-purin-6-amine (BA).