Plant regeneration from protoplasts of Dimorphotheca and Rudbeckia

Protoplasts were isolated from leaves, shoots, cotyledons, ray florets and callus cultures of Dimorphotheca aurantiaca (syn. D. sinuata) (Cape Marigold, Star of the Veldt) and Rudbeckia hirta, R. laciniata and R. purpurea; species of ornamental value. For Dimorphotheca, plants were regenerated from protoplasts of all sources apart from the ray floret, whilst for the Rudbeckia species, although protoplast division was induced in most cases, only leaf mesophyll protoplasts of R. hirta c.v. Marmalade gave plants. The establishment of plant regeneration for these ornamental species, from protoplasts, now provides a basis for their somatic hybridisation.Abbreviations BAP 6-benzylaminopurine - IAA indole-3-acetic acid - NAA naphthaleneacetic acid - K kinetin - GA₃ gibberellic acid - MS Murashige and Skoog (1962) - f.wt. fresh weight     

Ricerche Cariologiche e Embriologiche Sul Genere Rudbeckia (Asteraceae)

Summary

The author describes the different modalities of the cellularisation of the adult gametophyte of Rudbeckia laciniata L. The several cases are arranged according to the number and the type of differentiation of the cells of the gametopyte. Of each type it is stated the frequency, calculated in about 500 cases.

The author remarks that the differentiation of the single cells is owing to »an effect of the position«, which exists in the displacement of the nuclei of the gametophyte regarding the proendospermatic cell, to which cell, however, one can attribute a pre-eminent »power of organization«. The displacement of the nuclei is after all the consequente of the stage of the » polarisation «.     

Floral morphogenesis in Rudbeckia hirta in relation to polyamine concentration

Changes in polyamine concentration in the long day (LD) plant Rudbeckia hirta were examined over the course of floral initiation and development. Plants of R. hirta were grown to maturity under 9h, non-floral-inductive photoperiods. At maturity, half the plants were placed in ambient day length plus a 4- h night interruption. Plants were sampled at 0, 4, 8, 12 or 16 days for polyamine content and floral initiation. Polyamines were extracted from fully expanded leaves and the meristems were examined histologically. In another experiment, polyamines were extracted from the meristems under paired LD and short day (SD) conditions every 2 days from 0 to 22 days. A rise in free polyamines was linked to important cytological events during floral initiation. Free putrescine and spermidine levels increased after 4 LD and continued until 14 to 16 LD when the levels in the meristem began to decline. Events of floral initiation began between 4 and 8 LD with cell proliferation and the start of stem elongation. Initiation was irreversible after 14 to 16 LD, the period when putrescine and spermidine began to decline. After 4 LD, the polyamine level was consistently higher in the photoinduced plants. Our results from this study, using direct histological comparisons of meristematic development and polyamine concentration, clearly demonstrate a correlation of polyamines and flowering.     

Ricerche cariologiche ed embriologiche sul genere Rudbeckia (Asteraceae)

Riassunto

L'Autore ha studiato lo sviluppo del gametofito femminile di Rudbeckia speciosa Wender, pianta tetraploide apomittica, riscontrando una modalita analoga a quella osservata in Ixeris dentata (OKABE 1932). It gametofito diploide si costruisce attraverso quattro divisioni di cui la prima di tipo restituzionale. La formazione dell'embrione e preceduta dal fenomeno della semigamia.     

不同浸种方式对黑心菊种子萌发特性的影响

对发育良好的黑心菊（Rudbeckia hybrida）种子采用不同温度（40、50、60 ℃）温水和不同浓度（50、80、 110、140 mg/L）赤霉素（GA3）溶液分别浸种处理,研究其不同处理组合对种子萌发的影响。结果表明,以80 mg/L赤霉素溶液浸泡2 h处理的种子萌发效果最好,是促进黑心菊种子萌发的最优组合。     

Physiological and Hormonal Factors Influencing Organogenesis in Rudbeckia bicolor Explants Cultured In vitro

Factors influencing organogenetic responses and bolting of adventitiouslyformed buds were investigated in in vitro cultured cotyledon,stem and leaf explants of Rudbeckia bicolor. Application ofnaphthaleneacetic acid (NAA) induced adventitious root formationand that of benzyladenine (BA) induced adventitious bud differentiation.When NAA at a low concentration was added together with BA,bud initiation and development were promoted further, althoughoptimal concentrations of NAA and BA varied with the kind ofexplants used. Gibberellic acid caused stem elongation of adventitiousbuds, and occasionally differentiation of floral buds on theapices of developed shoots. The action of N-phenyl-N'-(4-pyridyl)urea(4PU) and its derivative (4PU-Cl) on adventitious bud formationwas also examined. (Received August 8, 1981; Accepted November 9, 1981)     

Floral initiation in Rudbeckia hirta (Asteraceae) under limited inductive photoperiodic treatments

Two experiments were conducted to examine the response of Rudbeckia hirta to limited inductive photoperiodic treatments. The first examined the effects on plants grown to an thesis of the second axillary inflorescence, and the second examined the early histological events within the meristem. Plants of Rudbeckia hirta were grown to maturity under short days (SD). At maturity, half the plants were placed in long days (LD). In the first experiment, the plants remained under LD for 0, 8, 16, 24, or 32 days before being returned to SD with an additional group remaining under LD as a control. In the second experiment, the plants remained under LD for 0, 4, 8, 12, 16, 20, 24, or 28 days before being returned to SD. Meristems were sampled 0, 4, 8, or 12 days after return to SD and histologically examined. Four groups of plants receiving 32, 36, 40, or 44 LD were used as a continuous LD control. When grown to anthesis, plant height and branch number increased as the number of inductive cycles increased. Plants receiving 24 or more LD reached anthesis earlier than plants receiving fewer LD. Histological examination of plants receiving only 4 LD showed they never progressed beyond early floral initiation. After 12 LD, the meristems continued to develop even when returned to SD, indicating that enough of the floral stimulus had reached the meristem to initiate flowering. Once involucral bract primordia initiated, floral development continued whether in LD or SD conditions.     

Genotypic interactions in an aphid-host plant relationship: Uroleucon rudbeckiae and Rudbeckia laciniata

Summary Four clones of the aphid Uroleucon rudbeckiae were grown on four clones of the host plant Rudbeckia laciniata. Age-specific fecundities were used to determine the fitness, F _i , of each individual aphid. The analysis of variance for F _i revealed that (1) plant genotype has a significant effect on aphid fitness; (2) there is an interaction between aphid and host plant genotypes with respect to aphid fitness; and (3) aphid fitness is affected by phenotypic differences among individual host plants. Result (2) supports the hypothesis that genotypic interactions between aphid and host may maintain genetic diversity in aphid populations. The results of a preference test, while not significant at customary probability levels, suggested that aphids will choose to feed on plants which confer greater fitness.     

地被菊的再生与转化系统的建立

文章初步建立了地被菊品种‘早小春’组织培养植株再生系统和农杆菌介导的稳定转化系统。幼蕾管状花瓣诱导培养获得再生植株的最适培养基为MS+2.0mg·L-1ZT+0.5mg·L-12,4-D,愈伤组织诱导率可达95%以上,不定芽的分化率达到87%以上。以再生植株叶片为外植体进行遗传转化实验的结果表明:用MS液体培养基稀释的农杆菌液效果最佳,以感染8min左右,共培养3d为宜。同时附加40mg·L-1卡那霉素和500mg·L-1头孢霉素是地被菊转化的最佳条件。     

Optimisation of the second phase of a two phase growth system for anthocyanin accumulation in callus cultures of Rudbeckia hirta

A two-phase growth system composed of modified Schenk-Hildebrandt medium and enriched Miller's medium was used to grow callus of R. hirta L. The second phase of the system has been optimised and the callus synthesised a 12-compound set of anthocyanins, comprising 4.97% of tissue mass (tubular flowers of the plant in nature only contain one compound comprising 0.28%). The beneficial effect of high content of cysteine on anthocyanin accumulation was noted. The predominant element of the anthocyanin set obtained in vitro is cyanidin-3-O-(6-O-malonyl-β-D-glucopyranoside), a relatively stable compound. This revised version was published online in June 2006 with corrections to the Cover Date.     

Stomatal behavior of ozone-sensitive and -insensitive coneflowers (Rudbeckia laciniata var. digitata) in Great Smoky Mountains National Park

* Morphological and physiological attributes were assessed to elucidate the underlying mechanisms of ozone (O(3)) sensitivity in a highly sensitive species, cutleaf coneflower (Rudbeckia laciniata var. digitata). * Foliage at the same height in the canopy on paired O(3)-sensitive and -insensitive cutleaf coneflowers was assessed for level of foliar symptoms, stomatal density, stomatal responsiveness to dynamic changes in light and leaf-to-air vapor pressure deficit (VPD), steady-state responses to light and CO(2), intrinsic transpirational efficiency, and plant water balance. * There were no morphological differences between the sensitivity types that might have contributed to greater O(3) uptake in sensitive individuals. Stomata of sensitive plants were less responsive than those of insensitive plants to experimentally increased and decreased light intensities, and to increased VPD. O(3)-insensitive plants had greater intrinsic transpirational efficiencies, greater maximum assimilation rates under saturating CO(2) and light, and greater carboxylation rates. * Different physiological attributes vary independently within an individual plant, which collectively confer sensitivity or insensitivity to O(3) injury.