Efficient Plant Regeneration System for New Guinea Impatiens (Impatiens Hawkeri W. Bull) CV. ‘Violet’and ‘Scarlet Bronze Leaf’

New Guinea Impatiens (Impatiens hawkeri W. Bull) is an eye-popping landscaping plant which is of bright and colorful blooms. A highly efficient in vitro plant regeneration system through direct shoot organogenesis was established for the first time from hypocotyl with partial cotyledons of New Guinea Impatiens. The results showed that Explant sterilization method, basic medium type,AgNO3,sucrose and plant growth regulators (PGRs) have greatly influences on in vitro morphogenesis.The regeneration rate in regeneration media that MS supplemented with 0.5mg·L−1 TDZ and 0.1mg·L−1 NAA was acceptable ,the induction rate of 'Violet' was 86.67%, and its proliferation coefficient was 5.27, while the induction rate of 'Scarlet Bronze Leaf' was 83.33%, and its proliferation coefficient was 5.13.PIC was unable to induce clumped sprouts, but it had a better effect on callus induction.We also included a shoot multiplication stage using regeneration New Guinea Impatiens medium that MS supplemented with 0.8mg·L−1 6-BA,0.5mg·L−1 TDZ and 0.05mg ·L−1 NAA.Reducing sucrose concentration to 20g·L−1 or adding 1mg·L−1AgNO3 could alleviate the vitrification phenomenon in the process of tufted bud proliferation.The optimal root culture medium for the regenerated seedlings of 'violet' and 'scarlet bronze leaf' of New Guinea Impatiens was MS supplemented with 0.05mg·L−1IBA, the rooting rate reached 100%.The study examined the micropropagation responses of New Guinea Impatiens in the presence of various growth regulators and provided a simple and more suitable protocol adapted for the mass propagation of clones.

Gibberellin and polyamines effects in growth and flowering of New Guinea impatiens

To meet the high demand of the consumer market for ornamental plants, various techniques are used to increase production and flowers quality, through growth regulators. Despite all the benefits arising from the use of regulators, it is essential to establish concentrations that meet the purpose of their use. The aim of the study was to evaluate the growing and flowering characteristics of Impatiens hawkeri, after the exogenous application of different dosages of spermine, spermidine and gibberellic acid. Two pulverizations were made separated by 15 days, with polyamines (500/2,000 and 1,000 μM), or gibberellic acid (50 and 100 μM), and for the control, water was used. The evaluated parameters were the number of leaves, plant height, number of flower buds, dry and fresh weights of the root system and the aerial parts, and also volume of the root system and the chlorophyll content (SPAD). The treatments with gibberellin caused higher averages in all measurements, except for SPAD. Based on the results obtained, the use of gibberellin with the dosage of 100 µM as a regulator is the most appropriate to meet the needs of the Impatiens hawkeri market with more vigorous plants and with a greater number of flowers.

A protocol for fast in vitro propagation of Impatiens hawkeri cv. Sweeties Blue Star, an important ornamental-cover species

Impatiens hawkeri is among the three important bedding plants in the world. There is no efficient protocol for fast micropropagation of Impatiens hawkeri cv. Sweeties Blue Star. Single nodes were germinated on Murashige and Skoog (MS) medium supplemented with 1-naphthaleneacetic acid (NAA; 0.00, 0.10 and 0.50 mg l-1), 6-benzyladenine (BA; 0.00, 0.10, 0.50 and 1.00 mg l-1) and kinetin (KIN; 0.00, 0.10, 0.50 and 1.00 mg l-1). The shoot length was highest in medium containing 0.10 mg l-1 NAA and control. The largest number of shoots (14.06 and 14.00 per explant) was produced in media supplemented with 1.00 mg l-1 BA, 0.50 mg l-1 NAA and 1.00 mg l-1 BA, 0.10 mg l-1 NAA, respectively. The 0.10 mg l-1 NAA along with 1.00 mg l-1 BA was found to be superior for production of leaf (57.13). Maximum root length (33.80 mm) and root number (29.13) were obtained on medium supplemented with 0.10 mg l-1 NAA without BA and KIN. Plantlets were transplanted to pots filled with perlite and peat moss (in ratio of 1:1) and transferred to the greenhouse for acclimatization. Regenerated plantlets were morphologically identical with mother plants. Upon ex vitro transfer, 100% of plants survived.

Complete Genome Sequence Resource for the Necrotrophic Plant-Pathogenic Bacterium Dickeya dianthicola 67-19 isolated from New Guinea Impatiens

New Guinea Impatiens (NGI, Impatiens hawkeri) are popular bedding plants that can be affected by a number of pathogens. Using 16S rDNA sequencing and genus-specific PCR, we identified the first Dickeya dianthicola strain isolated from NGI presented with blackleg symptoms, herein designated as D. dianthicola 67-19. Here, we report a high-quality complete and annotated genome sequence of D. dianthicola 67-19. The 4,851,809 bp genome was assembled with Nanopore reads and polished with Illumina reads, yielding 422× and 105× coverage, respectively. This closed genome provides a resource for future research on comparative genomics and biology of D. dianthicola, which could translate to improved detection and disease management.

Impatiens ‘New Guinea’ (Impatiens hawkeri Bull) Hormonal Effects during the Post-transplant Biomass Accumulation

Pot ornamental plant productivity is related to the environmental growth facilities but negatively affected by the pot root restriction syndrome so during nursery as the post-transplant stage. The physiological mechanism involved included both the synthesis and translocation of auxins and cytokinins. However, clear sink-source and dose-response relationships of exogenous plant regulators such as indole acetic acid (AIA) and benzyl amino purine (BAP) and environment on biomass accumulation in most ornamental foliage plants, including New Guinea Impatiens (Impatiens hawkeri) are lacking. The aim of this work was to analyze the effects of an exogenously shoot-applied auxin and a cytokinin, separately or successively, on the post-transplant biomass accumulation of I. hawkeri through the anatomical, morphological and physiological changes observed. Two experiments were performed. The first experiment included the response to only BAP-sprayed plants (0, 5, 50, or 100 mg L-1). For the second experiment, rooting cuttings of I. hawkeri were sprayed with different concentrations of IAA (0, 5, 50, or 100 mg L-1) followed by different BAP concentrations (0, 5, 50, or 100 mg L-1) one week later to run-off at sunset. Results showed that (a) a single BAP or AIA dose increased increase post-transplant biomass accumulation through a higher leaf area expansion and photo assimilate production, (b) as a result of both AIA and BAP spray, the higher NAR the higher post-transplant biomass accumulation, (c) leaf anatomical changes (leaf thickness, intercellular spaces) let a higher carbon dioxide diffusion and fixation with a correlative increase in photo assimilates, (d) a higher root system would be related to a higher cytokinin synthesis. In summary, similarities between responses to either hormone, together with the lack of any IAA - BAP interaction, provide two independent routes for commercial growers to increase the productivity of I. hawkeri ornamental plants by using early foliar sprays.

Growth Response of Herbaceous Ornamentals to Phosphorus Fertilization

A series of experiments investigated the effects of increasing phosphate–phosphorus (P) concentrations on the growth and development of four horticultural species. In experiment 1, petunia [Petunia atkinsiana (Sweet) D. Don ex W.H. Baxter] plants were grown using eight P concentrations, and we found that the upper bound for plant growth was at 8.72–9.08 mg·L−1 P, whereas concentrations ≤2.5 mg·L−1 P caused P deficiency symptoms. Experiment 2 investigated P growth response in two cultivars each of New Guinea impatiens (Impatiens hawkeri W. Bull) and vinca [Catharanthus roseus (L.) G. Don]. Growth for these plants was maximized with 6.43–12.42 mg·L−1 P. In experiment 3, ornamental peppers (Capsicum annuum L. ‘Tango Red’) were given an initial concentration of P for 6 weeks and then switched to 0 mg·L−1 P to observe whether plants could be supplied with sufficient levels of P, and finished without P to keep them compact. Plants switched to restricted P began developing P deficiency symptoms within 3 weeks; however, restricting P successfully limited plant growth. These experiments indicated that current P fertilization regimens exceed the P requirements of these bedding plants, and depending on species, concentrations of 5–15 mg·L−1 P maximize growth.

1-Methylcyclopropene Improves Ethylene Tolerance of Unrooted Herbaceous Cuttings but Delays Adventitious Root Development in Angelonia, Calibrachoa, Impatiens, Portulaca, Sutera, and Verbena Cultivars

Knowing which herbaceous taxa are ethylene sensitive and managing exposure of unrooted terminal stem cuttings to ethylene in those taxa are critical for maintaining high-quality propagules that root readily. Of 59 taxa surveyed, freshly harvested terminal cuttings of Begonia hybrid ‘Snowcap’, Lantana camara L. ‘Patriot Sunbeam’, and Portulaca oleracea L. ‘Fairytales Sleeping Beauty’ were sensitive to exogenous application of 1 μL·L−1 ethylene, as demonstrated by leaf abscission within 24 hours of treatment. Exposure to 1-methylcyclopropene (1-MCP) at 700 μL·L−1 for 4 hours before ethylene treatment prevented ethylene injury in these species/cultivars. Exposing unrooted cuttings to 700 μL·L−1 1-MCP induced significant endogenous ethylene biosynthesis in terminal cuttings of the five taxa tested: Euphorbia pulcherrima Willd. ex Klotzsch ‘Visions of Grandeur’, Impatiens hawkeri W. Bull ‘Sonic Red’, Pelargonium peltatum (L.) L’Hérit. ‘Mandarin’, Pelargonium ×hortorum Bailey (pro sp.) [inquinans × zonale] ‘Rocky Mountain White’, and Petunia ×hybrida Vilm. ‘Suncatcher Coral Prism’. Exogenous 1 μL·L−1 ethylene improved adventitious rooting in two cultivars: Begonia hybrid Anita Louise and Fuchsia triphylla L. Honeysuckle. Other trials showed that 1-MCP exposure reduced root number and length of P. ×hortorum ‘Kardino’ and delayed adventitious rooting in all six cultivars tested: Angelonia angustifolia Benth. ‘Carita Lavender’, Calibrachoa ×hybrida Llave & Lex. ‘Terra Cotta’, I. hawkeri ‘Sonic Red’, P. oleracea ‘Fairytales Sleeping Beauty’, Sutera cordata Kuntze ‘Abunda Blue Improved’, and Verbena ×hybrida Groenl. & Ruempl. ‘Aztec Wild Rose’. Subsequent exposure to 1 μL·L−1 ethylene partially mitigated the negative effects on rooting from exposing cuttings to 1-MCP.