Popular Bedding Plants Research Articles

An Integrated Analysis of Transcriptome and miRNA Sequencing Provides Insights into the Dynamic Regulations during Flower Morphogenesis in Petunia

Published genome sequences can facilitate multiple genome sequencing studies of flower development, which can serve as the basis for later analysis of variation in flower phenotypes. To identify potential regulators related to flower morphology, we captured dynamic expression patterns under five different developmental stages of petunia flowers, a popular bedding plant, using transcriptome and miRNA sequencing. The significant transcription factor (TF) families, including MYB, MADS, and bHLH, were elucidated. MADS-box genes exhibited co-expression patterns with BBR-BPC, GATA, and Dof genes in different modules according to a weighted gene co-expression network analysis. Through miRNA sequencing, a total of 45 conserved and 26 novel miRNAs were identified. According to GO and KEGG enrichment analysis, the carbohydrate metabolic process, photosynthesis, and phenylalanine metabolism were significant at the transcriptomic level, while the response to hormone pathways was significantly enriched by DEmiR-targeted genes. Finally, an miRNA–RNA network was constructed, which suggested the possibility of novel miRNA-mediated regulation pathways being activated during flower development. Overall, the expression data in the present study provide novel insights into the developmental gene regulatory network facilitated by TFs, miRNA, and their target genes.

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.

Insight into the petunia Dof transcription factor family reveals a new regulator of male-sterility

Petunia hybrida is a hybrid ornamental that serves as one of the most popular bedding plants in the world. Numerous petunia seeds are distributed on an annual basis, which requires labor-intensive hybrid-breeding. The Dof (DNA-binding with one finger) transcription factor family is a plant-specific member of the zinc finger superfamily. Dofs play diverse roles in regulating plant developmental processes; however, their functions during flower development are not well characterized, especially in ornamental species. In this study, we used genome-wide analysis to identify 35 Dof genes that are encoded in the P. inflata reference genome. These Petunia Dofs (PiDofs) can be organized into five distinct phylogenetic groups, based on the sequences of their highly conserved Dof domains. Expression analysis using quantitative-RT-PCR identified several PiDofs that exhibit unique expression patterns during reproductive development. Many of these reproductive PiDofs were expressed in all four floral whorls throughout flower development, while other PiDofs exhibited developmental stage and/or organ specific expression patterns. RNAi was used to knock-down the expression level of PiDof14, an anther-specific Dof. Reduced expression of PiDof14 promoted tapetum degradation and depressed meiotic divisions in the microsporocytes, ultimately leading to a male-sterile phenotype. The organ- and stage-specific expression patterns of many of the other PiDof genes indicate that additional members of this family may play specific roles in regulating male and female fertility. This work provides insight into a novel regulator of male-fertility in Petunia, and lays the foundation for targeted genome engineering of the larger Dof family in order to generate an efficient hybrid breeding system for P. hybrida.

Mechanical stimulation affects growth dynamics, IAA content and activity of POD and IAA oxidase in Petunia x atkinsiana

Ornamental plants are bred and purchased for their aesthetical features such as colorful flowers and leaves, as well as compact and elegant stature. Petunia is one of the most popular bedding plants for urban areas and gardens, therefore, control of its growth and branching is essential. In commercial horticulture, the most common method to control growth dynamics is via growth regulators. Mechanical stimulation is proposed as an environmentally friendly alternative to chemical regulators. In this study, the efficiency of MS was tested on two cultivars of Petunia x atkinsiana. A brushing apparatus was set to stroke apical parts of young plants 40, 60 or 80 times per day between 14 March and 25 April. Several parameters, such as stem length, the number of branches, mature leaf area, the number of open flowers, were measured four times during the whole experiment: three times during the stimulation period, on 20 March, 4 and 25 April, and the last time on 18 May, three weeks after the stimulation stopped. For biochemical analyses, 1 cm apical stem fragments were collected on 20 March, 25 April and 18 May. The results show that MS affects the growth dynamics in petunia, but the response appears to be cultivar specific. In both cultivars, brushing with 80 strokes per day produced the most spectacular effects in growth reduction. On the last day of brushing the POD and IAA oxidase activities in the strongly reacting cultivar were the highest in plants rubbed 80 x per day. The results indicate that MS can be very effective in controlling stem growth in at least some cultivars of petunia, replacing hormonal treatments.

Low Substrate pH–Induced Iron/Manganese Toxicity of New Guinea Impatiens: A Diagnostic Guide

New Guinea impatiens (Impatiens hawkeri) are popular bedding plants, but the knowledge of diagnosing abiotic disorders during greenhouse production is evolving. Symptomology of nutrient deficiencies and excessive fertilization have been extensively documented. Exact symptomology of low substrate pH (<5.5) and toxic iron (Fe) and/or manganese (Mn) leaf tissue levels are not defined or photographed, thereby aiding in diagnosis. Therefore, the objective of the diagnostic guide was to photograph symptomology and document the tissue levels in New Guinea impatiens to provide a definitive guide of low substrate pH–induced Fe and/or Mn toxicity.

Secrets of the world's most popular bedding plant unlocked.

Boosted by next-generation sequencing technology, there is now an ever-growing list of fully sequenced plant genomes. Recent additions to this list are two presumed ancestors of Petunia hybrida, the most popular bedding plant worldwide. These genome sequences provide new information on a species at a key position in plant phylogeny, and support the use of petunia as a research model plant species.

Insight into the evolution of the Solanaceae from the parental genomes of Petunia hybrida.

Petunia hybrida is a popular bedding plant that has a long history as a genetic model system. We report the whole-genome sequencing and assembly of inbred derivatives of its two wild parents, P. axillaris N and P. inflata S6. The assemblies include 91.3% and 90.2% coverage of their diploid genomes (1.4 Gb; 2n = 14) containing 32,928 and 36,697 protein-coding genes, respectively. The genomes reveal that the Petunia lineage has experienced at least two rounds of hexaploidization: the older gamma event, which is shared with most Eudicots, and a more recent Solanaceae event that is shared with tomato and other solanaceous species. Transcription factors involved in the shift from bee to moth pollination reside in particularly dynamic regions of the genome, which may have been key to the remarkable diversity of floral colour patterns and pollination systems. The high-quality genome sequences will enhance the value of Petunia as a model system for research on unique biological phenomena such as small RNAs, symbiosis, self-incompatibility and circadian rhythms.

Finishing Bedding Plants: A Comparison of an Unheated High Tunnel versus a Heated Greenhouse in Two Geographic Locations

Energy accounts for one of the largest costs in commercial greenhouse (GH) production of annual bedding plants. Therefore, many bedding plant producers are searching for energy efficient production methods. Our objectives were to quantify the impact of growing annual bedding plants in an unheated high tunnel (HT) compared with a traditional heated GH environment at two northern latitudes. Ten popular bedding plants [angelonia (Angelonia angustifolia), vinca (Catharanthus roseus), celosia (Celosia argentea), dianthus (Dianthus chinensis), geranium (Pelargonium ×hortorum), petunia (Petunia ×hybrida), french marigold (Tagetes patula), viola (Viola ×cornuta), snapdragon (Antirrhinum majus), and osteospermum (Osteospermum ecklonis)] were grown both in an unheated HT and a glass-glazed GH with an 18 °C temperature set point beginning on 1 Apr. 2011 at both Cornell University (Ithaca, NY) and Purdue University (West Lafayette, IN). Although seven of the species exhibited a delay in flowering in the HT as compared with the heated GH, there were no differences in days to flower (DTF) for geranium, osteospermum, and viola grown at Cornell and viola at Purdue. The remaining species exhibited delays in flowering in the HT environment, which varied based on species. At Purdue, several species were lost because of a cold temperature event necessitating a second planting. For the second planting, osteospermum was the only species grown that flowered significantly later in the HT; 7 days later than the GH-grown plants. Production of cold-tolerant annuals in unheated or minimally heated HTs appears to be a viable alternative for commercial producers aiming to reduce energy costs.

Seedling Emergence, Growth, and Mineral Nutrition of Ornamental Chile Peppers Irrigated with Saline Water

Ornamental chile peppers are popular bedding plants. As high-quality water supply becomes limited in many parts of the world, alternative waters such as municipal reclaimed water is encouraged to be used for landscape irrigation. The purpose of this study was to assess the relative salt tolerance of 10 cultivars of ornamental chile peppers by irrigating the mature plants with saline solutions and germinating seeds in saline substrate in a greenhouse. In the mature plant salt tolerance experiment, plants were irrigated with nutrient solution (no addition of salts, control) or saline solution at electrical conductance (EC) of 4.1 dS·m−1 or 8.1 dS·m−1 for 8 weeks. Plants in the EC of 4.1 dS·m−1 treatment did not have any foliar salt damage regardless of cultivar. At EC of 8.1 dS·m−1, ‘NuMex Memorial Day’ had the most severe foliar salt damage, whereas ‘NuMex April Fool’s Day’, ‘NuMex Cinco de Mayo’, ‘NuMex Thanksgiving’, and ‘NuMex Twilight’ had little or no foliar damage. Shoot dry weight (DW) reduction at EC of 8.1 dS·m−1 compared with control was smallest in ‘NuMex Thanksgiving’ (15%), whereas ‘NuMex Memorial Day’ had the greatest reduction of 74% followed by ‘NuMex Christmas’ of 61%. The highest shoot DW reduction in ‘NuMex Memorial Day’ coincided with lowest visual score, indicating that this cultivar was the least tolerant to salinity. The leaf Na+ and Cl− concentrations increased dramatically with increasing EC of the irrigation water in all cultivars. The highest Na+ concentration of 10.9 mg·g−1 DW at EC of 8.1 dS·m−1 was observed in ‘NuMex Christmas’. The highest Cl− concentration at EC of 8.1 dS·m−1 was found in ‘NuMex Memorial Day’ with 64.8 mg·g−1 DW, which was four times higher than the control. In the seedling emergence experiment, seeds of the 10 cultivars were germinated in substrate either moistened with reverse osmosis water (EC ≈0) or saline solution at EC of 17.1 dS·m−1. ‘NuMex Christmas’ and ‘NuMex Memorial Day’ had the lowest relative seedling emergence index, indicating that these two cultivars were the least tolerant to salinity during the seedling emergence stage. ‘NuMex Thanksgiving’ and ‘NuMex Cinco de Mayo’ had the highest relative seedling emergence index. Combining the results from both experiments, we concluded that ‘NuMex Cinco de Mayo’ and ‘NuMex Thanksgiving’ were the most tolerant cultivars, whereas ‘NuMex Christmas’ and ‘NuMex Memorial Day’ were the least tolerant ones.

Assessing Tolerance to Sodium Chloride Salinity in Fourteen Floriculture Species

The use of saline irrigation water may be inevitable in the future since the freshwater supply is decreasing over time. In some regions of the United States, producers of both ornamental and agronomic crops are already facing a limited supply of high-quality water. Therefore, it is necessary to determine the salt tolerance of commonly used greenhouse bedding plants to minimize potential salt damage before use of nonpotable water sources is mandated. Research screening several bedding plants has not taken place for more than two decades. Therefore, we undertook experiments to screen popular bedding plants for salt tolerance during greenhouse production. Transplants were exposed to 0 (control), 20, 40, 60, or 80 mm sodium chloride (NaCl) in the irrigation water for 5 weeks resulting in average substrate pour-thru electrical conductivity (EC) values of 4.0 (control), 7.0, 9.8, 12.1, or 14.2 dS·m−1, respectively. Pansy (Viola tricolor) and zinnia (Zinnia angustifolia), the most sensitive species examined, exhibited 100% mortality when exposed to an EC of 14.2 dS·m−1. The least affected species for dry weight (DW) was snapdragon (Antirrhinum majus) with a 54% reduction as EC increased from 4.0 to 14.2 dS·m−1. Only fuchsia (Fuchsia hybrida) and snapdragon were unaffected by an EC of 7.0 dS·m−1, whereas at 9.8 dS·m−1 all of the species had a significantly reduced DW as compared with control plants. Verbena (Verbena ×hybrida), petunia (Petunia ×hybrida), coleus (Solenostemon scutellarioides), and begonia (Begonia hiemalis) were the only species that did not undergo a significant height reduction in comparing 9.8 dS·m−1 to control. A classification of the 14 species is created here on the basis of plant DW to provide guidance as to which species could be irrigated with more saline water while not compromising plant growth and quality.

Pre-sowing seed treatment with a temperature-drop influences plant growth and flowering in marigold and pansy

SummaryThe effects of a pre-sowing seed treatment with a temperature drop (i.e., seed thermo-priming) on the growth and development of two popular bedding plant species, Tagetes patula nana L. (marigold) and Viola wittrockiana Gams. (pansy), were studied. A temperature drop from 22°C to 10°C was applied for 2 h each day during seed germination, over the 6 d before sowing. This seed priming increased plant dry mass, hastened flowering in both species, and increased flower numbers in marigold, but not in pansy. An involvement of certain phytochromes in these temperature-dependent effects on time-to-flowering is suggested.

Short-term Temperature Change Affects the Carbon Exchange Characteristics and Growth of Four Bedding Plant Species

Bedding plants are exposed to a wide range of environmental conditions, both during production and in the landscape. This research compared the effect of short-term temperature changes on the CO2 exchange rates of four popular bedding plants species. Net photosynthesis (Pnet) and dark respiration (Rdark) of geranium (Pelargonium ×hortorum L.H. Bail.), marigold (Tagetes patula L.), pansy (Viola ×wittrockiana Gams.), and petunia (Petunia ×hybrida Hort. Vilm.-Andr.) were measured at temperatures ranging from 8 to 38 °C (for Pnet) and 6 to 36 °C (for Rdark). Net photosynthesis of all species was maximal at 14 to 15 °C, while Rdark of all four species increased exponentially with increasing temperature. Gross photosynthesis (Pgross) was estimated as the sum of Pnet and Rdark, and was greater for petunia than for the other three species. Gross photosynthesis was less sensitive to temperature than either Pnet or Rdark, suggesting that temperature effects on Pnet were caused mainly by increased respiration at higher temperatures. Gas exchange-temperature response curves were not useful in determining the heat tolerance of these species. There were significant differences among species in the estimated Rdark at 0 °C and the Q10 for Rdark. Differences in the Q10 for Rdark were related to growth rate and plant size. Large plants had a greater Q10 for Rdark, apparently because these plants had a higher ratio of maintenance to growth respiration than small plants. The Q10 of the maintenance respiration coefficient was estimated from the correlation between the Q10 and relative growth rate, and was found to be 2.5 to 2.6.

The Effect of Field Irrigation Practices on Disease Suppression in Zinnia elegans

The objective of this study was to determine if field irrigation practices affect the development and suppression of three diseases, alternaria blight (Alternaria zinniae), powdery mildew (Erisyphe cichoracearum) and bacterial leaf and flower spot (Xanthomonas campestris pv. zinniae), on Zinnia elegans. Many commercial growers will no longer produce this popular bedding plant and cut flower crop due to high incidence of these three diseases. Plants of 17 different varieties of Z. elegans were started from seed and transplanted into cell-packs to be grown on as bedding plants. They were later transplanted into the field and subjected to one of three watering regimes: natural rainfall plus overhead irrigation, natural rainfall plus sub-irrigation, and natural rainfall only. Weekly evaluations were performed to rate each variety on its susceptibility to disease based upon severity of infection as well as portion of plant affected. Results will be presented on irrigation method and its influence on disease susceptibility and resistance on the 17 varieties evaluated.

Dibutylurea Reduces Photosynthesis, Growth, and Flowering of Petunia and Impatiens

Dibutylurea (DBU), a breakdown product of benomyl, may be partially responsible for the previously reported phytotoxicity of the fungicide Benlate DF. We quantified the effect of DBU on the growth of two popular bedding plant species, petunia (Petunia × hybrida) and impatiens (Impatiens wallerana Hook. f.). DBU reduced photosynthesis of both species, and its effect strongly depended on the amount of DBU applied. The effects of DBU were most apparent 2 to 4 days after treatment, at which time 1.20 g·m-2 (corresponding to 10% DBU in Benlate DF at maximum labeled drench rate) inhibited photosynthesis completely. DBU also decreased flower number and caused marginal necrosis. DBU effects were more pronounced in low relative humidity. Benlate DF containing 3.1% DBU and an equivalent amount of reagent grade DBU had similar effects on photosynthesis and petunia necrosis. Our results showed that DBU is responsible for at least part of the phytotoxic symptoms that can be caused by Benlate DF. However, other ingredients or breakdown products may also contribute to the phytotoxic symptoms of Benlate DF.

GROWTH AND DEVELOPMENT OF CATHARANTHUS ROSEUS UNDER VARIOUS ENVIRONMENTAL CONDITIONS

In recent years, Catharanthus roseus has become a popular bedding plant, but at present there is little cultural information available for growers. This study examines the effects of four different temperature regimes and two light levels on three cultivars of Catharanthus. Average daily temperature regimes ranged from 15.3°C to 27.3°C; light intensities were 125 μmolm-2s-1 and 250 μmolm-2s-1. Plants were harvested as each successive pair of true leaves reached 1.5 cm in length, from the first true leaf stage until flowering. Measurements included internode length, leaf length, leaf area, dry weight of stem and leaves, and number and length of shoots. The plants grown at the lowest temperature regime took four times as long to flower as those grown at the highest temperature regime. Plants grown at the coolest temperature also exhibited chlorosis, stunting, and unusual flower formation. Information obtained from this study should assist growers in determining their planting schedule and the optimum greenhouse temperature for desired plant habit.

Bedding Plant Phytotoxicity Evaluations, California, 1979,1980

Abstract Six insecticides were applied to selected bedding plants and phytotoxic effects were determined. The following chemical materials were selected based on their ability to control many pests commonly found on bedding plants and due to a lack of information necessary for their labeling in a nursery: Lannate 1.8L, Orthene 75S, Pirimor 50W, Pramex 2E, SPB-1382 2E, Vydate 2L. One application of each material was made per species of bedding plant. However, the most popular bedding plants were evaluated for phytotoxicity during all seasons in California. Materials were applied until run-off with a hand gun operating from a 2.5 gpm (9.5 litres per min) piston pump at 125 psi. Plants were sprayed outdoors at both locations and transferred onto black plastic sheets on the ground under shade. The soil was an amended Univ. of California mixture with a pH of ca 7.4. Data on phytotoxicity were recorded on a weekly basis for 4 weeks following the treatment. Damage was evaluated based on the overall appearance of the plants compared to an untreated check: 0 = no damage; 1 = slight damage, no effect on marketability; 2 = moderate damage, marketability reduced, 3 = heavy damage, unmarketable. If new growth occurred during the 4 weeks following spray application, this was evaluated for phytotoxicity. Observations on phytotoxicity were made by at least 2 Individuals on each date and where possible only the inner most plants within replicates were counted.

‘Marian’ Geranium1

Abstract The garden, or zonal geranium (Pelargonium. X hortorum Bailey) has been a popular bedding plant in American gardens many years in spite of its sensitivity to high summer night temp and humidities. This sensitivity is not unexpected in a plant whose putative ancestors are native to the subdesert of South Africa, and it remains a dominant trait in both clonal and seed-propagated cultivars. A degree of tolerance to these climatic conditions is evident in the diploid cultivars, ‘Mme. Bucher’ and Mme. Landry’, and is more fully expressed in the tetraploid cultivars ‘Pink Cloud’, ‘Greg-erson’s White’, and ‘Olympic Red’ (2). The objective of our breeding program is to develop a group of cultivars with greater heat tolerance. The first cultivar to successfully combine a compact, floriferous plant habit with satisfactory heat tolerance was ‘Galaxie’. In spite of its obvious faults of botrytis susceptibility and relatively weak flower color, ‘Galaxie’ became an important parent numbering among its progeny ‘Toreador’, ‘Hawkeye’ (1), ‘Skylark’, and the newly named ‘Pearl Bailey’

Cytology and Seed Set Studies in Viola tricolor Hortensis L.

Abstract The pansy, Viola tricolor Hortensis, L. is a popular bedding plant, however, the problem of low seed set has hindered genetic studies, plant breeding efforts, and the production of Fl hybrids. Twenty-nine commercial inbred pansy lines were investigated cytologically to establish a possible relationship between chromosome number and pollen fertility. The somatic chromosome number of all lines studied was found to be 2n=48 and pollen fertility was above 90 percent. Preliminary hybridization investigations suggest the problem may be an incompatibility system.

Cytology and Seed Set Studies in Viola tricolor Hortensis L.

Abstract The pansy, Viola tricolor Hortensis, L. is a popular bedding plant, however, the problem of low seed set has hindered genetic studies, plant breeding efforts, and the production of Fl hybrids. Twenty-nine commercial inbred pansy lines were investigated cytologically to establish a possible relationship between chromosome number and pollen fertility. The somatic chromosome number of all lines studied was found to be 2n=48 and pollen fertility was above 90 percent. Preliminary hybridization investigations suggest the problem may be an incompatibility system.