Gaillardia Grandiflora Research Articles

Static Headspace Analysis and Polyphenol Content of Tagetes erecta, Matthiola incana, Erysimum cheiri, Gaillardia grandiflora and Dahlia pinnata in Iran

Tagetes erecta L., Gaillardia grandiflora Hort. e×Van Houtte. and Dahlia pinnata Cav. belong to the family Asteraceae, Matthiola incana (L.) R.Br. and Erysimum cheiri (L.) Crantz. are in the family Brassicacea. These are common ornamental herbaceous plants with long history of traditional medicinal uses in many countries for curing various diseases. The present study was aimed to investigate the volatile and phenolic compounds of these common locally available floweres in Iran. The volatile components (VCs) were identified and analyzed by SHS (static headspace)-GC-MS on the Combi PAL System technique. The polyphenol compounds were identified by HPLC-DAD. Hexanal (34.5%), dimethyl trisulfide (66.7%), terpinolene (38.4%), β-pinene (35.7%) and myrcene (28.5%) were the main components of M. incana, E. cheiri, T. erecta, G. grandiflora and D. pinnata, respectively. It was found that the predominant phenolic constituents were quercetin, rosmarinic acid, eugenol, ellagic acid and catechin in the studied flowers. The ornamental flowers could be riched from volatile and phenolic compounds.

In situ phytoremediation of dyes from textile wastewater using garden ornamental plants, effect on soil quality and plant growth

In situ phytoremediation of dyes from textile wastewater was carried out in a high rate transpiration system ridges (91.4 m × 1.0 m) cultivated independently with Tagetes patula, Aster amellus, Portulaca grandiflora and Gaillardia grandiflora which reduced American Dye Manufacturers Institute color value by 59, 50, 46 and 73%, respectively within 30 d compared to dye accumulated in unplanted ridges. Significant increase in microbial count and electric conductivity of soil was observed during phytoremediation. Reduction in the contents of macro (N, P, K and C), micro (B, Cu, Fe and Mn) elements and heavy metals (Cd, As, Pb and Cr) was observed in the soil from planted ridges due to phyto-treatment. Root tissues of these plants showed significant increase in the specific activities of oxido-reductive enzymes such as lignin peroxidase, laccase, veratryl alcohol oxidase, tyrosinase and azo reductase during decolorization of textile dyes from soil. Anatomical studies of plants roots revealed the occurrence of textile dyes in tissues and subsequent degradation. A minor decrease in plant growth was also observed. Overall surveillance suggests that the use of garden ornamental plants on the ridges of constructed wetland for the treatment of dyes from wastewater along with the consortia of soil microbial flora is a wise and aesthetically pleasant strategy.

New Apigenin Glycoside, Polyphenolic Constituents, Anti-inflammatory and Hepatoprotective Activities of Gaillardia grandiflora and Gaillardia pulchella Aerial Parts.

Background:Gaillardia grandiflora Hort. ex Van Houte and Gaillardia pulchella Foug are flowering plants widely cultivated in Egypt for their ornamental value. Previous reports demonstrated that sesquiterpene derivatives represent the major compounds in both species. Moreover, only few flavones were identified from genus Gaillardia and few studies on the cytotoxicity of G. pulchella were found.Aim of the Study:Investigation of the phenolic constituents of the aerial parts of both species and evaluation of their anti-inflammatory and hepatoprotective activities.Materials and Methods:The 80% aqueous methanol extracts (AME) were prepared for both plants and evaluated for their biological activities. Phytochemical investigation of both extracts resulted in isolation of twelve compounds, which have been identified on the basis of ultraviolet, 1D and 2D nuclear magnetic resonance spectroscopy and negative ESI-MS.Results:The new 8-hydroxyapigenin 6-O-β-D-apiofuranosyl-(1’’’→6’’)-C-β-D-4C1-glucopyranoside was isolated from G. grandiflora for the first time in nature, along with schaftoside, luteolin 6-C-β-D-4C1-glucopyranoside 8-methyl ether, apigenin 6-C-β-D-4C1-glucopyranoside 8-methyl ether, isoorientin, isovitexin, 6-methoxyluteolin and hispidulin, as well as vicenin-2, vitexin, luteolin and apigenin, which were isolated from G. pulchella together with 6-methoxyluteolin. Furthermore, the AME of both species were found to be nontoxic to mice and exhibited significant anti-inflammatory and hepatoprotective activities in dose dependent manner.Conclusion:Current results shed light on the phenolic constituents of G. grandiflora and G. pulchella aerial parts and the safety of the AME of both species, in addition to their significant anti-inflammatory and hepatoprotective activities. Both plant species may be promising candidates for natural anti-inflammatory and hepatoprotective drugs.SUMMARY Phytochemical investigation of Gaillardia grandiflora and Gaillardia pulchella 80% aqueous methanol extracts of the aerial parts led to the isolation of twelve compoundsThe new compound 8-hydroxyapigenin 6-O-β-D-apiofuranosyl-(1’’’’→6’’)-C-β-D-4C1-glucopyranoside was isolated from G. grandiflora for the first time in natureSchaftoside, luteolin 6-C-β-D-4C1-glucopyranoside 8-methyl ether, apigenin 6-C-β-D-4C1-glucopyranoside 8-methyl ether, isoorientin, isovitexin, 6-methoxyluteolin and hispidulin were isolated from G. grandifloraVicenin-2, vitexin, luteolin, apigenin and 6-methoxyluteolin were isolated from G. pulchellaThe extracts of both species were nontoxic to mice up to 5 g/kg body weightBoth extracts exhibited significant anti-inflammatory and hepatoprotective activities in dose dependent manner Abbreviations used: ALP: Alkaline phosphatase; ALT: Alanine aminotransferase; AME: The 80% aqueous methanol extract of G. grandiflora or G. pulchella aerial parts; AST: Aspartate aminotransferase; br d: Broad doublet; Comp-PC: Comparative paper chromatography; d: Doublet; 2D-PC: Two-dimensional paper chromatography; DMSO-d6: Deuterated dimethyl sulfoxide; G.: Gaillardia; GPx: Glutathione peroxidase; GRd: Glutathione reductase; GSH: glutathione; GST: Glutathione-S-transferase; J: Nuclear spin-spin coupling constant; m: Multiplet; [M-H]−: Molecular ion peak; MDA: Malondialdehyde; m/z: Mass/charge ratio; NO: Nitric oxide; p: Probability; PC: Paper chromatography; Rf: Retention flow; rpm: Rotation per minute; s: Singlet; SDE: The ethanol extract of Scoparia dulcis; SE: Standard error; SOD: Superoxide dismutase; TMS: Tetramethylsilane; λmax: Maximum fluorescence emission wavelength.

Occurrence of Pelargonium leaf curl virus and Moroccan pepper virus on natural hosts

During a survey, in Shiraz area (Southern Iran), leaf samples from sweet william (Dianthus barbatus), blanket flower (Gaillardia grandiflora), oat (Avena sativa) and clover (Trifolium repens) showing characteristic symptoms of viral infection were investigated by Indirect-ELISA and RT-PCR and sequencing. Direct sequencing of coat protein (CP) gene confirmed the presence of Pelargonium leaf curl virus (PLCV) and Moroccan pepper virus (MPV) in samples. To our knowledge this is the first report of PLCV and MPV in these plants.

Detoxification and decolorization of a simulated textile dye mixture by phytoremediation using Petunia grandiflora and, Gailardia grandiflora: A plant–plant consortial strategy

In vitro grown Petunia grandiflora and Gaillardia grandiflora plantlets showed 76 percent and 62 percent American Dye Manufacturers Institute value (color) removal from a simulated dyes mixture within 36h respectively whereas their consortium gave 94 percent decolorization. P. grandiflora, G. grandiflora and their consortium could reduce BOD by 44 percent, 31 percent and, 69 percent and COD by 58 percent, 37 percent and 73 percent respectively. Individually, root cells of P. grandiflora showed 74 and 24 percent induction in the activities of veratryl alcohol oxidase and laccase respectively; whereas G. grandiflora root cells showed 379 percent, 142 percent and 77 percent induction in the activities of tyrosinase, riboflavin reductase and lignin peroxidase respectively. In the consortium set, entirely a different enzymatic pattern was observed, where P. grandiflora root cells showed 231 percent, 12 percent and 65 percent induction in the activities of veratryl alcohol oxidase, laccase and 2, 6-dichlorophenol-indophenol reductase respectively, while G. grandiflora root cells gave 300 percent, 160 percent, 79 percent and 55 percent inductions in the activities of lignin peroxidase, riboflavin reductase, tyrosinase and laccase respectively. Because of the synergistic effect of the enzymes from both the plants, the consortium was found to be more effective for the degradation of dyes from the mixture. Preferential dye removal was confirmed by analyzing metabolites of treated dye mixture using UV–vis spectroscopy, FTIR and biotransformation was visualized using HPTLC. Metabolites formed after the degradation of dyes revealed the reduced cytogenotoxicity on Allium cepa roots cells when compared with untreated dye mixture solution. Phytotoxicity study exhibited the less toxic nature of the metabolites.

Oxalate contributes to the resistance of Gaillardia grandiflora and Lupinus sericeus to a phytotoxin produced by Centaurea maculosa

Centaurea maculosa Lam. is a noxious weed in western North America that produces a phytotoxin, (+/-)-catechin, which is thought to contribute to its invasiveness. Areas invaded by C. maculosa often result in monocultures of the weed, however; in some areas, North American natives stand their ground against C. maculosa and show varying degrees of resistance to its phytotoxin. Two of these resistant native species, Lupinus sericeus Pursh and Gaillardia grandiflora Van Houtte, were found to secrete increased amounts of oxalate in response to catechin exposure. Mechanistically, we found that oxalate works exogenously by blocking generation of reactive oxygen species in susceptible plants and reducing oxidative damage generated in response to catechin. Furthermore, field experiments show that L. sericeus indirectly facilitates native grasses in grasslands invaded by C. maculosa, and this facilitation can be correlated with the presence of oxalate in soil. Addition of exogenous oxalate to native grasses and Arabidopsis thaliana (L.) Heynh grown in vitro alleviated the phytotoxic effects of catechin, supporting the field experiments and suggesting that root-secreted oxalate may also act as a chemical facilitator for plant species that do not secrete the compound.

Hydrophilic Polymer Amendment in Field Soil to Improve Establishment of Perennial Wildflowers at Transplanting

Perennial wildflowers, once established, are a low-maintenance alternative in a flowerbed. However, water stress and poor root development in field soil can be detrimental to young plants at the time of transplanting. A fully expanded hydrogel, HydroSource, was incorporated to replace 0% (control), 7.5%, 15% (recommended rate), and 30% of the volume of a clayey field soil to determine its effect on plant water status. Addition of hydrogel reduced water stress in Asclepias incarnata and Gaillardia grandiflora plants. Plants growing in hydrogel amended soil had: 1) significantly lower stomatal resistance (P < 0.01); and 2) significantly higher leaf water potential (P < 0.01). Gaillardia grandiflora control plants showed considerable wilting (reflected in high stomatal resistance and low water potential readings) on the 3rd day of the drought period while those with 15% and 30% hydrogel were turgid even on the 5th day. Hydrogel-amended soil appeared less compacted, and root growth in Asclepias incarnata increased with the increasing rate of hydrogel added to the soil.

Occurrence of Stem and Crown Rot of Gaillardia grandiflora, Caused by Sclerotinia sclerotiorum, in California.

Gaillardia grandiflora, or blanket flower, is a perennial, herbaceous composite used as an ornamental plant. Following a series of rains in January, 1997, landscape plantings of G. grandiflora in Monterey County, CA, exhibited symptoms of a previously undescribed disease. Affected stems turned gray to tan and became dry and brittle. Large branches often developed cracks. Attached leaves and flowers wilted and turned tan. Infections on the smaller stems and branches sometimes spread to the main stem and crown of the plant, resulting in plant death. White mycelia and large, irregular, black sclerotia (3 to 6 mm in diameter) were occasionally observed on external surfaces of infected stems and crowns. However, the internal pith cavity of diseased stems often contained abundant mycelia and sclerotia. Isolations from symptomatic stems, mycelia, and sclerotia produced colonies of Sclerotinia sclerotiorum. Pathogenicity was confirmed by culturing representative isolates on potato dextrose agar and allowing the fungus to colonize sterilized toothpicks placed on the surface of the agar (1). The pointed tips of the toothpicks were inserted approximately 3 mm deep into stems of potted G. grandiflora cv. Goblin plants, which were incubated in plastic bags for 48 h and then kept in a greenhouse. After 10 to 14 days, symptoms and mycelia similar to those originally observed developed on inoculated plants and S. sclerotiorum was reisolated. Stems on plants left for 21 or more days contained abundant sclerotia. Plants inoculated with sterile, uncolonized toothpicks did not develop disease. This pathogenicity test was repeated and the results were similar. This is the first report of G. grandiflora as a host of S. sclerotiorum. Reference: (1) Y. Yanar et al. Plant Dis. 80:342, 1996.

Responses of Nine Containerized Perennials to Sumagic

Nine perennial bedding plants were screened for responsiveness to the plant growth retardant, Sumagic (uniconazole-P). Two weeks after planting, plugs were treated with one foliar spray of Sumagic at 0, 40, 80, 120, or 160 ppm at the label-recommended volume. Plant growth of Gaillardia grandiflora `Goblin' was not reduced by Sumagic. Height of Achillea × `Moonshine' was reduced 8% to 12% at 4 weeks after treatment (WAT), and the reduction persisted through 8 weeks after planting (WAP) to the landscape. Phlox paniculata `Joliet' responded linearly to increasing Sumagic rate with a maximum height reduction of 32% at 160 ppm. Coreopsis grandiflora `Sunray', Rudbeckia fulgida var. Sullivantii `Goldsturm' and Monarda didyma `Blue Stocking' responded significantly to Sumagic with 30% to 60% height reductions at 4 WAT, but no persistent effects at 8 WAP. Height of Veronica alpine `Goodness Grows' was reduced 32% to 68% at 4 WAT, but all Sumagic rates resulted in persistent reductions in plant height at 12 WAP. Plant height of Alcea rosea mix and Echinacea purpurea were excessively reduced (up to 79%) at 4 WAT, but there were no persistent effects on height of Alcea in the landscape. All rates of Sumagic resulted in persistent reductions in height of Echinacea at 8 WAP, but only plants treated with 120 and 160 ppm Sumagic were still significantly shorter than controls at 12 WAP

Effect of Temperature on Time to Flower of Coreopsis grandiflora, Chrysanthemum superbum, Gaillardia grandiflora, and Rudbeckia fulgida

Scheduling crops to flower for specific dates requires a knowledge of the relationship between temperature and time to flower. Our objective was to determine the relationship between temperature and time to flower of four herbaceous perennials. Field-grown, bare-root Coreopsis grandiflora `Sunray', Gaillardia grandiflora `Goblin', Rudbeckia fulgida `Goldsturm', and tissue culture-propagated Chrysanthemum superbum `Snow Cap' were exposed to 5C for 10 weeks. They were grown at 15, 18, 21, 24 or 27C under 4-h night interruption lighting. Time to visible bud (VB) and first flower (FLW) were recorded. Days to VB, days to FLW, and days from VB to FLW decreased as temperature increased. Time to flower at 15C was 70, 64, 96, and 54 days and 24, 39, 48, and 36 days at 27C for Coreopsis, Gaillardia, Rudbeckia, and Chrysanthemum, respectively. The 27C temperature apparently caused devernalization on Coreopsis because only 40% of the plants flowered. The effects of temperature on flower size, flower bud number, and plant height also are presented.

Determining the Juvenile Phases of Coreopsis grandiflora, Gaillardia grandiflora, Heuchera sanguinea, and Rudbeckia fulgida

Most plants have a postgermination juvenile phase in which flower induction will not occur. Some species require a cold period for flower induction and will not respond to the cold treatments during the juvenile phase. We determined juvenile phases of Coreopsis grandiflora `Sunray', Gaillardia grandiflora `Goblin', Heuchera sanguinea `Bressingham', and Rudbeckia fulgida `Goldsturm'. Plants were exposed to 5C for 0, 10, or 15 weeks when Coreopsis had 0, 2, 4, 6, 8, or 10 leaves (>1 cm); Gallardia, 4, 8, 12, or 16 leaves; Heuchera, 8, 12, 16, or 20 leaves; Rudbeckia, 5, 10, 15, or 20 leaves. Plants were grown under a 4-h night interruption lighting (LD) or under a 9-h photoperiod (SD) after cold treatments. Based on time to flower and final leaf count, the juvenility of Coreopsis, Gaillardia, Heuchera, and Rudbeckia ended when they had about 6, 10, 12, and 15 leaves, respectively. Cold treatments were necessary for flower induction of Coreopsis and Heuchera and they increased the flowering percentage of Gaillardia and Rudbeckia. Heuhera was a day-neutral plant, Rudbeckia was on obligate LD plant, and Gaillardia and Coreopsis were quantitative LD plants.

Chopped Newspaper for Weed Control in Nursery Crops

Abstract Chopped newspaper was evaluated as a weed control mulch for nursery row crops. Newspaper mulch at 2.3 and 3.6 kg/m2 [4.2 lb/yd2 (≈ 10 cm or 4 in depth) and 6.3 lb/yd2 (≈ 15 cm or 6 in depth), resp.] suppressed weed germination for two seasons without a negative effect on Daphne burkwoodii ‘Carol Mackie’, Physostegia virginiana, and Salix caprea. Gaillardia grandiflora had less growth when mulched with newspaper during one experiment, but not in another. The authors observed that wetting the newspaper mulch after application followed by compression with a lawn roller pressed the paper into a mat which resisted blowing and weathering. Further reduction in blowing of paper mulch was achieved by applying a tackifier after rolling. Bark mulch at 19.4 dm3/m2 (988 in3/yd2 ≈ 10 cm or 4 in depth) resulted in weed suppression comparable to either of the two rates of newspaper mulch and better than bark at 9.7 dm3/m2 (494 in3/yd2 ≈ 5 cm or 2 in depth). All mulch treatments moderated maximum soil temperatures on July 5, 1993 at 7.5 cm (3 in) depth by more than 10C (18F) when non-mulched soil increased to 36C (96.8F). The rate or type of mulch applied resulted in similar summer soil temperatures at 2.5 and 7.5 cm (1 and 3 in) soil depth.

390 USE OF HARDENING TEMPERATURES ON SEVERAL SPECIES OF SEED-PROPAGATED HERBACEOUS PERENNIAL PLUGS PRIOR TO FREEZING

Storage of perennial plugs at subfreezing temperatures could be a valuable production tool since plants could be removed over relatively long periods for forcing. Several species of seed-propagated perennial plugs were pretreated at 0 and 5C under continuous 50 μmol·s-1m-2 PPF for 0, 2, 4, or 8 weeks. After each pretreatment period, plugs were placed into 4-mil polyethylene bags that were then sealed and placed at -2.5C for 0, 2, or 6 weeks. Plugs were then removed from the bags and placed into a 24C greenhouse for two weeks under ambient light levels and daylength, after which time they were rated for percent survival and general regrowth quality. Regrowth was not influenced by pretreatment temperature. Regrowth of Limonium dumosumtatarica, and Campanula carpatica `Blue Clips' following -2.5C storage was excellent with or without a pretreatment. Regrowth of Achillea filipendulina `Cloth of Gold,' Gaillardia grandiflora `Goblin,' and Iberis sempervirens `Snowflake' was improved on plugs given the 0 or 5C pretreatment. Hibiscus × hybrida `Disco Belle Mixed' regrowth was poor, regardless of pretreatment.

Comparison of Chopped Newspaper with Microfoam for Winter Protection of Container-grown Nursery Stock

Chopped newspaper at 3.5 and 7.0 kg.m-2 enclosed in white polyethylene sheeting or enclosed in nylon netting at 3.5 kg.m-2 was compared with two layers of 0.64-cm microfoam as winter covering of four taxa of container-grown nursery plants. White polyethylene-enclosed newspaper moderated winter temperatures more than net-enclosed newspaper or two layers of microfoam under white polyethylene. All coverings provided protection against winter injury, as evidenced by container temperature, but net-enclosed newspaper at 3.5 kg.m-2 resulted in a minimal percentage of Daphne burkwoodii `Carol Mackie' plants with three or more shoots longer than 2 cm in the spring. Gaillardia grandiflora, covered by newspaper during winter, had less spring growth than plants covered by microfoam, but all coverings provided protection for Juniperus horizontalis `Prince of Wales' and Physostegia virginiana.

THE EFFECTS OF LONG DAYS AND SHORT DAYS ON GROWTH OF SEVERAL SPECIES OF HERBACEOUS PERENNIALS FOLLOWING VERNALIZATION OF PLUG-GROWN SEEDLINGS

Achillea filipendulina `Cloth of Gold', Astilbe arendsii, Campanula carpatica `Blue Clips', Echinacea purpurea `Bravado', Gaillardia grandiflora `Goblin', Lavandula angustifolia `Munstead Dwarf', Oenothera missouriensis, Rudbeckia fulgida `Goldstrum' plugs were stored at 5C for 0, 2, 4, 6, 8, and 10 weeks under a 5 μmol· s-1· m-2 PPF. Sample plants were removed and planted in 10 cm pots and placed in a 19C, constant temperature greenhouse under short-day or long-day photoperiods. Long-days were provided with night-break lighting from 10:00 p.m. until 2:00 a.m. by incandescent lamps. In Achillea, Campanula and Gaillardia, only terminal buds grew in the long-day photoperiod while both terminal and lateral buds grew under short-days. Development of Astilbe, Echinacea, Oenothera, Rudbeckia was minimal under short-days compared to that under long-days. Lavandula in the early treatments remained vegetative, short, and compact under short days, whereas plants elongated and flowered while grown under long days. Longer durations of storage shortened the time from potting to flowering for Lavandula.

A new helenanolide, 11.BETA.H-dihydro-4-epineopulchellin, isolated from Gaillardia grandiflora.

A new pseudoguaianolide named 11βH-dihydro-4-epineopulcehllin (1a) was isolated from the methanol extract of Gaillardia grandiflora. The stereostructure was determined on the basis of spectral evidence, especially proton nuclear magnetic resonance (including the 1H-1H correlation spectroscopy technique), and was confirmed by the transformation from neopulchellin (2a).

The Roles of Plant Hormones in the Growth of the Corolla of Gaillardia grandiflora (Asteraceae) Ray Flowers

Corolla elongation and the roles of plant hormones in this process in Gaillardia grandiflora Van Houtte ray flowers were examined. The sterile ray flowers elongated during a 2-day period, and corolla growth was accompanied by fresh and dry weight increases and epidermal cell elongation (greatest near the base of the corolla) but not by cell division. Corollas excised from young ray flowers were measured during treatment in vitro with solutions of plant growth regulators. They elongated in response to gibberellins and fusicoccin but did not respond to auxins, cytokinins, abscisic acid, ethylene, or inhibitors of ethylene biosynthesis. Sequential and simultaneous hormone applications indicated no additive or synergistic effects between hormones, but auxin did reduce gibberellin-promoted growth. Analyses of endogenous auxins showed no significant variation, and ethylene production decreased prior to elongation, while a 20-fold increase in endogenous gibberellin activity was observed just prior to rapid corolla elongation. It appears that corolla growth in Gaillardia is accomplished by an increase in gibberellin activity alone, that multiple hormone interactions are not important in the control of corolla growth, and that part of the mode of action of gibberellin is acid-induced growth.

THE ROLES OF PLANT HORMONES IN STYLE AND STIGMA GROWTH IN GAILLARDIA GRANDIFLORA (ASTERACEAE)

Style and stigma elongation and stigma unfolding, and the roles of plant hormones in these processes in Gaillardia grandiflora Van Houtte were investigated. Style and stigma elongation in vivo began just after anthesis, and style elongation was accompanied by epidermal cell elongation (greatest near the stigma) and a fresh weight increase, but not by cell division or a dry weight increase. The stigma unfolded after the style and stigma elongated. Style‐stigma units excised from young disc flowers of this composite were measured as they responded to plant growth regulators applied singly, as well as in sequential and simultaneous combinations, in vitro. Style elongation was promoted by auxin, was inhibited by gibberellins and ethylene, and was unaffected by other growth regulators. Stigma elongation followed a similar pattern of response. Endogenous auxin levels and ethylene production showed parallel variation and endogenous gibberellin levels showed inverse variation with style and stigma elongation. Stigma unfolding was more sensitive to auxin applications and was promoted by applied ethylene. Ethylene production showed parallel variation and endogenous auxin levels showed inverse variation with stigma unfolding. AVG and Co2+ applications decreased auxin‐induced style elongation and fusicoccin promoted all of the growth responses of style‐stigma units in vitro. A gibberellin‐auxin‐ethylene‐acid growth interaction mode of control is proposed for these three growth processes.

THE ROLES OF AUXIN, ETHYLENE, AND ACID GROWTH IN FILAMENT ELONGATION IN GAILLARDIA GRANDIFLORA (ASTERACEAE)

Filament elongation and the role of auxin in this process in Gaillardia grandiflora was investigated. Filament elongation in vivo occurred just prior to anthesis and was accompanied by cell elongation and fresh weight increase. Filaments isolated and exposed to auxin in vitro grew more rapidly than controls and their growth was comparable to that of filaments in vivo. Furthermore, the natural auxin content of disc flowers (determined by double‐standard isotope dilution analyses) increased just prior to anthesis and filament elongation. These results imply that auxin controls filament elongation. Applied ethylene slightly promoted filament elongation in vitro, and ethylene production of the flowers (determined by gas chromatography) slightly increased prior to filament growth. Fusicoccin and acidic buffers also stimulated elongation of isolated filaments. Thus, the role of auxin in controlling filament elongation in Gaillardia may involve stimulation of ethylene biosynthesis and acid growth.

The Roles of Auxin, Ethylene, and Acid Growth in Filament Elongation in Gaillardia grandiflora (Asteraceae)

The Roles of Auxin, Ethylene, and Acid Growth in Filament Elongation in Gaillardia grandiflora (Asteraceae)