Petunia Hybrida Vilm Research Articles

Combination of u.v.-B. and ozone reduces pollen tube growth more than either stress alone

The rate of in vitro Nicotiana tabacum L. “Bel-W3” pollen tube growth was reduced 62 and 44%, respectively, when pollen tubes were exposed to 120 ppb ozone (O 3) for 3 hr or 300 μW/cm 2 ultraviolet-B (u.v.-B) radiation for 30 min. Petunia hybrida Vilm. “White Cascade” pollen tube growth was reduced 34 and 59%, respectively, upon exposure to O 3 or u.v.-B at the above doses. The combination of u.v.-B at 300 μW/cm 2 for 30 min, followed by O 3 at 120 ppb for 3 hr, reduced pollen tube growth by 79% for “Bel-W3” and 75% for “White Cascade”. The effect appeared to be additive, implying that different target areas may be affected by the two stressors. In the Northeast, plants are exposed to both u.v.-B and O 3 during the normal growing season. This may result in an unexpectedly higher stress on the reproductive system than had been previously suspected based on these two stressors acting individually.

Physical Properties of and Plant Responses to Rockwool-amended Media

Loose rockwool had a total porosity similar to peatmoss (92%, by volume) but with water retention capabilities similar to sand. Root media formulations containing loose rockwool were tested with seven plant species for plant response and nutrient uptake. The volume percent formulation, 20 rockwool : 10 peatmoss : 20 vermiculite : 45 pine bark : 5 perlite, was superior to formulations containing 10% or 30% rockwool. Plant response in this rockwool medium in bedding plant flats was superior to that in two high-performing commercial media for impatiens (Impatiens sultanii Hook), marigold (Tagetes patula L.), and petunia (Petunia hybrida Vilm) and equal to one commercial medium for tomato (Lycopersicon esculentum Mill.). However, response of chrysanthemum (Chrysanthemum × morifolium Ramat.), geranium (Pelargonium × hortorum Bailey), and poinsettia (Euphorbia pulcherrima Willd. ex Kl.) in 1.58-liter pots was inferior to both commercial media in one-half of the trials. Differential plant responses in the root media treatments did not relate directly to differences found to occur in plant nutrient composition. The high initial pH level of rockwool necessitated reduced application of limestone and increased application of calcium sulfate to offset Ca deficiency.

Transformation of callus cultures of nine plant species mediated by agrobacterium

A simple method for the Agrobacterium-mediated transformation of callus cultures of nine plant species, Lycopersicum esculentum Mill, Petunia hybrida Vilm, Pimpinella anisum L., Solanum melongena L., S. tuberosum L., Nicotiana glauca Graham, N. glutinosa L., N. plumbaginifolia Viviani and N. tabacum L., is described. Plant calli were resuspended in liquid media, co-cultivated with A. tumefaciens, and plated on restrictive media. The combination of a gene for kanamycin resistance and a gene for firefly luciferase was convenient in the selection and confirmation of hundreds of transformants. Four strains of A. tumefaciens, A208, A348, A281, and PC2760, were employed. All of the callus cultures were successfully transformed with at least one strain of A. tumefaciens, and A281 was the most effective of the four strains. N. glutinosa, N. plumbaginifolia, N. tabacum, P. hybrida and L. esculentum were transformed more efficiently than the other species tested.

Characterization of L-[5- 13C]-Proline Biosynthesis in Halophytic and Nonhalophytic Suspension Cultures by 13C NMR

Summary L-[5- 13 C]-Proline biosynthesis by the suspension cultures of two monocotyledonous halophytes ( Distichlis spicata L. and Spartina pectinata L.) and two nonhalophytes ( Petunia hybrida Vilm. and Panicum miliaceum L.) is described. Suspension cultures were transferred to medium containing 5mM L-[5- 13 C]- glutamic acid and 0, 130 or 380 mM NaCl for 24 h. 13 C-Glutamic acid was taken up at a rate of 14 to 112μmolg -1 24h -1 . 13 C-Label in the cells was found as L-[ 13 C-5]-proline as determined by 13 C NMR. In 380 mM NaCl, D. spicata contained the most 13 C-proline (8.1% of total proline) as compared with the other species (3.1 to 4.2%). 13 C-Proline increased in Petunia transferred to higher NaCl, while S. pectinata and P. miliaceum had more 13 C-proline (5.3 and 8.6%, respectively) on 130 mM NaCl than on 380 mM NaCl (3.7% and 3.1%, respectively). The proline biosynthetic enzymes of D. spicata may be better protected against inhibition by NaCl than those of the other species.

Effects of inhibitors of polyamine biosynthesis on growth and organization of meristematic centers in Petunia protoplast cultures

We examined the effects of inhibitors of the polyamine biosynthetic enzymes arginine decarboxylase (ADC), ornithine decarboxylase (ODC) and spermidine synthase (Spd synthase) on growth and organogenesis in cultures derived from mesophyll protoplasts of Petunia hybrida Vilm cv. Fire Chief. Both processes were dramatically inhibited when protoplasts were cultured in a mixture of dl-α-difluoromethylarginine (DFMA) and dl-ga-difluoromethylornithine (DFMO), specific inhibitors of ADC and ODC respectively, and cyclohexylamine sulfate (CHA) an inhibitor of Spd synthase. The inhibition was partially reversed by addition of micromolar amounts of both putrescine and spermidine. Treatment with DFMA markedly inhibited organization of meristematic centers and reduced levels of free and bound putrescine, while treatment with CHA was less effective. In contrast, treatment with DFMO promoted growth and organization with concomitant increases in bound putrescine and spermidine. The results suggest that putrescine synthesized via ADC is involved in growth and organogenesis.

The Importance of the Stigma in Flower Senescence in Petunia (Petunia hybrida)

Senescence of flowers of Petunia hybrida Vilm. cv Gypsy is characterized by colour changes, wilting and abscission. In emasculated detached flowers the onset of these processes is hastened by any treatment which reduces the vigour of the stigma. Thus pricking it, excising segments, or freezing with liquid nitrogen all reduce the time to morphological changes associated with corolla senescence. Removal of the stigma has the most dramatic effect, reducing lifespan of the flower by about 50 per cent, to 3 d. This reduction can be lessened if IAA or 2,4-D is applied to the cut surface of the style. In intact flowers, the style may usually be implicated in the production of a stimulus leading to corolla abscission, but abscission will also occur in the absence of the style. Some senescence acceleration takes place not only in the complete absence of the style, but also when the upper part of the ovary has been excised in addition. The speeding up of senescence and of corolla abscission cannot be due solely to damage per se since when the corolla limb was excised, leaving only the corolla tube, the tube abscised at about the same time as the controls, despite the quite extensive wounding. This also implies that the distal parts of the corolla do not play a major role in the development of the abscission zone at the base of the corolla tube. A healthy, undamaged stigma appears to be very important in corolla longevity and one of its roles may be to prevent the production of an abscission/wilting stimulus by some other component of the flower. Possibly auxins in the stigma are important in that either they are mobile and protect the abscission zone or they create a sink for other substances which are implicated in flower senescence.

Chromosome-mediated transformation via microinjection

Petunia hybrida Vilm. protoplasts were genetically transformed via the microinjection of P. alpicola Juss. chromosomes. Transformation was determined by changes in the relative activity of various enzymes in the flavonoid biosynthetic pathway. These changes were genetically inherited in a Mendelian manner.

TREATMENT OF THE STIGMA WITH AN EXTRACT OF A COMPATIBLE PISTIL OVERCOMES SELF‐INCOMPATIBILITY IN PETUNIA

SummaryTreatment of the stigma with an extract of a compatible pistil, just before pollination, was very effective in overcoming self‐incompatibility in Petunia hybrida Vilm. Progressive delay either in the application of the extract, or in pollination markedly reduced its efficacy in overcoming self‐incompatibility‐ The treatment seems to mask the self‐incompatibility recognition molecules of the pistil.

Sulfur dioxide effects on petunia pollen germination and seed set.

Information pertaining to SO/sub 2/ effects on sexual reproduction is extremely limited even though this complex process is critical especially in annual species. This study reports the SO/sub 2/ effect on both in vitro and in vivo pollen germination characteristics and in vivo seed set in Petunia hybrida Vilm.

Performance of germinated, imbibed and dry petunia seed fluid-drilled in two gels with nutrient additives

Seeds of ‘Commanche’ petunia ( Petunia hybrida Vilm.) were germinated (GE) or imbibed (IM) on the surface of Laponite 445 or Natrosol 250 HHR gels prepared from 0, 0.5 or 1.0-fold Hoagland's solution. These seeds and dry seed (DS) were incorporated in the gels and extruded onto peat—vermiculite. When compared to a dry-seed control (without gels), DS in either gel without nutrient additive did not increase percentage of transplantable seedlings, but IM and GE resulted in a 32% increase. In comparing only fluid-drilled treatments, percentage of transplantable seedlings was increased by GE relative to IM in both gels, but by IM relative to DS only in Laponite. In both gels, emergence rate ( T 50) and uniformity ( T 10–90) and shoot fresh weight were influenced in the order GE > IM > DS. Increasing nutrient concentration in both gels decreased T 10–90 but had no effect on T 50 or shoot fresh weight. Percentage of transplantable seedlings was increased in Laponite but decreased in Natrosol with increasing gel nutrient concentration. The highest percentage of transplantable seedlings was achieved with GE in Natrosol without nutrient additive (75.4%) and in Laponite with the highest nutrient concentration (81%), each giving approximately one-half of the T 50 and T 10–90 values of the dry-seed control which yielded 53% transplantable seedlings.

Effects of Light Intensity and Air Temperature in Simulated Postproduction Environment on Petunia hybrida Vilm.1,2

Abstract Plants of Petunia hybrida ‘Coral Sea’ were placed in postproduction conditions of low (300 µE m−2s−1), medium (600 µE m−2s−1) or high (900 µE m−2s−1) quantum flux density (QFD) at temperatures of 10, 20, or 30°C after first flower opening. Change in dry weight and number of senesced flowers were determined, and visual quality ratings were given. Plants kept at 20° and 30° had greatest dry weight accumulation and flower number but poorest visual rating at 10 days when kept under high QFD, compared with those kept under medium or low QFD. When plants were kept at 10°, QFD was of little importance to postproduction quality. All plants delined in visual quality by 15 days when kept at 20 or 30° but remained satisfactory when kept at 10°. Plants should be held at either medium or low QFD when placed at 20° or 30° postproduction temperature.

Ozone and Sulfur Dioxide Sensitivity of Petunia: Modification by Ethylenediurea1

Abstract N-[2-(2-oxo-l-imidazolidinyl)ethyl]-N’-phenylurea, (EDU or ethylenediurea) reduced the sensitivity of petunia plants (Petunia hybrida Vilm.) to ozone when treated with foliar or root applications. For most plants, EDU gave protection from visible injury within 24 hours of its application as a spray or soil drench. It was much more effective than butanedioic acid mono-(2,2-dimethylhydrazide) (daminozide) as a protectant from ozone injury. The activity of EDU was unaffected by the addition of a surfactant to the spray solution or soil drench, by day length, light conditions, temperature, and physiological preconditioning of the plants. Protection from injury by ozone lasted for at least 14 days. Furthermore, a concentration of 500 ppm either as a foliar spray of 1 to 2 ml per plant or as a soil drench of 100 ml per 10-cm diameter pot protected an ozone sensitive cultivar, ‘Snow Magic,’ the moderately sensitive cultivars, ‘White’ and ‘Pink Cascade,’ and the least sensitive cultivars, ‘Comanche Improved’ and ‘Sugar Plum’. Treatment with EDU afforded no protection against sulfur dioxide exposure doses which produced acute injury.

Response of Petunia Plants to SO2 and of Detached Leaves, Leaf Discs, and Callus to Sodium Sulfite1

Abstract Flowering plants of 5 cultivars of petunia (Petunia hybrida Vilm.), exposed to 2.8 ppm SO2 (16 hours) under controlled environmental conditions, exhibited variation in SO2 sensitivity based on the degree of water-soaked necrotic leaf lesions. The range of SO2 absorption rates was ± 14% of the mean for the 5 cultivars; however, there was a 2-fold difference in sensitivity among the cultivars, indicating that variation in SO2 absorption plays only a limited role in determining the genetic differences involved in the reaction of petunia to SO2. Detached leaves from all cultivars were equally sensitive to a 10 mM Na2SO3 solution. The injury response of leaf discs to Na2SO3 solutions was monitored by chlorophyll extracts. Although the cultivars varied in sensitivity, the ranking differed from that observed for whole plants to SO2. Callus cultures grown on Murashige and Skoog (MS) medium + naphthaleneacetic acid (NAA) at 2.0 mg/liter + ben-zylamino purine (BA) at 0.5 mg/liter were treated with Na2SO3. Their viability, when evaluated by triphenyl tetrazolium chloride (TTC), yielded a sensitivity ranking of the same cultivars which differed from that obtained with both leaf discs and whole plants. No differences in Na2SO3 sensitivity were observed for callus cultures of the cultivars cultured on MS + 1.0 mg/liter 2,4-dichlorophenoxyacetic acid (2,4-D). The dissimilar injury responses to SO3=/HSO3 − in different tests on explants of the same cultivars indicate that at each level of plant organization sensitivity to Na2SO3 is determined by different morphological and physiological factors from those which specify whole plant reaction to SO2.

Absorption of ozone, sulphur dioxide, and nitrogen dioxide by petunia plants

Petunia plants ( Petunia hybrida Vilm.) of three varieties with differing air pollutant sensitivities were grown in controlled environments and the absorption rates of ozone (O 3), sulphur dioxide (SO 2) and nitrogen dioxide (NO 2) determined during single gas and mixed gas exposures. Additional experiments were conducted to evaluate effects of duration of exposure, leaf age, and plant growth stage on absorption of O 3. Absorption of all pollutants from single gases or the mixture was generally greater for the more sensitive varieties. Absorption from single gases was generally greater than from the mixed gases. Absorption rates tended to decrease gradually throughout the day and from day to day with continuous exposure. Absorption of O 3 was proportional to exposure concentration and decreased with time at differing rates for each variety. More O 3 was absorbed by older than younger leaves and by plants at the early vegetative stage compared with those in the prefloral stage.

Inheritance of Peroxyacetyl Nitrate Resistance in Petunia1

Abstract The inheritance of peroxyacetyl nitrate (PAN) resistance in Petunia hybrida Vilm. was studied using the inbred parents of ‘White Cascade’, a susceptible F1 hybrid, and ‘Coral Magic’, a resistant hybrid. In each of 6 experiments, 4-week-old plants of the parents, their reciprocal F1 hybrids, the F2 generation, and reciprocal backcross generations were simultaneously tested for PAN resistance. Plants were exposed to 742 μg/m3 (0.15 ppm) PAN for 1.5 hours in a controlled environment chamber. The percent area of bifacial necrosis was determined for each leaf on a plant and an average was calculated to yield an injury rating. Significant genetic variation was detected in each experiment, but the best fitting genetic model varied among experiments, indicating large genotype by environment interaction. In the experiment with the most severe PAN injury, genes for susceptibility exhibited almost complete dominance to those for resistance and epistatic effects were not significant. In other experiments with lower levels of PAN injury, resistance was partially dominant to susceptibility and one or more epistatic parameters were significant.

Progeny Testing for Self Incompatibility in Inbred Lines of Petunia hybrida1

Abstract Self progenies obtained from bud pollination or from self pollination following high temperature treatment of 7 self incompatible (SI) Petunia hybrida Vilm. plants representing the I1, I4, I6, and I7 generations were tested for SI in both summer and winter greenhouse environments. Five exhibited increased self seed set (pseudo-self compatibility, PSC) after winter pollinations, 1 was more PSC after summer pollinations, and 1 set no self seed in either pollination environment. Comparison of sibling progenies within a line at the I8 generation and differences in PSC between lines at the I7 and I8 generations indicate that inbreeding has not destroyed the possibility of recovering SI.

B chromosomes and structural hybridity in Petunia hybrida Vilm.

B chromosomes have been recorded in some plants of Petunia hybrida Vilm.. A single B chromosome was observed in the pollen mother cells and two in the seeds set by these plants. In all these plants during the male meiosis chromosomes formed multivalents indicating thereby that these are translocation heterozygotes also. Details of somatic and meiotic chromosomes in these plants are described.

Sorption of Ozone and Sulfur Dioxide by Petunia Leaves

AbstractShoots of three cultivars of Petunia hybrida Vilm. of differing ozone (O3) and sulphur dioxide (SO2) sensitivity were exposed to O3 and SO2 in closed chambers for observation of pollutant absorption through the stomates and adsorption by leaf surfaces. The cultivar least sensitive to injury, ‘Capri’, absorbed the least ozone or SO2 but adsorbed the most. The sensitive ‘White Cascade’ had the opposite sorption pattern. Absorption of the individual gases was generally less from the mixture, whereas adsorption rates were similar whether the gases were supplied singly or in mixture. The existence of substantial differences in surface adsorption could introduce error in measurements of pollutant absorption by leaves.

Effect of Light Quality and Temperature on Fe3+ Reduction, and Chlorophyll Concentration in Plants1

AbstractPlant species differ in their response to light; some grow best in full sunlight, some in partial shade, and others in full shade. Inside, under growth chamber conditions, cool white fluorescent (CWF) lamps, in combination with supplemental incandescent (Inc) lamps, have been a satisfactory light source. Low pressure sodium (UPS) lamps have also been used. The spectral radiant power curve for the CWF lamps extends from 350 (includes UV and blue) to above 700 nm, whereas the spectral curve for LPS lamps is between 560 to 610 nm (no UV or blue) with no radiation below 550 nm. This study was conducted to determine affect of LPS and CWF lamps, alone and in combination with Inc lamps, on plant growth and reduction of Fe3+ to Fe2+. Lettuce (Lactuca saliva L. ‘Grand Rapids’), cotton (Gossypium hirsutum L. ‘M8’) and petunia (Petunia hybrida Vilm. ‘Pink Cascade’) were grown in environmental control cabinets at 22 and 28 C under LPS or CWF lamps, with and without Inc lamps. Reduction of Fe3+ to Fe2+ was determined as Fe2+ ferrorine [disodium salt of 3‐(2‐pyridyl)‐ 5,6‐bis(4‐phenylsulfonic acid‐l,2,4‐triazine] in solution under all light treatments to determine if chlorophyll concentration in plant tops was related to Fe3+ reduction in solution. We had observed that cotton was chlorotic under LPS, but not under CWF lamps. Only small amounts of Fe3+ were reduced to Fe2+ at wavelengths above 420 nm, and more Fe3+ was reduced to Fe2+ in solution under CWF than under LPS lamps. Chlorophyll concentration in lettuce and cotton leaves followed about the same pattern as Fe3+ reduced to Fe2+ in solution. Chlorophyll levels were greater in leaves grown under CWF than under LPS lamps, and generally greater in leaves grown at 28 than at 22 C. If we assume that CWF light mediates reduction of Fe3+ to Fe2+ in plant foliage as it does in ferric‐ferrozine solutions then it could make Fe2+ available for biochemical reactions related to chlorophyll synthesis. Petunia did not respond to the light regimes and temperature as did lettuce and cotton.

Stomatal and Leaf Surface Features as Related to the Ozone Sensitivity of Petunia Cultivars1

Abstract Under the light microscope the stomata of 3 cultivars of Petunia hybrida Vilm. were similar in shape and type. However, scanning electron microscopic examination of ‘White Cascade’ petunia (O3 sensitive) revealed guard cell cuticle was not raised above the epidermal surface. ‘Capri’ (O3 insensitive) had the greatest number of stomata/mm2 and the shortest pore length whereas ‘White Cascade’ had the lowest number but the longest pore length. The cultivar with intermediate O3 sensitivity, ‘White Magic’, had an intermediate stomatal density and pore size. The stomatal pore area (mm2/mm2 leaf surface area) was found to be about equal in all 3 cultivars. ‘Capri’ had many more trichomes per unit area than ‘White Cascade’ while ‘White Magic’ had intermediate numbers. No major differences existed in leaf diffusive resistance among the cvs. in either light or dark. The O3 insensitivity of ‘Capri’ was not explained by inherently fewer stomata and/or smaller stomatal size and/or greater leaf diffusive resistance than those of the sensitive ‘White Cascade’. Number of trichomes, sizes of epidermal cells and configuration of guard cell cuticle in relation to epidermal cells may be related to sensitivity.