Interactive effects of GAs,CKs and growth retardants on the germination of celery seeds

The germination of whole seeds of celery (Apium graveolens L.) was inhibited by paclobutrazol, ancymidol and lower concentrations of uniconazole. The growth retardants daminozide, AMO 1618 and chlormequat chloride inhibited the germination of cut seeds only, indicating that the seed coat prevents the penetration of these compounds at the examined concentrations. Application of a mixture of the gibberellins A4 and A7 (GA 4/7) reversed the inhibition of all the examined growth retardants. Cytokinins (artificial or natural) had no effect when applied alone and did not interact with GA4/7 in the light. However, in the dark the cytokinins at some concentrations and GA4/7 had a synergistic effect in reversing the inhibition caused by growth retardants to whole seeds or in promoting the germination of whole seeds. It is therefore suggested that the major effect on seed of exogenous cytokinins when applied together with GA's is to increase the uptake of gibberellins by the seeds.Abbreviations AMO 1618 (2 isopropyl-5-methyl-4-trimethylammonium chloride-phenyl-1-Piperidinium-carboxylate - ancymidol -cyclopropyl-[4-methoxyphenyl]-5-pyrimidinemeth anol] - chlormequat chloride 2-chloroethyltrimethylommonium chloride - daminozide succinin acid 2,2-diamethyl hydrazide - paclobutrazol [2 RS, 3 RS]-1-(4-chlorophenyl)-4,4-dimethyl-2-(1 H-1,2,4-triazol-1-yl) pentan-3-ol - uniconazole (E)-1-(P-chlorophenyl)-4,4-dimethyl-2-(1,2,4 triazol-1-yl)-1 penten-3-ol     

Effect of ethrel,chlormequat chloride and paclobutrazol on growth and pyrethrins accumulation in <Emphasis Type="Italic">Chrysanthemum cinerariaefolium</Emphasis> Vis.

Pyrethrins and flower yield of pyrethrum (Chrysanthemum cinerariaefolium Viz.) plants were determined after application of ethrel, chlormequat chloride and paclobutrazol. Ethrel at 50, 100, 250 and 500 mg l^−l produced a significant positive effect on pyrethrins level, decreased plant height, while 50 and 100 mg l^−l significantly increased fresh and dry flower yield. Chlormequat chloride at 1000 and 2000 mg l^−l and paclobutrazol (80 and 160 mg l^−l) increased pyrethrins level, single flower weight and decreased plant height and flower yield. ¹⁴C-acetate incorporation studies further substantiated positive effect of growth retardants on pyrethrins biosynthesis. The effect of growth retardants on pyrethrins seems to be mediated through its effect on biosynthesis.     

Regulation of growth of Lilium plantlets in liquid medium by application of paclobutrazol or ancymidol, for its amenability in a bioreactor system: growth parameters

Effect of growth retardants (paclobutrazol or ancymidol) was studied in Lilium plantlets growing in liquid culture. A significant increase in leaf chlorophyll, epicuticular wax, plant dry weight and bulb starch contents were found in plantlets treated with growth retardants. A similar increase in the number of leaves, roots and bulbs was also noted. However, total leaf area and the fresh weight increased only marginally. These features resulted in robust plantlets that showed significantly improved ex vitro survival. Based on these features, a comprehensive index (CI) was calculated as a measure of quality of the plantlets, and it correlated well with their ex vitro survival. Treatment of plantlets with 3.4 μM paclobutrazol was found to be the best and its carry over effects were also minimal.     

Leucojum aestivum L. in vitro bulbs induction and acclimatization

The effects of growth retardants (paclobutrazol and ancymidol), sucrose, GA₃ (gibberellic acid) and physical state of the medium (solid and liquid — Rita® temporary immersion system) on in vitro induction of Leucojum aestivum bulbs and their acclimatization were studied. Paclobutrazol, regardless of the physical state of the medium, stimulated the formation of bulbs (99.3%). Under the influence 90 g L^?1 of sucrose or paclobutrazol the bulbs with the highest fresh weight (FW) were formed (250 mg and 208.8 mg, respectively). However, the addition of ancymidol to the liquid medium led to obtaining the bulbs showing the highest number of leaves and roots (63.2% and 91.7%, respectively). The scanning microscopy study proved that plants obtained in the medium containing GA₃ produced the stomata which most closely resembled to the one observed in the mother plant. Cytometric analysis of all regenerants revealed absence of changes in the nuclear DNA content. The maximum survival rate (100%) was observed for plants derived from liquid medium containing 90 g L^?1 of sucrose. Somewhat fewer plants were acclimatized after their cultivations in liquid medium enriched with paclobutrazol or ancymidol. The temporary immersion system led to perform successful ex vitro adaptation of Leucojum aestivum plants.     

Promotion of asparagus shoot and root growth by growth retardants

Plantlets regenerated from shoot-tip culture of Asparagus officinalis L. possessed weak shoots and roots. Various combinations of auxins and cytokinins did not improve the plantlets. Incorporation of a number of growth retardants, viz. ancymidol, B-995, phosfon, Amo 1618, cycocel and paclobutrazol, promoted growth of stronger shoots and roots. The effectiveness of the growth retardants varied, with ancymidol being most effective and cycocel least effective.The response to ancymidol was prevented by exogenous GA₃ and GA_4/7. GA_1/3 and GA_4/7-like activities were detected in asparagus shoot-tip culture and these activities were reduced by the presence of the growth retardants ancymidol, Amo-1618, and cycocel.     

Effects of Chemical Growth Retardants on Growth and Development of Sweetpotato (Ipomoea batatas (L.) Lam.) in Vitro

Plant growth retardants were evaluated for their ability to reduce the growth rate of sweetpotato (Ipomoea batatas (L.) Lam.) in vitro. Nodal sections of cv. Jewel were cultured for 30 days on medium containing NDA, ancymidol, phosfon, TIBA, difenzoquat, chlormequat, ACC, mepiquat chloride, or daminozide at 0, 10⁻⁴, 10⁻⁵, 10⁻⁶, 10⁻⁷, or 10⁻⁸ m. Difenzoquat, NDA, phosfon, and TIBA, at 10⁻⁴ m, were lethal to axillary bud explants. A low concentration (10⁻⁸ m) of chlorflurenol or NDA stimulated shoot elongation. The effective concentration range for most growth retardants was 10⁻⁵ to 10⁻⁶ m. Small (2- to 4-mm diameter) storage root-like swellings were observed on roots in cultures containing TIBA or ancymidol. The growth-inhibiting effects of ancymidol and NDA were transitory and did not persist through a 180-day culture period. Shoots cultured on medium containing 10⁻⁵ m phosfon, TIBA, or difenzoquat were significantly shorter than control plants after a 180-day culture period. Culture on medium containing TIBA, NDA, ancymidol, or ACC resulted in abnormal leaf and stem development. Plants derived from nodal explants cultured on medium containing either phosfon or chlormequat were near normal in appearance but with some plants exhibiting interveinal chlorosis and reduced root system development. Received May 9, 1997; accepted August 14, 1997     

The preparation in vitro of chrysanthemum for transplantation to soil

Plantlets of Dendranthema grandiflora Pennine Reel were grown from nodal sections on Sorbarods saturated with liquid medium containing 0–3 mg 1^–1 of various growth retardants. After 4 weeks they were transferred to compost and maintained at a relative humidity of 42% at 27.5°C. Wilting was assessed over a period of 3 h. Plantlets treated with paclobutrazol, flurprimidol, triapenthenol, chlorphonium chloride, uniconazol and ancymidol showed dose-related reductions in wilting up to a concentration of 3 mg 1^–1. Responses to tetcyclacis and mepiquat chloride were weaker, and no responses to chlormequat chloride, BTS 44584 or diaminozide could be detected. These observations are compatible with an hypothesis that resistance to wilting derives from inhibited synthesis of gibberellins.     

Exogenously applied paclobutrazol modulates growth in salt-stressed wheat plants

Effect of paclobutrazol (PBZ) treatment on salinity tolerance of wheat (Triticum aestivum) was investigated on a salt-tolerant (Karchia-65) and salt-sensitive (Ghods) cultivars. Salinity significantly reduced the investigated growth parameters such as plant height, length and area of sixth leaf, root length, fresh and dry weight of shoot, roots and sixth leaf, water content (WC) of plant and seeds weight in the both cultivars. The negative effect of salinity in Ghods cultivar was more than Karchia cultivar. However, PBZ treatment reduced the growth in both cultivars, the differences in plant growth among various levels of NaCl decreased in PBZ-treated plants. Salt stress resulted in high accumulation of Na⁺ in the sixth leaf and roots in both cultivars, particularly in Ghods cultivar. Against Karchia cultivar, salt stress decreased the storage of K⁺, P and N in sixth leaf and roots in Ghods cultivar. In the both cultivars, PBZ treatment enhanced the K⁺, P and N contents in sixth leaf and roots by increasing salinity. Although PBZ treatment decreased the growth of plants, it improved the weight of seeds against stress damage. PBZ treatment reduced the accumulation of harmful Na⁺ ion in plant tissues while increased the K⁺, P and N contents. These observations suggest that PBZ treatment may increase tolerance by diminishing ionic imbalance caused by salt stress.     

Morphological control and mensuration of potato plantlets from tissue cultures for automated micropropagation

Automation in plant micropropagation can be greatly simplified if the propagated plantlets have some morphological properties that facilitate automatic chopping and subsequent inspection and classification of the pre-cut plantlet segments by machine vision as viable propagules. We were able to control the morphogenic pattern of in vitro-propagated potato plantlets by adding various concentrations of ancymidol to the nutrient solution. It was found that plantlets cultured in 0.25 mg l^–1 ancymidol best fit the requirements for automated mass micropropagation; the mean internode length was sufficiently large (9–10 mm), the color contrast between leaves and stems was significantly enhanced, the stem was thicker than in the control treatment and the number of axillary buds per plantlet was maximized. Microtuber formation on segments isolated from plants cultured in 0.25 and 0.5 mg l^–1 ancymidol media was enhanced shortly after transfer to tuber induction medium in vitro. On shoot segments from control plants, microtuber formation started after 24–28 days.Machine vision was used to evaluate the morphological and color changes in cultured potato plants. Geometrical and color features such as the number of buds, internode length and color contrast between leaf and stem were precisely measured and automatically logged. Features were measured that till now could only be observed qualitatively.Abbreviations F/W fresh weight - RGB red, green, blue principal color components - VTR video tape recorder     

Genotypic differences in the uptake and distribution of radiocaesium in plants

The ability of endophytic bacteria to influence Erwinia carotovora var. atroseptica (Eca) growth and disease development was examined in potatoes. Bacterial populations isolated from within the tubers of five potato (Solanum tuberosum L.) cultivars (Kennebec, Butte, Green Mountain, Russet Burbank and Sebago) showed antibiosis toward Eca in an in vitro assay. Sebago was host to the highest percentage of bacterial isolates inhibiting Eca growth in vitro (49.5%), followed by Green Mountain (33.3%), Kennebec (29.3%), Russet Burbank (12.9%) and Butte (1.8%). Of these, Curtobacterium luteum was the most common species. Few endophytic bacteria from Butte were inhibitory to Erwinia; all were from Pantoea agglomerans. Significantly higher populations of Erwinia-inhibiting bacteria were recovered from Kennebec (1.89 × 10⁶ cfu fresh weight tuber tissue) as compared to the other cultivars; the lowest populations were recovered from Butte (0.01 × 10⁶ cfu per g fresh weight tuber tissue). Published levels of cultivar disease resistance to blackleg did not correspond to actual bacterial soft rot development (induced by Eca) in an in vivo (tuber) assay. However, bacterial soft rot development was negatively correlated with the density of tuber populations of endophytic bacteria found able to inhibit Eca growth in vitro (R=−0.879, p=0.05).     

The effects of ancymidol,abscisic acid,uniconazole and paclobutrazol on somatic embryogenesis of asparagus

Summary The effects of ancymidol, abscisic acid (ABA), uniconazole, and paclobutrazol on asparagus somatic embryogenesis were evaluated. Calli induced from seedlings of genotype G447 were transferred to embryo induction medium (MS plus 3% sucrose, 0.1 mg L^–1 NAA, 0.5 mg L^–1 kinetin and 3% gelrite), with different concentrations of these compounds. After 8 weeks, the recovered bipolar or globular embryos were placed on germination medium (MS plus 6% sucrose, 0.1 mg L^–1 NAA, 0.1 mg L^–1 kinetin, 0.75 mg L^–1 ancymidol, 40 mg L^–1 adenine sulphate dihydrate, 0.17 mg L^–1 sodium phosphate monobasic and 3% gelrite) for conversion to plantlets. Inclusion of ancymidol, ABA, uniconazole and paclobutrazol in the embryo induction medium did not affect the total number of somatic embryos produced relative to the control without these compounds. However, ancymidol, ABA and uniconazole significantly improved embryo development by increasing the production of bipolar embryos 250–750% and decreasing that of globular embryos 8–35% relative to the control. The bipolar embryos produced with any of the four compounds in the embryo induction medium converted to plantlets at rates 700–1100% greater than the control. None of the globular embryos converted to plantlets. Ancymidol (0.75 mg L^–1) and ABA (0.05 mg L^–1) were the most effective treatments; 61 and 46 bipolar embryos g^–1 callus were produced, and 38% and 37% of the bipolar embryos converted to plantlets, respectively. These results indicated that ancymidol, ABA, uniconazole and paclobutrazol significantly enhanced the production of asparagus somatic embryos and their conversion to plantlets, and ancymidol and ABA were more effective than uniconazole and paclobutrazol.Abbreviations Ancymidol a-cyclopropyl-a(4-methoxyphenyi)-5-pyrimidine methanol - NAA 1-naphthaleneacetic acid - Paclobutrazol I-(4-chlorophenyl)-4,4-dimethyl-2(1H-1,2,4-triazol-1-yl)-pentan-3-ol - Uniconazole (E)-(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-pentan-3-ol - ABA abscisic acid - GA gibberellic acid     

Effect of jasmonic acid on in vitro explant growth and microtuberization in potato

The shoot fresh mass, root length and root numbers of two potato (Solanum tuberosum L.) cultivars Favorita and Helanwuhua were increased significantly by the application of 0.2 – 2 mg dm⁻³ jasmonic acid (JA) in the Murashige and Skoog medium. However, the growth of potato explants was inhibited by JA at high concentrations (20 – 50 mg dm⁻³). Chlorophyll content in explant leaves decreased with an increase in the concentration of JA. In leaves treated with 0.2 mg dm⁻³ JA acid peroxidase activity increased, while in the leaves treated with more than 2 mg dm⁻³ JA peroxidase activity decreased. Under the dark, the microtuber numbers, fresh mass and percentage of big microtubers of two potato cultivars were not promoted by the application of 0.2 – 50 mg dm⁻³ JA.     

Bud proliferation and plant regeneration in liquid-cultured philodendron treated with ancymidol and paclobutrazol

Philodendron plants propagated in liquid shake or bioreactor cultures proliferated profusely in the presence of paclobutrazol (PAC) and to a lesser extent in the presence of ancymidol (ANC). The growth retardants inhibited leaf development and induced the formation of bud clusters. Short transient treatments with low concentrations (1.7–3.4 μM) of the growth retardants limited leaf growth and proliferation to a lesser extent than higher concentrations (6.8–17 μM). The growth retardants had a carryover dwarfing effect in the semi-solid hardening medium, which was more pronounced at the higher concentrations or prolonged exposure periods. Regenerated plants resumed normal growth 3–6 weeks after transplanting. Treatment with growth retardants may become a useful method in the prevention of abnormal leaf growth in large-scale liquid cultures, as well as in enhancing bud proliferation.     

Paclobutrazol Inhibits Abscisic Acid Biosynthesis in Cercospora rosicola

Three plant growth regulators, paclobutrazol, ancymidol, and decylimidazole, which are putative inhibitors of gibberellin (GA) biosynthesis, were studied to determine their effect on abscisic acid (ABA) biosynthesis in the fungus Cercospora rosicola. All three compounds inhibited ABA biosynthesis, and paclobutrazol was the most effective, inhibiting ABA 33% at 0.1 micromolar concentrations. In studies using (E,E,)-[1-¹⁴C] farnesyl pyrophosphate, it was shown that ancymidol blocked biosynthesis prior to farnesyl pyrophosphate (FPP), whereas paclobutrazol and decylimidazole acted after FPP. The three inhibitors did not prevent 4′-oxidation of (2Z,4E)-α-ionylideneacetic acid. C. rosiciola metabolized ancymidol by demethylation to α-cyclopropyl-α-(p-hydroxyphenyl)-5-pyrimidine methyl alcohol. Paclobutrazol was not metabolized by the fungus. Information that these plant growth regulators inhibit ABA as well as GA biosynthesis should prove useful in determining the full range of action of these compounds.     

Bud proliferation and plant regeneration in liquid-cultured philodendron treated with ancymidol and paclobutrazol

Philodendron plants propagated in liquid shake or bioreactor cultures proliferated profusely in the presence of paclobutrazol (PAC) and to a lesser extent in the presence of ancymidol (ANC). The growth retardants inhibited leaf development and induced the formation of bud clusters. Short transient treatments with low concentrations (1.7–3.4 M) of the growth retardants limited leaf growth and proliferation to a lesser extent than higher concentrations (6.8–17 M). The growth retardants had a carryover dwarfing effect in the semi-solid hardening medium, which was more pronounced at the higher concentrations or prolonged exposure periods. Regenerated plants resumed normal growth 3–6 weeks after transplanting. Treatment with growth retardants may become a useful method in the prevention of abnormal leaf growth in large-scale liquid cultures, as well as in enhancing bud proliferation.     

Effect of 5-Aminolevulinic Acid on Development and Salt Tolerance of Potato (Solanum tuberosum L.) Microtubers in vitro

The effects of 5-aminolevulinic acid (ALA), a key precursor in the biosynthesis of porphyrins such as chlorophyll and heme, on development and salt tolerance of microtubers of two potato (Solanum tuberosum L.) cultivars Jingshi-2 and Zihuabai were examined under in vitro conditions. ALA at 0.3–3 mg/l promoted microtuber formation by increasing the average number, diameter, and fresh weight of microtubers especially under 0.5% NaCl stress conditions, but further increase in ALA concentration resulted in a reduction of microtuber yield irrespective of NaCl stress. Under 1.0% NaCl stress conditions, microtuberization was seriously repressed and could not be restored by the addition of ALA. The accumulation of malondialdehyde in the microtubers treated with 30 mg/l ALA increased by 22% compared to the controls (no salinity), while only a 7% increase was observed when the microtubers were exposed to 0.5% NaCl, indicating that ALA functions as a protectant against oxidative damages of membranes. Under 0.5% NaCl stress conditions, the highest activities of peroxidase and polyphenoloxidase were detected in microtubers treated with ALA at 0.3 and 3 mg/l, being by 73% and by 28% greater than those in the untreated controls, respectively. These results demonstrate that ALA at lower concentrations of 0.3–3 mg/l promotes development and growth of potato microtubers in vitro and enhances protective functions against oxidative stresses, but ALA at 30 mg/l and higher concentrations seems to induce oxidative damage probably through formation and accumulation of photooxidative porphyrins.     

Stimulation of in vitro root and shoot growth of potato by increasing sucrose concentration in the presence of fluridone,an inhibitor of abscisic acid synthesis

Fluridone, an inhibitor of abscisic acid (ABA) biosynthesis, strongly stimulated rooting of nodal stem segments of potato (Solanum tuberosum L.) cultivar Arran Banner cultured in darkness on tuberisation medium. Inclusion of 10^-6 M ABA in the culture medium prevented this rooting response, indicating that root proliferation in the presence of fluridone could be due to inhibition of ABA synthesis. The rooting response to fluridone (increased total root number and root fresh weight) was obtained only at high sucrose concentrations (0.175 and 0.234 M) and was demonstrated with two potato cultivars and two culture media; one which favoured tuberisation and one which did not. Shoot numbers were also increased, but to a lesser extent than root numbers, and total fresh weight of plant material per culture was greatly increased by inclusion of both fluridone (10^-6 or 10^-5 M) and 0.234 M sucrose in the culture medium. The role of sucrose was not simply osmotic because when the osmolarity of fluridone medium was increased using mixtures of mannitol and sucrose, no root proliferation occurred unless sucrose predominated in the mixture.     

Response of durum wheat cultivars to immature embryo culture,callus induction and in vitro salt stress

Response of twenty eight cultivars of durum wheat (Triticum turgidum var. durum) to immature embryo culture, callus production and in vitro salt tolerance was evaluated. For assessment of cultivars to salt tolerance, growing morphogenic calli were exposed to different concentrations of NaCl (0, 0.3, 0.6, 0.9, 1.2, 1.5, 1.8 and 2.1% w/v) added to the culture medium during two subsequent subcultures (4 weeks each). Comparison of cultivars for callus induction from immature embryo was based on callus induction frequency and fresh weight growth of callus (FWG). While, for salt tolerance, the relative fresh weight growth (RFWG) and necrosis percent of callus were used. There were significant differences among cultivars for potential of regeneration from immature embryo, and ‘Shahivandi’ a native durum wheat cultivar originating from western Iran was superior among the cultivars tested. The FWG distinguished cultivars more than callus induction frequency did for callus induction evaluation. Hence, a range of FWG from 1.23 to 14.65 g was observed in ‘Mexical-75’ and ‘Omrabi-5’ cultivars, respectively. Growing calli derived from cultivars ‘PI 40100’ and ‘Dipper-6’ showed superiority for tolerating salinity under in vitro conditions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effect of soil cadmium application and pH on growth and cadmium accumulation in roots, leaves and fruit of strawberry plants (Fragaria × ananassa Duch.)

Three strawberry (Fragaria × ananassa Duch.) cultivars Rainier, Totem and Selva were grown under greenhouse conditions in a Parkhill sandy loam soil with a background DTPA-extractable Cd concentration of 0.18 mg kg^-1 and a pH of 5.1. Experimental treatments included combinations of 4 Cd applications (0, 15, 30 and 60 mg Cd kg^-1 soil) applied as CdSO₄ and 2 soil pH values 5.1 and 6.8. Both the application of Cd and pH of the soil significantly affected plant growth, yield and Cd accumulation in plant tissue anf fruit. Although roots accumulated the highest concentrations of Cd of all plant parts investigated, increased soil Cd application reduced leaf weight more than root weight. In general, yield of strawberries was decreased by an increase in amount of soil-applied Cd, however the yield response varied among cultivars. At 60 mg Cd kg^-1 soil, yield of Rainier cultivar was reduced to 17.6% of control plants. Over 90% of total Cd taken up by plants grown in Cd-treated soil accumulated in roots, regardless of the Cd level in the soil. Root Cd concentrations ranged from 2.6 mg kg^-1 (control plants) to 505.7 mg kg^-1 (Totem plants grown in soil at highest Cd and a soil pH 5.1) and were directly related to soil Cd concentrations. Cd translocation from roots to leaves and fruit was very limited, resulting in a maximum Cd concentration in root leaf tissue of 10.2 mg kg^-1. Accumulation of Cd in fruit was found to correlate well with leaf Cd, although even at the highest amount of applied Cd, fruit Cd concentration did not exceed 700 g kg^-1 of fresh weight.Contribution no. 951     

In vitro bulb development in shallot (Allium cepa L. Aggregatum Group): effects of anti-gibberellins,sucrose and light

Bulbing was studied in shallot plants cultured in vitro. Bulbing occurred under a 16 h photoperiod with fluorescent + incandescent light and 30-50 g 1(-1) sucrose in the culture medium. Exogenous gibberellin (10 microM GA3) inhibited leaf and root growth and bulbing. When added to the medium at a concentration of 10 microM, three inhibitors of gibberellin biosynthesis (ancymidol, flurprimidol and paclobutrazol) promoted bulb formation and the percentage of bulbing. When ancymidol was used in combination with GA3, it did not reverse the effect of GA3 applied alone. Under treatments with 30-70 g l(-1) sucrose, bulbing ratios greater than those found in control plants were achieved by addition of ancymidol, and bulb fresh weight was increased in the same way. Ancymidol caused a 66% decrease in sucrose content in leaf bases but greatly increased the glucose, fructose and fructan contents. The increase in fructan content by ancymidol could result from the three-fold rise in total [14C]sucrose uptake per plant from the culture medium associated with a marked increase in leaf base labelling at the expense of root labelling. The possible role of ancymidol is discussed and evidence supports a major regulatory role for gibberellins in bulbing.