Effects of 1-MCP on the vase life and ethylene response of cut flowers

Pretreatment for 6 h with low concentrations of 1-MCP (1-Methylcyclopropene, formerly designated as SIS-X), a cyclic ethylene analog, inhibits the normal wilting response of cut carnations exposed continuously to 0.4 μl·l^?1 ethylene. The response to 1-MCP was a function of treatment concentration and time. Treatment with 1-MCP was as effective in inhibiting ethylene effects as treatment with the anionic silver thiosulfate complex (STS), the standard commercial treatment. Other ethylene-sensitive cut flowers responded similarly to carnations. In the presence of 1 μl·l^?1 ethylene, the vase life of 1-MCP-treated flowers was up to 4 times that of the controls.     

Effect of antagonists of ethylene action on binding of ethylene in cut carnations

Five hours after cut carnations had been treated with a pulse of 1 or 4 mM silver thiosulfate (STS), in vivo ethylene binding in petals was inhibited by 22 and 29%, respectively. When binding was measured 4 days after the 4-mM STS treatment, binding was inhibited by 81%. 2,5-Norbornadiene, which substantially delays carnation senescence, inhibited ethylene binding by 41% at a concentration of 1000 l/l. The Kd for ethylene binding in carnations was estimated to be 0.1 l/l in petals and 0.09 l/l in leaves. The concentration of binding sites was estimated to be 6.0×10^–9 mol/kg of petals and 2.0×10^–9 mol/kg of leaves     

Comparison of cyclopropene, 1-methylcyclopropene, and 3,3-dimethylcyclopropene as ethylene antagonists in plants

A comparison has been made of cyclopropene (CP), 1-methylcyclopropene (1-MCP), and 3,3-dimethyl-cyclopropene (3,3-DMCP) in their ability to protect plants against ethylene. In bananas, both CP and 1-MCP are effective around 0.5 nL L^–1, and 3,3-DMCP was effective at 1 L L^–1. Bananas treated with CP and 1-MCP again become sensitive to ethylene at 12 days and those treated with 3,3-DMCP at 7 days. Mature green tomatoes are protected by 5–7 nL L^–1 of 1-MPC for 8 days at 25°C and tomatoes treated with 3,3-DMCP at 5–10 L L^–1 are protected for 5 days. Carnation flowers are protected with CP or 1-MCP after exposure to 0.5 nL L^–1 for 24 hours and by 1 L L^–1 of 3,3-DMCP. The display life of Campanula flowers is increased from 3.3 to 5.4 days by 10 L L^–1 of 3,3-DMCP and to 9 days by 20 nL L^–1 of 1-MCP. Ethylene inhibition of pea seedlings is reduced by treatment with 1-MCP at 10 L L^–1 of ethylene but as ethylene is increased to 3000 L L^–1 growth inhibition increases. 3,3-DMCP treatment causes very little reduction of the ethylene effect even at very low concentrations.     

Effect of 1-methylcyclopropene and methylenecyclopropane on ethylene binding and ethylene action on cut carnations

1-Methylcyclopropene (1-MCP), formerly designated as Sis-X, has been shown to be an effective inhibitor of ethylene responses in carnation flowers in either the light or the dark. The binding appears to be to the receptor and to be permanent. A 6 h treatment at 2.5 nl l^–1 is sufficient to protect against ethylene, and 0.5 nl l^–1 is sufficient if exposure is for 24 h. As carnation flowers age, a little higher concentration appears to be needed. Most of the natural increase in ethylene production during senescence is prevented by treatment with 1-MCP. A closely related compound, methylenecyclopropane shows ethylene activity. A tritium labelled 1-MCP (60 mCi mmol^–1) has been prepared. A higher specific activity is needed for more critical studies.     

Changes in respiration of mitochondria isolated from cotyledons of ethylene-treated pea seedlings

Treatment of intact, germinating pea (Pisum sativum L. cv. Homesteader) seedlings with ethylene enhanced the cyanide-resistant respiration of mitochondria isolated from the cotyledons. The level of enhancement depended on the concentration of ethylene. Thus, exposure to 0.9 l·l^-1 of ethylene in air for days 4–6 of germination had little effect on cyanide-resistant respiration, while exposure to 130 l·l^-1 increased it from 10 to 50 nmol O₂·min^-1·(mg protein)^-1. The length of exposure to ethylene also affected the degree of enhancement. According to some literature data, lipoxygenase (EC 1.13.11.12) activity can be mistaken for cyanide-resistant respiration, but in our preparations of purified pea mitochondria ethylene had no effect on lipoxygenase activity, nor did the gas disrupt the outer mitochondrial membrane. Bahr and Bonner plots of respiration in the presence of salicylhydroxamic acid (SHAM) indicated that ethylene did not affect respiration proceeding via the cytochrome pathway. Thus, increases in total respiration in mitochondria from cotyledons of ethylene-treated pea seedlings reflect increases in cyanide-resistant respiration.Abbreviations Cyt c cytochrome c - SHAM salicylhydroxamic acid     

Tissue culture ofKarwinskia humboldtiana—a plant producing toxins with antitumoural effects

Isolated embryos ofKarwinskia humboldtiana were cultured in vitro. The growth of embryos and development to plantlets on woody plant medium supplemented with indole-3-acetic acid 6.10^-2 mol l^–1, gibberellic acid (GA₃) 3.10^-2 mol l^–1, and 6-benzylaminopurine (BA) 2 mol l^–1 was obtained. Multiplication of shoots and rooting of excised shoots has been achieved. Callus formation on modified Murashige-Skoog medium supplemented with 1-naphthaleneacetic acid 10 mol l^–1, GA₃ 14 mol l^–1, and kinetin 5 mol l^–1 on hypocotyls, or on root cultures on medium supplemented with 2.4-dichlorophenoxyacetic acid 10 mol l^–1 and BA 10 mol l^–1 was induced.Abbreviations BA 6-benzylaminopurine - 2,4-d 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - TEM transmission electron microscopy     

Changes in 1-aminocyclopropane-1-carboxylic-acid content of cut carnation flowers in relation to their senescence

The rise in ethylene production accompanying the respiration climacteric and senescence of cut carnation flowers (Dianthus caryophyllus L. cv. White Sim) was associated with a 30-fold increase in the concentration of 1-aminocyclopropane-1-carboxylic acid (ACC) in the petals (initial content 0.3 nmol/g fresh weight). Pretreatment of the flowers with silver thiosulfate (STS) retarded flower senescence and prevented the increase in ACC concentration in the petals. An increase in ACC in the remaining flower parts, which appeared to precede the increase in the petals, was only partially prevented by the STS pretreatment. Addition of aminoxyacetic acid (2 mM) to the solution in which the flowers were kept completely inhibited accumulation of ACC in all flower parts.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid - AOA -aminoxyacetic acid - STS silver thiosulfate complex     

Light response of D1 turnover and photosystem II efficiency in the seagrassZostera capricorni

Biochemical and biophysical parameters, including D1-protein turnover, chlorophyll fluorescence, oxygen evolution activity and zeaxanthin formation were measured in the marine seagrassZostera capricorni (Aschers) in response to limiting (100 mol·m^–2·^–1), saturating (350 mol·m^–2·s^–1) or photoinhibitory (1100 mol·m^–2·s^–1) irradiances. Synthesis of D1 was maximal at 350 mol·m^–2·s^–1 which was also the irradiance at which the rate of photosynthetic O₂ evolution was maximal. Degradation of D1 was saturated at 350 mol·m^–2·s^–1. The rate of D1 synthesis at 1100 mol·m^–2·s^–1 was very similar to that at 350 mol·m^–2·s^–1 for the first 90 min but then declined. At limiting or saturating irradiance little change was observed in the ratio of variable to maximal fluorescence (Fv/Fm) measured after dark adaptation of the leaves, while significant photoinhibition occurred at 1100 mol·m^–2·s^–1. The proportion of zeaxanthin in the total xanthophyll pool increased with increasing irradiance, indicative of the presence of a photoprotective xanthophyll cycle in this seagrass. These results are consistent with a high level of regulatory D1 turnover inZostera under non-photoinhibitory irradiance conditions, as has been found previously for terrestrial plants.We would like to thank Professor Peter Böger (Department of Plant Biochemistry, University of Konstanz, Germany) for the kind gift of D1 antibodies. This work was partly supported by a University of Queensland Enabling Grant to CC.     

Role of ethylene in postharvest quality of cut oriental lily ‘Stargazer’

The effects of endogenous and exogenous C₂H₄ and C₂H₄ inhibitors on the postharvest leaf and flower quality of Oriental lily Stargazer were investigated. Endogenous C₂H₄ was not produced by freshly harvested excised leaves or flowers. Treatment of freshly harvested excised flowers, buds, leaves, and intact cut stems with C₂H₄ concentrations as high as 10 µl·l^–1 did not affect bud opening or longevity or the development of leaf yellowing. Therefore, treatment with anti-C₂H₄ compounds, such as silver thiosulfate (STS) and 1-methylcyclopropene (1-MCP), did not improve the quality of the flowers. Data thus indicate that freshly harvested Stargazer were not sensitive to C₂H₄. Sensitivity of Stargazer to C₂H₄, however, increased dramatically following cold storage, as exposure of cold-stored stems to C₂H₄ concentrations as low as 0.3 µl·l^–1 significantly affected bud opening. The development of leaf yellowing on cold-stored stems was not affected by the exogenous C₂H₄. Pretreating cold-stored stems with 1-MCP significantly reduced blasting of small buds that failed to develop due to carbohydrate depletion and reduced the percentage of buds that did not fully open. Concurrently, 1-MCP did not affect the quality of the leaves. These data indicate that sensitivity of cut lilies to C₂H₄ differs following cold storage and that 1-MCP is a more suitable anti-C₂H₄ compound than STS. Furthermore, studies on endogenous C₂H₄ production revealed that, while C₂H₄ was not detected in freshly harvested buds and leaves, it was produced by both following cold storage. The latter produced C₂H₄ at a higher rate than the former. Results of this study clearly indicate that there are two situations in which lilies will benefit from pretreatment with an anti-C₂H₄ compound (1) when cut stems contain buds that are marginally small for opening and (2) when cut stems will be cold stored before marketing.     

Induction of fertile male flowers in genetically female Cannabis sativa plants by silver nitrate and silver thiosulphate anionic complex

Summary Apical application of silver nitrate (AgNO₃; 50 and 100 g per plant) and silver thiosulphate anionic complex (Ag(S₂O₃) ₂ ^3– ; STS; 25, 50 and 100 g per plant) to female plants of Cannabis sativa induced the formation of reduced male, intersexual and fully altered male flowers on the newly formed primary lateral branches (PLBs); 10 g per plant of AgNO₃ was ineffective and 150 g treatment proved inhibitory. A maximum number of fully altered male flowers were formed in response to 100 g STS. The induced male flowers produced pollen grains that germinated on stigmas and effected seed set. Silver ion applied as STS was more effective than AgNO₃ in inducing flowers of altered sex. The induction of male flowers on female plants demonstrated in this work is useful for producing seeds that give rise to only female plants. This technique is also useful for maintaining gynoecious lines.     

The effect of triacontanol on micropropagation of Capsicum frutescens and Decalepis hamiltonii W & A

We studied the effect of triacontanol (TRIA) on shoot multiplication and rooting of in vitro derived shoot tips of Capsicum frutescens and Decalepis hamiltonii W & A. In both shoot multiplication and rooting phases, TRIA was administered at 2-20 g l^–1. TRIA resulted in highest promotion of axillary shoot proliferation at 2 g l^–1 in Capsicum frutescens and 20 g l^–1 in Decalepis hamiltonii while rooting was maximum at 5 and 10 g l^–1 for Capsicum frutescens and Decalepis hamiltonii respectively. TRIA enhanced shoot growth and chlorophyll content of leaves and also influenced root induction and supported growth of the roots. This work reveals that TRIA can be used as an effective growth regulator in the micropropagation of Capsicum frutescens and Decalepis hamiltonii, an endangered shrub of Deccan peninsular India.     

Influence of inorganic microelements on the production of camptothecin with suspension cultures of <Emphasis Type="Italic">Camptotheca acuminata</Emphasis>

The effects of eight microelements (I^–, BO₃ ^3–, MoO₄ ^2–, Co²⁺, Cu²⁺, Mn²⁺, Fe²⁺, Zn²⁺) on the biosynthesis of camptothecin and the growth of suspension cultures of Camptotheca acuminata were studied. The increase of I^– to 25 M l^–1, Cu²⁺ to 1 M l^–1, Co²⁺ to 2 M l^–1 and MoO₄ ^2– to 10 M l^–1 in Murashige and Skoog (MS) medium resulted in 1.66, 2.84, 2.53 and 2.04 times higher of camptothecin yield than that in standard MS medium respectively. Combined treatment of I^– (25 M l^–1), Cu²⁺ (1 M l^–1), Co²⁺ (2 M l^–1) and MoO₄ ^2– (10 M l^–1) lead to improve cell dry weight, camptothecin content, and camptothecin yield to 30.56 g l^–1, 0.0299%, and 9.15 mg l^–1, respectively, which were 20.2, 208.9 and 273.8% increment respectively when compared with those of control.     

Stimulation of photosynthesis by 2% oxygen at low temperatures is restored by phosphate

The effect of phosphate feeding on the influence of low (2%) oxygen on photosynthetic carbon assimilation has been investigated in leaf discs of spinach (Spinacia oleracea L.) at 12°C. The following observations were made. First, after the transition from 20% O₂ to 2% O₂, the rate of CO₂ uptake was inhibited at CO₂ concentrations between about 250 and about 800 l CO₂·l^-1. Second, phosphate feeding stimulated the rate of CO₂ uptake in 20% O₂ at higher concentrations of CO₂ (500–900 l·l^-1). Third, phosphate feeding stimulated the rate of CO₂ uptake in 2% O₂ at all but the highest (900 l·l^-1) and lowest 74 (l·l^-1) concentrations of CO₂ employed. Phosphate thereby restored the stimulation of photosynthesis by 2% O₂ and it did so over a wide range of lower temperatures. Fourth, oscillatory behaviour, however generated, was dampened by phosphate feeding, even at very low concentrations of CO₂. Contents of leaf metabolites were measured during the transition to 2% O₂ in control and phosphate-fed leaf discs. During this period the ratio glycerate-3-phosphate/triose phosphate rose steeply, but fell again only in the phosphate-treated leaf discs. These data, taken together with measured ATP/ADP ratios, showed that assimilatory power, the ratio [ATP]·[NAD(P)H]/[ADP]·[Pi]·[NAD(P)], decreased when leaves were exposed to 2% O₂, but that this decrease was minimised by previous feeding of phosphate. The mechanism of phosphate limitation is discussed in the light of the results.Abbreviations C_i intercellular concentration of CO₂ - RuBP ribulose-1,5-bisphosphate     

Abscisic acid- and ethylene-induced defoliation of Radermachera sinica L.

Radermachera sinica L. is an ornamental plant with demonstrated sensitivity to ethylene-induced leaf abscission. In this study, we examine the relationship between abscisic acid (ABA) and ethylene in initiating the abscission response. Treatment with 1 l L^\s-1 of ethylene, 1 mM 1-aminocyclopropane-1-carboxylic acid (ACC) or 1 mM ABA resulted in complete defoliation of leaf explants. Application of 0.125 mM silver thiosulfate (STS) inhibited ethylene- and ACC-induced abscission but had no effect on explants treated with ABA. The ABA-induced abscission was unaffected by treatment with aminoethoxyvinylglycine (AVG) or aminooxyacetic acid (AOA). Treatment of explants with 1 mM cobalt chloride (CoCl₂) or 2000 l L^\s-1 of norbornadiene (NBD) completely inhibited abscission in explants treated with 1 l L^\s-1 ethylene or 1 mM ACC but they were only marginally effective in blocking ABA-induced abscission despite the lower level of endogenous ethylene. ABA appeared to increase the sensitivity of explants to ethylene. However, the evidence suggests that ABA may also function independent of ethylene to induce leaf abscission in R. sinica.Abbreviations ABA abscisic acid - ACC 1-aminocyclopropane-1-carboxylic acid - AOA aminooxyacetic acid - AVG aminoethoxyvinylglycine - CoCl₂ cobalt chloride - NBD norbornadiene - STS silver thiosulfate     

Somatic embryogenesis in callus culture of Mussaenda erythrophylla cvs. Queen Sirikit and Rosea

Somatic embryogenesis was achieved from mid-rib and internodal calluses of Mussaenda erythrophylla L. cvs. Queen Sirikit and Rosea cultured on Murashige and Skoog basal medium containing 8.9 M BA+0.57 M IAA+10 mg l^-1 ascorbic acid. Clumps of somatic embryos were separated and grown into complete plantlets when transferred to 1/2 MS medium+37 M adenine sulphate with 2% (w/v) sucrose.     

Basal oxygen consumption,ventilatory frequency,and heart rate during the protracted spawning run of the Southern Hemisphere lamprey Geotria australis

Summary Basal oxygen consumption, ventilatory frequency, and heart rate were recorded at four different times during the unusually protracted 15–16-month spawning run of the Southern Hemisphere lamprey Geotria australis. At 15°C, the mean basal oxygen consumption of G. australis caught immediately after they had left the sea and embarked on the spawning run (45 l · g^-1 · h^-1) was less than in young adults about to commence their marine feeding phase (64 l · g^-1 · h^-1), but greater than in large ammocoetes (26.5 l · g^-1 · h^-1). Basal oxygen consumption fell progressively during the spawning-run of to 33 l · g^-1 · h^-1 after 5 months and 25 l · g^-1 · h^-1 after 10 months, before rising to 35 l · g^-1 · h^-1 after 15 months when the animals were approaching sexual maturity. The downwards trend in basal oxygen consumption contrasts with that recorded during the spawning run of Lampetra fluviatilis. Furthermore, these values for spawning-run of G. australis are far lower than those measured at any time during the upstream migration of L. fluviatilis or during the parasitic phase of landlocked Petromyzon marinus. A low and declining metabolic rate during much of the spawning run of G. australis would facilitate the conservation of energy reserves during this very long non-feeding period. Trends shown by ventilatory frequency and heart rate essentially parallel those of basal oxygen consumption. The Q₁₀s for basal oxygen consumption, ventilatory frequency and heart rate over the temperature range 5–25°C were 1.6, 1.6, and 1.7, respectively. The trends shown by basal oxygen consumption during metamorphosis and the upstream migration did not parallel those exhibited by circulating thyroid hormones.     

Enhanced paclitaxel production induced by the combination of elicitors in cell suspension cultures of Taxus chinensis

Taxus chinensis suspension cells were cultured in the modified Gamborg's B5 medium. Addition of 50 mg chitosan l^–1, 60 M methyl jasmonate and 30 M Ag⁺ resulted in the greatest paclitaxel production, at 25 mg l^–1 in the cultures, being almost 40 times higher than that of the control culture, 10 times higher than that of the culture exposed to Ag⁺, 6 times higher than that of the culture elicited by chitosan and almost double that of the culture elicited by methyl jasmonate.     

Anatomical and physiological effects of silver thiosulfate on ethylene-induced abscission inColeus

Petioles of expiants ofColeus blumei Benth. exposed to 20 l/l ethylene abscised within 36 h. Pretreatment of expiants with 4 mM silver thiosulfate (STS) inhibited ethylene-induced abscission. Delaying treatment with STS reduced its effectiveness in retarding ethylene-promoted abscission, suggesting that some events leading to abscission are initiated during the first hours of ethylene treatment. Microscopic study of abscission zones of ethylene-treated expiants showed greatly increased amounts of rough endoplasmic reticulum, disruptions of the plasma membrane, and some cell separation in the region of the middle lamella. Pretreatment with STS prevented ethylene-induced reorganization of the endomembrane system and the subsequent middle lamellar dissolution.     

Presence of an X AG − carrier in frog (Rana esculenta) red blood cells

Evidence is presented that the high levels of internal l-glutamic and l-aspartic acid in frog Rana esculenta red blood cells are due to the existence of a specific carrier for acidic amino acids of high affinity K _m = 3 m and low capacity (V_max) 0.4 mol l-Glu · Kg^–1 dry cell mass · 10 min^–1. It is Na+ dependent and the incorporation of l-glutamic acid can be inhibited by l and d-aspartate and l-cysteic acid, while d-glutamic does not inhibit. Moreover, this glutamic uptake shows a bell-shaped dependence on the external pH. All these properties show that this carrier belongs to the system X _AG ^– family. Besides the incorporation through this system, l-glutamic acid is also taken up through the ASC system, although, under physiological conditions, this transport is far less important, since it has relatively low affinity K _m 39 m but high capacity (V _max) 1.8 mol l-Glu · Kg^–1 dry cell mass · 10 min^–1.     

Adventitious shoot regeneration from leaf explants of tissue cultured and greenhouse-grown raspberry

Adventitious shoot regeneration was observed using leaf-petiole explants from shoot-proliferating cultures of Comet red raspberry (Rubus idaeus L.). A maximum regeneration rate of 70% (3.7 shoots/explant) was obtained using 4.5–9.1 M (1–2 mg l^–1) N-phenyl-N-1,2,3-thiadiazol-5-ylurea (thidiazuron or TDZ) with 2.5–4.9 M (0.5–1 mg l^–1) 1H-indole-3-butanoic acid (IBA) or 2.3 M (0.5 mg l^–1) TDZ with 4.9 M (1 mg l^–1) IBA in modified Murashige-Skoog medium. TDZ was more effective than N-(phenylmethyl)-1H-purin-6-amine (BA) at promoting regeneration in combinations tested with IBA (maximum 50% regeneration rate; 1.8 shoots/explant). Variation in the agar concentration or incubation temperature, orientation or scoring of the leaf-petiole explants and use of separate leaf or petiole explants had no effect on shoot regeneration. Incubation in the dark for 1, 2 or 3 weeks prior to growth in the light did not influence the percent regeneration rate but depressed the number of adventitious shoots. Explant source, from micropropagated shoots or greenhouse-grown plants, had an effect on shoot regeneration that was genotype dependent. Only 8 of 22 (36%) raspberry cultivars were capable of regeneration from leaf explants derived from greenhouse-grown plants.