Influence of Etherel and Gibberellic Acid on Carbon Metabolism, Growth, and Essential Oil Accumulation in Spearmint (Mentha Spicata)

Changes in growth parameters and ¹⁴CO₂ and [U-¹⁴C]-sucrose incorporation into the primary metabolic pools and essential oil were investigated in leaves and stems of M. spicata treated with etherel and gibberellic acid (GA). Compared to the control, GA and etherel treatments induced significant phenotypic changes and a decrease in chlorophyll content, CO₂ exchange rate, and stomatal conductance. Treatment with etherel led to increased total incorporation of ¹⁴CO₂ into the leaves wheras total incorporation from ¹⁴C sucrose was decreased. When ¹⁴CO₂ was fed, the incorporation into the ethanol soluble fraction, sugars, organic acids, and essential oil was significantly higher in etherel treated leaves than in the control. However, [U-¹⁴C]-sucrose feeding led to decreased label incorporation in the ethanol-soluble fraction, sugars, organic acids, and essential oils compared to the control. When ¹⁴CO₂ was fed to GA treated leaves, label incorporation in ethanol-insoluble fraction, sugars, and oils was significantly higher than in the control. In contrast, when [U-¹⁴C]-sucrose was fed the incorporation in the ethanol soluble fraction, sugars, organic acids, and oil was significantly lower than in the control. Hence the hormone treatment induces a differential utilization of precursors for oil biosynthesis and accumulation and differences in partitioning of label between leaf and stem. Etherel and GA influence the partitioning of primary photosynthetic metabolites and thus modify plant growth and essential oil accumulation. This revised version was published online in June 2006 with corrections to the Cover Date.     

Interaction of Photoperiod, Chilling and Exogenous Gibberellic Acid on Growth of Strawberry Petioles

Gibberellic acid (GA₃) was applied to strawberry plants in varyingdoses. Lengths of successively emergent petioles increased ina manner indicating that they were responsive to exogenous GA₃during both pre- and especially postemergence phases of ontogeny.Exogenous GA₃ interacted with photoperiod and chilling, but,because the responses were complicated by competition from aberrantstem elongation, GA₃ could not be shown to replace the endogenousstimulus completely, although it may do so in part. On the otherhand, a large component of the endogenous stimulus which promotesgrowth in long daylength and after chilling was not replacedby exogenous GA₃. This is interpreted as evidence for non-gibberellinfactors in the endogenous system. It appears that the stimuli generated by long daylength andby chilling are different, but the evidence is against the suggestionthat one mediates the gibberellin system and the other the non-gibberellinone.     

Benzyladenine-induced inhibition of flowering in Chenopodium rubrum in vitro is not related to the levels of isoprenoid cytokinins

The effect of 6-benzylaminopurine (BAP) on floweringand on endogenous levels of isoprenoid cytokinins wasinvestigated in explanted terminal shoots of Chenopodium rubrum cultivated in vitro. Themother plants were grown under continuous light andexplants were cut off when the 6th leaf primordiumoriginated at the shoot apex. The explants wereexposed to one dark period of 13 hours inductive forflowering or to continuous light on medium with orwithout BAP (0.05;0.2;0.4 mg.l^-1). Undernon-inductive conditions no flowering was observedeither in the control or after BAP treatment. Afterreceiving one inductive dark period, the controlexplants flowered. However, BAP application either atthe beginning of the inductive dark period and/orduring the following light cultivation inhibitedflowering and stimulated initiation and growth of leafprimordia. In the case of the most efficient BAPconcentration (0.05 mg.l^-1) flowering wasinhibited by 80% and the number of leaf primordia wasincreased by 3. Explantation caused a significantincrease in the total amount of endogenous cytokininsin the explants within first 13 h, provided they werekept in light. When explants were kept in darkness,only a slight increase in cytokinin levels wasobserved. BAP treatment had no influence on the levelsof endogenous cytokinins either in light or indarkness. We may thus conclude, that BAP applicationinhibited flowering of photoperiodically inducedterminal shoot explants and stimulated leaf primordiaformation with no significant effect on changes inlevels of endogenous isoprenoid cytokinins. This maysuggest the direct ability of BAP to regulate morphogenesis.     

The Effect of Gibberellic Acid and Guanosine Monophosphates on Extension Growth, Leaf Production and Flowering of Impatiens balsamina

Gibberellic acid (GA₃) increases the height of Impatiens balsamina under both 8- and 24-h photoperiods. The height also increases with all guanosine monophosphates (GMPs) under 8-h photoperiods but only with 5′-GMP under 24-h photoperiods. GA₃ as well as GMPs increase the number of leaves under 8-h but not under 24-h photoperiods. GA₃ as well as GMPs induce floral buds under strictly non-inductive photoperiods and increase the number of floral buds under 8-h photoperiods. The floral bud initiation occurs earlier when cGMP is used in combination with 100 mg/l GA₃.     

The Effects of Growth Regulators on Flowering of Chenopodium murale Plants in vitro

In vitro culture of Chenopodium murale L. (ecotype 197) green and herbicide SAN 9789 - treated "white" plants was established and the effects of benzylaminopurine (BAP), indole-3-acetic acid (IAA) and gibberellic acid (GA₃) on growth and flowering were tested. Green plants did not flower on glucose free media, while 17 % of plants flowered on 5 % glucose-containing medium. SAN 9789 (10^–5 M) inhibited growth and flowering. BAP and IAA (0.1 – 5 mg dm^–3) also inhibited growth and flowering of green and "white" plants. GA₃ (10 mg dm^–3) stimulated leaf development in green plants, but had no significant effect on "white" plants, and stimulated flowering of green (41 %) and "white" (33 %) plants.     

Effects of Cytokinins on In Vitro Seed Germination and Early Seedling Morphogenesis in Lotus corniculatus L.

We determined the effects of zeatin (ZEA), isopentenyl adenine (2iP), kinetin (KIN), benzyladenine (BA), and thidiazuron (TDZ) on seed germination, elongation of seedling shoots and roots, frequency of regeneration, and the number of regenerants per seedling in Lotus corniculatus L. Sterilized seeds were cultured in vitro on Murashige and Skoog (1962) medium containing 3% sucrose, 0.7% agar, and various cytokinins (0, 0.08, 0.22, 0.35, 0.80, 2.20, and 3.50 μM). After 30 days, seedlings were transferred to cytokinin-free medium for another 60 days. All cytokinins stimulated the rate and percentage of seed germination at least twofold in optimum concentrations; TDZ and ZEA were the most active, followed closely by BA, whereas KIN and 2iP stimulated germination in higher concentrations only. Elongation of shoots and roots was strongly inhibited at the lowest TDZ and BA concentrations, whereas ZEA, KIN, and 2iP exerted moderate, dose-dependent inhibition. The frequency of regenerant-producing seeds was highest on ZEA and BA, whereas the greatest number of regenerants per seedling was found on TDZ. It is concluded that the culture of seeds on cytokinin-containing media, followed by transfer to cytokinin-free medium, is a suitable procedure for rapid production of a large number of uniform regenerants. The presumed role of particular cytokinins is discussed.     

Effects of Abscisic Acid on the Growth Pattern of the Shoot Apical Meristem and on Flowering in Chenopodium rubrum L.

Abscisic acid (ABA) at 1 x 10^–4 M or 3 x 10^–4 Mwas applied to the apical buds of Chenopodium rubrum plantsexposed to different photoperiodic treatments and showing differentpatterns of floral differentiation. Stimulation of growth inwidth of the apical meristem of the shoot and/or inhibitionof growth in length was obtained under all photoperiodic treatments.This change of growth pattern was followed by different effectson flowering. In non-induced plants grown under continuous light ABA stimulatedpericlinal divisions in the peripheral zone and the initiationof leaves as well as the growth in width of bud primordia. Inplants induced by two short days reduced growth of the meristemcoincided with ABA application. Longitudinal growth of the meristemwas inhibited in this case and only a temporary stimulationof inflorescence formation took place. In plants induced ata very early stage, ABA exerted a strong inhibitory effect onflowering. A permanent and reproducible stimulatory effect onflowering was obtained in plants induced by three sub-criticalphotoperiodic cycles if ABA was applied to apices released fromapical dominance. In this case formation of lateral organs andinternodes was promoted by ABA and was followed by stimulatedinflorescence formation. Gibberellic acid (GA2) at 1x 10^–4M or 3 x 10^–4 M brought about a similar effect on floweringas ABA, although the primary growth effect was different, i.e.GA₂ stimulated longitudinal growth. The effects of ABA and GA₂ on floral differentiation have beencompared with earlier results obtained from auxin and kinetinapplications. These growth hormones are believed to regulateflowering by changing cellular growth within the shoot apex.Depending on the actual state of the meristem identical growthresponses may result in different patterns of organogenesisand even in opposite effects on flowering. Shoot apex, flowering, photoperiodic induction, abscisic acid, gibberellic acid, Chenopodium rubrum L.     

The Effects of H<Superscript>+</Superscript>-ATPase Activator and Inhibitors on Cell Growth in the Maize Root

We studied the effects of H⁺-ATPase activator fusicoccin (FC) and its inhibitors, sodium orthovanadate (Na₃VO₄) and diethylstilbestrol (DES), on the rate of proton secretion by root regions located at various distances from the root tip, the rate of root growth, the length of the fully-elongated root cells, the sizes of growth zones, the relative growth rate of cells along the root length, and the number of fully-elongated cells in the root length increment. FC (10⁻⁶ M) stimulated proton secretion by root segments and enhanced root growth due to the greater length of fully-elongated cells. DES (10⁻⁴ M) suppressed proton secretion and retarded root growth, decreased the length of fully-elongated cells, inhibited cell division, and slowed down cell transition to elongation by prolonging the life-span of cells in the meristem. Na₃VO₄ (10⁻³ and 10⁻⁴ M) exerted similar effects. FC, DES, and orthovanadate did not affect the ratio of the relative rate of cell growth in the elongation zone to that in meristem.__________Translated from Fiziologiya Rastenii, Vol. 52, No. 4, 2005, pp. 558–565.Original Russian Text Copyright © 2005 by Mesenko, Ivanov.     

The Effects of Boric Acid and Gibberellic Acid on the Growth of Fiber of Phragmites cormmuhis Trin

Water-cultured young plants of Phragmites communis Trin. were used in this experiment. They were treated with boric acid and gibberellic acid, separately or in combination, by method of foliage spraying. The results are summarized as follows: 1. In comparation with the controls, the length of the fibre cells was remarkably increased following the treatment with boric acid at concentrations ranging from 1 to 200 μmol/l. The optimum concentration of boric acid was found to be 100 μmol/l. Gibberellic acid alone at the concentration of 50 μmol/l also enhanced the length of the fibre cells. However, the best result was obtained in the group treated with a combination of boric acid and gibmberellic acid at a ratio of 200:50 μmol/l. A maximum increasement of fibre length and a greater ratio of length to width were observed in this experimental group. 2. Microscopic study indicates that the increase in both the number of the fibre cells and ,the thickness of the fibre layer are apparent in histological preparation. 3. In addition, The authors have also found that the incorporation of H3-glucose into the fibre cell wall was greatly enhanced by such combination treatment. 4. In conclusion, it has been demonstrated clearly that the boric acid and the gibberellic acid, when used in combination, produces an augmentative effect on both the growth and the development of the fibre cells of Phragmites communis Trin.     

Growth and Development of Romanomermis culicivorax In Vitro

Various combinations of vertebrate and invertebrate tissue culture and microbiological media were utilized in an attempt to culture Romanomermis culicivorax (Mermithidae: Nematoda) in vitro. Most media were unsuitable and caused nematodes to become lumpy, vacuolated, and granular. Slow and limited growth and development of internal structures of the nematodes were obtained with variously supplemented Grace''s tissue culture and Schneider''s Drosophila media. In an enriched Grace''s medium, development attained by the nematodes after 3-4 wk was comparable to 4-5-day-old parasites grown in vivo in the mosquito host, Culex pipiens. Two molts were observed in vitro. Maximum dimensions in vitro were 7.0-mm length and 87-μm width at the widest point. The stichosome, stichocytes, and trophosome developed prominently. A filiform tail and highly cuticularized tube persisted throughout the culture period in vitro.     

The Effects of Fusicoccin,Abscisic Acid,and Benzyladenine on the Transport and Partitioning of Substances as Related to Cytokinin Sink Activity

We tested the possible cytokinin effect on the functioning of the active transport system involved in the assimilate loading into the phloem as a cause for the cytokinin sink and retention effect. This effect is manifested in the deceleration of substance export from and the stimulation of substance import to the sites of local phytohormone application to the mature detached leaf from untreated leaf areas. To affect the membrane mechanisms of the substance transport, we used leaf treatment with the phytotoxin fusicoccin, an enhancer of plasmalemmal H⁺-ATPase and a potential stimulator of assimilates export, and with the phytohormone ABA affecting transport, metabolism, and plant growth. However, fusicoccin did not enhance ¹⁴C-sucrose export from the leaf blade and did not interfere with the cytokinin-induced export deceleration. ABA reduced substantially ¹⁴C export from the leaf but eliminated the cytokinin effect on this process. Similar results were obtained for broad bean (Vicia faba L.) leaves with apoplastic phloem loading, involving H⁺-ATPase activity, and pumpkin (Cucurbita pepo L.) leaves with symplastic phloem loading, that is, occurring without sucrose transmembrane translocation and without H⁺-ATPase involvement. The conclusion is that the cytokinin-induced development of sink zones in source leaves is not related to the membrane mechanisms of the substance transport in the mesophyll–phloem system. The data obtained support the idea that the cause for the cytokinin sink and retention effect is the enhancement of elongation growth and total activation of metabolism in the mesophyll cells of the detached leaf.     

Effects of ethylene on tuberization in radish (Raphanus sativus)

The effects of ethylene on the elongation of radish hypocotyls and on dry matter partitioning between tubers and shoots were analysed in order to gain insight into the possible role of ethylene in the regulation of tuberization. Treatment of very young seedlings with ethylene results in heavier tubers (Vreugdenhil et al. 1984). Here we report that addition of ethylene or ethephon two days after germination inhibited the elongation of the hypocotyl; trapping of endogenously produced ethylene had a stimulative effect on elongation. Ethephon, sprayed at a later stage, changed the partitioning of assimilates between tubers and shoots, resulting in lower tuber weights. It is concluded that ethylene had a dual effect on tuberization in radish: at a very early stage of development it inhibited elongation of the hypocotyl, resulting in earlier tuber formation and heavier tubers. At a later stage, it had a negative effect on tuber weight by changing dry matter partitioning.     

Glucose metabolism,H+ production and Na+/H+- exchanger mRNA levels in ischemic hearts from diabetic rats

Glycolysis uncoupled from glucose oxidation is a major reason for the intracellular acidosis that occurs during severe myocardial ischemia. The imbalance between glycolysis and glucose oxidation, and the resultant H⁺ produced from glycolytically derived ATP hydrolysis in the diabetic rat heart is the focus of this study. Isolated working hearts from 6 week streptozotocin diabetic rat hearts were perfused with 11 mM glucose and 1.2 mM palmitate and subjected to a 25 min period of global ischemia. A second series of experiments were also performed in which hearts from control, diabetic, and islet-transplanted diabetic rats were subjected to a 30 min aerobic perfusion, followed by a 60 min period of low-flow ischemia (coronary flow = 0.5 ml/min) and 30 min of aerobic reperfusion. H⁺ production from glucose metabolism was measured throughout the two protocols by simultaneous measurement of glycolysis and glucose oxidation using perfusate labelled with [5-³H/U-¹⁴C]-glucose. Rates of H⁺ production were calculated by measuring the difference between glycolysis and glucose oxidation. The H⁺ production throughout the perfusion was generally lower in diabetic rat hearts compared to control hearts, while islet-transplantation of diabetic rats increased H⁺ production to rates similar to those seen in control hearts. This occurred primarily due to a dramatic increase in the rates of glycolysis. Despite the difference in H⁺ production between control, diabetic and islet-transplanted diabetic rat hearts, no difference in mRNA levels of the cardiac Na⁺/H⁺-exchanger (NHE-1) was seen. This suggests that alterations in the source of protons (i.e. glucose metabolism) are as important as alterations in the fate of protons, when considering diabetes-induced changes in cellular pH. Furthermore, our data suggests that alterations in Na⁺/H⁺-exchange activity in the diabetic rat heart occur at a post-translational level, possibly due to direct alterations in the sarcolemmal membranes.     

Influence of Etherel and Gibberellic Acid on Carbon Metabolism,Growth, and Essential Oil Accumulation in Spearmint (Mentha Spicata)

Controlled environment chamber and glasshouse studies were conducted on six herbaceous annual species grown at 350 (AC) and 700 (EC) mol(CO₂) mol^-1 to determine whether growth at EC resulted in acclimation of the apparent quantum yield of photosynthesis (QY) measured at limiting photosynthetic photon flux density (PPFD), or in acclimation of net photosynthetic rate (P _N) measured at saturating PPFD. It was also determined whether acclimation in P _N at limiting PPFD was correlated with acclimation of carboxylation efficiency or ribulose-1,5-bisphosphate (RuBP) regeneration rate measured at saturating PPFD. Growth at EC reduced both the QY and P _N at limiting PPFD in three of the six species. The occurrence of photosynthetic acclimation measured at a rate limiting PPFD was independent of whether photosynthetic acclimation was apparent at saturating measurement PPFD. At saturating measurement PPFD, acclimation to EC in the apparent carboxylation efficiency and RuBP regeneration capacity also occurred independently. Thus at least three components of the photosynthetic system may adjust independently when leaves are grown at EC. Estimates of photosynthetic acclimation at both high and low PPFD are necessary to accurately predict photosynthesis at the whole plant or canopy level as [CO₂] increases.     

Plant Growth Based on Interrelation between Carbon and Nitrogen Translocation from Leaves

In individual leaves, the photon-saturated photosynthetic activity (P _sat, expressed on a dry mass basis) was closely related to the nitrogen content (Nc) as follows: P _sat = Cf Nc + P _sat0, where Cf and P _sat0 are constants. On a whole plant basis, the relative growth rate (RGR) was closely related to Nc in canopy leaf as follows: RGR = DMf Nc + RGR₀, where DMf and RGR₀ are constants. However, the coefficients Cf and DMf were markedly different among plant species. To explain these differences, it is suggested that carbon assimilation (or dry matter production) is controlled by both the Nc in a leaf (or leaves) and by the net N translocation from leaves. This is supported by the finding that P _sat is related to the rate of ³⁵S-methionine translocation from leaves. We propose another estimation method for the net N translocation rate (NFR) from leaves: Nc, after full leafing, is expressed as a function of time: Nc = (Nc₀ – Ncd) exp(–Nft) + Ncd, where Nf is a coefficient, t is the number of days after leaf emergence, Nc₀ is the initial value of Nc, and Ncd is the Nc of the dead leaf. The NFR is then calculated as NFR = Nc/t = –Nf (Nc – Ncd). Thus Nf is the coefficient for the NFR per unit Nc. NFR is a good indicator of net N translocation from leaves because NFR is closely related to the rate of ³⁵S-methionine translocation from leaves. Since P _sat is related to the ¹⁴C-photosynthate translocation rate, Cf (or DMf) corresponds to the coefficient of saccharide translocation rate per unit amount of Nc. Cf (or DMf) is closely related to the Nf of individual leaves (or the Nf of canopy leaf). This indicates that C assimilation and C translocation from leaves are related to Nc and N translocation from leaves (net translocation of N). Cf and Nf are negatively correlated with leaf longevity, which is important because a high or low CO₂ assimilation rate in leaves is accompanied by a correspondingly high or low N translocation in leaf, and the degree of N translocation in leaves decreases or increases leaf longevity. Thus, since a relatively high P _sat (or RGR) is accompanied by a rapid Nc decrease in leaves, it is difficult to maintain a high P _sat (or RGR) for a sustained time period.     

Involvement of Amino Acid 36 in TM1 in Voltage Sensitivity in Mouse Na<Superscript>+</Superscript>/Glucose Cotransporter SGLT1

Human SGLT1 protein is an established sodium-glucose cotransporter. Despite widespread use of the mouse as a model organism, the mouse SGLT1 homologue has yet to be functionally characterized. Additionally, the crystal structure of a sugar transporter homologue, Vibrio SGLT, has recently been described, however, it offers limited information about the role of transmembrane segments outside of the core ligand binding domains. In particular, the amino acids in TM1 were not assigned in the structure. To examine the contribution of TM1 to the function of SGLT1, we have cloned and characterized the biophysical properties of SGLT1 from mouse, mSGLT1, and compared it to a clone containing an amino acid substitution in TM1, F36S. As predicted, both proteins formed functional Na⁺/sugar cotransporters, but F36S-mSGLT1 showed decreased rates of sugar uptake and decreased apparent affinities for both Na⁺ and sugar compared to mSGLT1. Analysis of pre-steady-state currents and comparison with the crystal structure of Vibrio SGLT provide plausible mechanisms to explain the differences in function of these two proteins. Our data suggest that amino acids in TM1, which are not involved in ligand binding and translocation pathways, significantly influence the functional properties of sodium-glucose carrier proteins.     

Triacontanol-Induced Changes in the Growth, Photosynthetic Pigments, Cell Metabolites, Flowering and Yield of Green Gram

Seedlings of green gram [Vigna radiata (L.) Wilezek] cultivar KM-2 were sprayed with different concentrations of triacontanol (TRIA) (0, 0.5, 1.0, and 2.0 mg dm^-3) at 15 and 25 days after sowing. Foliar spray of 0.5 mg dm^-3 TRIA significantly promoted the plant height, fresh mass, and contents of chlorophylls, saccharides, starch, soluble proteins, amino acid and phenols. Leaf nitrate content was reduced by 0.5 and 1.0 mg dm^-3 TRIA with a corresponding increase in nitrate reductase activity. TRIA of 0.5 mg dm^-3 stimulated the onset of flowering, pod production and retention, but less number of pods and seeds per plant were observed at 2.0 mg dm^-3 treatment.     

The Role of Gibberellic Acid and Paclobutrazol on Oxidative Stress Responses Induced by In Vitro Salt Stress in Sweet Sorghum

Russian Journal of Plant Physiology - Gibberellic acid (GA3) application has been shown to affect salinity tolerance through modulating oxidative stress processes. Moreover, paclobutrazol (PBZ) as...     

In Vitro Effects of SB202190 on Echinococcus granulosus

Spillage of cyst contents during surgical operation is the major cause of recurrence after hydatid cyst surgery. Instillation of a scolicidal agent into a hepatic hydatid cyst is the most commonly employed measure to prevent this complication. SB202190 is a pyridinyl imidazole derivative and is known to be a specific inhibitor of p38 MAPK. In the present study, the scolicidal effect of SB202190 was investigated. Freshly isolated Echinococcus granulosus protoscolices were subjected to SB202190 treatment (10, 20, 40, and 80 µM), and the effects on parasite viability were monitored by trypan blue staining. Corresponding effects were visualized by scanning and transmission electron microscopy. Dose-dependent protoscolex death within a few days of SB202190 treatment was observed. Although the in vitro scolicidal effect of SB202190 was satisfactory, the in vivo efficacy of this drug and also possible side effects remain to be further investigated.