Effect of Organic Ligands on Accumulation of Copper in Hyperaccumulator and Nonaccumulator Commelina communis

Better understanding of copper uptake and accumulation regulation in plants is critical to the phytoremediation of copper contaminated soil. This study employed a 30-day pot experiment to assess the relationship between organic ligands and copper accumulation in plants. Hyperaccumulator and nonaccumulator varieties of Commelina communis were used, different organic ligands were applied, and the data of copper accumulation in shoots were collected. The six organic ligands included ethylenediaminetetraacetic acid and organic acids (formic acid, citric acid, malic acid, tartaric acid, and succinic acid). The results showed that organic ligands added to culture increased the copper accumulation both varieties. The results of the copper accumulation in shoots agreed with the study of the root uptake kinetics of copper influx. The addition of organic acids could increase copper accumulation in shoots because the copper influx in roots was increased. The results also indicated that the copper influx of hyperaccumulator roots was higher than that of nonaccumulator roots. This is one of the mechanisms by which a hyperaccumulator could amass large amounts of copper in its shoots. In this accumulation process, little effect on the leaf relative water content was in the hyperaccumulator and nonaccumulator of leaves and normal physiological condition of plants.     

Effect of the Mesophyll on Stomatal Opening in Commelina communis

The effect of a number of factors on the opening of stomatain the intact leaf and in the isolated leaf epidermis of Commelinacommunishas been investigated. Stomata in the intact leaf opened widein the light and closed rapidly on transfer to the dark. Theywere also sensitive to CO₂. In contrast, stomata in isolatedepidermis floated on an incubation solution containing 100 molm^–3KCl responded neither to light nor CO₂. They opened as widelyas those in the intact leaf when treated with fusicoccin. Stomata in isolated epidermis opened almost as wide as thosein the intact leaf when they were incubated with isolatedmesophyllcells in the light. The solution in which the mesophyll cellswere incubated was separated by centrifugation. Themedium fromcells previously incubated in the light caused the stomata inisolated epidermis to open but that from cells kept inthe darkhad no effect. A similar effect was observed when isolated chloroplastswere incubated with the isolated epidermis.However, the supernatantfrom the chloroplast suspension had no significant effect onstomatal opening. These results indicate that the mesophyll plays an importantrole in stomatal opening in the light. The mesophyll appearstoproduce in the light, but not in the dark, a soluble compoundwhich moves to the guard cells to bring about stomatal opening.Theexperiments with isolated chloroplasts suggest that this substanceis a product of photosynthesis. Key words: Commelina communis, stomata, light, mesophyll     

Profiles of Chloride Concentration and PD in the Root of Commelina communis L.

Chloride concentrations in longitudinal files of cells acrossthe root of Commelina communis have been determined. Vacuolarsap was taken from the root using a microsampling techniqueand chloride concentration determined on nanolitre samples byelectrometric microtitration. No radial gradient in vacuolar chloride was observed, eitherfor roots grown in a nutrient solution containing a low level,or for those grown in a solution containing a high level, ofchloride. Vacuolar electrical potentials were also determined,on attached and excised roots. The PD was found not to varysignificantly across the root from epidermis to pericycle despitethe PD in attached roots being 50 mV more negative than thatin excised roots. These results are discussed in relation tothe mechanism of ion transport across the root.     

Effect of boron on stomatal opening in epidermal strips of Commelina communis

Boron enhances stomalal opening in epidermal strips of Commelina communis L. under conditions conductive to opening, i.e . light and KCI. This effect is obtained when boron is given together or before KCI application. Since boron increases ⁸⁶Rb net uptake in both illuminated epidermal strips and illuminated isolated guard cells, it is suggested that boron acts either by reducing potassium leakage or by increasing its uptake, thus leading to increased osmotic potential and, as a result, to stomatal opening.     

Water and Sulphate Uptake at Root Reduction in Ricinus communis

The aim of the investigation was to study the influence of the rate of water uptake on the uptake of sulphate at supernormal rates of water flow. This was achieved by reducing the size of the root system of 42 days old Ricinus plants. The rate of water flow through the root increased 3 times by reducing the root system to 20 percent. This did not change the retention of sulphate in the roots. The uptake of sulphate was proportional to the size of the root system and thus independent of the rate of water flow while the water uptake (transpiration) was a function of the size of the shoot and the resistance of the root. This was contrary to the conditions at a moderate rate of water flow, when water and sulphate uptake followed each other. The results are discussed in terms of the salt uptake as a series of active and passive processes.     

The Effect of Phloem Ringing on Root Growth and Potassium Uptake by Helianthus annuus

The effect of phloem ringing on the uptake and transport ofpotassium by the roots of 4 week old sunflower plants has beeninvestigated. Ringing caused a rapid decline in both K⁺ uptakeand its transport (⁸⁶Rb tracer) to the shoot. The rate of rootelongation and the levels of sucrose in the root showed paralleldecreases after ringing. Measurement on isolated roots indicatedthat the effect of ringing the stem on K⁺ uptake by the rootswas confined to the apical 10 mm that included the extensionzone. It is postulated that the decline in potassium uptakeand transport, brought about by ringing, is due to the severanceof the sucrose supply which stops root growth. Key words: Roots, Growth, Salt uptake     

Effect of total alkaloids from Commelina communis L. on lung damage by influenza virus infection

Whether administration of total alkaloids from Commelina communis L. (TAC) reduces lung damage in influenza virus-infected mice was investigated. Compared with untreated mice, significantly less severe damage was found in the lungs of mice administered TAC at 8 mg/kg per day for 6 days. TAC significantly decreased viral loads in the lungs. The concentrations of IFN-γ in the serum of TAC-treated mice were significantly lower than those of virus control mice at 4 and 6 days post-infection. The results indicate that TAC imparted partial protection to the mice by reducing pulmonary viral loads and limiting lesions in the lungs.     

Uptake and Distribution of Copper in Chrysanthemum morifolium

The effects of various levels of copper on the uptake and distributionof copper in Chrysanthemum morifolium grown in solution cultureand peat-sand have been examined. Whole plants growing in shortdays were sampled at regular intervals, divided into roots,stem, leaves and lateral shoots, and analysed for copper. Thepartitioning of copper between these tissues showed that a relativelylarge proportion (30–40 per cent) of the total plant copperwas accumulated in the roots of normal plants during the harvestingperiod, compared with approximately 10 per cent in the rootsof copper deficient plants. Whilst the copper content (ug g^–1) of leaves and stemfrom normal plants was negatively correlated with the amountof dry matter produced (P < 0·001), the correspondingcopper deficient tissues showed little variation in copper contentwith increases in tissue dry weight. A more detailed investigationof the copper content of leaves from normal plants showed thatgradients existed within the plant with respect to both leafposition and time of harvest which could be described by a singlecubic surface equation (P < 0·001).     

Root Growth and Water Uptake by Maize Plants in Drying Soil

Sharp, R. E and Da vies, W. J. 1985. Root growth and water uptakeby maize plants in drying soil.— J. exp. Bot. 36: 1441–1456. The influence of soil drying on maize (Zea mays L.) root distributionand use of soil water was examined using plants growing in thegreenhouse in soil columns. The roots of plants which were wateredwell throughout the 18 d experimental period penetrated thesoil profile to a depth of 60 cm while the greatest percentageof total root length was between 20–40 cm. High soil waterdepletion rates corresponded with these high root densities.Withholding water greatly restricted root proliferation in theupper part of the profile, but resulted in deeper penetrationand higher soil water depletion rates at depth, compared withthe well watered columns. The deep roots of the unwatered plantsexhibited very high soil water depletion rates per unit rootlength. Key words: Maize, roots, water deficit, soil water depletion     

Growth, Nitrogen Uptake and Flow in Maize Plants Affected by Root Growth Restriction

The objective of the present study was to investigate the influence of a reduced maize root-system size on root growth and nitrogen (N) uptake and flow within plants. Restriction of shoot-borne root growth caused a strong decrease in the absorption of root: shoot dry weight ratio and a reduction in shoot growth. On the other hand, compensatory growth and an increased N uptake rate in the remaining roots were observed. Despite the limited long-distance transport pathway in the mesocotyl with restriction of shoot-borne root growth, N cycling within these plants was higher than those in control plants, implying that xylem and phloem flow velocities via the mesocotyl were considerably higher than in plants with an intact root system. The removal of the seminal roots in addition to restricting shoot-borne root development did not affect whole plant growth and N uptake, except for the stronger compensatory growth of the primary roots. Our results suggest that an adequate N supply to maize plant is maintained by compensatory growth of the remaining roots, increased N uptake rate and flow velocities within the xylem and phloem via the mesocotyl, and reduction in the shoot growth rate.     

Growth,Nitrogen Uptake and Flow in Maize Plants Affected by Root Growth Restriction

The objective of the present study was to investigate the influence of a reduced maize root-system size on root growth and nitrogen （N） uptake and flow within plants. Restriction of shoot-borne root growth caused a strong decrease in the absorption of root ： shoot dry weight ratio and a reduction in shoot growth. On the other hand, compensatory growth and an increased N uptake rate in the remaining roots were observed. Despite the limited long-distance transport pathway in the mesocotyl with restriction of shoot-borne root growth, N cycling within these plants was higher than those in control plants, implying that xylem and phloem flow velocities via the mesocotyl were considerably higher than in plants with an intact root system. The removal of the seminal roots in addition to restricting shoot-borne root development did not affect whole plant growth and N uptake, except for the stronger compensatory growth of the primary roots. Our results suggest that an adequate N supply to maize plant is maintained by compensatory growth of the remaining roots, increased N uptake rate and flow velocities within the xylem and phloem via the mesocotyl, and reduction in the shoot growth rate.     

Ion-Stimulated Stomatal Opening Induced by Preillumination in Epidermal Strips of Commelina communis

The effects of preillumination were investigated on ion-stimulated stomatal opening of epidermal strips isolated from Commelina communis L. leaves, which are dark-starved 24 hours or more. The rate and the extent of ion-stimulated stomatal openings were increased by preexposure of epidermal strips to light. The evidences are interpreted as indicating that the energy induced by preillumination can be conserved in guard cells for considerable time periods and then used for a delayed stomatal opening in the presence of higher concentration of potassium or sodium ions. Action spectrum showed two peaks, one in blue and one in the red light region. The ratio of the blue peak to the red peak is 1.2; which is the smallest reported value in action spectra of stomatal movements. 3-(4-chlorophenyl)-1,-1-Dimethylurea suppressed the ion-stimulated stomatal opening induced by the preillumination. We conclude that the photosynthetic electron transport system, containing photosystem II, in guard cell chloroplasts is a basic system of energy acquirement for stomatal opening.     

Role of Ca and EGTA on Stomatal Movements in Commelina communis L

Ca²⁺ (0.1-1.0 millimolar) accelerated dark-induced stomatal closure and reduced stomatal apertures in the light in epidermal peels of Commelina communis L. In contrast, ethyleneglycol-bis-(β-aminoethyl ether) N,N′tetraacetic acid (EGTA) (2 millimolar), a Ca²⁺ chelator, prevented closure in the dark and accelerated opening in the light. EGTA did not promote significant opening in the dark. It is therefore concluded that EGTA does not increase ion uptake into guard cells, but rather prevents ion efflux. Addition of EGTA to incubating solutions with 10 millimolar KCl resulted in steady state apertures of 15.6 micrometers, whereas in the absence of EGTA similar apertures required 55 millimolar KCl and 150 millimolar KCl was needed in the presence of 1 millimolar CaCl₂. The results demonstrate the importance of Ca²⁺ in the regulation of stomatal closure and point to a role of Ca²⁺ in the regulation of K⁺ efflux from stomatal guard cells.     

Effect of pH on IAA Uptake by Maize Root Segments

The uptake of [5-³H]indoleacetic acid (IAA) by Zea mays L. root segments involves nonsaturable and saturable processes. The pH optimum of the saturable component was found to be 5.0. The proton ionophore carbonylcyanide p-trifluoromethoxyphenylhydrazone inhibited at 100 micromolar the saturable component of IAA uptake but had no effect on non-saturable uptake. This indicates that the saturable component of IAA uptake is dependent on the proton gradient across the plasmalemma. The high level of proton extrusion in the elongation zone of the root will stimulate nonsaturable and saturable uptake of IAA in that zone.     

Uptake of Different Species of Iodine by Water Spinach and Its Effect to Growth

A hydroponic experiment has been carried out to study the influence of iodine species [iodide (I(-)), iodate ([Formula: see text]), and iodoacetic acid (CH(2)ICOO(-))] and concentrations on iodine uptake by water spinach. Results show that low levels of iodine in the nutrient solution can effectively stimulate the growth of biomass of water spinach. When iodine levels in the nutrient solution are from 0 to 1.0 mg/l, increases in iodine levels can linearly augment iodine uptake rate by the leafy vegetables from all three species of iodine, and the uptake effects are in the following order: [Formula: see text]. In addition, linear correlation was observed between iodine content in the roots and shoots of water spinach, and their proportion is 1:1. By uptake of I(-), vitamin C (Vit C) content in water spinach increased, whereas uptake of [Formula: see text] and CH(2)ICOO(-) decreased water spinach Vit C content. Furthermore, through uptake of I(-) and [Formula: see text], the nitrate content in water spinach was increased by different degrees.     

Studies on the Properties of Carboxylating Enzymes in the Epidermis of Commelina communis

A spectrophotometric assay has been used to measure the activityof PEP carboxylase and RuBP carboxylase in the epidermal andmesophyll tissue of Commelina communis. On both a chlorophylland protein basis the PEP carboxylase activity was always greaterin the epidermis than in the mesophyll, whereas RuBP carboxylaseactivity was always highest in the mesophyll. PEP carboxylaseactivity in epidermal extracts was lost very slowly and itspH optimum was a broad one in the range 7·5–8·0.The K_m values for PEP carboxylase in the epidermis and mesophyllobtained from light- and dark-treated plants were not very differentalthough its V_max was much lower in dark-treated tissue. Thesedata are discussed in relation to the possible role of PEP carboxylasein guard cell metabolism.     

紫竹梅、吊竹梅和鸭跖草气孔分布与比较

用无色指甲油印痕法对鸭跖草科的紫竹梅、吊竹梅和鸭跖草的幼茎、成熟茎、成熟叶鞘的外表皮和幼叶、成熟叶和上、下表皮的气孔分布进行观察。并借助于计算机对三种植物的各器官各部分的气孔分布进行差异性检验和总体比较。结果表明 :三种植物的幼茎、成熟茎和成熟叶鞘外表皮的上部、中部、基部的气孔分布均无显著性差异 ,而幼叶和成熟叶的上、中、下部的气孔分布存在着显著性差异或极显著差异。三种植物的总体比较 ,只有幼茎无显著性差异。同科不同属的三种植物不同器官的气孔分布存在差异与其遗传和生境条件有关。在植物不同的器官中 ,叶表面的气孔分布特征可以作为植物分类的佐证。     

Regulation of Mg,K-ATPase Activity in Guard Cells of Commelina communis by Phytochrome and ABA

The microsomal fraction obtained from guard cell protoplastswas assayed for ATPase activity at pH 6.5. Triton X-100 didnot affect this stimulation of activity of ATPase by K⁺ up to5 mM, but the detergent abolished the stimulatory effect ofK⁺ at higher concentrations. The ATPase activity was inhibitedby N,N-dicyclohexylcarbodiimide and ABA. Irradiation with redlight enhanced the ATPase activity more than did irradiationwith far-red light. ABA and irradiation with red or far-redlight were effective only in the presence of K⁺. These resultssuggest the possibility that the ATPase activity is modulatedonly indirectly by light and ABA. (Received January 9, 1989; Accepted July 10, 1989)