Symplastic and apoplastic uptake and root to shoot translocation of nickel in wheat as affected by exogenous amino acids

This study investigated the effect of exogenous amino acids on apoplastic and symplastic uptake and root to shoot translocation of nickel (Ni) in two wheat cultivars. Seedlings of a bread (Triticum aestivum cv. Back Cross) and a durum wheat cultivar (T. durum cv. Durum) were grown in a modified Johnson nutrient solution and exposed to two levels (50 and 100 μM) of histidine, glycine, and glutamine. Application of amino acids resulted in increasing symplastic to apoplastic Ni ratio in roots of both wheat cultivars, although glutamine and glycine were more effective than histidine under our experimental conditions. The amino acid used in the present study generally increased the relative transport of Ni from the roots to shoots in both wheat cultivars. Higher amounts of Ni were translocated to wheat shoots in the presence of histidine than the other amino acids studied, which indicated that histidine was more effective in translocation of Ni from roots to shoots. Amino acids used in the present study largely increased root symplastic Ni, but shoot Ni accumulation was much lower than the total Ni accumulation in roots, indicating a large proportion of Ni was retained or immobilized in wheat roots (either in the apoplastic or symplastic space), with only a very small fraction of Ni being translocated from the root to the shoot. According to the results, glutamine and glycine were more effective than histidine in enhancing the symplastic to apoplastic Ni ratio in the roots, while more Ni was translocated from the roots to the shoots in the presence of histidine.     

Differential responses of microsomal proteins and metabolites in two contrasting cadmium (Cd)-accumulating soybean cultivars under Cd stress

While there are significant genotypic differences in cadmium (Cd) uptake and distribution in soybean cultivars, little attention has been paid to the underlying molecular mechanisms. We adopted a comparative proteomic approach coupled with metabolite analysis to examine Cd uptake and translocation in two contrasting Cd-accumulating soybean cultivars, Enrei and Harosoy, which accumulate higher amount of Cd in the roots and aerial parts, respectively. Proteins extracted from the root microsomal fraction were evaluated by immunoblot analysis using different subcellular marker proteins. Analysis of control and Cd-exposed samples by two-dimensional gel electrophoresis coupled with mass spectrometry revealed a total of 13 and 11 differentially expressed proteins in the Enrei and Harosoy cultivars, respectively. Metabolome profiling identified a total of 32 metabolites, the expression of 18 of which was significantly altered in at least in one cultivar in response to Cd stress. Analysis of the combined proteomic and metabolomic results revealed that proteins and amino acids associate with Cd-chelating pathways are highly active in the Enrei cultivar. In addition, proteins associated with lignin biosynthesis are significantly upregulated in the Enrei cultivar under Cd stress. Our results indicate that in the Enrei cultivar, Cd-chelating agents may bind excess free Cd ion and that translocation of Cd from the roots to the aerial parts might be prevented by increased xylem lignification.     

Autolysis in vitro of cotton (Gossypium hirsutum) fibre cell walls

Root growth of partly defoliated young peach seedlings [ Prunus persica (L.) Batsch. cv. Lovell] was significantly promoted by application of myo-inositol to the cut surface of the stem. Addition of benzylaminopurine (BA) combined with sucrose enhanced the promotive effect of myo-inositol on root growth, but addition of sucrose alone, suppressed it. Spraying rooted peach cuttings (nectarine cv. Sunred) with myo-inositol and defoliating them after 5 days increased the incorporation of amino acids into proteins in excised roots, obtained from the sprayed plants, as compared with roots from plants sprayed with water, or sucrose, or sucrose + myo-inositol. Myo-inositol applied in combination with kinetin or BA to stems of young peach seedlings (cv. Lovell) or rooted peach cuttings (cv. Almog) promoted the basipctal translocation of the two cytokinins in the stem and acropetally into the small lateral roots. Addition of sucrose voided this effect on the cytokinins. BA, when applied together with myo-inositol, was partly converted into an additional cytokinin-active compound in the roots.
Application of BA to either roots or tops of rooted peach cuttings (cv. Almog) resulted in the accumulation of myo-inositol (supplied through the cut surface of the stem) in the plant part to which BA had been applied.     

Fluorene and Phenanthrene Uptake and Accumulation by Wheat,Alfalfa and Sunflower from the Contaminated Soil

Polycyclic Aromatic Hydrocarbons (PAHs) are diverse organic contaminants released into the environment by both natural and anthropogenic activities. These compounds have negative impacts on plants growth and development. Although there are many reports on their existence in different parts of plant, their uptake and translocation pathways and mechanisms are not well understood yet. This paper highlights the uptake, translocation and accumulation of PAHs by wheat, sunflower and alfalfa through an experimental study under controlled conditions. Seeds were cultivated in a soil containing 50 mg/kg of phenanthrene and fluorene and their concentrations in plants roots and shoots were determined using a gas chromatograph after 7 and 14 days. The results showed that phenanthrene and fluorene concentrations in the treated plants were increased over the time. PAHs bioavailability was time and species dependent and generally, phenanthrene uptake and translocation was faster than that of fluorene, probably due to their higher K_ow. Fluorene tended to accumulate in roots, but phenanthrene was transported to aerial parts of plants.     

Evidence for separate translocation pathways in determining cadmium accumulation in grain and aerial plant parts in rice

Background  

Cadmium (Cd) translocation and accumulation in the grain and aerial plant parts of rice (Oryza sativa L.) is an important aspect of food safety and phytoextraction in areas with contaminated soil. Because control of Cd translocation and accumulation is likely to be determined by the plants genetics, the Cd contents of grain and the aerial parts of rice may be manipulated to improve food safety and for phytoextraction ability. This study studied Cd translocation and accumulation and their genetic control in aerial parts of rice to provide a starting point for improving food safety and phytoextraction in Cd-contaminated soils.     

Role of roots in differences in seed cadmium concentration among soybean cultivars—proof by grafting experiment

Soybean cultivars show significant differences in cadmium (Cd) concentrations in seeds, due primarily to genetics, not environmental factors. We previously suggested that low-Cd cultivars accumulate Cd in their roots and thus prevent its translocation to the rest of the plant. Through grafting experiments, we drew the following conclusions about Cd absorption and translocation: (1) The amount of Cd accumulated in shoots is determined by the Cd accumulation capacity of roots: cultivars with a small capacity to accumulate Cd in roots translocate more Cd and accumulate it in shoots; (2) The Cd concentration in shoots is determined by the Cd accumulation capacity of roots and the shoot productive ability of the scion cultivar; (3) The Cd tolerance of shoots differs among cultivars. Enrei, with a high-Cd accumulation capacity of roots, had a low Cd tolerance of shoots compared with Suzuyutaka and Hatayutaka, with a low Cd accumulation capacity of roots; (4) Cultivars differ in their distribution of Cd to seed; (5) These results show that seed Cd concentration is influenced by the differences among cultivars in ease of translocation of Cd to seed and in Cd accumulation capacity of roots.     

Induction of phenolic compounds in two dark-grown lentil cultivars with different tolerance to copper ions

The influence of a high copper sulphate concentration on growth, Cu accumulation, lipid peroxidation as well as on the contents of total phenolic compounds (PhC) and UV-absorbing compounds (UVAC) in roots of lentil (Lens culinars Medic.) cvs. Krak and Tina was investigated. The plants were subjected to 0.5 mM Cu²⁺ for 3 and 5 days in darkness. Growth inhibition and increased lipid peroxidation in the roots of both cultivars, especially in cv. Tina which accumulated more Cu, were observed. Cu²⁺ treatment caused greater PhC and UVAC accumulation in cv. Krak; however, constitutive levels of these compounds were higher in cv. Tina. The maximum absorption peak of UVAC was determined at 270 nm. HPLC analyses of these compounds revealed the presence of two main derivatives of the soluble (aglycone and ester-bound) fraction of the hydroxycinnamic acids, ferulic (FA) and p-coumaric (p-CA) acids and the flavonol, kaempferol (Kam). Greater changes in the content of phenolic acids than of Kam may suggest that the former play a more important role in protecting lentil roots against high Cu²⁺ concentration. Thus, while the lower PhC levels at a higher Cu content in the roots of cv. Tina were probably due to stress, their higher levels in cv. Krak could have been a response to ROS signaling. However, though the high concentration of Cu²⁺ stimulated PhC in cv. Krak, it was not sufficient to counteract the amount of ROS generated by metal presence. These observations may suggest that ROS can serve as a common signal for acclimation to Cu²⁺ stress and cause PhC accumulation in dark-grown roots. The role of PhC in lentil tolerance to Cu²⁺ stress is discussed.     

Deoxypodophyllotoxin content and antioxidant activity of aerial parts of Anthriscus sylvestris Hoffm

Deoxypodophyllotoxin content of the aerial parts of Anthriscus sylvestris Hoffm. growing at different altitudes was evaluated in comparison to the roots. The lignan accumulation in ground parts was at least double compared to aerial ones. In addition antioxidant-guided fractionation of the crude methanol extract of aerial parts was performed with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test. Active fractions contained mainly luteolin-7-O-glucoside and chlorogenic acid. Antioxidant properties of both crude extract and isolated compounds were also investigated with the Briggs-Rauscher (BR) oscillating reaction. A satisfactory agreement between the results obtained with the two methods was observed.     

Identification of hot pepper cultivars containing low Cd levels after growing on contaminated soil: uptake and redistribution to the edible plant parts

Aims

This study aimed to screen and identify low-cadmium (Cd) hot pepper (Capsicum annuum L.) cultivars and to clarify the mechanisms of low Cd accumulation in fruits.

Methods

A pot experiment was conducted to investigate the variations of fruit Cd concentration among 30 hot pepper cultivars and to determine the differences in uptake and translocation of Cd between low- and high-Cd cultivars in the control and two Cd treatments.

Results

There are significant differences among the cultivars in their ability to accumulate Cd in fruits. Fruit Cd concentrations are positively and significantly correlated with the translocation of Cd from roots to aboveground parts and the Cd concentrations of leaves and stems. However, no correlation was observed between the fruit’s Cd concentration and the root’s Cd uptake ability.

Conclusions

Two hot pepper cultivars, Yeshengchaotianjiao (No. 16) and Heilameixiaojianjiao (No. 23), were identified as low-Cd cultivars, and two, Jinfuzaohuangjiao (No. 13) and Shuduhong (No. 18), were treated as high-Cd cultivars. The difference in fruit Cd concentrations between low- and high-Cd cultivars is attributable to the difference in Cd translocation from roots to aboveground parts and from leaves and stems to fruits, rather than to the root’s Cd uptake ability.     

Analysis of the essential oil from the roots of Eupatorium cannabinum subsp. corsicum (L.) by GC, GC-MS and 13C-NMR

Eupatorium cannabinum subsp. corsicum (L.) is an endemic subspecies from the island of Corsica. The essential oil from the roots of this aromatic plant has been studied by GC, GC-MS and by 13C-NMR. In contrast to the essential oil from the aerial parts, which is dominated by hydrocarbon compounds (76.9%) and particularly by sesquiterpene components (43.3%), the essential oil from the roots was characterized by a high content of oxygenated compounds (61.0%), particularly oxygenated monoterpenes (54.0%). In the root oil, 106 components were identified representing 96.1% of the total amount. This oil was dominated by the monoterpenes esters (33%), the major components of which were neryl isobutyrate (17.6%), thymyl methyl oxide (15.1%), delta-2-carene (14.5%) and beta-pinene (5.7%). Aromatic esters, nerol derivatives (esters and diesters) and a benzofuran were investigated by GC-MS using different ionization modes including electron impact ionization, and positive- and negative-chemical ionization. These components have not previously been reported in the essential oil of aerial parts of E. cannabinum from Corsica island.     

Different Effect of Humidity on Growth and Salt Tolerance of Two Soybean Cultivars

Two soybean (Glycine max (L.) Merr.) cultivars, Tachiyutaka and Dare, were grown in pots at 30 and 70 % relative humidity (RH) and treated with 0 (control), 40 (moderate), 80 and 120 (severe) mM NaCl for 3 weeks. Increasing RH enhanced growth of salt sensitive cultivar, Tachiyutaka, but had no effect on salt tolerant cultivar, Dare, under control and moderate saline conditions. Both cultivars benefited from elevated humidity under severe saline conditions. Cultivar Tachiyutaka had poorer ability for controlling translocation of Na⁺ to the leaves, lower Na⁺ exclusion ability in the roots, and lower root activity under NaCl treatment, compared with cv. Dare. The increased growth of cv. Tachiyutaka at high RH was consistent with decreased Na⁺ accumulation in the leaves, increased stomatal conductance and root activity, while the unchanged growth of cv. Dare was consistent with similar Na⁺ accumulation in the leaves, and the decreased root activity.     

A Major Latex-Like Protein Is a Key Factor in Crop Contamination by Persistent Organic Pollutants

This is the first report, to our knowledge, to reveal important factors by which members of the Cucurbitaceae family, such as cucumber (Cucumis sativus), watermelon (Citrullus lanatus), melon (Cucumis melo), pumpkin (Cucurbita pepo), squash (C. pepo), and zucchini (C. pepo), are selectively polluted with highly toxic hydrophobic contaminants, including organochlorine insecticides and dioxins. Xylem sap of C. pepo ssp. pepo, which is a high accumulator of hydrophobic compounds, solubilized the hydrophobic compound pyrene into the aqueous phase via some protein(s). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of xylem sap of two C. pepo subspecies revealed that the amount of 17-kD proteins in C. pepo ssp. pepo was larger than that in C. pepo ssp. ovifera, a low accumulator, suggesting that these proteins may be related to the translocation of hydrophobic compounds. The protein bands at 17 kD contained major latex-like proteins (MLPs), and the corresponding genes MLP-PG1, MLP-GR1, and MLP-GR3 were cloned from the C. pepo cultivars Patty Green and Gold Rush. Expression of the MLP-GR3 gene in C. pepo cultivars was positively correlated with the band intensity of 17-kD proteins and bioconcentration factors toward dioxins and dioxin-like compounds. Recombinant MLP-GR3 bound polychlorinated biphenyls immobilized on magnetic beads, whereas recombinant MLP-PG1 and MLP-GR1 did not. These results indicate that the high expression of MLP-GR3 in C. pepo ssp. pepo plants and the existence of MLP-GR3 in their xylem sap are related to the efficient translocation of hydrophobic contaminants. These findings should be useful for decreasing the contamination of fruit of the Cucurbitaceae family as well as the phytoremediation of hydrophobic contaminants.Numerous agricultural fields and crops have been contaminated with persistent organic pollutants (POPs), including dioxins, such as polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs); dioxin-like compounds, such as coplanar polychlorinated biphenyls (PCBs) and the insecticide dichlorodiphenyltrichloroethane; drins, such as aldrin, dieldrin, and endrin; and chlordane (Hashimoto, 2005; Uegaki et al., 2006; Hilber et al., 2008). POPs show carcinogenicity, teratogenicity, immunotoxicity, and estrogenicity toward humans and wildlife after accumulation through the food chain. Despite the fact that the use of PCBs and these insecticides was prohibited several decades ago, environmental and crop contamination remains a problem due to their high hydrophobicity and chemical stability.Members of the Cucurbitaceae family, such as cucumber (Cucumis sativus), watermelon (Citrullas lanatus), melon (Cucumis melo), pumpkin (Cucurbita pepo), and zucchini (C. pepo), are some of the major crops in the world. Previous studies reported that members of the Cucurbitaceae family, particularly C. pepo, which includes pumpkin and zucchini, accumulated higher levels of PCDDs and PCDFs (Hülster et al., 1994; Inui et al., 2008), 2,2-bis(p-chlorophenyl) 1,1-dichloroethylene (p,p′-DDE; White et al., 2003), PCBs (Aslund et al., 2008; Inui et al., 2008), chlordane (Mattina et al., 2004), and drins (Otani et al., 2007) compared with the levels in other plant species. Thus, it appears that the Cucurbitaceae family has unique mechanisms of POP uptake and translocation. Lunney et al. (2004) reported that the shoots of pumpkin and zucchini plants showed much higher concentrations of dichlorodiphenyltrichloroethane than those of tall fescue (Festuca arundinacea), alfalfa (Medicago sativa), and ryegrass (Lolium multiflorum), whereas concentrations in roots were similar among these plants. Likewise, significant differences were found between C. pepo ssp. pepo and ssp. ovifera in concentrations of dioxins and dioxin-like compounds in the aerial parts, whereas the concentrations in their roots were similar (Inui et al., 2011). These results suggest that the mechanisms causing the high accumulation of POPs in C. pepo plants mainly occur during translocation from the roots to the aerial parts.The transport of substances such as nutrients and signal molecules over long distances in higher land plants is mediated by the vascular bundles, which consist of phloem and xylem strands. In addition to inorganic salts, organic nutrients such as amino acids, sugars, and organic acids are translocated through the xylem from the roots to the aerial parts (Satoh, 2006). Furthermore, the fact that POPs such as chlordane, dieldrin, and PCBs were detected in xylem sap of C. pepo suggests that their accumulation in the aerial parts of plants occurs during the translocation from roots to aerial parts in xylem sap (Mattina et al., 2004; Murano et al., 2010b; Greenwood et al., 2011). A recent study revealed that there were protein-like materials with the ability to dissolve dieldrin in xylem sap (Murano et al., 2010a). However, these materials have yet to be identified, and the mechanisms underlying the high transport ability and high accumulation of POPs in C. pepo plants are not fully understood.In this study, to clarify the molecular mechanisms of the efficient uptake and high accumulation of POPs by C. pepo plants, xylem sap proteins related to the transport of POPs in xylem sap were identified. The aim of this research is to provide a means of preventing cucumber, melon, watermelon, pumpkin, and zucchini fruits from being contaminated by POPs.     

Phytochemical profile of aerial parts and roots of Wachendorfia thyrsiflora L. studied by LC-DAD-SPE-NMR

Hyphenated liquid chromatography – diode array detection – solid phase extraction – nuclear magnetic resonance spectroscopy (LC-DAD-SPE-NMR) was used to investigate the phytochemical composition of aerial parts and roots of Wachendorfia thyrsiflora (Haemodoraceae). Eleven phenylphenalenones and related compounds were identified in the aerial parts of the plant, ten compounds were found in the roots, and four additional compounds occurred in both plant parts. Twelve compounds are previously unreported natural products including five alkaloids (phenylbenzoisoquinolinones) are described here for the first time. In the work presented here, phenylphenalenones with an intact C₁₉ core structure were found only in the roots. Oxa analogs with a C₁₈O scaffold occurred both in the roots and in the aerial plant parts, while most of the aza analogs with a C₁₈N scaffold were detected in the aerial plant parts. This distribution pattern suggests that phenylphenalenones form in the roots, then the intact C₁₉ skeleton is converted into oxa analogs in the roots, translocated into the leaves and further reacted with amines or amino acids to form aza analogs (phenylbenzoisoquinolin-1,6-dione alkaloids).     

Translocation of selenium in the bean plant (Phaseolus vulgaris) and the field bean (Vicia faba)

Selenium distribution in the bean plant ( Phaseolus vulgaris L. cv. Contender) was studied using autoradiographs of the whole plant and of sections of organs. A few hours after the incubation of the roots with (⁷⁵Se) selenate, a major part of the selenate accumulates in the roots, while the fraction conveyed towards the aerial organs is unevenly distributed, resulting in accumulation of ⁷⁵Se in the young leaves, the buds and the epicotyl. This distribution results from a general translocation of selenium through the xylem. A secondary process of redistribution is then immediately linked to the transport of ⁷⁵Se labeled products (such as seleno-amino acids) in the phloem from the mature leaves. A similar pattern of translocation of selenium was found in the field bean ( Vicia faba L. cv. Aguadulce) by using aphids that insert their stylets into the sieve tubes. Measurement of the radioactivity of these insects shows that the ⁷⁵Se content of the phloem sap was reduced to low levels when all the mature leaves were excised. The mature leaves thus serve as relaying organs, redistributing the selenium which is carried in by the movement of water through the xylem.     

Inbreeding effects on blossom volatiles in Cucurbita pepo subsp. texana (Cucurbitaceae)

Self-pollination by plants gives rise to inbreeding depression. There is increasing recognition that plant inbreeding can have significant implications for interactions between plants and other organisms, including insects and pathogens. Many of these interactions are mediated by plant-derived volatiles, but the effects of inbreeding on volatile production have not previously been investigated. We examined variation in flower volatile production by the wild gourd Cucurbita pepo subsp. texana as a function of inbreeding, sex of the flower, and maternal line. We compared first-generation selfed progeny to outcrossed progeny to assess variation in blossom volatiles due to mating system. Our data indicate that self-pollination reduces total volatile production and changes the relative composition of individual compounds released by C. pepo subsp. texana blossoms. These findings have potentially important implications for interactions between C. pepo subsp. texana and its pollinators and herbivores-including diabroticite cucumber beetles, which vector the bacterial pathogen Erwinia tracheiphila-because previous studies have shown that a number of the individual compounds that vary with inbreeding level can influence insect behavior. We also found significant differences between the volatile profiles of male and female flowers and across maternal families.     

Neue α-santalen- und labdan-derivate aus Ayapana amygdalina

While the roots of Ayapana amygdalina contain typical euparine derivatives, the aerial parts afforded in addition to known compounds two new α-santalene derivatives as well as twelve new labdane derivatives with a partly unusual oxidation pattern, two being norditerpenes. Furthermore, a new bisabolene isomer is present. The structures were elucidated by spectroscopic methods and a few chemical transformations. The chemotaxonomy is discussed briefly.     

Two further 6,12-cis-germacranolides from Montanoa tomentosa subsp. xanthiifolia

The aerial parts of Montanoa tomentosa subsp. xanthiifolia gave two further 6,12-cis-germacranolides while the roots contained large amounts of kaurane derivatives.     

Phosphorus effect on the uptake,translocation and accumulation of the14C-urea in orchard grass (Dactylis glomerata L.)

Summary The effect of different phosphorus supplies on the uptake, translocation and accumulation of¹⁴C-urea by orchard grass was investigated. Phosphorus starvation inhibits the uptake, translocation and accumulation of the carbon of urea similarly to the nitrogen of urea. As compared with the uptake process the reduction of the accumulation is much more effected by the inhibition of the carbon translocation from roots to the aboveground parts. Lack of phosphorus also decreases the incorporation of the¹⁴C of urea into high-molecular compounds. The effect of phosphorus deficit on the accumulation of¹⁴C-urea increases with time of starvation.     

Changes in Peroxidase Activity during Potato Ring Rot Infection

The effects of the ring rot causal agent Clavibacter michiganensis subsp. sepedonicus (a virulent strain 5369) on the peroxidase activity of various tissues of potato plants grown under axenic conditions were studied. Root infection enhanced peroxidase activity in all plant tissues (roots, leaves, and stems). In the resistant cv. Lugovskoi, peroxidase activity was much higher than in the susceptible cv. Luk'yanovskii. Co-culturing of the suspension cells of these potato cultivars with the bacterial pathogen also activated peroxidase in the cells of the resistant cultivar; in the cells of the susceptible cultivar, peroxidase activation was less pronounced. Treating suspension cell with exopolysaccharides secreted by the pathogen enhanced the activity of extra- and intracellular peroxidases, and the degree of this enhancement differed in the two potato cultivars.     

Peroxidase activities of two rice cultivars differing in salinity tolerance as affected by proline and NaCl

Proline content, ion accumulation, cell wall and soluble peroxidase activities were determined in control and salt-treated calli (150 nM NaCl) and whole plants (30 mM NaCl) of two rice cultivars (salt sensitive cv. IKP and salt tolerant cv. Aiwu). Under salinity, the highest accumulation of Na⁺, Cl^? and proline occurred in calli, roots and younger leaves of cv. IKP, coupled with the highest decrease in K⁺ content; accumulations of Na⁺ and Cl^? were restricted to older leaves in cv. Aiwu. Relative growth rates of calli and roots or shoots from both cultivars were not linked to peroxidase activities. High concentrations (1 M) of exogenously applied glycerol did not inhibitin vitro activities of soluble peroxidase extracted from control and salt-treated calli or plants. Conversely, 35–55% (in cv. IKP) or 60–80% (in cv. Aiwu) of soluble peroxidase activities were found in presence of isosmotic proline concentration. There were no differences between proline and glycerol effects onin vitro cell wall peroxidase activities.