Fe In Shoots Research Articles

Inhibition of shoot-expressed NRT1.1 improves reutilization of apoplastic iron under iron-deficient conditions.

Iron deficiency is a major constraint for plant growth in calcareous soils. The interplay between NO3 - and Fe nutrition affects plant performance under Fe-deficient conditions. However, how NO3 - negatively regulates Fe nutrition at the molecular level in plants remains elusive. Here, we showed that the key nitrate transporter NRT1.1 in Arabidopsis plants, especially in the shoots, was markedly downregulated at post-translational levels by Fe deficiency. However, loss of NRT1.1 function alleviated Fe deficiency chlorosis, suggesting that downregulation of NRT1.1 by Fe deficiency favors plant tolerance to Fe deficiency. Further analysis showed that although disruption of NRT1.1 did not alter Fe levels in both the shoots and roots, it improved the reutilization of apoplastic Fe in shoots but not in roots. In addition, disruption of NRT1.1 prevented Fe deficiency-induced apoplastic alkalization in shoots by inhibiting apoplastic H+ depletion via NO3 - uptake. In vitro analysis showed that reduced pH facilitates release of cell wall-bound Fe. Thus, foliar spray with an acidic buffer promoted the reutilization of Fe in the leaf apoplast to enhance plant tolerance to Fe deficiency, while the opposite was true for the foliar spray with a neutral buffer. Thus, downregulation of the shoot-part function of NRT1.1 prevents apoplastic alkalization to ensure the reutilization of apoplastic Fe under Fe-deficient conditions. Our findings may provide a basis for elucidating the link between N and Fe nutrition in plants and insight to scrutinize the relevance of shoot-expressed NRT1.1 to the plant response to stress.

Synchrotron X-ray Fluorescence Technique Identifies Contribution of Node Iron and Zinc Accumulations to the Grain of Wheat.

Increasing iron (Fe) and zinc (Zn) concentrations in crop grains with high yield is an effective measure to ensure food supply and alleviate mineral malnutrition in humans. Micronutrient concentrations in grains depend on not only their availability in soils but also their uptake in roots and translocation to shoots and grains. In this three-year field study, we investigated genotypic variation in Fe and Zn uptake and translocation within six wheat cultivars and examined in detail Fe and Zn distributions in various tissues of two cultivars with similar high yield but different grain Fe and Zn concentrations using synchrotron micro-X-ray fluorescence. Results revealed that root Fe and Zn concentrations were 11 and 44% greater in high-nutrient (HN) than in low-nutrient (LN) concentration cultivar. Although both cultivars accumulated similar amounts of Fe in shoots, HN cultivar had greater accumulation of Fe in grain and greater accumulation of Zn in both shoots and grain. Grain Zn concentration was positively correlated with shoot Zn accumulation, and grain Fe concentration was positively correlated with the ability to translocate Fe from leaves/stem to grains. In the first nodes of shoots, HN cultivar had 482% greater Fe and 36% greater Zn concentrations in the enlarged vascular bundle (EVB) than LN cultivar. In top nodes, HN cultivar had 225 and 116% greater Fe and Zn concentrations in the transit vascular bundle and 77 and 71% greater in the EVB when compared to LN cultivar. HN cultivar also had a greater ability to allocate Fe and Zn to the grain than LN cultivar. In conclusion, HN cultivar had greater capacity of Fe and Zn acquirement by roots and translocation and partitioning from shoots into grains. Screening wheat cultivars for larger Fe and Zn concentrations in shoot nodes could be a novel strategy for breeding crops with greater grain Fe and Zn concentrations.

Genome-wide Identification of Metal Tolerance Protein Genes in Peanut: Differential Expression in the Root of Two Contrasting Cultivars Under Metal Stresses.

Metal tolerance proteins (MTP) are Me2+/H+(K+) antiporters that play important roles in the transport of divalent cations in plants. However, their functions in peanut are unknown. In the present study, a total of 24 AhMTP genes were identified in peanut, which were divided into seven groups belonging to three substrate-specific clusters (Zn-CDFs, Zn/Fe-CDFs, and Mn-CDFs). All AhMTP genes underwent whole genome or segmental gene duplication events except AhMTP12. Most AhMTP members within the same subfamily or group generally have similar gene and protein structural characteristics. However, some genes, such as AhMTP1.3, AhMTP2.4, and AhMTP12, showed wide divergences. Most of AhMTP genes preferentially expressed in reproductive tissues, suggesting that these genes might play roles in metal transport during the pod and seed development stages. Excess metal exposure induced expressions for most of AhMTP genes in peanut roots depending on cultivars. By contrast, AhMTP genes in the root of Fenghua 1 were more sensitive to excess Fe, Cd, and Zn exposure than that of Silihong. Stepwise linear regression analysis showed that the percentage of Fe in shoots significantly and positively correlated with the expression of AhMTP4.1, AhMTP9.1, and AhMTPC4.1, but negatively correlated with that of AhMTPC2.1 and AhMTP12. The expression of AhMTP1.1 showed a significant and negative correlation with the percentage of Mn in shoots. The percentage of Zn in shoots was significantly and positively correlated with the expression of AhMTP2.1 but was negatively correlated with that of AhMTPC2.1. The differential responses of AhMTP genes to metal exposure might be, at least partially, responsible for the different metal translocation from roots to shoots between Fenghua 1 and Silihong.

Fe and Zn stress induced gene expression analysis unraveled mechanisms of mineral homeostasis in common bean (Phaseolus vulgaris L.)

Iron (Fe) and zinc (Zn) stress significantly affects fundamental metabolic and physiological processes in plants that results in reduction of plant growth and development. In the present study, common bean variety; Shalimar French Bean-1 (SFB-1) was used as an experimental material. Four different MGRL media i.e. normal MGRL medium (Control), media without Fe (0-Fe), media without Zn (0-Zn) and media with excess Zn (300-Zn) were used for growing seeds of SFB-1 under in vitro condition for three weeks under optimum conditions. Three week old shoot and root tissues were harvested from the plants grown in these four different in vitro conditions and were, subjected to Fe and Zn estimation. Further, extraction of total RNA for differential gene expression of ten candidate genes selected based on our in silico investigation and their classification, phylogeny and expression pattern was unraveled. Expression analysis of three candidate genes (OPT3, NRAMP2 and NRAMP3) in roots revealed possible cross talk among Fe/Zn stress that was further confirmed by observing less accumulation of Fe in roots under both these conditions. However, we observed, higher accumulation of Fe in shoots under 0-Fe condition compared to control that suggests precise sensing for priority based compartmentalization and partitioning leading to higher accumulation of Fe in shoots. Furthermore, the expression analysis of IRT1, FRO1 and Ferritin 1 genes under Fe/Zn stress suggested their role in uptake/transport and signaling of Fe and Zn, whereas the expression of ZIP2, NRAMP1, HA2 and GLP1 genes were highly responsive to Zn in Phaseolus vulgaris. The identified genes highly responsive to Fe and Zn stress condition can be potential candidates for overcoming mineral stress in dicot crop plants.

Effects of Bicarbonate and Fe Sources on Vegetative Growth and Physiological Traits of Four Grapevine Cultivars

ABSTRACT High bicarbonate concentration in alkaline and calcareous soils is an important inducing factor of iron (Fe) chlorosis in plants. The purpose of this study was to investigate the effects of bicarbonate (15 and 30 mM) and Fe sources (FeEDTA and FeSO4.7 H2O) on vegetative growth and physiological traits of four grapevine cultivars in hydroponic systems. In this study a factorial experiment was conducted based on a completely randomized design with four replications. Results showed that bicarbonate and Fe-deficient (FD) treatments decreased total fresh and dry weights in all cultivars. Results also indicated that absolute growth rate significantly decreased under high bicarbonate (HB) concentration in all cultivars. The concentration of total Fe in shoot decreased under HB in Yaghouti, Flame Seedless and Rotabi cultivars (26%, 25%, 23% compared to their control plant respectively) however, the existence of bicarbonate had little effect on shoot Fe concentration of Thompson Seedless cultivar in both Fe sources (FeEDTA and FeSO4.7 H2O). Results indicated that leaf malondialdehyde (MDA) contents increased under HB in all cultivars and both Fe sources whereas MDA was increased in Thompson Seedless and Flame Seedless as well as Rotabi cultivars under FD treatment. Generally according to our results, cultivars showed different responses to bicarbonate and Fe deficiency, Thompson Seedless cultivar showed higher tolerance to bicarbonate application and Yaghouti and Flame Seedless cultivars had more tolerance under Fe-deficient conditions.

Biofortification of Silage Maize with Zinc, Iron and Selenium as Affected by Nitrogen Fertilization.

Agronomic biofortification is one of the main strategies for alleviation of micronutrient deficiencies in human populations and promoting sustainable production of food and feed. The aim of this study was to investigate the effect of nitrogen (N)fertilization on biofortification of maize crop (Zea mays L.) with zinc (Zn), iron (Fe) and selenium (Se) grown on a micronutrient deficient soil under greenhouse conditions. Factorial design experiment was set under greenhouse conditions. The experiment consisted of two levels of each N, Zn, Fe and Se. The levels for N were 125 and 250 mg N kg−1 soil; Zn were 1 and 5 mg Zn kg−1 soil; levels of Fe were 0 and 10 mg Fe kg−1 soil; levels of Se were 0 and 0.02 mg Se kg−1 soil. An additional experiment was also conducted to study the effect of the Zn form applied as a ZnO or ZnSO4 on shoot growth, shoot Zn concentration and total shoot Zn uptake per plant. Shoot Zn concentrations increased by increasing soil Zn application both with ZnSO4 and ZnO treatments, but the shoot Zn concentration and total Zn uptake were much greater with ZnSO4 than the ZnO application. Under given experimental conditions, increasing soil N supply improved shoot N concentration; but had little effect on shoot dry matter production. The concentrations of Zn and Fe in shoots were significantly increased by increasing N application. In case of total uptake of Zn and Fe, the positive effect of N nutrition was more pronounced. Although Se soil treatment had significant effect, N application showed no effect on Se concentration and accumulation in maize shoots. The obtained results show that N fertilization is an effective tool in improving the Zn and Fe status of silage maize and contribute to the better-quality feed.

Phytoextraction with Maize of Soil Contaminated with Copper after Application of Mineral and Organic Amendments

This study aimed to determine the possibility to increase the the effect of different amendments (compost, bentonite and zeolite) on the shoot yield and the concentration of trace elements in shoots of maize (Zea mays L.) on soil contaminated with Cu. The yield of shoots and concentration of the trace elements in shoots of maize depended on Cu dose and amendment incorporation into the sandy soil. Cu-spiked soil caused an increase the yield of shoots (only to 100 mg Cu/kg of soil), in the concentration of Cu, Co, Mn, Ni and Fe in shoots of maize and, to a smaller degree, in the concentration of Zn and bioconcentration factor (BCF) of all elements except copper, compared to the control soil without Cu. Under the influence of 150 and 200 mg Cu per kg of soil, a decrease in yield of shoots of maize was observed. Compost, bentonite and zeolite increased the yield of shoots and reduced the concentration of Cu, Co, Mn, Fe and Zn in shoots of maize. Bentonite had a more positive effect than compost and zeolite on the yield of shoots and the concentration of Co, Mn and Zn in shoots of maize. The effect of these amendments on the Cu and Fe concentration in shoots of maize was reverse. A reverse effect of these amendments (especially bentonite and zeolite) on the Ni concentration in plants was observed. The amendments applied to soil, especially compost, increased the BCF of Ni and, to a small degree, BCF of Cu in shoots of maize, compared to the control series. Compost, zeolite and especially bentonite are very good amendments in the restoration of maize growth in polluted areas.

The Crotalaria juncea metal transporter CjNRAMP1 has a high Fe uptake activity, even in an environment with high Cd contamination

Large quantities of Fe and Cd accumulate in the leaves of the metal-accumulating leguminous plant, Crotalaria juncea. A member of the metal transporter NRAMP family was cloned from C. juncea. The amino acid sequence of this clone, designated CjNRAMP1, was similar to the sequence of Arabidopsis AtNRAMP1, which is involved in Fe and Cd transport. Organ-specific analysis showed that CjNRAMP1 mRNA was expressed mainly in the leaves of C. juncea plants, as well as in stems and roots. Use of green fluorescent protein fused to CjNRAMP1 suggested its localization to the plasma membranes of plant cells. Complementation experiments using yeast strains with impaired metal transport systems showed that CjNRAMP1 transported both Fe and Cd in an inward direction within the cells. Transgenic Arabidopsis plants overexpressing CjNRAMP1 showed high tolerance to Cd, with Cd translocation from roots to leaves being substantially greater in transgenic than in wild-type plants. Overexpression of CjNRAMP1 resulted in a greater accumulation of Fe in shoots and roots, suggesting that CjNRAMP1 recognizes Fe and Cd as substrates and that the high Cd tolerance of CjNRAMP1 is due to its strong Fe uptake activity, even in the presence of high Cd concentrations in the rhizosphere.

Nitrogen rates associated with the inoculation of Azospirillum brasilense and application of Si: Effects on micronutrients and silicon concentration in irrigated corn

Abstract The aim of this study was to analyze whether there are differences between the inoculation with Azospirillum brasilense and the silicon application, thus enabling a higher efficiency of nitrogen fertilization, evaluating micronutrients and silicon concentration in shoots and roots of irrigated corn (Zea mays). The experiment was conducted in Selviria, Brazil, under a no-till system, on a Typic Rhodic Hapludox. The experiment was set up as a randomized block design with four replications, in a 2 × 5 × 2 factorial arrangement consisting of two soil corrective sources (dolomitic limestone and Ca and Mg silicate as source of Si); five N rates (0, 50, 100, 150 and 200 kg ha-1); with and without inoculation with A. brasilense. N rates increased B, Cu and Fe concentrations in shoots and B, Cu, Fe, Mn, Zn and Si in roots. Inoculation provided greater concentrations of B and Fe in shoots, and B in roots. Although inoculation with A. brasilense favored micronutrient uptake, it negatively affected Si concentration in shoots in 2015/16 crop. The use of Si in the form of Ca and Mg silicate promotes an increase in Mn, Si and Zn uptake in shoots and Mn and Si concentration in roots.

Aluminum exclusion from root zone and maintenance of nutrient uptake are principal mechanisms of Al tolerance in Pisum sativum L.

Our study aimed to evaluate intraspecific variability of pea (Pisum sativum L.) in Al tolerance and to reveal mechanisms underlying genotypic differences in this trait. At the first stage, 106 pea genotypes were screened for Al tolerance using root re-elongation assay based on staining with eriochrome cyanine R. The root re-elongation zone varied from 0.5mm to 14mm and relationships between Al tolerance and provenance or phenotypic traits of genotypes were found. Tolerance index (TI), calculated as a biomass ratio of Al-treated and non-treated contrasting genotypes grown in hydroponics for 10days, varied from 30% to 92% for roots and from 38% to 90% for shoots. TI did not correlate with root or shoot Al content, but correlated positively with increasing pH and negatively with residual Al concentration in nutrient solution in the end of experiments. Root exudation of organic acid anions (mostly acetate, citrate, lactate, pyroglutamate, pyruvate and succinate) significantly increased in several Al-treated genotypes, but did not correlate with TI. Al-treatment decreased Ca, Co, Cu, K, Mg, Mn, Mo, Ni, S and Zn contents in roots and/or shoots, whereas contents of several elements (P, B, Fe and Mo in roots and B and Fe in shoots) increased, suggesting that Al toxicity induced substantial disturbances in uptake and translocation of nutrients. Nutritional disturbances were more pronounced in Al sensitive genotypes. In conclusion, pea has a high intraspecific variability in Al tolerance and this trait is associated with provenance and phenotypic properties of plants. Transformation of Al to unavailable (insoluble) forms in the root zone and the ability to maintain nutrient uptake are considered to be important mechanisms of Al tolerance in this plant species.

Bradyrhizobia and arbuscular mycorrhizal fungi modulate manganese, iron, phosphorus, and polyphenols in soybean (Glycine max (L.) Merr.) under excess zinc

The effect of Bradyrhizobia (R) and Arbuscular mycorrhiza (AM) on manganese, iron, phosphorus, and polyphenols was investigated in soybean cultivated in Zn treated soils. In a completely randomized 3×4 factorial, the experimental treatments – Zn addition (0, 200, and 400mg Zn kg−1 of soil), and Inoculation (uninoculated control, R, AM, and R+AM dual inoculation) were set up in the greenhouse. Zinc treatment increased Zn in roots and shoots, Fe in roots, frequency of root mycorrhization, P in root, and Mn translocation; but decreased Fe translocation, Mn in root, and total polyphenols. Symbionts effected micronutrient balancing in the plants. Mycorrhizal inoculants increased Zn in shoots, and modulated Mn and Fe in shoots and roots; within the whole-plant crosstalk in Zn, Mn, and Fe status. In dual inoculation, synergy for much enhanced Mn translocation was indicated in 400mg Zn kg−1 treatment. Modulations of Zn-Mn-Fe nutrition in dual inoculation was supported with a reduction in cumulative number of fallen leaves, and increases in leaf greenness, shoot P, and root polyphenols, to give higher shoot biomass. Our results suggest the possibility of optimizing the crop production and bio-inoculation outcomes by targeting Mn and Fe status (in roots, shoots, translocation, and ratios with Zn) during cultivation under excess Zn.

Salicylic acid modulates arsenic toxicity by reducing its root to shoot translocation in rice (Oryza sativa L.)

Arsenic (As) is posing serious health concerns in South East Asia where rice, an efficient accumulator of As, is prominent crop. Salicylic acid (SA) is an important signaling molecule and plays a crucial role in resistance against biotic and abiotic stress in plants. In present study, ameliorative effect of SA against arsenate (AsV) toxicity has been investigated in rice (Oryza sativa L.). Arsenate stress hampered the plant growth in terms of root, shoots length, and biomass as well as it enhanced the level of H2O2 and MDA in dose dependent manner in shoot. Exogenous application of SA, reverted the growth, and oxidative stress caused by AsV and significantly decreased As translocation to the shoots. Level of As in shoot was positively correlated with the expression of OsLsi2, efflux transporter responsible for root to shoot translocation of As in the form of arsenite (AsIII). SA also overcame AsV induced oxidative stress and modulated the activities of antioxidant enzymes in a differential manner in shoots. As treatment hampered the translocation of Fe in the shoot which was compensated by the SA treatment. The level of Fe in root and shoot was positively correlated with the transcript level of transporters responsible for the accumulation of Fe, OsNRAMP5, and OsFRDL1, in the root and shoot, respectively. Co-application of SA was more effective than pre-treatment for reducing As accumulation as well as imposed toxicity.

Effects of Lead on Iron, Manganese, and Zinc Concentrations in Different Varieties of Maize (Zea mays)

To investigate the effects of different levels of lead (Pb) on the concentration of iron (Fe), manganese (Mn), and zinc (Zn) in Zea mays, an experiment was conducted in a completely randomized design and 4 × 8 factorial arrangement with three replicates on a calcareous soil in a greenhouse. Factors included four levels of Pb (0 as control, 100, 200, and 400 mg Pb kg−1 soil) from PbCl2 source and eight varieties of maize (single cross 260, 301, 302, 500, 604, and 647 and double cross 370). Results showed that the accumulation of Pb was greater in roots than shoots in the maize varieties studied. Increased Pb concentration in soil decreased Mn and Fe in shoot and elevated Fe concentration in roots. The Mn concentration of roots on different levels of Pb was not affected. Zinc concentration of almost all varieties increased in shoots and decreased in roots with the increase of Pb in soil.

Effects of inorganic and organic amendments on the uptake of lead and trace elements by Brassica chinensis grown in an acidic red soil

A greenhouse study was conducted to investigate the effects of inorganic (phosphate rock, single superphosphate and calcium magnesium phosphate) and organic amendments (peat, straw manure and pig manure) on the uptake of lead (Pb) and trace elements by Chinese Cabbage (Brassica chinensis) grown in an acidic red soil. The application of all organic amendments increased the soil pH while inorganic amendments such as single superphosphate did not. Both inorganic and organic amendments decreased the availability and uptake of Pb while the organic amendments were superior to the inorganic (phosphate) amendments in reducing the availability of the more labile (soluble and exchangeable Pb) forms of soil Pb. More Pb was taken up by roots than shoots with all soil amendments. Among the organic amendments, straw manure and pig manure caused the largest decrease in Pb availability at 456.5 and 457.3mgkg−1, respectively, when a high level of 30g organic amendments kg−1 was applied. The organic amendments greatly increased the fraction D targeted to Fe–Mn oxides bound Pb, and decreased the fraction A (water-soluble), B (exchangeable), and C (carbonate-bound), thereby decreasing the solubility and mobility of Pb in soil. The organic amendments also significantly improved the concentrations of Fe, Mn, Cu and Zn in the soil and shoots (except Fe in shoots and/or roots), which are essential for plant nutrition. The organic amendments of straw and pig manure lowered the availability and uptake of Pb but not that of other trace metals. Thus, these amendments have the potential to remediate Pb-contaminated soils in situ.

Iron availability thresholds for the inoculation of cucumber with Trichoderma asperellum T34

AbstractInoculation with biocontrol agents can affect iron (Fe) uptake by plants. The objective of this research was to study the necessity of defining a Fe threshold in growth media for the inoculation with the biocontrol agent Trichoderma asperellum T34. A completely randomized experiment with cucumber (Cucumis sativus L.) was performed involving two factors: Fe rate in the growth medium in the form of ferrihydrite (0, 8, 16, 32.5, and 75 mg kg–1 of citrate‐ascorbate‐extractable Fe (CA‐Fe), and plant inoculation with T34. Dry matter (DM) of aerial parts of cucumber was decreased by T34. This was related to a decreased accumulation of Fe in plants, more in aerial parts than in roots. However, at the highest Fe rate (75 mg kg–1), differences in DM yield, plant height, and the content and concentration of Fe in shoots between inoculated and noninoculated plants were not significant. The threshold of CA‐Fe in the medium for DM yield of cucumber was 37 mg kg–1 without T34. With T34, this threshold was 65 mg kg–1, which implies that, below this limit, additional Fe supply is required for inoculation with T34.

Responses of barley to hypoxia and salinity during seed germination, nutrient uptake, and early plant growth in solution culture

AbstractThe resistance of most plants to salt can be impaired by concurrent waterlogging. However, few studies have examined this interaction during germination and early seedling growth and its implications for nutrient uptake. The aim of the study was to examine the response of germination, early growth, and nutrient uptake to salt (NaCl) and hypoxia applied to barley (Hordeum vulgare L. cv. Stirling), in solution culture. Hypoxia, induced by covering seeds with water, lowered the germination from 94% to 28% but salinity and hypoxia together lowered it further to 13% at 120 mM NaCl. While the germination was 75% at 250 mM NaCl in aerated solution, it was completely inhibited at this NaCl concentration under hypoxia. Sodium ion (Na+) concentrations in germinated seedlings increased with increasing salinity under both aerated and hypoxic conditions during germination, while K+ and Mg+ concentrations were decreased with increasing salinity in 6 d old seedlings. After 20 d, control seedlings had the same dry weights of the roots and shoots with and without hypoxia but at 10 mM NaCl and higher, shoot and root dry weight was depressed with hypoxia. Sodium ion increased in roots and shoots with increased NaCl under both aerated and hypoxic conditions while K+ was depressed when salinity and hypoxia were applied together and Ca2+ was mostly decreased by NaCl. In general, hypoxia had greater effects on nutrient concentrations than NaCl by decreasing N, P, S, Mg, Mn, Zn, and Fe in shoots and by increasing B concentrations. The threshold salinity levels decreased markedly for germination, uptake of a range of nutrients, and for seedling growth of barley under hypoxic compared to well‐aerated conditions.

Changes in nutrient allocation between roots and shoots of young maize plants during sulfate deprivation

AbstractHydroponically grown maize (Zea mays L.) plants were deprived of the external source of sulfate following an initial period of 13 d during which the sulfur (S) supply was sufficient. The amounts of dry mass (DM), water, sulfate, sulfur, nitrate, ammonium, nitrogen, phosphorus, potassium, magnesium, calcium, boron, iron, copper, zinc, and manganese were monitored in the shoots and the roots for 10 d. The deprivation altered the nutritional balance between them, causing a 70% decrease of sulfate in shoots and roots after 2 d. At 10 d, 95% of sulfate had vanished in both shoots and roots. Total S remained rather constant in shoots or was slightly decreased in roots after 4 d. This coincided with a decrease of Fe in shoots after 4 d. The calculated decreases of S and Fe in –S shoots, up to 6 d were linearly correlated. Kinetic analysis of the changes revealed a sequence in their onset, and we distinguished early and late changes. Among the early changes, we highlight the following ones: (1) an increased amount of Cu in both shoots and roots at 2 d; Fe was 40% decreased in both shoots and roots at 2 d; (2) a decrease in transpiration rate by 35% after 2 d; (3) alterations in boron allocation; in –S shoots the % changes in S were linearly correlated with the corresponding % changes in B; (4) calcium content was not affected by the S deprivation in –S shoots, whilst it increased in –S root after d 2; (5) Mn and Mg decreased from the beginning and in a uniform fashion in both –S shoots and roots. Day 6 may be considered as the boundary between the early and late changes. The root fraction of DM increased progressively after 4 d. Changes in DM seemed to be similar to those of P. Changes of Zn also took place rather late. In –S shoots and for the time interval between 6 d and 10 d, linear correlations were found between the corresponding % changes of the pairs DM–S, DM–P, DM–N, DM–water, S–N, S–P, and N–P.

Characterizing the role of rice NRAMP5 in Manganese, Iron and Cadmium Transport

Metals like manganese (Mn) and iron (Fe) are essential for metabolism, while cadmium (Cd) is toxic for virtually all living organisms. Understanding the transport of these metals is important for breeding better crops. We have identified that OsNRAMP5 contributes to Mn, Fe and Cd transport in rice. OsNRAMP5 expression was restricted to roots epidermis, exodermis, and outer layers of the cortex as well as in tissues around the xylem. OsNRAMP5 localized to the plasma membrane, and complemented the growth of yeast strains defective in Mn, Fe, and Cd transport. OsNRAMP5 RNAi (OsNRAMP5i) plants accumulated less Mn in the roots, and less Mn and Fe in shoots, and xylem sap. The suppression of OsNRAMP5 promoted Cd translocation to shoots, highlighting the importance of this gene for Cd phytoremediation. These data reveal that OsNRAMP5 contributes to Mn, Cd, and Fe transport in rice and is important for plant growth and development.

Mineral composition of dominant plant species growing in a phosphorus mining area

To evaluate the potential of native plants for phytoremediation, a field survey of terrestrial plants growing in a phosphorus (P) mining area in Shifang, China, was conducted to identify the variation of mineral composition in the soil and plants. The mineral composition [nitrogen (N), P, potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn)] of roots and shoots and the rhizosphere soil were determined. To quantify the relative contribution of each component to the overall correlation, path analyses were carried out. The results indicate that the P accumulators (Polygonum hydropiper and Pilea sinofasciata) had an advantage in mineral composition. In roots, the highest concentrations of Mg, Fe and Cu were found in P. hydropiper, and the highest concentrations of Ca were found in P. sinofasciata. Moreover, P. sinofasciata demonstrated the highest concentrations of Ca and Fe in shoots, which were 2.4 and 4.4 times higher than the mean of all other species. High concentrations of Fe and Mn were also found in the shoots of P. sinofasciata. In the roots of both plants, Fe had the highest negative direct effect on P, while Ca had a higher positive direct effect on P. In shoots, N had a higher positive direct effect on P, and K had a negative direct effect on P. Interactions between nutrients are important for determining the optimum nutrition for P accumulators. Key words: Interaction, mineral composition, nutrient, phosphorus accumulator, phytoremediation.

The effect of mycorrhiza on the growth and elemental composition of Ni-hyperaccumulating plant Berkheya coddii Roessler

The effect of arbuscular mycorrhizal fungi (AMF) on growth and element uptake by Ni-hyperaccumulating plant, Berkheya coddii, was studied. Plants were grown under laboratory conditions on ultramafic soil without or with the AM fungi of different origin. The AM colonization, especially with the indigenous strain, significantly enhanced plants growth and their survival. AMF affected also the elemental concentrations that were studied with Particle-induced X-ray emission (PIXE). AMF (i) increased K and Fe in shoots, Zn and Mn in roots, P and Ca both, in roots and shoots; (ii) decreased Mn in shoots, Co and Ni both, in shoots and roots. Due to higher biomass of mycorrhizal plants, total Ni content was up to 20 times higher in mycorrhizal plants compared to the non-mycorrhizal ones. The AMF enhancement of Ni uptake may therefore provide an improvement of a presently used technique of nickel phytomining.