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1.
Salinity-induced ion flux patterns from the excised roots of <Emphasis Type="Italic">Arabidopsis sos</Emphasis> mutants 总被引:5,自引:0,他引:5
The SOS signal-transduction pathway is known to be important for ion homeostasis and salt tolerance in plants. However, there
is a lack of in planta electrophysiological data about how the changes in signalling and ion transport activity are integrated at the cellular and
tissue level. In this study, using the non-invasive ion flux MIFE technique, we compared net K+, H+ and Na+ fluxes from elongation and mature root zones of Arabidopsis wild type Columbia and sos mutants. Our results can be summarised as follows: (1) SOS mutations affect the function of the entire root, not just the
root apex; (2) SOS signalling pathway is highly branched; (3) Na+ effects on SOS1 may by-pass the SOS2/SOS3 complex in the root apex; (4) SOS mutation affects H+ transport even in the absence of salt stress; (5) SOS1 mutation affects intracellular K+ homeostasis with a plasma membrane depolarisation-activated outward-rectifying K+ channel being a likely target; (6) H+ pump also may be a target of SOS signalling. We provide an improved model of SOS signalling and discuss physiological mechanisms
underlying salt stress perception and signalling in plants. Our work shows that in planta studies are essential for understanding the functional genomics of plant salt tolerance. 相似文献
2.
Heterologous expression of the yeast HAL5 gene in tomato enhances salt tolerance by reducing shoot Na+ accumulation in the long term 总被引:1,自引:0,他引:1
Benito Pineda Paloma Sanchez‐Bel Andres Belver Begoña Garcia‐Sogo Francisco B. Flores Alejandro Atares Vicente Moreno Maria C. Bolarin 《Physiologia plantarum》2014,152(4):700-713
3.
Daily Patterns under the Life Cycle of a Maize Crop 总被引:3,自引:0,他引:3
Together with photosynthesis, transpiration and respiration, the daily uptake of NO3?, NH4+, H2PO4?, K+, Ca2+, Mg2+, SO42?, the root respiration, root volume increase and root excretions have been studied by daily measurements during the growth period of whole maize plants (Zea mays L. cv. INRA F7 × F2) raised until complete maturity on nutrient solution. The uptake patterns show a maximum absorption of NO3?, K+ and Ca2+ during the vegetative growth phase. The absorption of these ions declines during maturation while that of H2PO4? reaches a maximum. Root respiration and particularly the uptake of NO3? and K+ are well correlated with the rate of root growth. Root excretion is more notable in young plants than in the old. It represents less than 0.2% of the net assimilation of adult plants. 相似文献
4.
Potassium (K+) and chloride (Cl−) are two essential elements for plant growth and development. While it is known that plants possess specific membrane transporters
for transporting K+ and Cl−, it remains unclear if they actively use K+-coupled Cl− cotransporters (KCC), as used in animals, to transport K+ and Cl−. We have cloned an Oryza sativa cDNA encoding for a member of the cation–Cl− cotransporter (CCC) family. Phylogenetic analysis revealed that plant CCC proteins are highly conserved and that they have
greater sequence similarity to the sub-family of animal K+–Cl− cotransporters than to other cation–Cl− cotransporters. Real-time PCR revealed that the O. sativa cDNA, which was named OsCCC1, can be induced by KCl in the shoot and root and that the expression level was higher in the leaf and root tips than in any
other part of the rice plant. The OsCCC1 protein was located not only in onion plasma membrane but also in O. sativa plasma membrane. The OsCCC1 gene-silenced plants grow more slowly than wild-type (WT) plants, especially under the KCl treatment regime. After 1 month
of KCl treatment, the leaf tips of the gene-silenced lines were necrosed. In addition, seed germination, root length, and
fresh and dry weight were distinctly lower in the gene-silenced lines than in WT plants, especially after KCl treatment. Analysis
of Na+, K+, and Cl− contents of the gene-silenced lines and WT plants grown under the NaCl and KCl treatment regimes revealed that the former
accumulated relatively less K+ and Cl− than the latter but that they did not differ in terms of Na+ contents, suggesting OsCCC1 may be involved in K+ and Cl− transport. Results from different tests indicated that the OsCCC1 plays a significant role in K+ and Cl− homeostasis and rice plant development. 相似文献
5.
Molecular mechanisms of potassium and sodium uptake in plants 总被引:20,自引:0,他引:20
Potassium (K+) is an essential nutrient and the most abundant cation in plants, whereas the closely related ion sodium (Na+) is toxic to most plants at high millimolar concentrations. K+ deficiency and Na+ toxicity are both major constraints to crop production worldwide. K+ counteracts Na+ stress, while Na+, in turn, can to a certain degree alleviate K+ deficiency. Elucidation of the molecular mechanisms of K+ and Na+ transport is pivotal to the understanding – and eventually engineering – of plant K+ nutrition and Na+ sensitivity. Here we provide an overview on plant K+ transporters with particular emphasis on root K+ and Na+ uptake. Plant K+-permeable cation transporters comprise seven families: Shaker-type K+ channels, `two-pore' K+ channels, cyclic-nucleotide-gated channels, putative K+/H+ antiporters, KUP/HAK/KT transporters, HKT transporters, and LCT1. Candidate genes for Na+ transport are the KUP/HAK/KTs, HKTs, CNGCs, and LCT1. Expression in heterologous systems, localization in plants, and genetic disruption in plants will provide insight into the roles of transporter genes in K+ nutrition and Na+ toxicity. 相似文献
6.
In order to identify physiological components that contribute to salinity tolerance, we compared the effects of Na+, Mg2+ and K+ salts (NaCl, Na2SO4, MgCl2, MgSO4, KCl and K2SO4), Ca2+ (CaSO4), mannitol and melibiose on the wild type and the single-gene NaCl-tolerant mutants stl1 and stl2 of Ceratopteris richardii. Compared with gametophytic growth of the wild type, stl2 showed a low level of tolerance that was restricted to Na+ salts and osmotic stress. stl2 exhibited high tolerance to both Na+ and Mg2+ salts, as well as to osmotic stress. In response to short-term exposure (3 d) to NaCl, accumulation of K+ and Na+ was similar in the wild type and stl1. In contrast, stl2 accumulated higher levels of K+ and lower levels of Na+. Ca2+ supplementation (1.0 mol m?3) ameliorated growth inhibition by Na+ and Mg2+ stress in wild type and stll, but not in stl2. In addition, under Na+ stress (175 mol m?3) wild-type, stll and stl2 gametopbytes maintained higher tissue levels of K+ and lower levels of Na+ when supplemented with Ca2+ (1.0 mol m?3). stl2 gametophytes were extremely sensitive to K+ supplementation. Growth of stl2 was greater than or equal to that of the wild type at trace concentrations of K+ but decreased substantially with increasing K+ concentration. Supplementation with K+ from 0 to 1.85 mol m?3 alleviated some of the inhibition by 75 mol m?3 NaCl in the wild type and in stl1. In stl2, growth at 75 mol m?3 NaCl was similar at 0 and 1.85 mol m?3 K+ supplementation. Although K+ supplementation above 1.85 mol m?3 did not alleviate inhibition of growth by Na+ in any genotype, stl2 maintained greater relative tolerance to NaCl at all K+ concentrations tested. 相似文献
7.
Leone FA Masui DC de Souza Bezerra TM Garçon DP Valenti WC Augusto AS McNamara JC 《The Journal of membrane biology》2012,245(4):201-215
We investigated modulation by ATP, Mg2+, Na+, K+ and NH4
+ and inhibition by ouabain of (Na+,K+)-ATPase activity in microsomal homogenates of whole zoeae I and decapodid III (formerly zoea IX) and whole-body and gill
homogenates of juvenile and adult Amazon River shrimps, Macrobrachium amazonicum. (Na+,K+)-ATPase-specific activity was increased twofold in decapodid III compared to zoea I, juveniles and adults, suggesting an
important role in this ontogenetic stage. The apparent affinity for ATP (K
M = 0.09 ± 0.01 mmol L−1) of the decapodid III (Na+,K+)-ATPase, about twofold greater than the other stages, further highlights this relevance. Modulation of (Na+,K+)-ATPase activity by K+ also revealed a threefold greater affinity for K+ (K
0.5 = 0.91 ± 0.04 mmol L−1) in decapodid III than in other stages; NH4
+ had no modulatory effect. The affinity for Na+ (K
0.5 = 13.2 ± 0.6 mmol L−1) of zoea I (Na+,K+)-ATPase was fourfold less than other stages. Modulation by Na+, Mg2+ and NH4
+ obeyed cooperative kinetics, while K+ modulation exhibited Michaelis-Menten behavior. Rates of maximal Mg2+ stimulation of ouabain-insensitive ATPase activity differed in each ontogenetic stage, suggesting that Mg2+-stimulated ATPases other than (Na+,K+)-ATPase are present. Ouabain inhibition suggests that, among the various ATPase activities present in the different stages,
Na+-ATPase may be involved in the ontogeny of osmoregulation in larval M. amazonicum. The NH4
+-stimulated, ouabain-insensitive ATPase activity seen in zoea I and decapodid III may reflect a stage-specific means of ammonia
excretion since functional gills are absent in the early larval stages. 相似文献
8.
Xian Zhi Fang Xing Xing Liu Ya Xing Zhu Jia Yuan Ye Chong Wei Jin 《Plant physiology》2020,184(4):1900
K+ and NO3− are the major forms of potassium and nitrogen that are absorbed by the roots of most terrestrial plants. In this study, we observed that a close relationship between NO3− and K+ in Arabidopsis (Arabidopsis thaliana) is mediated by NITRATE TRANSPORTER1.1 (NRT1.1). The nrt1.1 knockout mutants showed disturbed K+ uptake and root-to-shoot allocation, and were characterized by growth arrest under K+-limiting conditions. The K+ uptake and root-to-shoot allocation of these mutants were partially recovered by expressing NRT1.1 in the root epidermis-cortex and central vasculature using SULFATE TRANSPORTER1;2 and PHOSPHATE1 promoters, respectively. Two-way analysis of variance based on the K+ contents in nrt1.1-1/K+ transporter1, nrt1.1-1/high-affinity K+ transporter5-3, nrt1.1-1/K+ uptake permease7, and nrt1.1-1/stelar K+ outward rectifier-2 double mutants and the corresponding single mutants and wild-type plants revealed physiological interactions between NRT1.1 and K+ channels/transporters located in the root epidermis–cortex and central vasculature. Further study revealed that these K+ uptake-related interactions are dependent on an H+-consuming mechanism associated with the H+/NO3− symport mediated by NRT1.1. Collectively, these data indicate that patterns of NRT1.1 expression in the root epidermis–cortex and central vasculature are coordinated with K+ channels/transporters to improve K+ uptake and root-to-shoot allocation, respectively, which in turn ensures better growth under K+-limiting conditions.Potassium (K) is an essential element for plant growth and development and contributes to determining the yield and quality of crops in agriculture production (Wang and Wu, 2013). However, the concentrations of soluble K+ in most soils are relatively low, which often limits plant growth (Maathuis, 2009). Although crop production can be increased by applying large amounts of potassic fertilizers to agricultural fields, only approximately one-half of the applied fertilizers is available to plants; the remainder accumulates as residues in soils, consequently leading to environmental contamination (Meena et al., 2016). Therefore, there is a pressing need to gain a more complete understanding of the molecular mechanisms underlying K+ transport and regulation in order to enhance the K+ utilization efficiency of plants. Accordingly, in the past few decades, researchers have focused on identifying K+ channels and transporters in plants, as well as the mechanisms underlying their regulation.In Arabidopsis (Arabidopsis thaliana), 71 K+ channels and transporters have been identified and categorized into three channel (Shaker, Tandem-Pore K+, and Kir-like) and three transporter (K+ uptake permeases [KT/HAK/KUP], High-affinity K+ transporters [HKT], and cation/proton antiporter [CPA]) families (Wang and Wu, 2010). Among these, the shaker inward K+ channel K+ TRANSPORTER1 (AKT1) and the KT/HAK/KUP K+ transporter HIGH-AFFINITY K+ TRANSPORTER5 (HAK5) have been characterized as the two major components that contribute to K+ uptake in roots, although they have been found to operate at different K+ levels (Pyo et al., 2010; Wang and Wu, 2013). AKT1 functions in plant K+ uptake over a wide range of K+ concentrations, whereas HAK5 shows high-affinity K+ transport activity (Gierth et al., 2005). Following its uptake into root epidermal cells, K+ is distributed to different plant organs or tissues. The Arabidopsis shaker-like outward-rectifying K+ channel STELAR K+ OUTWARD RECTIFIER (SKOR), the expression of which was first identified in stelar tissues, has been shown to facilitate K+ secretion into xylem sap, which is a critical step in long-distance K+ transport from roots to shoots (Gaymard et al., 1998). Recently, K+ UPTAKE PERMEASE7 (KUP7), a member of the KT/HAK/KUP family, was functionally characterized as a K+ transporter participating in both root K+ uptake and root-to-shoot K+ allocation, particularly under K+-limiting conditions (Han et al., 2016). However, the uptake affinity for K+ has been found to be considerably lower in KUP7 than in HAK5 (Wang and Wu, 2017).In addition to the aforementioned K+ channels and transporters, other mineral elements, including Na+, Ca2+, and N, are known to have pronounced effects on K+ nutrition in plants. Given that N is the nutrient that is required in the greatest quantity by most plants and is the most widely used fertilizer nutrient in crop production, the relationships between N and K have long been investigated (Fageria and Baligar, 2005; Wang and Wu, 2013; Meng et al., 2016; Shin, 2017). Since the 1960s, physiological studies have revealed a close relationship between NO3− and K+ with regard to uptake and translocation (Zioni et al., 1971; Blevins et al., 1978; Barneix and Breteler, 1985; Drechsler et al., 2015). However, the coordination between these two nutrients in plant transport pathways remains to be extensively studied at the molecular level. We hypothesized that transporters involved in the transference of NO3− across cell membranes may play a role in controlling K+ nutrition in plants. Recently, NITRATE TRANSPORTER1.5 (NRT1.5), a member of the nitrate transporter1/peptide transporter family (NPF), initially identified as a pH-dependent bidirectional NO3− transporter (Lin et al., 2008), was shown to be involved in the control of K+ allocation in plants (Drechsler et al., 2015; Li et al., 2017; Du et al., 2019). Nevertheless, it was subsequently established that this function was merely associated with its role as a proton-coupled H+/K+ antiporter for K+ loading into the xylem (Li et al., 2017; Du et al., 2019), which is not associated with the transport of NO3−. In this study, we showed that the loss of another nitrate transporter1 member, NRT1.1/NPF6.3, in nrt1.1 mutants led to the development of a more pronounced K+-deficiency phenotype under conditions of low-K+ stress. Further physiological and genetic evidence revealed that both the uptake and root-to-shoot allocation of K+ in plants require NRT1.1. However, NRT1.1 acts as a coordinator rather than a K+ channel/transporter in K+ uptake and root-to-shoot allocation, which could depend on its NO3−-related transport activity. Our findings highlight the significance of nutrients and nutrient interactions in ensuring plant growth, and indicate that the modification of NRT1.1 homolog activity in crops using biological engineering techniques might be a promising approach that could simultaneously contribute to enhancing the utilization efficiencies of K and N fertilizers in agricultural production. 相似文献
9.
Physiological responses of the mangrove Rhizophora mangle grown in the absence and presence of NaCl 总被引:4,自引:1,他引:3
Abstract. Propagules of the mangrove, Rhizophora mangle L., were precultivated for 9 months in a greenhouse. The young plants were transferred into unaerated nutrient solutions without and with 200 mol m 3 NaCl and subsequently their growth, their water relations and the photosynthetic properties of their leaves were studied. Growth of the salttreated plants was significantly increased, while the control plants gradually died off after finishing the experiments. The shoot water potential and the stomatal resistance of the leaves were lowered while the chlorophyll contents and the chlorophyll a/b ratio in the leaves of salt-treated plants were increased by NaCl, the net result being an enhanced rate of CO2 assimilation. The leaves of both sets of plants showed diurnal fluctuations in malic acid concentration which were more pronounced in the leaves of salt treated plants which, additionally, were more succulent. However, the plants showed no net CO2 fixation at night, indicating that Rhizophora mangle is a CAM-cycling plant. After 200 d of cultivation without or with NaCl, the Na+, Cl and K+ concentrations in tissues and vacuoles were measured. Energy-dispersive X-ray microprobe analyses on root vacuoles of control plants reveal Na+ preference, on those of salt treated plants a strong K+ preference. Vacuolar K+ concentrations are neither affected by NaCl nor do they vary across the root radius. High vacuolar Na+ and Cl concentrations are found in the hypodermis followed by a stepwise decrease towards the inner root cortex cells. Ion concentrations of the photosynthetically active leaf tissues seem to be regulated by (1) radial filtration across the root cortex: (2) ion exchange of the xlem parenchyma cells: and (3) sequestration of Na+ and Cl in the hypodermal water storage tissue of the leaves. 相似文献
10.
Paul Jensén 《Physiologia plantarum》1982,56(3):259-265
Effects of interrupted K+ supply on different parameters of growth and mineral cation nutrition were evaluated for spring wheat (Triticum aestivum L. cv. Svenno). K+ (2.0 mM) was supplied to the plants during different periods in an otherwise complete nutrient solution. Shoot growth was reduced before root growth after interruption in K+ supply. Root structure was greatly affected by the length of the period in K+ -free nutrient solution. Root length was minimal, and root branching was maximal within a narrow range of K+ status of the roots. This range corresponded to cultivation for the last 1 to 3 days, of 11 in total, in K+ -free nutrient solution, or to continuous cultivation in solution containing 0.5 to 2 mM K+. In comparison, both higher and lower internal/external K+ concentrations had inhibitory effects on root branching. However, the differing root morphology probably had no significant influence on the magnitude of Ca2+, Mg2+ and Na+ uptake. Uptake of Ca2+ and especially Mg2+ significantly increased after K+ interruption, while Na+ uptake was constant in the roots and slowly increased in the shoots. The two divalent cations could replace K+ in the cells and maintain electroneutrality down to a certain minimal range of K+ concentrations. This range was significantly higher in the shoot [110 to 140 μmol (g fresh weight)?1] than in the root [20 to 30 μmol (g fresh weight)?1]. It is suggested that the critical K+ values are a measure of the minimal amount of K+ that must be present for physiological activity in the cells. At the critical levels, K+ (86Rb) influx and Ca2+ and Mg2+ concentrations were maximal. Below the critical K+ values, growth was reduced, and Ca2+ and Mg2+ could no longer substitute for K+ for electrostatic balance. In a short-term experiment, the ability of Ca2+ to compete with K+ in maintaining electroneutrality in the cells was studied in wheat seedlings with different K+ status. The results indicate that K+, which was taken up actively and fastest at the external K+ concentration used (2.0 mM), partly determines the size of Ca2+ influx. 相似文献
11.
Ons Talbi Zribi Nehla Labidi Inès Slama Ahmed Debez Riadh Ksouri Mokded Rabhi Abderrazak Smaoui Chedly Abdelly 《Plant Growth Regulation》2012,66(1):75-85
Hordeum maritimum (Poacea) is a facultative halophyte potentially useful for forage production in saline zones. Here, we assessed whether moderate
NaCl-salinity can modify the plant response to phosphorus (P) shortage. Plants were cultivated for 55 days under low or sufficient
P supply (5 or 60 μmol plant−1 week−1 KH2PO4, respectively), with or without 100 mM NaCl. When individually applied, salinity and P deficiency significantly restricted
whole-plant growth, with a more marked effect of the latter stress. Plants subjected to P deficiency showed a significant
increase in root growth (as length and dry weight) and root/shoot DW ratio. Enhanced root growth and elongation presumably
correspond to the well-known root adaptive response to mineral deficiency. However, leaf relative water content, leaf P concentration,
and leaf gas exchange parameters were significantly restricted. The interactive effects of salinity and P deficiency were
not added one to another neither on whole plant biomass nor on plant nutrient uptake. Indeed, 100 mM NaCl-addition to P-deficient
plants significantly restored the plant growth and improved CO2 assimilation rate, root growth, K+/Na+ ratio and leaf proline and soluble sugar concentrations. It also significantly enhanced leaf total antioxidant capacity and
leaf anthocyanin concentration. This was associated with significantly lower leaf osmotic potential, leaf Na+ and malondialdehyde (MDA) concentration. Taken together, these results suggest that mild salinity may mitigate the adverse
effects of phosphorus deficiency on H. maritimum by notably improving the plant photosynthetic activity, the osmotic adjustment capacity, the selective absorption of K+ over Na+ and antioxidant defence. 相似文献
12.
13.
HvAKT2 and HvHAK1 confer drought tolerance in barley through enhanced leaf mesophyll H+ homoeostasis
Xue Feng Wenxing Liu Cheng‐Wei Qiu Fanrong Zeng Yizhou Wang Guoping Zhang Zhong‐Hua Chen Feibo Wu 《Plant biotechnology journal》2020,18(8):1683-1696
Plant K+ uptake typically consists low—affinity mechanisms mediated by Shaker K+ channels (AKT/KAT/KC) and high‐affinity mechanisms regulated by HAK/KUP/KT transporters, which are extensively studied. However, the evolutionary and genetic roles of both K+ uptake mechanisms for drought tolerance are not fully explored in crops adapted to dryland agriculture. Here, we employed evolutionary bioinformatics, biotechnological and electrophysiological approaches to determine the role of two important K+ transporters HvAKT2 and HvHAK1 in drought tolerance in barley. HvAKT2 and HvHAK1 were cloned and functionally characterized using barley stripe mosaic virus‐induced gene silencing (BSMV‐VIGS) in drought‐tolerant wild barley XZ5 and agrobacterium‐mediated gene transfer in the barley cultivar Golden Promise. The hallmarks of the K+ selective filters of AKT2 and HAK1 are both found in homologues from strepotophyte algae, and they are evolutionarily conserved in strepotophyte algae and land plants. HvAKT2 and HvHAK1 are both localized to the plasma membrane and have high selectivity to K+ and Rb+ over other tested cations. Overexpression of HvAKT2 and HvHAK1 enhanced K+ uptake and H+ homoeostasis leading to drought tolerance in these transgenic lines. Moreover, HvAKT2‐ and HvHAK1‐overexpressing lines showed distinct response of K+, H+ and Ca2+ fluxes across plasma membrane and production of nitric oxide and hydrogen peroxide in leaves as compared to the wild type and silenced lines. High‐ and low‐affinity K+ uptake mechanisms and their coordination with H+ homoeostasis play essential roles in drought adaptation of wild barley. These findings can potentially facilitate future breeding programs for resilient cereal crops in a changing global climate. 相似文献
14.
Effects of NaCl on ion relations and carbohydrate status of roots and on osmotic regulation of roots and shoots of Atriplex amnicola 总被引:2,自引:2,他引:0
Abstract Atriplex amnicola was grown at 25, 200 or 400 mol m3 NaCl. Root tissues at different stages of development were investigated for concentrations of K+, Na+ and Mg2+, and in some cases for Cl?. Sugar and starch concentrations were measured for plants grown at 25 or 400 mol m3 NaCl. In the ‘slightly vaeuolated’ root tips, Na+ was only 40 mol m?3 at an external concentration of 400 mol m?3 NaCl. The concentrations of K+ were not affected substantially by external NaCl between 25 mol m?3 and 400 mol m?3. The ‘highly vacuolated’ root tissues had substantially higher concentrations of K+, Na+ and Cl? in plants grown at 200 and 400 mol m 3 NaCl than in plants grown at 25 mol m?3 NaCl. Concentrations of Cr and of the sum of the cations in recently expanded tissue were similar to those in the bulk of the roots, consisting mainly of old cells. However, the K+: Na+ decreased with age; at 400 mol m?3 external NaCl with a K+: Na+ of 0.012, the K+: Na+ in recently expanded 12 mm root tips was as high as 1.6, compared with 0.7 for the bulk of the roots. These ion data were used to estimate cytoplasmic and vacuolar concentrations of K+ and Na +. Such calculations indicated that between 25 mol m3 and 400 mol m?3 external NaCl the concentration of the sum of (Na++K+) in the cytoplasm was maintained at about 180–200 mol m?3 (cell water basis). In contrast, the (Na++ K+) concentration in the vacuole was 170 mol m?3 for plants grown at 25 mol m?3 NaCl and 420 mol 400 mol m?3 NaCl. The expanding root (issues exhibited greatly decreased soluble sugars and starch between dusk and dawn. Ai both times, sugar and starch concentrations in these tissues were 2.5–4.0 times greater in plants grown at 400 mol m?3 NaCl compared with plants grown at 25 mol m?3 NaCl. In contrast, carbohydrate concentrations in expanded root tissues were very similar at 25 and 400 mol m?3 and showed little diurnal fluctuation. This paper considers the causes for the slower growth of A. amnicola at 400 than at 25 mol m”3 NaCl, using the data for the roots described here, and those for the shoots presented in the preceding paper (Aslam et al., 1986). There is no support for possible adverse effects by high internal ion concentrations. Instead, there may be deficiencies in supply of organic solutes for osmotic regulation; during part of the night a limited supply of such solutes may well restrict the rate of expansion of cells in plants growing at 400 mol m?3 NaCl. There is insufficient evidence to decide whether this limitation in the expanding tissues is particularly prominent for the roots or for the shoots. 相似文献
15.
Kun Mei Guo Olga Babourina David A. Christopher Tamas Borsic Zed Rengel 《Physiologia plantarum》2010,139(3):303-312
The suppression of the cyclic nucleotide‐gated channel (CNGC) AtCNGC10 alters K+ transport in Arabidopsis plants. Other CNGCs have been shown to transport Ca2+, K+, Li+, Cs+ and Rb+ across the plasma membrane when expressed in heterologous systems; however, the ability of the AtCNGC10 channel to transport nutrients other than K+ in plants has not been previously tested. The ion fluxes along different zones of the seedling roots, as estimated by the non‐invasive ion‐specific microelectrode technique, were significantly different in two AtCNGC10 antisense lines (A2 and A3) in comparison to the wild type (WT). Most notably, the influxes of H+, Ca2+ and Mg2+ in the meristem and distal elongation zones of the antisense A2 and A3 lines were significantly lower than in the WT. The lower Ca2+ influx from the external media corresponded to a lower intracellular Ca2+ activity, which was estimated by fluorescence lifetime imaging measurements (FLIM). On the other hand, the intracellular pH values in the meristem zone of the roots of A2 and A3 seedlings were significantly lower (more acidic) than that of the WT, which might indicate a feedback block of H+ influx into meristematic cells caused by low intracellular pH. Under the control conditions, mature plants from the A2 and A3 lines contained significantly higher K+ and lower Ca2+ and Mg2+ content in the shoots, indicating disturbed long‐distance ion transport of these cations, possibly because of changes in xylem loading/retrieval and/or phloem loading. Exposing the plants in the flowering stage to various K+, Ca2+ and Mg2+ concentrations in the solution led to altered K+, Ca2+ and Mg2+ content in the shoots of A2 and A3 plants in comparison with the WT, suggesting a primary role of AtCNGC10 in Ca2+ (and probably Mg2+) transport in plants, which in turn regulates K+ transporters' activities. 相似文献
16.
To assess whether foliar application of K+S as potassium sulfate (K2SO4) could alleviate the adverse effects of salt on sunflower (Helianthus annuus L. cv. SF-187) plants, a greenhouse experiment was conducted. There were two NaCl levels (0 and 150 mM) applied to the growth medium and six levels of K+S as K2SO4 (NS (no spray), WS (spray of water+0.1% Tween 20 solution), 0.5% K+0.21% S, 1.0% K+0.41% S, 1.5% K+0.62% S, and 2.0% K+0.82% S in 0.1% Tween-20 solution) applied two times foliarly to non-stressed and salt-stressed sunflower plants. Salt stress markedly repressed the growth, yield, photosynthetic pigments, water relations and photosynthetic attributes, quantum yield (Fv/Fm), leaf and root K+, Mg2+, P, Ca2+, N as well as K+/Na+ ratios, while it enhanced the cell membrane permeability, and leaf and root Na+ and Cl− concentrations. Foliar application of potassium sulfate significantly improved growth, achene yield, photosynthetic and transpiration rates, stomatal conductance, water use efficiency, leaf turgor and enhanced shoot and leaf K+ of the salt-stressed sunflower plants, but it did not improve leaf and root Na+, Cl−, Mg2+, P, Ca2+, N as well as K+/Na+ ratios. The most effective dose of K+S for improving growth and achene yield was found to be 1.5% K+0.62% S and 1% K+0.41% S, respectively. Improvement in growth of sunflower plants due to exogenously applied K2SO4 was found to be linked to enhanced photosynthetic capacity, water use efficiency, leaf turgor and relative water content. 相似文献
17.
18.
Imen Tarchoune Elena Degl’Innocenti Rym Kaddour Lucia Guidi Mokhtar Lachaâl Flavia Navari-Izzo Zeineb Ouerghi 《Acta Physiologiae Plantarum》2012,34(2):607-615
Basil (Ocimum basilicum L., cultivar Genovese) plants were grown in Hoagland solution with or without 50 mM NaCl or 25 mM Na2SO4. After 15 days of treatment, Na2SO4 slowed growth of plants as indicated by root, stem and leaf dry weight, root length, shoot height and leaf area, and the
effects were major of those induced by NaCl. Photosynthetic response was decreased more by chloride salinity than by sulphate.
No effects in both treatments on leaf chlorophyll content, maximal efficiency of PSII photochemistry (F
v/F
m) and electron transport rate (ETR) were recorded. Therefore, an excess of energy following the limitation to CO2 photoassimilation and a down regulation of PSII photochemistry was monitored under NaCl, which displays mechanisms that play
a role in avoiding PSII photodamage able to dissipate this excess energy. Ionic composition (Na+, K+, Ca2+, and Mg2+) was affected to the same extent under both types of salinity, thus together with an increase in leaves Cl−, and roots SO4
2− in NaCl and Na2SO4-treated plants, respectively, may have resulted in the observed growth retardation (for Na2SO4 treatment) and photosynthesis activity inhibition (for NaCl treatment), suggesting that those effects seem to have been due
to the anionic component of the salts. 相似文献
19.
Contributions of arbuscular mycorrhizal fungi to growth,photosynthesis, root morphology and ionic balance of citrus seedlings under salt stress 总被引:5,自引:0,他引:5
A pot study was conducted to determine the effects of arbuscular mycorrhizal (AM) fungi (Glomus mosseae and Paraglomus occultum) and salt (NaCl) stress on growth, photosynthesis, root morphology and ionic balance of citrus (Citrus tangerine Hort. ex Tanaka) seedlings. Eighty-five-day-old seedlings were exposed to 100 mM NaCl for 60 days to induce salt stress.
Mycorrhizal colonization of citrus seedlings was not affected by salinity when associated with P. occultum, but significantly decreased when with G. mosseae. Compared with the non-mycorrhizal controls, mycorrhizal seedlings generally had greater plant height, stem diameter, shoot,
root and total plant biomass, photosynthetic rate, transpiration rate and stomatal conductance under the 0 and 100 mM NaCl
stresses. Root length, root projected area and root surface area were also higher in the mycorrhizal than in the non-mycorrhizal
seedlings, but higher root volume in seedlings with G. mosseae. Leaf Na+ concentrations were significantly decreased, but leaf K+ and Mg2+ concentrations and the K+/Na+ ratio were increased when seedlings with both G. mosseae and P. occultum. Under the salt stress, Na+ concentrations were increased but K+ concentrations decreased in the mycorrhizal seedlings. Under the salt stress, Ca2+ concentrations were increased in the seedlings with P. occultum or without AM fungi (AMF), but decreased with G. mosseae. Ratios of both Ca2+/Na+ and Mg2+/Na+ were also increased in seedlings with G. mosseae under the non-salinity stress, while only the Mg2+/Na+ ratio was increased in seedlings with P. occultum under the salt stress. Our results suggested that salt tolerance of citrus seedlings could be enhanced by associated AMF
with better plant growth, root morphology, photosynthesis and ionic balance. 相似文献
20.
Minh-Hoang Le Khuong V. Dinh Hung Quoc Pham 《Zeitschrift fur angewandte Ichthyologie》2021,37(6):893-908
We previously determined changes in sperm quality of Psammoperca waigiensis during its spawning season and the optimal cation concentrations and osmolality for sperm preservation of this species at the peak of the reproductive season. In this study, we went one important step further by assessing the effects of the most adequate medium, considering the dilution ratio, osmolality, and cations (Na+, K+, Mg2+, and Ca2+) on the motility of P. wasigiensis sperm collected during the early, peak, and late spawning season. We determined the maximum velocity (VAP), and percentage of sperm motility (MOT), and the duration of sperm motility (DSM). Under optimal dilution, temperature, pH and osmolarity, MOT, VAP, and DSM did not statistically differ during early, peak, and late spawning season. However, under suboptimal external conditions, MOT, VAP, and DSM showed inconsistent trends during different spawning periods. We recommend using one of three different artificial motile activating media: (1) 0.55 M Na+, (2) 0.6 M K+ or (3) 1200 mOsm/kg for early; or (1) 0.6 M Na+, (2) 0.6 M K+ or (3) 1100 mOsm/kg for the peak; and (1) 0.65 M Na+, (2) 0.55 M K+ or (3) 1200 mOsm/kg for late spawning season; all at the dilution of 1:150 (v:v of semen: artificial motile activating medium). 相似文献