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Coleto I, Marín-Peña AJ, Urbano-Gámez JA, González-Hernández AI, Shi W, Li G, Marino D. Interaction of ammonium nutrition with essential mineral cations. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:6131-6144. [PMID: 37279530 DOI: 10.1093/jxb/erad215] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 06/01/2023] [Indexed: 06/08/2023]
Abstract
Plant growth and development depend on sufficient nutrient availability in soils. Agricultural soils are generally nitrogen (N) deficient, and thus soils need to be supplemented with fertilizers. Ammonium (NH4+) is a major inorganic N source. However, at high concentrations, NH4+ becomes a stressor that inhibits plant growth. The cause of NH4+ stress or toxicity is multifactorial, but the interaction of NH4+ with other nutrients is among the main determinants of plants' sensitivity towards high NH4+ supply. In addition, NH4+ uptake and assimilation provoke the acidification of the cell external medium (apoplast/rhizosphere), which has a clear impact on nutrient availability. This review summarizes current knowledge, at both the physiological and the molecular level, of the interaction of NH4+ nutrition with essential mineral elements that are absorbed as cations, both macronutrients (K+, Ca2+, Mg2+) and micronutrients (Fe2+/3+, Mn2+, Cu+/2+, Zn2+, Ni2+). We hypothesize that considering these nutritional interactions, and soil pH, when formulating fertilizers may be key in order to boost the use of NH4+-based fertilizers, which have less environmental impact compared with nitrate-based ones. In addition, we are convinced that better understanding of these interactions will help to identify novel targets with the potential to improve crop productivity.
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Affiliation(s)
- Inmaculada Coleto
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), 48940 Leioa, Spain
| | - Agustín J Marín-Peña
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), 48940 Leioa, Spain
| | - José Alberto Urbano-Gámez
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), 48940 Leioa, Spain
| | | | - Weiming Shi
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Guangjie Li
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Daniel Marino
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), 48940 Leioa, Spain
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2
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Dreyer I, Li K, Riedelsberger J, Hedrich R, Konrad KR, Michard E. Transporter networks can serve plant cells as nutrient sensors and mimic transceptor-like behavior. iScience 2022; 25:104078. [PMID: 35378857 PMCID: PMC8976136 DOI: 10.1016/j.isci.2022.104078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 02/03/2022] [Accepted: 03/11/2022] [Indexed: 12/25/2022] Open
Abstract
Sensing of external mineral nutrient concentrations is essential for plants to colonize environments with a large spectrum of nutrient availability. Here, we analyzed transporter networks in computational cell biology simulations to understand better the initial steps of this sensing process. The networks analyzed were capable of translating the information of changing external nutrient concentrations into cytosolic H+ and Ca2+ signals, two of the most ubiquitous cellular second messengers. The concept emerging from the computational simulations was confirmed in wet-lab experiments. We document in guard cells that alterations in the external KCl concentration were translated into cytosolic H+ and Ca2+ transients as predicted. We show that transporter networks do not only serve their primary task of transport, but can also take on the role of a receptor without requiring conformational changes of a transporter protein. Such transceptor-like phenomena may be quite common in plants.
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Affiliation(s)
- Ingo Dreyer
- Centro de Bioinformática, Simulación y Modelado (CBSM), Facultad de Ingeniería, Universidad de Talca, Campus Talca, Avenida Lircay, Talca 3460000, Chile
| | - Kunkun Li
- Department of Botany I, Julius-Von-Sachs Institute for Biosciences, University of Wuerzburg, Julius-von-Sachs-Platz 2, 97082 Wuerzburg, Germany
| | - Janin Riedelsberger
- Centro de Bioinformática, Simulación y Modelado (CBSM), Facultad de Ingeniería, Universidad de Talca, Campus Talca, Avenida Lircay, Talca 3460000, Chile
| | - Rainer Hedrich
- Department of Botany I, Julius-Von-Sachs Institute for Biosciences, University of Wuerzburg, Julius-von-Sachs-Platz 2, 97082 Wuerzburg, Germany
| | - Kai R. Konrad
- Department of Botany I, Julius-Von-Sachs Institute for Biosciences, University of Wuerzburg, Julius-von-Sachs-Platz 2, 97082 Wuerzburg, Germany
| | - Erwan Michard
- Instituto de Ciencias Biológicas, Universidad de Talca, Campus Talca, Avenida Lircay, Talca 3460000, Chile
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3
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Dreyer I. Nutrient cycling is an important mechanism for homeostasis in plant cells. PLANT PHYSIOLOGY 2021; 187:2246-2261. [PMID: 34890457 PMCID: PMC8644529 DOI: 10.1093/plphys/kiab217] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 04/23/2021] [Indexed: 05/02/2023]
Abstract
Homeostasis in living cells refers to the steady state of internal, physical, and chemical conditions. It is sustained by self-regulation of the dynamic cellular system. To gain insight into the homeostatic mechanisms that maintain cytosolic nutrient concentrations in plant cells within a homeostatic range, we performed computational cell biology experiments. We mathematically modeled membrane transporter systems and simulated their dynamics. Detailed analyses of 'what-if' scenarios demonstrated that a single transporter type for a nutrient, irrespective of whether it is a channel or a cotransporter, is not sufficient to calibrate a desired cytosolic concentration. A cell cannot flexibly react to different external conditions. Rather, at least two different transporter types for the same nutrient, which are energized differently, are required. The gain of flexibility in adjusting a cytosolic concentration was accompanied by the establishment of energy-consuming cycles at the membrane, suggesting that these putatively "futile" cycles are not as futile as they appear. Accounting for the complex interplay of transporter networks at the cellular level may help design strategies for increasing nutrient use efficiency of crop plants.
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Affiliation(s)
- Ingo Dreyer
- Center of Bioinformatics, Simulation and Modeling (CBSM), Faculty of Engineering, Universidad de Talca, Talca CL-3460000, Chile
- Author for communication:
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4
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Britto DT, Coskun D, Kronzucker HJ. Potassium physiology from Archean to Holocene: A higher-plant perspective. JOURNAL OF PLANT PHYSIOLOGY 2021; 262:153432. [PMID: 34034042 DOI: 10.1016/j.jplph.2021.153432] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 04/22/2021] [Accepted: 04/22/2021] [Indexed: 05/27/2023]
Abstract
In this paper, we discuss biological potassium acquisition and utilization processes over an evolutionary timescale, with emphasis on modern vascular plants. The quintessential osmotic and electrical functions of the K+ ion are shown to be intimately tied to K+-transport systems and membrane energization. Several prominent themes in plant K+-transport physiology are explored in greater detail, including: (1) channel mediated K+ acquisition by roots at low external [K+]; (2) K+ loading of root xylem elements by active transport; (3) variations on the theme of K+ efflux from root cells to the extracellular environment; (4) the veracity and utility of the "affinity" concept in relation to transport systems. We close with a discussion of the importance of plant-potassium relations to our human world, and current trends in potassium nutrition from farm to table.
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Affiliation(s)
- Dev T Britto
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada; School of BioSciences, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Devrim Coskun
- Département de Phytologie, Faculté des Sciences de l'Agriculture et de l'Alimentation (FSAA), Université Laval, Québec, QC, G1V 0A6, Canada
| | - Herbert J Kronzucker
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada; School of BioSciences, The University of Melbourne, Parkville, Victoria, 3010, Australia.
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5
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Zhang L, Song H, Li B, Wang M, Di D, Lin X, Kronzucker HJ, Shi W, Li G. Induction of S-nitrosoglutathione reductase protects root growth from ammonium toxicity by regulating potassium homeostasis in Arabidopsis and rice. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:4548-4564. [PMID: 33772588 DOI: 10.1093/jxb/erab140] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 03/24/2021] [Indexed: 05/12/2023]
Abstract
Ammonium (NH4+) is toxic to root growth in most plants already at moderate levels of supply, but mechanisms of root growth tolerance to NH4+ remain poorly understood. Here, we report that high levels of NH4+ induce nitric oxide (NO) accumulation, while inhibiting potassium (K+) acquisition via SNO1 (sensitive to nitric oxide 1)/SOS4 (salt overly sensitive 4), leading to the arrest of primary root growth. High levels of NH4+ also stimulated the accumulation of GSNOR (S-nitrosoglutathione reductase) in roots. GSNOR overexpression improved root tolerance to NH4+. Loss of GSNOR further induced NO accumulation, increased SNO1/SOS4 activity, and reduced K+ levels in root tissue, enhancing root growth sensitivity to NH4+. Moreover, the GSNOR-like gene, OsGSNOR, is also required for NH4+ tolerance in rice. Immunoblotting showed that the NH4+-induced GSNOR protein accumulation was abolished in the VTC1- (vitamin C1) defective mutant vtc1-1, which is hypersensititive to NH4+ toxicity. GSNOR overexpression enhanced vtc1-1 root tolerance to NH4+. Our findings suggest that induction of GSNOR increases NH4+ tolerance in Arabidopsis roots by counteracting NO-mediated suppression of tissue K+, which depends on VTC1 function.
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Affiliation(s)
- Lin Zhang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Haiyan Song
- Academic Affairs Office, Foshan University, Foshan, China
| | - Baohai Li
- MOE Key Laboratory of Environment Remediation and Ecological Health, College of Environmental & Resource Sciences, Zhejiang University, HangzhouChina
| | - Meng Wang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Dongwei Di
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Xianyong Lin
- MOE Key Laboratory of Environment Remediation and Ecological Health, College of Environmental & Resource Sciences, Zhejiang University, HangzhouChina
| | - Herbert J Kronzucker
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada
- School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Weiming Shi
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Guangjie Li
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
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6
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Hussain S, Hussain S, Ali B, Ren X, Chen X, Li Q, Saqib M, Ahmad N. Recent progress in understanding salinity tolerance in plants: Story of Na +/K + balance and beyond. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2021; 160:239-256. [PMID: 33524921 DOI: 10.1016/j.plaphy.2021.01.029] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 01/18/2021] [Indexed: 05/07/2023]
Abstract
High salt concentrations in the growing medium can severely affect the growth and development of plants. It is imperative to understand the different components of salt-tolerant network in plants in order to produce the salt-tolerant cultivars. High-affinity potassium transporter- and myelocytomatosis proteins have been shown to play a critical role for salinity tolerance through exclusion of sodium (Na+) ions from sensitive shoot tissues in plants. Numerous genes, that limit the uptake of salts from soil and their transport throughout the plant body, adjust the ionic and osmotic balance of cells in roots and shoots. In the present review, we have tried to provide a comprehensive report of major research advances on different mechanisms regulating plant tolerance to salinity stress at proteomics, metabolomics, genomics and transcriptomics levels. Along with the role of ionic homeostasis, a major focus was given on other salinity tolerance mechanisms in plants including osmoregulation and osmo-protection, cell wall remodeling and integrity, and plant antioxidative defense. Major proteins and genes expressed under salt-stressed conditions and their role in enhancing salinity tolerance in plants are discussed as well. Moreover, this manuscript identifies and highlights the key questions on plant salinity tolerance that remain to be discussed in the future.
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Affiliation(s)
- Sadam Hussain
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China; Department of Agronomy, University of Agriculture, Faisalabad, Pakistan
| | - Saddam Hussain
- Department of Agronomy, University of Agriculture, Faisalabad, Pakistan; Shanghai Center for Plant Stress Biology, Chinese Academy of Agricultural Sciences, Shanghai, China.
| | - Basharat Ali
- Department of Agronomy, University of Agriculture, Faisalabad, Pakistan
| | - Xiaolong Ren
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
| | - Xiaoli Chen
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
| | - Qianqian Li
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
| | - Muhammad Saqib
- Agronomic Research Institute, Ayub Agricultural Research Institute, Faisalabad, Pakistan
| | - Naeem Ahmad
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
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Hu W, Ren T, Meng F, Cong R, Li X, White PJ, Lu J. Leaf photosynthetic capacity is regulated by the interaction of nitrogen and potassium through coordination of CO 2 diffusion and carboxylation. PHYSIOLOGIA PLANTARUM 2019; 167:418-432. [PMID: 30690727 DOI: 10.1111/ppl.12919] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Accepted: 12/18/2018] [Indexed: 06/09/2023]
Abstract
Combined application of nitrogen (N) and potassium (K) fertilizer could significantly enhance crop yield. Crop yield and photosynthesis are inseparable. However, the influence of N and K interaction on photosynthesis is still not fully understood. Field and hydroponic experiments were conducted to examine the effects of N and K interaction on leaf photosynthesis characteristics and to explore the mechanisms in the hydroponic experiment. CO2 conductance and carboxylation characteristic parameters of oilseed leaves were measured under different N and K supplies. Results indicated that detectable increases in leaf area, biomass and net photosynthetic rate (An ) were observed under optimal N and K supply in field and hydroponic experiments. The ratio of total CO2 diffusion conductance to the maximum carboxylation rate (gtot /Vcmax ) and An presented a linear-plateau relationship. Under insufficient N, increased K contributed to the CO2 transmission capacity and improved the proportion of N used for carboxylation, promoting gtot /Vcmax . However, the low Vcmax associated with N insufficiency limited the An . High N supply obviously accelerated Vcmax , yet K deficiency led to a reduction of gtot , which restricted Vcmax . Synchronous increases in N and K supplementation ensured the appropriate ratio of N to K content in leaves, which simultaneously facilitated gtot and Vcmax and preserved a gtot /Vcmax suitable for guaranteeing CO2 transmission and carboxylation coordination; the overall effect was increased An and leaf area. These results highlight the suitable N and K nutrients to coordinate CO2 diffusion and carboxylation, thereby enhancing photosynthetic capacity and area to obtain high crop yield.
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Affiliation(s)
- Wenshi Hu
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan 430070, China
| | - Tao Ren
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan 430070, China
| | - Fanjin Meng
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan 430070, China
| | - Rihuan Cong
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan 430070, China
| | - Xiaokun Li
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan 430070, China
| | | | - Jianwei Lu
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Wuhan 430070, China
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8
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Kobayashi R, Kobayashi NI, Tanoi K, Masumori M, Tange T. Potassium supply reduces cesium uptake in Konara oak not by an alteration of uptake mechanism, but by the uptake competition between the ions. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 208-209:106032. [PMID: 31466011 DOI: 10.1016/j.jenvrad.2019.106032] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 07/23/2019] [Accepted: 08/20/2019] [Indexed: 06/10/2023]
Abstract
Radiocesium contamination of forests has been a severe problem after the Fukushima Daiichi Nuclear Power Plant accident in 2011. Bed logs of Konara oak (Quercus serrata Murray), used for mushroom cultivation, were an economically important product from the forests prior to their contamination. One of the potential countermeasures to reduce radiocesium content in trees is potassium fertilization, but the evidence for the effect of K+ in reducing Cs+ uptake has not been obtained yet in the woody plant. Therefore, we investigated the ability of rhizospheric K+ to suppress uptake and translocation of Cs+ in Konara oak seedlings through hydroponic experiments in order to clarify the effect of K+. Elemental analysis showed that the seedlings cultivated for 4 weeks under low-K (K+ = 50 μM) contained higher amount of Cs comparing to the seedlings cultivated under high-K (K+ = 3 mM). Then, the uptake rate of Cs+ and K+ in the seedlings from the solution having 50 μM K+ and 0.1 μM Cs+ was calculated using radioactive 137Cs+ and 42K+ to evaluate the effect of growth condition on the ion uptake mechanism. The interference between Cs+ and K+ at the site of root uptake was also evaluated based on the Cs+ and K+ uptake rates at K+ concentrations of 50 μM, 200 μM, and 3 mM in the seedlings grown under the medium-K (K+ = 200 μM) condition. As a result, the Cs+ uptake rate at 50 μM K+ was not influenced by the growth condition, whereas Cs+ uptake decreased when the uptake solution itself was supplemented with 3 mM K+. In addition, the Cs/K ratio in the seedlings was found to rise to exceed the Cs/K ratio in the culture solution as the rhizospheric K+ concentration increased, which was in contrast with previous findings in herbaceous plants. Our experiments demonstrated the first direct evidence for woody plants that a high K+ concentration can suppress Cs accumulation in Konara oak and that it was derived from competition for uptake between K+ and Cs+ in the rhizosphere, not from the growth K+ condition.
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Affiliation(s)
- Riona Kobayashi
- Graduate School of Agriculture and Life Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Natsuko I Kobayashi
- Graduate School of Agriculture and Life Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
| | - Keitaro Tanoi
- Graduate School of Agriculture and Life Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Masaya Masumori
- Graduate School of Agriculture and Life Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Takeshi Tange
- Graduate School of Agriculture and Life Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
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9
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Adaptation of Plants to Salt Stress: Characterization of Na+ and K+ Transporters and Role of CBL Gene Family in Regulating Salt Stress Response. AGRONOMY-BASEL 2019. [DOI: 10.3390/agronomy9110687] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Salinity is one of the most serious factors limiting the productivity of agricultural crops, with adverse effects on germination, plant vigor, and crop yield. This salinity may be natural or induced by agricultural activities such as irrigation or the use of certain types of fertilizer. The most detrimental effect of salinity stress is the accumulation of Na+ and Cl− ions in tissues of plants exposed to soils with high NaCl concentrations. The entry of both Na+ and Cl− into the cells causes severe ion imbalance, and excess uptake might cause significant physiological disorder(s). High Na+ concentration inhibits the uptake of K+, which is an element for plant growth and development that results in lower productivity and may even lead to death. The genetic analyses revealed K+ and Na+ transport systems such as SOS1, which belong to the CBL gene family and play a key role in the transport of Na+ from the roots to the aerial parts in the Arabidopsis plant. In this review, we mainly discuss the roles of alkaline cations K+ and Na+, Ion homeostasis-transport determinants, and their regulation. Moreover, we tried to give a synthetic overview of soil salinity, its effects on plants, and tolerance mechanisms to withstand stress.
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10
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Zhang L, Li G, Wang M, Di D, Sun L, Kronzucker HJ, Shi W. Excess iron stress reduces root tip zone growth through nitric oxide-mediated repression of potassium homeostasis in Arabidopsis. THE NEW PHYTOLOGIST 2018; 219:259-274. [PMID: 29658100 DOI: 10.1111/nph.15157] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 03/09/2018] [Indexed: 05/08/2023]
Abstract
The root tip zone is regarded as the principal action site for iron (Fe) toxicity and is more sensitive than other root zones, but the mechanism underpinning this remains largely unknown. We explored the mechanism underpinning the higher sensitivity at the Arabidopsis root tip and elucidated the role of nitric oxide (NO) using NO-related mutants and pharmacological methods. Higher Fe sensitivity of the root tip is associated with reduced potassium (K+ ) retention. NO in root tips is increased significantly above levels elsewhere in the root and is involved in the arrest of primary root tip zone growth under excess Fe, at least in part related to NO-induced K+ loss via SNO1 (sensitive to nitric oxide 1)/SOS4 (salt overly sensitive 4) and reduced root tip zone cell viability. Moreover, ethylene can antagonize excess Fe-inhibited root growth and K+ efflux, in part by the control of root tip NO levels. We conclude that excess Fe attenuates root growth by effecting an increase in root tip zone NO, and that this attenuation is related to NO-mediated alterations in K+ homeostasis, partly via SNO1/SOS4.
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Affiliation(s)
- Lin Zhang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71 East Beijing Road, Nanjing, 210008, China
- University of the Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing, 100049, China
| | - Guangjie Li
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71 East Beijing Road, Nanjing, 210008, China
| | - Meng Wang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71 East Beijing Road, Nanjing, 210008, China
| | - Dongwei Di
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71 East Beijing Road, Nanjing, 210008, China
| | - Li Sun
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71 East Beijing Road, Nanjing, 210008, China
| | - Herbert J Kronzucker
- School of BioSciences, The University of Melbourne, Parkville, Vic., 3010, Australia
| | - Weiming Shi
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71 East Beijing Road, Nanjing, 210008, China
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11
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Flam-Shepherd R, Huynh WQ, Coskun D, Hamam AM, Britto DT, Kronzucker HJ. Membrane fluxes, bypass flows, and sodium stress in rice: the influence of silicon. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:1679-1692. [PMID: 29342282 PMCID: PMC5889039 DOI: 10.1093/jxb/erx460] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 12/12/2017] [Indexed: 05/14/2023]
Abstract
Provision of silicon (Si) to roots of rice (Oryza sativa L.) can alleviate salt stress by blocking apoplastic, transpirational bypass flow of Na+ from root to shoot. However, little is known about how Si affects Na+ fluxes across cell membranes. Here, we measured radiotracer fluxes of 24Na+, plasma membrane depolarization, tissue ion accumulation, and transpirational bypass flow, to examine the influence of Si on Na+ transport patterns in hydroponically grown, salt-sensitive (cv. IR29) and salt-tolerant (cv. Pokkali) rice. Si increased growth and lowered [Na+] in shoots of both cultivars, with minor effects in roots; neither root nor shoot [K+] were affected. In IR29, Si lowered shoot [Na+] via a large reduction in bypass flow, while in Pokkali, where bypass flow was small and not affected by Si, this was achieved mainly via a growth dilution of shoot Na+. Si had no effect on unidirectional 24Na+ fluxes (influx and efflux), or on Na+-stimulated plasma-membrane depolarization, in either IR29 or Pokkali. We conclude that, while Si can reduce Na+ translocation via bypass flow in some (but not all) rice cultivars, it does not affect unidirectional Na+ transport or Na+ cycling in roots, either across root cell membranes or within the bulk root apoplast.
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Affiliation(s)
- Rubens Flam-Shepherd
- Department of Biological Sciences and Canadian Centre for World Hunger Research (CCWHR), University of Toronto, Toronto, Canada
| | - Wayne Q Huynh
- Department of Biological Sciences and Canadian Centre for World Hunger Research (CCWHR), University of Toronto, Toronto, Canada
- School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Devrim Coskun
- Department of Biological Sciences and Canadian Centre for World Hunger Research (CCWHR), University of Toronto, Toronto, Canada
- Département de Phytologie, Faculté des Sciences de l’Agriculture et de l’Alimentation (FSAA), Université Laval, Québec, Canada
| | - Ahmed M Hamam
- Department of Biological Sciences and Canadian Centre for World Hunger Research (CCWHR), University of Toronto, Toronto, Canada
| | - Dev T Britto
- Department of Biological Sciences and Canadian Centre for World Hunger Research (CCWHR), University of Toronto, Toronto, Canada
| | - Herbert J Kronzucker
- Department of Biological Sciences and Canadian Centre for World Hunger Research (CCWHR), University of Toronto, Toronto, Canada
- School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
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12
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Coskun D, Britto DT, Kronzucker HJ. The nitrogen-potassium intersection: membranes, metabolism, and mechanism. PLANT, CELL & ENVIRONMENT 2017; 40:2029-2041. [PMID: 26524711 DOI: 10.1111/pce.12671] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Revised: 10/13/2015] [Accepted: 10/14/2015] [Indexed: 05/21/2023]
Abstract
Nitrogen (N) and potassium (K) are the two most abundantly acquired mineral elements by plants, and their acquisition pathways interact in complex ways. Here, we review pivotal interactions with respect to root acquisition, storage, translocation and metabolism, between the K+ ion and the two major N sources, ammonium (NH4+ ) and nitrate (NO3- ). The intersections between N and K physiology are explored at a number of organizational levels, from molecular-genetic processes, to compartmentation, to whole plant physiology, and discussed in the context of both N-K cooperation and antagonism. Nutritional regulation and optimization of plant growth, yield, metabolism and water-use efficiency are also discussed.
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Affiliation(s)
- Devrim Coskun
- Department of Biological Sciences and the Canadian Centre for World Hunger Research (CCWHR), University of Toronto, 1265 Military Trail, Toronto, Ontario, Canada, M1C 1A4
| | - Dev T Britto
- Department of Biological Sciences and the Canadian Centre for World Hunger Research (CCWHR), University of Toronto, 1265 Military Trail, Toronto, Ontario, Canada, M1C 1A4
| | - Herbert J Kronzucker
- Department of Biological Sciences and the Canadian Centre for World Hunger Research (CCWHR), University of Toronto, 1265 Military Trail, Toronto, Ontario, Canada, M1C 1A4
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13
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Li C, Tang Z, Wei J, Qu H, Xie Y, Xu G. The OsAMT1.1 gene functions in ammonium uptake and ammonium-potassium homeostasis over low and high ammonium concentration ranges. J Genet Genomics 2016; 43:639-649. [PMID: 27889499 DOI: 10.1016/j.jgg.2016.11.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 09/16/2016] [Accepted: 11/03/2016] [Indexed: 12/19/2022]
Abstract
Rice (Oryza sativa) grown in paddy fields is an ammonium (NH4+)-preferring crop; however, its AMT-type NH4+ transporters that mediate root N acquisition have not been well characterized yet. In this study, we analyzed the expression pattern and physiological function of the OsAMT1.1 gene of the AMT1 subfamily in rice. OsAMT1.1 is located in the plasma membrane and is mainly expressed in the root epidermis, stele and mesophyll cells. Disruption of the OsAMT1.1 gene decreased the uptake of NH4+, and the growth of roots and shoots under both low NH4+ and high NH4+ conditions. OsAMT1.1 contributed to the short-term (5 min) 15NH4+ influx rate by approximately one-quarter, irrespective of the NH4+ concentration. Knockout of OsAMT1.1 significantly decreased the total N transport from roots to shoots under low NH4+ conditions. Moreover, compared with the wild type, the osamt1.1 mutant showed an increase in the potassium (K) absorption rate under high NH4+ conditions and a decrease under low NH4+ conditions. The mutants contained a significantly high concentration of K in both the roots and shoots at a limited K (0.1 mmol/L) supply when NH4+ was replete. Taken together, the results indicated that OsAMT1.1 significantly contributes to the NH4+ uptake under both low and high NH4+ conditions and plays an important role in N-K homeostasis in rice.
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Affiliation(s)
- Chang Li
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Zhong Tang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Jia Wei
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Hongye Qu
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Yanjie Xie
- Laboratory Center of Life Sciences, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Guohua Xu
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
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14
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Coskun D, Britto DT, Kochian LV, Kronzucker HJ. How high do ion fluxes go? A re-evaluation of the two-mechanism model of K(+) transport in plant roots. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2016; 243:96-104. [PMID: 26795154 DOI: 10.1016/j.plantsci.2015.12.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 12/04/2015] [Accepted: 12/08/2015] [Indexed: 05/21/2023]
Abstract
Potassium (K(+)) acquisition in roots is generally described by a two-mechanism model, consisting of a saturable, high-affinity transport system (HATS) operating via H(+)/K(+) symport at low (<1mM) external [K(+)] ([K(+)]ext), and a linear, low-affinity system (LATS) operating via ion channels at high (>1mM) [K(+)]ext. Radiotracer measurements in the LATS range indicate that the linear rise in influx continues well beyond nutritionally relevant concentrations (>10mM), suggesting K(+) transport may be pushed to extraordinary, and seemingly limitless, capacity. Here, we assess this rise, asking whether LATS measurements faithfully report transmembrane fluxes. Using (42)K(+)-isotope and electrophysiological methods in barley, we show that this flux is part of a K(+)-transport cycle through the apoplast, and masks a genuine plasma-membrane influx that displays Michaelis-Menten kinetics. Rapid apoplastic cycling of K(+) is corroborated by an absence of transmembrane (42)K(+) efflux above 1mM, and by the efflux kinetics of PTS, an apoplastic tracer. A linear apoplastic influx, masking a saturating transmembrane influx, was also found in Arabidopsis mutants lacking the K(+) transporters AtHAK5 and AtAKT1. Our work significantly revises the model of K(+) transport by demonstrating a surprisingly modest upper limit for plasma-membrane influx, and offers insight into sodium transport under salt stress.
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Affiliation(s)
- Devrim Coskun
- Department of Biological Sciences & Canadian Centre for World Hunger Research (CCWHR), University of Toronto, Toronto, Ontario M1C 1A4, Canada.
| | - Dev T Britto
- Department of Biological Sciences & Canadian Centre for World Hunger Research (CCWHR), University of Toronto, Toronto, Ontario M1C 1A4, Canada.
| | - Leon V Kochian
- Robert W. Holley Center for Agriculture and Health, USDA-ARS, Cornell University, Ithaca, New York 14853, USA.
| | - Herbert J Kronzucker
- Department of Biological Sciences & Canadian Centre for World Hunger Research (CCWHR), University of Toronto, Toronto, Ontario M1C 1A4, Canada.
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15
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Britto DT, Kronzucker HJ. Sodium efflux in plant roots: what do we really know? JOURNAL OF PLANT PHYSIOLOGY 2015; 186-187:1-12. [PMID: 26318642 DOI: 10.1016/j.jplph.2015.08.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 08/03/2015] [Accepted: 08/03/2015] [Indexed: 05/27/2023]
Abstract
The efflux of sodium (Na(+)) ions across the plasma membrane of plant root cells into the external medium is surprisingly poorly understood. Nevertheless, Na(+) efflux is widely regarded as a major mechanism by which plants restrain the rise of Na(+) concentrations in the cytosolic compartments of root cells and, thus, achieve a degree of tolerance to saline environments. In this review, several key ideas and bodies of evidence concerning root Na(+) efflux are summarized with a critical eye. Findings from decades past are brought to bear on current thinking, and pivotal studies are discussed, both "purely physiological", and also with regard to the SOS1 protein, the only major Na(+) efflux transporter that has, to date, been genetically characterized. We find that the current model of rapid transmembrane sodium cycling (RTSC), across the plasma membrane of root cells, is not adequately supported by evidence from the majority of efflux studies. An alternative hypothesis cannot be ruled out, that most Na(+) tracer efflux from the root in the salinity range does not proceed across the plasma membrane, but through the apoplast. Support for this idea comes from studies showing that Na(+) efflux, when measured with tracers, is rarely affected by the presence of inhibitors or the ionic composition in saline rooting media. We conclude that the actual efflux of Na(+) across the plasma membrane of root cells may be much more modest than what is often reported in studies using tracers, and may predominantly occur in the root tips, where SOS1 expression has been localized.
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Affiliation(s)
- D T Britto
- University of Toronto, Canadian Centre for World Hunger Research, Canada
| | - H J Kronzucker
- University of Toronto, Canadian Centre for World Hunger Research, Canada.
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16
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Gómez DA, Carpena RO. Effect of 1-naphthaleneacetic acid on organic acid exudation by the roots of white lupin plants grown under phosphorus-deficient conditions. JOURNAL OF PLANT PHYSIOLOGY 2014; 171:1354-1361. [PMID: 25046756 DOI: 10.1016/j.jplph.2014.05.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 05/27/2014] [Accepted: 05/31/2014] [Indexed: 06/03/2023]
Abstract
The effect of NAA (1-naphthaleneacetic acid) on organic acid exudation in white lupin plants grown under phosphorus deficiency was investigated. Plants were sampled periodically for collecting of organic acids (citrate, malate, succinate), and also were used to study the effect on proton extrusion and release of Na(+), K(+), Ca(2+) and Mg(2+). The tissues were later processed to quantify the organic acids in tissues, the phosphorus content and the effects on plant biomass. The exogenous addition of NAA led to an increase in organic acid exudation, but this response was not proportional to the concentration of the dose applied, noticing the largest increments with NAA 10(-8)M. In contrast the increase in root weight was proportional to the dose applied, which shows that with higher doses the roots produced are not of proteoid type. Proton extrusion and the release of cations were related to the NAA dose, the first was proportional to the dose applied and the second inversely proportional. Regarding the analysis of tissues, the results of citrate and phosphorus content in shoots show that the overall status of these parts are the main responsible of the organic acids exuded. NAA served as an enhancer of the organic acid exudation that occurs under phosphorus deficient conditions, with a response that depends on the dose applied, not only in its magnitude, but also in the mechanism of action of the plant hormone.
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Affiliation(s)
- Diego A Gómez
- Department of Agricultural Chemistry, Facultad de Ciencias, Universidad Autónoma de Madrid, Carretera Colmenar Viejo km 15, 28049 Madrid, Spain.
| | - Ramón O Carpena
- Department of Agricultural Chemistry, Facultad de Ciencias, Universidad Autónoma de Madrid, Carretera Colmenar Viejo km 15, 28049 Madrid, Spain
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17
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Coskun D, Britto DT, Hamam AM, Kronzucker HJ. Measuring fluxes of mineral nutrients and toxicants in plants with radioactive tracers. J Vis Exp 2014:51877. [PMID: 25177829 PMCID: PMC4758755 DOI: 10.3791/51877] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Unidirectional influx and efflux of nutrients and toxicants, and their resultant net fluxes, are central to the nutrition and toxicology of plants. Radioisotope tracing is a major technique used to measure such fluxes, both within plants, and between plants and their environments. Flux data obtained with radiotracer protocols can help elucidate the capacity, mechanism, regulation, and energetics of transport systems for specific mineral nutrients or toxicants, and can provide insight into compartmentation and turnover rates of subcellular mineral and metabolite pools. Here, we describe two major radioisotope protocols used in plant biology: direct influx (DI) and compartmental analysis by tracer efflux (CATE). We focus on flux measurement of potassium (K(+)) as a nutrient, and ammonia/ammonium (NH3/NH4(+)) as a toxicant, in intact seedlings of the model species barley (Hordeum vulgare L.). These protocols can be readily adapted to other experimental systems (e.g., different species, excised plant material, and other nutrients/toxicants). Advantages and limitations of these protocols are discussed.
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Affiliation(s)
- Devrim Coskun
- Department of Biological Sciences, University of Toronto
| | - Dev T Britto
- Department of Biological Sciences, University of Toronto
| | - Ahmed M Hamam
- Department of Biological Sciences, University of Toronto
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18
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Coskun D, Britto DT, Li M, Becker A, Kronzucker HJ. Rapid ammonia gas transport accounts for futile transmembrane cycling under NH3/NH4+ toxicity in plant roots. PLANT PHYSIOLOGY 2013; 163:1859-67. [PMID: 24134887 PMCID: PMC3850193 DOI: 10.1104/pp.113.225961] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 10/14/2013] [Indexed: 05/17/2023]
Abstract
Futile transmembrane NH3/NH4(+) cycling in plant root cells, characterized by extremely rapid fluxes and high efflux to influx ratios, has been successfully linked to NH3/NH4(+) toxicity. Surprisingly, the fundamental question of which species of the conjugate pair (NH3 or NH4(+)) participates in such fluxes is unresolved. Using flux analyses with the short-lived radioisotope (13)N and electrophysiological, respiratory, and histochemical measurements, we show that futile cycling in roots of barley (Hordeum vulgare) seedlings is predominately of the gaseous NH3 species, rather than the NH4(+) ion. Influx of (13)NH3/(13)NH4(+), which exceeded 200 µmol g(-1) h(-1), was not commensurate with membrane depolarization or increases in root respiration, suggesting electroneutral NH3 transport. Influx followed Michaelis-Menten kinetics for NH3 (but not NH4(+)), as a function of external concentration (Km = 152 µm, Vmax = 205 µmol g(-1) h(-1)). Efflux of (13)NH3/(13)NH4(+) responded with a nearly identical Km. Pharmacological characterization of influx and efflux suggests mediation by aquaporins. Our study fundamentally revises the futile-cycling model by demonstrating that NH3 is the major permeating species across both plasmalemma and tonoplast of root cells under toxicity conditions.
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Affiliation(s)
- Devrim Coskun
- Department of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
| | - Dev T. Britto
- Department of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
| | - Mingyuan Li
- Department of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
| | - Alexander Becker
- Department of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
| | - Herbert J. Kronzucker
- Department of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
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19
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Coskun D, Britto DT, Li M, Oh S, Kronzucker HJ. Capacity and plasticity of potassium channels and high-affinity transporters in roots of barley and Arabidopsis. PLANT PHYSIOLOGY 2013; 162:496-511. [PMID: 23553635 PMCID: PMC3641226 DOI: 10.1104/pp.113.215913] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 03/31/2013] [Indexed: 05/03/2023]
Abstract
The role of potassium (K(+)) transporters in high- and low-affinity K(+) uptake was examined in roots of intact barley (Hordeum vulgare) and Arabidopsis (Arabidopsis thaliana) plants by use of (42)K radiotracing, electrophysiology, pharmacology, and mutant analysis. Comparisons were made between results from barley and five genotypes of Arabidopsis, including single and double knockout mutants for the high-affinity transporter, AtHAK5, and the Shaker-type channel, AtAKT1. In Arabidopsis, steady-state K(+) influx at low external K(+) concentration ([K(+)]ext = 22.5 µm) was predominantly mediated by AtAKT1 when high-affinity transport was inhibited by ammonium, whereas in barley, by contrast, K(+) channels could not operate below 100 µm. Withdrawal of ammonium resulted in an immediate and dramatic stimulation of K(+) influx in barley, indicating a shift from active to passive K(+) uptake at low [K(+)]ext and yielding fluxes as high as 36 µmol g (root fresh weight)(-1) h(-1) at 5 mm [K(+)]ext, among the highest transporter-mediated K(+) fluxes hitherto reported. This ammonium-withdrawal effect was also established in all Arabidopsis lines (the wild types, atakt1, athak5, and athak5 atakt1) at low [K(+)]ext, revealing the concerted involvement of several transport systems. The ammonium-withdrawal effect coincided with a suppression of K(+) efflux and a significant hyperpolarization of the plasma membrane in all genotypes except athak5 atakt1, could be sustained over 24 h, and resulted in increased tissue K(+) accumulation. We discuss key differences and similarities in K(+) acquisition between two important model systems and reveal novel aspects of K(+) transport in planta.
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Affiliation(s)
- Devrim Coskun
- Department of Biological Sciences, University of Toronto, Toronto, Ontario, Canada M1C 1A4
| | - Dev T. Britto
- Department of Biological Sciences, University of Toronto, Toronto, Ontario, Canada M1C 1A4
| | - Mingyuan Li
- Department of Biological Sciences, University of Toronto, Toronto, Ontario, Canada M1C 1A4
| | - Saehong Oh
- Department of Biological Sciences, University of Toronto, Toronto, Ontario, Canada M1C 1A4
| | - Herbert J. Kronzucker
- Department of Biological Sciences, University of Toronto, Toronto, Ontario, Canada M1C 1A4
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20
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Wang M, Zheng Q, Shen Q, Guo S. The critical role of potassium in plant stress response. Int J Mol Sci 2013; 14:7370-90. [PMID: 23549270 PMCID: PMC3645691 DOI: 10.3390/ijms14047370] [Citation(s) in RCA: 435] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 02/23/2013] [Accepted: 03/21/2013] [Indexed: 02/02/2023] Open
Abstract
Agricultural production continues to be constrained by a number of biotic and abiotic factors that can reduce crop yield quantity and quality. Potassium (K) is an essential nutrient that affects most of the biochemical and physiological processes that influence plant growth and metabolism. It also contributes to the survival of plants exposed to various biotic and abiotic stresses. The following review focuses on the emerging role of K in defending against a number of biotic and abiotic stresses, including diseases, pests, drought, salinity, cold and frost and waterlogging. The availability of K and its effects on plant growth, anatomy, morphology and plant metabolism are discussed. The physiological and molecular mechanisms of K function in plant stress resistance are reviewed. This article also evaluates the potential for improving plant stress resistance by modifying K fertilizer inputs and highlights the future needs for research about the role of K in agriculture.
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Affiliation(s)
- Min Wang
- Agricultural Ministry Key Lab of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, Nanjing Agricultural University, No. 1 Weigang, Nanjing 210095, China; E-Mails: (M.W.); (Q.Z.); (Q.S.)
| | - Qingsong Zheng
- Agricultural Ministry Key Lab of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, Nanjing Agricultural University, No. 1 Weigang, Nanjing 210095, China; E-Mails: (M.W.); (Q.Z.); (Q.S.)
| | - Qirong Shen
- Agricultural Ministry Key Lab of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, Nanjing Agricultural University, No. 1 Weigang, Nanjing 210095, China; E-Mails: (M.W.); (Q.Z.); (Q.S.)
| | - Shiwei Guo
- Agricultural Ministry Key Lab of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, Nanjing Agricultural University, No. 1 Weigang, Nanjing 210095, China; E-Mails: (M.W.); (Q.Z.); (Q.S.)
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21
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Coskun D, Britto DT, Jean YK, Kabir I, Tolay I, Torun AA, Kronzucker HJ. K+ efflux and retention in response to NaCl stress do not predict salt tolerance in contrasting genotypes of rice (Oryza sativa L.). PLoS One 2013; 8:e57767. [PMID: 23460903 PMCID: PMC3583904 DOI: 10.1371/journal.pone.0057767] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 01/25/2013] [Indexed: 12/25/2022] Open
Abstract
Sudden elevations in external sodium chloride (NaCl) accelerate potassium (K(+)) efflux across the plasma membrane of plant root cells. It has been proposed that the extent of this acceleration can predict salt tolerance among contrasting cultivars. However, this proposal has not been considered in the context of plant nutritional history, nor has it been explored in rice (Oryza sativa L.), which stands among the world's most important and salt-sensitive crop species. Using efflux analysis with (42)K, coupled with growth and tissue K(+) analyses, we examined the short- and long-term effects of NaCl exposure to plant performance within a nutritional matrix that significantly altered tissue-K(+) set points in three rice cultivars that differ in salt tolerance: IR29 (sensitive), IR72 (moderate), and Pokkali (tolerant). We show that total short-term K(+) release from roots in response to NaCl stress is small (no more than 26% over 45 min) in rice. Despite strong varietal differences, the extent of efflux is shown to be a poor predictor of plant performance on long-term NaCl stress. In fact, no measure of K(+) status was found to correlate with plant performance among cultivars either in the presence or absence of NaCl stress. By contrast, shoot Na(+) accumulation showed the strongest correlation (a negative one) with biomass, under long-term salinity. Pharmacological evidence suggests that NaCl-induced K(+) efflux is a result of membrane disintegrity, possibly as result of osmotic shock, and not due to ion-channel mediation. Taken together, we conclude that, in rice, K(+) status (including efflux) is a poor predictor of salt tolerance and overall plant performance and, instead, shoot Na(+) accumulation is the key factor in performance decline on NaCl stress.
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Affiliation(s)
- Devrim Coskun
- Department of Biological Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Dev T. Britto
- Department of Biological Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Yuel-Kai Jean
- Department of Biological Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Imtiaz Kabir
- Department of Biological Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Inci Tolay
- Department of Agriculture, Akdeniz University, Antalya, Turkey
| | - Ayfer A. Torun
- Department of Soil Science & Plant Nutrition, Cukurova University, Adana, Turkey
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22
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Abstract
Standard procedures for the tracing of ion fluxes into roots of plants are described here, with emphasis on cations, especially potassium (K(+)). We focus in particular on the measurement of unidirectional influx by use of radiotracers and provide a brief introduction to compartmental analysis by tracer efflux (CATE).
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Affiliation(s)
- D T Britto
- Department of Biological Sciences, University of Toronto, Toronto, ON, Canada
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23
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Zou N, Li B, Dong G, Kronzucker HJ, Shi W. Ammonium-induced loss of root gravitropism is related to auxin distribution and TRH1 function, and is uncoupled from the inhibition of root elongation in Arabidopsis. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:3777-88. [PMID: 22407650 DOI: 10.1093/jxb/ers068] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Root gravitropism is affected by many environmental stresses, including salinity, drought, and nutrient deficiency. One significant environmental stress, excess ammonium (NH(4)(+)), is well documented to inhibit root elongation and lateral root formation, yet little is known about its effects on the direction of root growth. We show here that inhibition of root elongation upon elevation of external NH(4)(+) is accompanied by a loss in root gravitropism (agravitropism) in Arabidopsis. Addition of potassium (K(+)) to the treatment medium partially rescued the inhibition of root elongation by high NH(4)(+) but did not improve gravitropic root curvature. Expression analysis of the auxin-responsive reporter gene DR5::GUS revealed that NH(4)(+) treatment delayed the development of gravity-induced auxin gradients across the root cap but extended their duration once initiated. Moreover, the β-glucuronidase (GUS) signal intensity in root tip cells was significantly reduced under high NH(4)(+) treatment over time. The potassium carrier mutant trh1 displayed different patterns of root gravitropism and DR5::GUS signal intensity in root apex cells compared with the wild type in response to NH(4)(+). Together, the results demonstrate that the effects of NH(4)(+) on root gravitropism are related to delayed lateral auxin redistribution and the TRH1 pathway, and are largely independent of inhibitory effects on root elongation.
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Affiliation(s)
- Na Zou
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
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24
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Schulze LM, Britto DT, Li M, Kronzucker HJ. A pharmacological analysis of high-affinity sodium transport in barley (Hordeum vulgare L.): a 24Na+/42K+ study. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:2479-89. [PMID: 22268152 PMCID: PMC3346217 DOI: 10.1093/jxb/err419] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 11/21/2011] [Accepted: 11/23/2011] [Indexed: 05/19/2023]
Abstract
Soil sodium, while toxic to most plants at high concentrations, can be beneficial at low concentrations, particularly when potassium is limiting. However, little is known about Na(+) uptake in this 'high-affinity' range. New information is provided here with an insight into the transport characteristics, mechanism, and ecological significance of this phenomenon. High-affinity Na(+) and K(+) fluxes were investigated using the short-lived radiotracers (24)Na and (42)K, under an extensive range of measuring conditions (variations in external sodium, and in nutritional and pharmacological agents). This work was supported by electrophysiological, compartmental, and growth analyses. Na(+) uptake was extremely sensitive to all treatments, displaying properties of high-affinity K(+) transporters, K(+) channels, animal Na(+) channels, and non-selective cation channels. K(+), NH(4)(+), and Ca(2+) suppressed Na(+) transport biphasically, yielding IC(50) values of 30, 10, and <5 μM, respectively. Reciprocal experiments showed that K(+) influx is neither inhibited nor stimulated by Na(+). Sodium efflux constituted 65% of influx, indicating a futile cycle. The thermodynamic feasibility of passive channel mediation is supported by compartmentation and electrophysiological data. Our study complements recent advances in the molecular biology of high-affinity Na(+) transport by uncovering new physiological foundations for this transport phenomenon, while questioning its ecological relevance.
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Affiliation(s)
| | | | | | - Herbert J. Kronzucker
- Department of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, ON, Canada M1C 1A4
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25
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Li G, Dong G, Li B, Li Q, Kronzucker HJ, Shi W. Isolation and characterization of a novel ammonium overly sensitive mutant, amos2, in Arabidopsis thaliana. PLANTA 2012; 235:239-52. [PMID: 21866344 DOI: 10.1007/s00425-011-1504-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 08/11/2011] [Indexed: 05/09/2023]
Abstract
Ammonium (NH(4)(+)) toxicity is a significant agricultural problem globally, compromising crop growth and productivity in many areas. However, the molecular mechanisms of NH(4)(+) toxicity are still poorly understood, in part due to a lack of valuable genetic resources. Here, a novel Arabidopsis mutant, amos2 (ammonium overly sensitive 2), displaying hypersensitivity to NH(4) (+) in both shoots and roots, was isolated. The mutant exhibits the hallmarks of NH(4)(+) toxicity at significantly elevated levels: severely suppressed shoot biomass, increased leaf chlorosis, and inhibition of lateral root formation. Amos2 hypersensitivity is associated with excessive NH(4)(+) accumulation in shoots and a reduction in tissue potassium (K(+)), calcium (Ca(2+)), and magnesium (Mg(2+)). We show that the lesion is specific to the NH(4)(+) ion, is independent of NH(4)(+) metabolism, and can be partially rescued by elevated external K(+). The amos2 lesion was mapped to a 16-cM interval on top of chromosome 1, where no similar mutation has been previously mapped. Our study identifies a novel locus controlling cation homeostasis under NH(4)(+) stress and provides a tool for the future identification of critical genes involved in the development of NH(4)(+) toxicity.
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Affiliation(s)
- Guangjie Li
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No 71 East Beijing Road, Nanjing 210008, China
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Coskun D, Britto DT, Jean YK, Schulze LM, Becker A, Kronzucker HJ. Silver ions disrupt K⁺ homeostasis and cellular integrity in intact barley (Hordeum vulgare L.) roots. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:151-62. [PMID: 21948852 PMCID: PMC3245464 DOI: 10.1093/jxb/err267] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 07/23/2011] [Accepted: 07/26/2011] [Indexed: 05/19/2023]
Abstract
The heavy metals silver, gold, and mercury can strongly inhibit aquaporin-mediated water flow across plant cell membranes, but critical examinations of their side effects are rare. Here, the short-lived radiotracer (42)K is used to demonstrate that these metals, especially silver, profoundly change potassium homeostasis in roots of intact barley (Hordeum vulgare L.) plants, by altering unidirectional K(+) fluxes. Doses as low as 5 μM AgNO(3) rapidly reduced K(+) influx to 5% that of controls, and brought about pronounced and immediate increases in K(+) efflux, while higher doses of Au(3+) and Hg(2+) were required to produce similar responses. Reduced influx and enhanced efflux of K(+) resulted in a net loss of >40% of root tissue K(+) during a 15 min application of 500 μM AgNO(3), comprising the entire cytosolic potassium pool and about a third of the vacuolar pool. Silver also brought about major losses of UV-absorbing compounds, total electrolytes, and NH(4)(+). Co-application, with silver, of the channel blockers Cs(+), TEA(+), or Ca(2+), did not affect the enhanced efflux, ruling out the involvement of outwardly rectifying ion channels. Taken together with an examination of propidium iodide staining under confocal microscopy, the results indicate that silver ions affect K(+) homeostasis by directly inhibiting K(+) influx at lower concentrations, and indirectly inhibiting K(+) influx and enhancing K(+) efflux, via membrane destruction, at higher concentrations. Ni(2+), Cd(2+), and Pb(2+), three heavy metals not generally known to affect aquaporins, did not enhance K(+) efflux or cause propidium iodide incorporation. The study reveals strong and previously unknown effects of major aquaporin inhibitors and recommends caution in their application.
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Affiliation(s)
| | | | | | | | | | - Herbert J. Kronzucker
- Department of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
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Jamil A, Riaz S, Ashraf M, Foolad MR. Gene Expression Profiling of Plants under Salt Stress. CRITICAL REVIEWS IN PLANT SCIENCES 2011; 30:435-458. [PMID: 0 DOI: 10.1080/07352689.2011.605739] [Citation(s) in RCA: 228] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
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