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Kochian LV, Piñeros MA, Hoekenga OA. The physiology, genetics and molecular biology of plant aluminum resistance and toxicity. ACTA ACUST UNITED AC 2005. [DOI: 10.1007/1-4020-4099-7_9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
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Arroyo-Serralta GA, Kú-González A, Hernández-Sotomayor SMT, Zúñiga Aguilar JJ. Exposure to toxic concentrations of aluminum activates a MAPK-like protein in cell suspension cultures of Coffea arabica. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2005; 43:27-35. [PMID: 15763663 DOI: 10.1016/j.plaphy.2004.12.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2004] [Accepted: 12/06/2004] [Indexed: 05/02/2023]
Abstract
Addition of a toxic concentration of aluminum (Al) to cell suspension cultures of Coffea arabica L. induced the rapid and transient activation of a protein kinase that phosphorylates myelin basic protein (MBP), as revealed by in-gel kinase assays. This enzyme with an apparent molecular mass of 58 kDa was activated shortly after cells were exposed to 50 microM AlCl(3), a concentration previously shown to produce toxicity in plant cells in vitro. The activity of this kinase dropped to basal levels after 20 min of Al addition; this activity is specific for MBP as it could not be detected when casein or histone H1 were used as substrates. Analysis of the same cell extracts with antibodies that specifically recognize bis-phosphorylated (active) mitogen-activated protein kinases (MAP kinases), revealed the presence of a phosphoprotein with an apparent molecular mass of 58 kDa, which showed the same response to Al as the protein kinase revealed by the in-gel kinase assays. Furthermore, immunoprecipitation with an antibody directed against mammalian MAP kinases depleted both the enzymatic activity and the phosphoprotein from the cell extracts, suggesting that the 58 kDa kinase and the 58 kDa phosphoprotein from C. arabica cells are the same protein, and that it can be actually a member of the MAP kinase family of protein kinases. Since its activity is enhanced dramatically after addition of AlCl(3) to the medium, we can speculate that Al toxicity in plants could be perceived through the MAP kinase signal transduction pathway.
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Affiliation(s)
- Gabriela A Arroyo-Serralta
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán, Mérida 97200, Yucatán, México.
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53
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George TS, Simpson RJ, Hadobas PA, Richardson AE. Expression of a fungal phytase gene in Nicotiana tabacum improves phosphorus nutrition of plants grown in amended soils. PLANT BIOTECHNOLOGY JOURNAL 2005; 3:129-40. [PMID: 17168905 DOI: 10.1111/j.1467-7652.2004.00116.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Transgenic Nicotiana tabacum plants expressing a chimeric phytase gene (ex::phyA) from the soil fungus Aspergillus niger were generated. Three independently transformed lines showed increased extracellular phytase activity compared with a vector control and wild-type plants, both of which had no detectable extracellular phytase. Transgenic N. tabacum plants grown in sterile agar supplied with phosphorus (P) as phytate accumulated 3.7-fold more P than vector control plants. Despite this, the expression of ex::phyA in plants did not lead to an improved accumulation of P from two unamended P-deficient soils. However, when soils were amended with either phytate or phosphate and lime, transgenic plants accumulated up to 52% more P than controls. Positive responses by transgenic plants were, in some instances, coincident with a putative increase in soil phytate. We conclude that the development of plants that exude phytase to the soil may not ensure improved plant P nutrition, as the availability of phytate in the soil also appears to be critical. Nevertheless, if plants that express ex::phyA are combined with soil amendments that promote the availability of phytate, there is the potential to enhance the P nutrition of crop plants and to improve the efficiency of P fertilizer use in agricultural systems.
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Affiliation(s)
- Timothy S George
- CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia
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54
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Gray GR, Maxwell DP, Villarimo AR, McIntosh L. Mitochondria/nuclear signaling of alternative oxidase gene expression occurs through distinct pathways involving organic acids and reactive oxygen species. PLANT CELL REPORTS 2004; 23:497-503. [PMID: 15322810 DOI: 10.1007/s00299-004-0848-1] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Revised: 07/06/2004] [Accepted: 07/09/2004] [Indexed: 05/04/2023]
Abstract
Cultured cells of tobacco (Nicotiana tabacum L. cv Petit Havana) were used to investigate signals regulating the expression of the "model" nuclear gene encoding the alternative oxidase (AOX) (AOX1), the terminal oxidase of the mitochondrial alternative respiratory pathway. Several conditions shown to induce AOX1 mRNA accumulation also result in an increase in cellular citrate concentrations, suggesting that citrate and/or other tricarboxylic acid (TCA) cycle intermediates may be important signal metabolites. In addition, mitochondrial reactive oxygen species (ROS) production has recently been shown to be a factor mediating mitochondria-to-nucleus signaling for the expression of AOX1. We found that the exogenously supplied TCA cycle organic acids citrate, malate and 2-oxoglutarate caused rapid and dramatic increases in the steady-state level of AOX1 mRNA at low, near physiological concentrations (0.1 mM). Furthermore, an increase in AOX1 induced by the addition of organic acids occurs independently of mitochondrial ROS formation. Our results demonstrate that two separate pathways for mitochondria-to-nucleus signaling of AOX1 may exist, one involving ROS and the other organic acids.
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Affiliation(s)
- G R Gray
- Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK, Canada, S7N 5A8.
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Delhaize E, Ryan PR, Hebb DM, Yamamoto Y, Sasaki T, Matsumoto H. Engineering high-level aluminum tolerance in barley with the ALMT1 gene. Proc Natl Acad Sci U S A 2004; 101:15249-54. [PMID: 15471989 PMCID: PMC524075 DOI: 10.1073/pnas.0406258101] [Citation(s) in RCA: 196] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2004] [Indexed: 11/18/2022] Open
Abstract
Acidity is a serious limitation to plant production on many of the world's agricultural soils. Toxic aluminium (Al) cations solubilized by the acidity rapidly inhibit root growth and limit subsequent uptake of water and nutrients. Recent work has shown that the ALMT1 gene of wheat (Triticum aestivum) encodes a malate transporter that is associated with malate efflux and Al tolerance. We generated transgenic barley (Hordeum vulgare) plants expressing ALMT1 and assessed their ability to exude malate and withstand Al stress. ALMT1 expression in barley conferred an Al-activated efflux of malate with properties similar to those of Al-tolerant wheat. The transgenic barley showed a high level of Al tolerance when grown in both hydroponic culture and on acid soils. These findings provide additional evidence that ALMT1 is a major Al-tolerance gene and demonstrate its ability to confer effective tolerance to acid soils through a transgenic approach in an important crop species.
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Affiliation(s)
- Emmanuel Delhaize
- Commonwealth Scientific and Industrial Research Organization Plant Industry, GPO Box 1600, Canberra ACT 2601, Australia.
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56
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Hammond JP, Broadley MR, White PJ. Genetic responses to phosphorus deficiency. ANNALS OF BOTANY 2004; 94:323-32. [PMID: 15292042 PMCID: PMC4242181 DOI: 10.1093/aob/mch156] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2004] [Revised: 04/21/2004] [Accepted: 05/15/2004] [Indexed: 05/17/2023]
Abstract
BACKGROUND Phosphorus (P) is an essential macronutrient for plants. Plants take up P as phosphate (Pi) from the soil solution. Since little Pi is available in most soils, P fertilizers are applied to crops. However, the use of P fertilizers is unsustainable and may cause pollution. Consequently, there is a need to develop more P-use-efficient (PUE) crops and precise methods to monitor crop P-status. SCOPE Manipulating the expression of genes to improve the PUE of crops could reduce their P fertilizer requirement. This has stimulated research towards the identification of genes and signalling cascades involved in plant responses to P deficiency. Genes that respond to P deficiency can be grouped into 'early' genes that respond rapidly and often non-specifically to P deficiency, or 'late' genes that impact on the morphology, physiology or metabolism of plants upon prolonged P deficiency. SUMMARY The use of micro-array technology has allowed researchers to catalogue the genetic responses of plants to P deficiency. Genes whose expression is altered by P deficiency include various transcription factors, which are thought to coordinate plant responses to P deficiency, and other genes involved in P acquisition and tissue P economy. Several common cis-regulatory elements have been identified in the promoters of these genes, suggesting that their expression might be coordinated. It is suggested that knowledge of the genes whose expression changes in response to P deficiency might allow the development of crops with improved PUE, and could be used in diagnostic techniques to monitor P deficiency in crops either directly using 'smart' indicator plants or indirectly through transcript profiling. The development of crops with improved PUE and the adoption of diagnostic technology could reduce production costs, minimize the use of a non-renewable resource, reduce pollution and enhance biodiversity.
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57
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Ligaba A, Shen H, Shibata K, Yamamoto Y, Tanakamaru S, Matsumoto H. The role of phosphorus in aluminium-induced citrate and malate exudation from rape (Brassica napus). PHYSIOLOGIA PLANTARUM 2004; 120:575-584. [PMID: 15032819 DOI: 10.1111/j.0031-9317.2004.0290.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Exudation of organic anions is believed to be a common tolerance mechanism for both aluminium toxicity and phosphorus deficiency. Nevertheless, which of these stresses that actually elicit the exudation of organic anions from rape (Brassica napus L) remains unknown, and the combined effects of Al toxicity and P deficiency on rape have not been reported before. Therefore, in the current study, Brassica napus var. Natane nourin plants grown with or without 0.25 mM P were exposed to 0 or 50 micro M AlCl(3) and several parameters related to the exudation of organic anions from the roots were investigated. Eight days of P deficiency resulted in a significant growth reduction, but P deficiency alone did not induce exudation of organic anions. In contrast, Al strongly induced organic acid exudation, while simultaneously inhibiting root growth. Increased in-vitro activity of citrate synthase (CS, EC 4.1.3.7), malate dehydrogenase (MDH, EC 1.1.1.37) and phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31), together with reduced root respiration, indicated that the Al-induced accumulation and subsequent exudation of citrate and malate were associated with both increased biosynthesis and reduced metabolism of citric and malic acid. Phosphorus-sufficient plants showed more pronounced aluminium-induced accumulation and exudation of organic anions than P-deficient plants. A divided root chamber experiment showed the necessity of direct contact between Al and roots to elicit exudation of organic anions. Prolonged exposure (10 days) to Al resulted in a decrease in the net exudation of citrate and malate, and the rate of decrease was much more rapid in P-deficient plants than in P-sufficient plants. It is concluded that P nutrition affects the level of Al-induced synthesis and exudation of organic anions. However, the mechanism needs further investigation.
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Affiliation(s)
- Ayalew Ligaba
- Research Institute for Bioresources, Okayama University, Chuo 2-20-1, Kurashiki 710-0046, Japan
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58
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Kochian LV, Hoekenga OA, Pineros MA. How do crop plants tolerate acid soils? Mechanisms of aluminum tolerance and phosphorous efficiency. ANNUAL REVIEW OF PLANT BIOLOGY 2004; 55:459-93. [PMID: 15377228 DOI: 10.1146/annurev.arplant.55.031903.141655] [Citation(s) in RCA: 731] [Impact Index Per Article: 36.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Acid soils significantly limit crop production worldwide because approximately 50% of the world's potentially arable soils are acidic. Because acid soils are such an important constraint to agriculture, understanding the mechanisms and genes conferring tolerance to acid soil stress has been a focus of intense research interest over the past decade. The primary limitations on acid soils are toxic levels of aluminum (Al) and manganese (Mn), as well as suboptimal levels of phosphorous (P). This review examines our current understanding of the physiological, genetic, and molecular basis for crop Al tolerance, as well as reviews the emerging area of P efficiency, which involves the genetically based ability of some crop genotypes to tolerate P deficiency stress on acid soils. These are interesting times for this field because researchers are on the verge of identifying some of the genes that confer Al tolerance in crop plants; these discoveries will open up new avenues of molecular/physiological inquiry that should greatly advance our understanding of these tolerance mechanisms. Additionally, these breakthroughs will provide new molecular resources for improving crop Al tolerance via both molecular-assisted breeding and biotechnology.
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Affiliation(s)
- Leon V Kochian
- U.S. Plant, Soil, and Nutrition Laboratory, USDA-ARS, Cornell University, Ithaca, New York 14853, USA.
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59
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Kihara T, Wada T, Suzuki Y, Hara T, Koyama H. Alteration of citrate metabolism in cluster roots of white lupin. PLANT & CELL PHYSIOLOGY 2003; 44:901-908. [PMID: 14519771 DOI: 10.1093/pcp/pcg115] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Organic acid excretion plays a key role in the superior P(i)-acquisition of barely soluble inorganic P sources from soils. Seedlings of white lupin (Lupinus albus L.) grown for 37 d in -P nutrient solution showed typical -P symptoms, such as low P content, increased root/shoot ratio and the development of cluster roots which released large amounts of citrate. Citrate concentration in the cluster roots was 21.5 micro mol (g FW)(-1), which corresponded to a 4.3- and 2.6-fold increase of +P and -P root apexes, respectively. Cluster roots possessed higher phosphoenolpyruvate carboxylase and phosphoenolpyruvate phosphatase activity than those in +P root apexes, which could result in increasing the supply of substrate for citrate synthase. On the other hand, the cytosolic pathway which converts citrate to 2-oxoglutarate consists of aconitase and NADP-specific isocitrate dehydrogenase activity that was lower in the cluster roots than in +P root apexes, and may contribute to citrate accumulation. Thus, metabolic balance with these alterations would play an important role in increasing citrate concentration in the cluster roots. The molecular characterization of NADP-specific isocitrate dehydrogenase indicated that the cytosolic isoenzyme functions as a hetero-dimer, and that the activity would be regulated by the transcript levels for both isoforms.
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Affiliation(s)
- Tomonori Kihara
- Laboratory of Plant Cell Technology, Faculty of Agriculture, Gifu University, 1-1, Yanagido, Gifu, 501-1193 Japan
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60
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Ma JF, Furukawa J. Recent progress in the research of external Al detoxification in higher plants: a minireview. J Inorg Biochem 2003; 97:46-51. [PMID: 14507459 DOI: 10.1016/s0162-0134(03)00245-9] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Aluminum (Al) is highly toxic to plant growth. The toxicity is characterized by rapid inhibition of root elongation. However, some plant species and cultivars have evolved some mechanisms for detoxifying Al both internally and externally. In this review, the recent progress made in the research of external detoxification of Al is described. Accumulating evidence has shown that organic acids play an important role in the detoxification of Al. Some plant species and cultivars respond to Al by secreting citrate, malate or oxalate from the roots. Recently, the anion channel of malate and citrate in the plasma membrane has been characterized and a gene encoding the malate channel has been cloned. The metabolism of organic acids seems to be poorly correlated with the Al-induced secretion of organic acid anions. A number of QTLs (quantitative trait loci) for Al resistance have been identified in rice, Arabidopsis, and other species. Transgenic plants with enhanced resistance to Al have also been reported, but introduction of multiple genes may be required to gain high Al resistance in future.
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Affiliation(s)
- Jian Feng Ma
- Faculty of Agriculture, Kagawa University, Ikenobe 2393, Miki-cho, Kita-gun, Kagawa 761-0795, Japan.
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61
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Anoop VM, Basu U, McCammon MT, McAlister-Henn L, Taylor GJ. Modulation of citrate metabolism alters aluminum tolerance in yeast and transgenic canola overexpressing a mitochondrial citrate synthase. PLANT PHYSIOLOGY 2003; 132:2205-17. [PMID: 12913175 PMCID: PMC181304 DOI: 10.1104/pp.103.023903] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2003] [Revised: 04/21/2003] [Accepted: 05/12/2003] [Indexed: 05/18/2023]
Abstract
Aluminum (Al) toxicity is a major constraint for crop production in acid soils, although crop cultivars vary in their tolerance to Al. We have investigated the potential role of citrate in mediating Al tolerance in Al-sensitive yeast (Saccharomyces cerevisiae; MMYO11) and canola (Brassica napus cv Westar). Yeast disruption mutants defective in genes encoding tricarboxylic acid cycle enzymes, both upstream (citrate synthase [CS]) and downstream (aconitase [ACO] and isocitrate dehydrogenase [IDH]) of citrate, showed altered levels of Al tolerance. A triple mutant of CS (Deltacit123) showed lower levels of citrate accumulation and reduced Al tolerance, whereas Deltaaco1- and Deltaidh12-deficient mutants showed higher accumulation of citrate and increased levels of Al tolerance. Overexpression of a mitochondrial CS (CIT1) in MMYO11 resulted in a 2- to 3-fold increase in citrate levels, and the transformants showed enhanced Al tolerance. A gene for Arabidopsis mitochondrial CS was overexpressed in canola using an Agrobacterium tumefaciens-mediated system. Increased levels of CS gene expression and enhanced CS activity were observed in transgenic lines compared with the wild type. Root growth experiments revealed that transgenic lines have enhanced levels of Al tolerance. The transgenic lines showed enhanced levels of cellular shoot citrate and a 2-fold increase in citrate exudation when exposed to 150 micro M Al. Our work with yeast and transgenic canola clearly suggest that modulation of different enzymes involved in citrate synthesis and turnover (malate dehydrogenase, CS, ACO, and IDH) could be considered as potential targets of gene manipulation to understand the role of citrate metabolism in mediating Al tolerance.
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Affiliation(s)
- Valar M Anoop
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9.
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62
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Kobayashi Y, Koyama H. QTL analysis of Al tolerance in recombinant inbred lines of Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2002; 43:1526-1533. [PMID: 12514250 DOI: 10.1093/pcp/pcf174] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Quantitative trait loci (QTLs) and epistasis for Arabidopsis thaliana aluminum (Al) tolerance were analyzed using a recombinant inbred (RI) population of 100 lines derived from a cross between Landsberg erecta and Columbia (Col). Root growth of the RI population was determined in hydroponics using solutions containing 0 or 4 micro M of AlCl(3 )and a series of nutrients, except P(i), at pH 5.0. Al tolerance was defined as relative root length [RRL: plus Al/minus Al (%)], and the RI lines ranged from 22.6 to 97.4% with a broad sense heritability of 0.99. Using the composite interval mapping method, two significant single factor QTLs (P<0.05) were detected by RRL on chromosomes 1 and 4, where the Col allele showed positive and negative effects on the Al tolerance. These QTLs could explain about 43% of the total variation of Al tolerance among the RI population. On the other hand, five epistatic loci pairs were identified by the complete pair-wise search method (P<0.0005). No single factor QTL and epistatic loci pairs were shared by the root length in the control and the RRL, suggesting that the loci identified by the RRL would be specific for Al treatment and controlling Al tolerance among the RI population.
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Affiliation(s)
- Yuriko Kobayashi
- Laboratory of Plant Cell Technology, Faculty of Agriculture, Gifu University, 1-1 Yanagido, Gifu, 501-1193 Japan
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63
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Clemens S, Palmgren MG, Krämer U. A long way ahead: understanding and engineering plant metal accumulation. TRENDS IN PLANT SCIENCE 2002; 7:309-15. [PMID: 12119168 DOI: 10.1016/s1360-1385(02)02295-1] [Citation(s) in RCA: 513] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Some plants can hyperaccumulate metal ions that are toxic to virtually all other organisms at low dosages. This trait could be used to clean up metal-contaminated soils. Moreover, the accumulation of heavy metals by plants determines both the micronutrient content and the toxic metal content of our food. Complex interactions of transport and chelating activities control the rates of metal uptake and storage. In recent years, several key steps have been identified at the molecular level, enabling us to initiate transgenic approaches to engineer the transition metal content of plants.
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Affiliation(s)
- Stephan Clemens
- Leibniz Institute of Plant Biochemistry, Weinberg 3, D-06120 Halle, Germany.
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64
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Neumann G, Martinoia E. Cluster roots--an underground adaptation for survival in extreme environments. TRENDS IN PLANT SCIENCE 2002; 7:162-167. [PMID: 11950612 DOI: 10.1016/s1360-1385(02)02241-0] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Cluster roots are a characteristic of members of the Proteaceae and of several other plant species that are adapted to habitats of extremely low soil fertility, usually without formation of mycorrhizal associations. Functionally linked with intense mobilization of nutrients (P, Fe, Zn, Mn) by root-induced chemical changes (pH, root exudates, redox potential) in the rhizosphere, cluster-rooted plant species can serve as model plants to study rhizosphere processes and regulatory aspects of plant adaptations for chemical mobilization of nutrients in the rhizosphere.
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Affiliation(s)
- Günter Neumann
- Institut für Planzenernährung (330), Universität Hohenheim, 70593 Stuttgart, Germany.
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65
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Grotz N, Guerinot ML. Limiting nutrients: an old problem with new solutions? CURRENT OPINION IN PLANT BIOLOGY 2002; 5:158-163. [PMID: 11856613 DOI: 10.1016/s1369-5266(02)00247-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Iron and phosphorus are essential minerals for both humans and plants. Advances in our understanding of the molecular mechanisms involved in the mobilization, transport and storage of these minerals now allow us to engineer plants to improve the yield and mineral nutrition of crops. Strategies range from increasing the expression of endogenous genes, such as that encoding the iron storage protein ferritin, to expressing a phytase gene from the fungus Aspergillus in Arabidopsis, thereby allowing the plants to obtain a previously unusable pool of phosphorus.
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Affiliation(s)
- Natasha Grotz
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA
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66
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Sasaki T, Ezaki B, Matsumoto H. A gene encoding multidrug resistance (MDR)-like protein is induced by aluminum and inhibitors of calcium flux in wheat. PLANT & CELL PHYSIOLOGY 2002; 43:177-185. [PMID: 11867697 DOI: 10.1093/pcp/pcf025] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A cDNA clone exclusively induced by aluminum (Al) was isolated from root apices of wheat (Triticum aestivum L.) by the differential display method. The predicted amino acid sequence exhibited homology to the multidrug resistance (MDR) proteins that is known as a member of the ATP-binding cassette (ABC) protein superfamily. Thus this gene was named TaMDR1 (Triticum aestivum MDR). TaMDR1 was induced as a function of Al concentration in the range from 5 to 50 microM, which is in the range of Al content in natural acid soil environment. The concentration required for the induction was lower in the Al-sensitive cultivar than in the Al-tolerant cultivar, indicating that the accumulation of TaMDR1 mRNA was associated with the events caused by Al toxicity rather than Al tolerance. TaMDR1 was significantly induced by the exposure to lanthanum, gadolinium and ruthenium red, which are known as inhibitors of calcium channels. Furthermore, decreasing of calcium ion in growth medium caused stimulation of the gene expression. These results suggested that the induction of TaMDR1 is caused by the breaking of calcium homeostasis which occurred at early stage of Al toxicity.
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Affiliation(s)
- Takayuki Sasaki
- Bio-oriented Technology Research Advancement Institution, Nisshin 1-40-2, Saitama, Saitama, 331-8537 Japan
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67
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Poirier Y, Bucher M. Phosphate transport and homeostasis in Arabidopsis. THE ARABIDOPSIS BOOK 2002; 1:e0024. [PMID: 22303200 PMCID: PMC3243343 DOI: 10.1199/tab.0024] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Affiliation(s)
- Yves Poirier
- Institute of Ecology, Laboratory of Plant Biotechnology, University of Lausanne, CH-1015 Lausanne, Switzerland, Fax, 41 21 692 4195;
| | - Marcel Bucher
- Federal Institute of Technology (ETH) Zurich, Biology Department, Institute of Plant Sciences, Plant Biochemistry & Physiology Group, Experimental Station Eschikon 33, CH-8315 Lindau, Switzerland, Fax, 41 52 354 9219;
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Abstract
As plant cells are highly compartmentalized, the entrance and exit points of metabolic pathways frequently involve membrane passages of solutes. Transport proteins are often located in strategic positions to control whole pathways and have to be considered in the development of metabolic engineering strategies. Here, we discuss examples of pathways (in carbohydrate metabolism, amino acid and secondary compound synthesis, and mineral metabolism) in which membrane transport steps are considered to exert major control and in which transport proteins have been employed to manipulate metabolic fluxes.
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Affiliation(s)
- Reinhard Kunze
- Botanical Institute, University of Cologne, Gyrhofstrasse 15, 50931 Cologne, Germany.
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69
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Tesfaye M, Temple SJ, Allan DL, Vance CP, Samac DA. Overexpression of malate dehydrogenase in transgenic alfalfa enhances organic acid synthesis and confers tolerance to aluminum. PLANT PHYSIOLOGY 2001; 127:1836-1844. [PMID: 11743127 DOI: 10.1104/pp.010376] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Al toxicity is a severe impediment to production of many crops in acid soil. Toxicity can be reduced through lime application to raise soil pH, however this amendment does not remedy subsoil acidity, and liming may not always be practical or cost-effective. Addition of organic acids to plant nutrient solutions alleviates phytotoxic Al effects, presumably by chelating Al and rendering it less toxic. In an effort to increase organic acid secretion and thereby enhance Al tolerance in alfalfa (Medicago sativa), we produced transgenic plants using nodule-enhanced forms of malate dehydrogenase and phosphoenolpyruvate carboxylase cDNAs under the control of the constitutive cauliflower mosaic virus 35S promoter. We report that a 1.6-fold increase in malate dehydrogenase enzyme specific activity in root tips of selected transgenic alfalfa led to a 4.2-fold increase in root concentration as well as a 7.1-fold increase in root exudation of citrate, oxalate, malate, succinate, and acetate compared with untransformed control alfalfa plants. Overexpression of phosphoenolpyruvate carboxylase enzyme specific activity in transgenic alfalfa did not result in increased root exudation of organic acids. The degree of Al tolerance by transformed plants in hydroponic solutions and in naturally acid soil corresponded with their patterns of organic acid exudation and supports the concept that enhancing organic acid synthesis in plants may be an effective strategy to cope with soil acidity and Al toxicity.
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Affiliation(s)
- M Tesfaye
- Department of Plant Pathology, University of Minnesota, St. Paul, Minnesota 55108, USA
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Tesfaye M, Temple SJ, Allan DL, Vance CP, Samac DA. Overexpression of malate dehydrogenase in transgenic alfalfa enhances organic acid synthesis and confers tolerance to aluminum. PLANT PHYSIOLOGY 2001. [PMID: 11743127 DOI: 10.1007/s11738-010-0522-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Al toxicity is a severe impediment to production of many crops in acid soil. Toxicity can be reduced through lime application to raise soil pH, however this amendment does not remedy subsoil acidity, and liming may not always be practical or cost-effective. Addition of organic acids to plant nutrient solutions alleviates phytotoxic Al effects, presumably by chelating Al and rendering it less toxic. In an effort to increase organic acid secretion and thereby enhance Al tolerance in alfalfa (Medicago sativa), we produced transgenic plants using nodule-enhanced forms of malate dehydrogenase and phosphoenolpyruvate carboxylase cDNAs under the control of the constitutive cauliflower mosaic virus 35S promoter. We report that a 1.6-fold increase in malate dehydrogenase enzyme specific activity in root tips of selected transgenic alfalfa led to a 4.2-fold increase in root concentration as well as a 7.1-fold increase in root exudation of citrate, oxalate, malate, succinate, and acetate compared with untransformed control alfalfa plants. Overexpression of phosphoenolpyruvate carboxylase enzyme specific activity in transgenic alfalfa did not result in increased root exudation of organic acids. The degree of Al tolerance by transformed plants in hydroponic solutions and in naturally acid soil corresponded with their patterns of organic acid exudation and supports the concept that enhancing organic acid synthesis in plants may be an effective strategy to cope with soil acidity and Al toxicity.
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Affiliation(s)
- M Tesfaye
- Department of Plant Pathology, University of Minnesota, St. Paul, Minnesota 55108, USA
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71
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Ma JF, Ryan PR, Delhaize E. Aluminium tolerance in plants and the complexing role of organic acids. TRENDS IN PLANT SCIENCE 2001; 6:273-8. [PMID: 11378470 DOI: 10.1016/s1360-1385(01)01961-6] [Citation(s) in RCA: 576] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The aluminium cation Al(3+) is toxic to many plants at micromolar concentrations. A range of plant species has evolved mechanisms that enable them to grow on acid soils where toxic concentrations of Al(3+) can limit plant growth. Organic acids play a central role in these aluminium tolerance mechanisms. Some plants detoxify aluminium in the rhizosphere by releasing organic acids that chelate aluminium. In at least two species, wheat and maize, the transport of organic acid anions out of the root cells is mediated by aluminium-activated anion channels in the plasma membrane. Other plants, including species that accumulate aluminium in their leaves, detoxify aluminium internally by forming complexes with organic acids.
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Affiliation(s)
- J F Ma
- Faculty of Agriculture, Kagawa University, Ikenobe 2393, Miki-cho, Kita-gun, 761-0795, Kagawa, Japan.
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Ryan PR, Delhaize E, Jones DL. FUNCTION AND MECHANISM OF ORGANIC ANION EXUDATION FROM PLANT ROOTS. ANNUAL REVIEW OF PLANT PHYSIOLOGY AND PLANT MOLECULAR BIOLOGY 2001; 52:527-560. [PMID: 11337408 DOI: 10.1146/annurev.arplant.52.1.527] [Citation(s) in RCA: 537] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The rhizosphere is the zone of soil immediately surrounding plant roots that is modified by root activity. In this critical zone, plants perceive and respond to their environment. As a consequence of normal growth and development, a large range of organic and inorganic substances are exchanged between the root and soil, which inevitably leads to changes in the biochemical and physical properties of the rhizosphere. Plants also modify their rhizosphere in response to certain environmental signals and stresses. Organic anions are commonly detected in this region, and their exudation from plant roots has now been associated with nutrient deficiencies and inorganic ion stresses. This review summarizes recent developments in the understanding of the function, mechanism, and regulation of organic anion exudation from roots. The benefits that plants derive from the presence of organic anions in the rhizosphere are described and the potential for biotechnology to increase organic anion exudation is highlighted.
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Affiliation(s)
- PR Ryan
- CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia; e-mail: ; , School of Agricultural and Forest Sciences, University of Wales, Bangor, Gwynedd, LL57 2UW, United Kingdom; e-mail:
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