International Journal of Molecular Sciences

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14 pages, 4176 KiB

Open AccessArticle

Molecular Characterization of ZosmaNRT2, the Putative Sodium Dependent High-Affinity Nitrate Transporter of Zostera marina L.

by Lourdes Rubio, Jordi Díaz-García, Vítor Amorim-Silva, Alberto P. Macho, Miguel A. Botella and José A. Fernández

Int. J. Mol. Sci. 2019, 20(15), 3650; https://doi.org/10.3390/ijms20153650 - 26 Jul 2019

Cited by 5 | Viewed by 3381

Abstract

One of the most important adaptations of seagrasses during sea colonization was the capacity to grow at the low micromolar nitrate concentrations present in the sea. In contrast to terrestrial plants that use H⁺ symporters for high-affinity NO₃⁻ uptake, seagrasses [...] Read more.

One of the most important adaptations of seagrasses during sea colonization was the capacity to grow at the low micromolar nitrate concentrations present in the sea. In contrast to terrestrial plants that use H⁺ symporters for high-affinity NO₃⁻ uptake, seagrasses such as Zostera marina L. use a Na⁺-dependent high-affinity nitrate transporter. Interestingly, in the Z. marina genome, only one gene (Zosma70g00300.1; NRT2.1) is annotated to this function. Analysis of this sequence predicts the presence of 12 transmembrane domains, including the MFS domains of the NNP transporter family and the “nitrate signature” that appears in all members of the NNP family. Phylogenetic analysis shows that this sequence is more related to NRT2.5 than to NRT2.1, sharing a common ancestor with both monocot and dicot plants. Heterologous expression of ZosmaNRT2-GFP together with the high-affinity nitrate transporter accessory protein ZosmaNAR2 (Zosma63g00220.1) in Nicotiana benthamiana leaves displayed four-fold higher fluorescence intensity than single expression of ZosmaNRT2-GFP suggesting the stabilization of NRT2 by NAR2. ZosmaNRT2-GFP signal was present on the Hechtian-strands in the plasmolyzed cells, pointing that ZosmaNRT2 is localized on the plasma membrane and that would be stabilized by ZosmaNAR2. Taken together, these results suggest that Zosma70g00300.1 would encode a high-affinity nitrate transporter located at the plasma membrane, equivalent to NRT2.5 transporters. These molecular data, together with our previous electrophysiological results support that ZosmaNRT2 would have evolved to use Na⁺ as a driving ion, which might be an essential adaptation of seagrasses to colonize marine environments. Full article

(This article belongs to the Special Issue Uptake and Compartmentalisation of Mineral Nutrients in Plants)

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19 pages, 4278 KiB

Open AccessArticle

Characterization of the Copper Transporters from Lotus spp. and Their Involvement under Flooding Conditions

by Francisco J. Escaray, Cristian J. Antonelli, Guillermo J. Copello, Sergi Puig, Lola Peñarrubia, Oscar A. Ruiz and Ana Perea-García

Int. J. Mol. Sci. 2019, 20(13), 3136; https://doi.org/10.3390/ijms20133136 - 27 Jun 2019

Cited by 8 | Viewed by 2878

Abstract

Forage legumes are an important livestock nutritional resource, which includes essential metals, such as copper. Particularly, the high prevalence of hypocuprosis causes important economic losses to Argentinian cattle agrosystems. Copper deficiency in cattle is partially due to its low content in forage produced [...] Read more.

Forage legumes are an important livestock nutritional resource, which includes essential metals, such as copper. Particularly, the high prevalence of hypocuprosis causes important economic losses to Argentinian cattle agrosystems. Copper deficiency in cattle is partially due to its low content in forage produced by natural grassland, and is exacerbated by flooding conditions. Previous results indicated that incorporation of Lotus spp. into natural grassland increases forage nutritional quality, including higher copper levels. However, the biological processes and molecular mechanisms involved in copper uptake by Lotus spp. remain poorly understood. Here, we identify four genes that encode putative members of the Lotus copper transporter family, denoted COPT in higher plants. A heterologous functional complementation assay of the Saccharomyces cerevisiae ctr1∆ctr3∆ strain, which lacks the corresponding yeast copper transporters, with the putative Lotus COPT proteins shows a partial rescue of the yeast phenotypes in restrictive media. Under partial submergence conditions, the copper content of L. japonicus plants decreases and the expression of two Lotus COPT genes is induced. These results strongly suggest that the Lotus COPT proteins identified in this work function in copper uptake. In addition, the fact that environmental conditions affect the expression of certain COPT genes supports their involvement in adaptive mechanisms and envisages putative biotechnological strategies to improve cattle copper nutrition. Full article

(This article belongs to the Special Issue Uptake and Compartmentalisation of Mineral Nutrients in Plants)

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18 pages, 2100 KiB

Open AccessArticle

High External K⁺ Concentrations Impair Pi Nutrition, Induce the Phosphate Starvation Response, and Reduce Arsenic Toxicity in Arabidopsis Plants

by Reyes Ródenas, Vicente Martínez, Manuel Nieves-Cordones and Francisco Rubio

Int. J. Mol. Sci. 2019, 20(9), 2237; https://doi.org/10.3390/ijms20092237 - 7 May 2019

Cited by 17 | Viewed by 4883

Abstract

Potassium (K⁺) and phosphorous (Pi) are two of the most important nutrients required by plants and there is an interest in studying how they are acquired. Most studies have focused on the characterization of the mechanisms involved in K⁺ and [...] Read more.

Potassium (K⁺) and phosphorous (Pi) are two of the most important nutrients required by plants and there is an interest in studying how they are acquired. Most studies have focused on the characterization of the mechanisms involved in K⁺ and Pi uptake and their distribution within the plants, as well as the regulatory mechanisms involved. Evidence is emerging which points to interactions in the nutrition of different nutrients and to the existence of crosstalk in the signaling cascades regulating their acquisition. However, the interaction between K⁺ and Pi has been scarcely studied. Here we show that high concentrations of K⁺ in the external solution inhibit Pi uptake and impair Pi nutrition in Arabidopsis plants, resulting in the induction of phosphate starvation response (PSR) and the upregulation of genes encoding root phosphate uptake systems. The high K⁺-induced PSR depends on the PHR1 and PHL1 transcription factors that are key pieces of Pi signaling in Arabidopsis. Importantly, high K⁺ reduces arsenic accumulation in plants and its toxic effects. The results presented may help to design strategies to reduce Pi deficiency as well as the accumulation of arsenic in crops. Full article

(This article belongs to the Special Issue Uptake and Compartmentalisation of Mineral Nutrients in Plants)

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Review

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32 pages, 2026 KiB

Open AccessReview

Chloride as a Beneficial Macronutrient in Higher Plants: New Roles and Regulation

by José M. Colmenero-Flores, Juan D. Franco-Navarro, Paloma Cubero-Font, Procopio Peinado-Torrubia and Miguel A. Rosales

Int. J. Mol. Sci. 2019, 20(19), 4686; https://doi.org/10.3390/ijms20194686 - 21 Sep 2019

Cited by 86 | Viewed by 8783

Abstract

Chloride (Cl⁻) has traditionally been considered a micronutrient largely excluded by plants due to its ubiquity and abundance in nature, its antagonism with nitrate (NO₃⁻), and its toxicity when accumulated at high concentrations. In recent years, there has [...] Read more.

Chloride (Cl⁻) has traditionally been considered a micronutrient largely excluded by plants due to its ubiquity and abundance in nature, its antagonism with nitrate (NO₃⁻), and its toxicity when accumulated at high concentrations. In recent years, there has been a paradigm shift in this regard since Cl⁻ has gone from being considered a harmful ion, accidentally absorbed through NO₃⁻ transporters, to being considered a beneficial macronutrient whose transport is finely regulated by plants. As a beneficial macronutrient, Cl⁻ determines increased fresh and dry biomass, greater leaf expansion, increased elongation of leaf and root cells, improved water relations, higher mesophyll diffusion to CO₂, and better water- and nitrogen-use efficiency. While optimal growth of plants requires the synchronic supply of both Cl⁻ and NO₃⁻ molecules, the NO₃⁻/Cl⁻ plant selectivity varies between species and varieties, and in the same plant it can be modified by environmental cues such as water deficit or salinity. Recently, new genes encoding transporters mediating Cl⁻ influx (ZmNPF6.4 and ZmNPF6.6), Cl⁻ efflux (AtSLAH3 and AtSLAH1), and Cl⁻ compartmentalization (AtDTX33, AtDTX35, AtALMT4, and GsCLC2) have been identified and characterized. These transporters have proven to be highly relevant for nutrition, long-distance transport and compartmentalization of Cl⁻, as well as for cell turgor regulation and stress tolerance in plants. Full article

(This article belongs to the Special Issue Uptake and Compartmentalisation of Mineral Nutrients in Plants)

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16 pages, 625 KiB

Open AccessReview

Exploring the Relationship between Crassulacean Acid Metabolism (CAM) and Mineral Nutrition with a Special Focus on Nitrogen

by Paula Natália Pereira and John C. Cushman

Int. J. Mol. Sci. 2019, 20(18), 4363; https://doi.org/10.3390/ijms20184363 - 5 Sep 2019

Cited by 14 | Viewed by 4054

Abstract

Crassulacean acid metabolism (CAM) is characterized by nocturnal CO₂ uptake and concentration, reduced photorespiration, and increased water-use efficiency (WUE) when compared to C₃ and C₄ plants. Plants can perform different types of CAM and the magnitude and duration of CAM [...] Read more.

Crassulacean acid metabolism (CAM) is characterized by nocturnal CO₂ uptake and concentration, reduced photorespiration, and increased water-use efficiency (WUE) when compared to C₃ and C₄ plants. Plants can perform different types of CAM and the magnitude and duration of CAM expression can change based upon several abiotic conditions, including nutrient availability. Here, we summarize the abiotic factors that are associated with an increase in CAM expression with an emphasis on the relationship between CAM photosynthesis and nutrient availability, with particular focus on nitrogen, phosphorus, potassium, and calcium. Additionally, we examine nitrogen uptake and assimilation as this macronutrient has received the greatest amount of attention in studies using CAM species. We also discuss the preference of CAM species for different organic and inorganic sources of nitrogen, including nitrate, ammonium, glutamine, and urea. Lastly, we make recommendations for future research areas to better understand the relationship between macronutrients and CAM and how their interaction might improve nutrient and water-use efficiency in order to increase the growth and yield of CAM plants, especially CAM crops that may become increasingly important as global climate change continues. Full article

(This article belongs to the Special Issue Uptake and Compartmentalisation of Mineral Nutrients in Plants)

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25 pages, 1348 KiB

Open AccessReview

How Plants Handle Trivalent (+3) Elements

by Charlotte Poschenrieder, Silvia Busoms and Juan Barceló

Int. J. Mol. Sci. 2019, 20(16), 3984; https://doi.org/10.3390/ijms20163984 - 16 Aug 2019

Cited by 29 | Viewed by 5663

Abstract

Plant development and fitness largely depend on the adequate availability of mineral elements in the soil. Most essential nutrients are available and can be membrane transported either as mono or divalent cations or as mono- or divalent anions. Trivalent cations are highly toxic [...] Read more.

Plant development and fitness largely depend on the adequate availability of mineral elements in the soil. Most essential nutrients are available and can be membrane transported either as mono or divalent cations or as mono- or divalent anions. Trivalent cations are highly toxic to membranes, and plants have evolved different mechanisms to handle +3 elements in a safe way. The essential functional role of a few metal ions, with the possibility to gain a trivalent state, mainly resides in the ion’s redox activity; examples are iron (Fe) and manganese. Among the required nutrients, the only element with +3 as a unique oxidation state is the non-metal, boron. However, plants also can take up non-essential trivalent elements that occur in biologically relevant concentrations in soils. Examples are, among others, aluminum (Al), chromium (Cr), arsenic (As), and antimony (Sb). Plants have evolved different mechanisms to take up and tolerate these potentially toxic elements. This review considers recent studies describing the transporters, and specific and unspecific channels in different cell compartments and tissues, thereby providing a global vision of trivalent element homeostasis in plants. Full article

(This article belongs to the Special Issue Uptake and Compartmentalisation of Mineral Nutrients in Plants)

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15 pages, 946 KiB

Open AccessReview

The Role of Soil Fungi in K⁺ Plant Nutrition

by Rosario Haro and Begoña Benito

Int. J. Mol. Sci. 2019, 20(13), 3169; https://doi.org/10.3390/ijms20133169 - 28 Jun 2019

Cited by 35 | Viewed by 6115

Abstract

K⁺ is an essential cation and the most abundant in plant cells. After N, its corresponding element, K, is the nutrient required in the largest amounts by plants. Despite the numerous roles of K in crop production, improvements in the uptake and [...] Read more.

K⁺ is an essential cation and the most abundant in plant cells. After N, its corresponding element, K, is the nutrient required in the largest amounts by plants. Despite the numerous roles of K in crop production, improvements in the uptake and efficiency of use of K have not been major focuses in conventional or transgenic breeding studies in the past. In research on the mineral nutrition of plants in general, and K in particular, this nutrient has been shown to be essential to soil-dwelling-microorganisms (fungi, bacteria, protozoa, nematodes, etc.) that form mutualistic associations and that can influence the availability of mineral nutrients for plants. Therefore, this article aims to provide an overview of the role of soil microorganisms in supplying K⁺ to plants, considering both the potassium-solubilizing microorganisms and the potassium-facilitating microorganisms that are in close contact with the roots of plants. These microorganisms can influence the active transporter-mediated transfer of K⁺. Regarding the latter group of microorganisms, special focus is placed on the role of endophytic fungus. This review also includes a discussion on productivity through sustainable agriculture. Full article

(This article belongs to the Special Issue Uptake and Compartmentalisation of Mineral Nutrients in Plants)

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27 pages, 3768 KiB

Open AccessReview

Dual Role of Metallic Trace Elements in Stress Biology—From Negative to Beneficial Impact on Plants

by Ewa Muszyńska and Mateusz Labudda

Int. J. Mol. Sci. 2019, 20(13), 3117; https://doi.org/10.3390/ijms20133117 - 26 Jun 2019

Cited by 77 | Viewed by 6119

Abstract

Heavy metals are an interesting group of trace elements (TEs). Some of them are minutely required for normal plant growth and development, while others have unknown biological actions. They may cause injury when they are applied in an elevated concentration, regardless of the [...] Read more.

Heavy metals are an interesting group of trace elements (TEs). Some of them are minutely required for normal plant growth and development, while others have unknown biological actions. They may cause injury when they are applied in an elevated concentration, regardless of the importance for the plant functioning. On the other hand, their application may help to alleviate various abiotic stresses. In this review, both the deleterious and beneficial effects of metallic trace elements from their uptake by roots and leaves, through toxicity, up to the regulation of physiological and molecular mechanisms that are associated with plant protection against stress conditions have been briefly discussed. We have highlighted the involvement of metallic ions in mitigating oxidative stress by the activation of various antioxidant enzymes and emphasized the phenomenon of low-dose stimulation that is caused by non-essential, potentially poisonous elements called hormesis, which is recently one of the most studied issues. Finally, we have described the evolutionary consequences of long-term exposure to metallic elements, resulting in the development of unique assemblages of vegetation, classified as metallophytes, which constitute excellent model systems for research on metal accumulation and tolerance. Taken together, the paper can provide a novel insight into the toxicity concept, since both dose- and genotype-dependent response to the presence of metallic trace elements has been comprehensively explained. Full article

(This article belongs to the Special Issue Uptake and Compartmentalisation of Mineral Nutrients in Plants)

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37 pages, 4502 KiB

Open AccessReview

Saccharomyces cerevisiae as a Tool to Investigate Plant Potassium and Sodium Transporters

by Antonella Locascio, Nuria Andrés-Colás, José Miguel Mulet and Lynne Yenush

Int. J. Mol. Sci. 2019, 20(9), 2133; https://doi.org/10.3390/ijms20092133 - 30 Apr 2019

Cited by 18 | Viewed by 7265

Abstract

Sodium and potassium are two alkali cations abundant in the biosphere. Potassium is essential for plants and its concentration must be maintained at approximately 150 mM in the plant cell cytoplasm including under circumstances where its concentration is much lower in soil. On [...] Read more.

Sodium and potassium are two alkali cations abundant in the biosphere. Potassium is essential for plants and its concentration must be maintained at approximately 150 mM in the plant cell cytoplasm including under circumstances where its concentration is much lower in soil. On the other hand, sodium must be extruded from the plant or accumulated either in the vacuole or in specific plant structures. Maintaining a high intracellular K⁺/Na⁺ ratio under adverse environmental conditions or in the presence of salt is essential to maintain cellular homeostasis and to avoid toxicity. The baker’s yeast, Saccharomyces cerevisiae, has been used to identify and characterize participants in potassium and sodium homeostasis in plants for many years. Its utility resides in the fact that the electric gradient across the membrane and the vacuoles is similar to plants. Most plant proteins can be expressed in yeast and are functional in this unicellular model system, which allows for productive structure-function studies for ion transporting proteins. Moreover, yeast can also be used as a high-throughput platform for the identification of genes that confer stress tolerance and for the study of protein–protein interactions. In this review, we summarize advances regarding potassium and sodium transport that have been discovered using the yeast model system, the state-of-the-art of the available techniques and the future directions and opportunities in this field. Full article

(This article belongs to the Special Issue Uptake and Compartmentalisation of Mineral Nutrients in Plants)

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