Search

We, herein, report the synthesis of 13C2‐labeled natural products from the mugineic acid and avenic acid family. These phytosiderophores ("plant iron carriers") are built up from non‐proteinogenic amino acids and play a key role in micronutrient uptake in gramineous plants. In this work, two central building blocks are prepared from labeled starting materials (13C2‐bromoacetic acid, 13C2‐glycine) and further employed in our recently reported divergent, branched synthetic strategy delivering eight isotopically labeled phytosiderophores. The required labeled building blocks (13C2‐l‐allylglycine and a related hydroxylated derivative) were prepared via enantioselective phase‐transfer catalysis and enantio‐ and diastereoselective aldol condensation with a chiral auxiliary, respectively, both potentially valuable themselves for other synthetic routes toward labeled (natural) products. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is a very important cereal worldwide, since it is the staple food for more than half of the world's population. Iron (Fe) deficiency is among the most important agronomical concerns in calcareous soils where rice plants may suffer from this deficiency. Current production systems are based on the use of high-yielding varieties and the application of large quantities of agrochemicals, which can cause major environmental problems. The use of beneficial rhizosphere microorganisms is considered a relevant sustainable alternative to synthetic fertilizers. The main goal of this study was to determine the ability of the nonpathogenic strain Fusarium oxysporum FO12 to induce Fe-deficiency responses in rice plants and its effects on plant growth and Fe chlorosis. Experiments were carried out under hydroponic system conditions. Our results show that the root inoculation of rice plants with FO12 promotes the production of phytosiderophores and plant growth while reducing Fe chlorosis symptoms after several days of cultivation. Moreover, Fe-related genes are upregulated by FO12 at certain times in inoculated plants regardless of Fe conditions. This microorganism also colonizes root cortical tissues. In conclusion, FO12 enhances Fe-deficiency responses in rice plants, achieves growth promotion, and reduces Fe chlorosis symptoms. [ABSTRACT FROM AUTHOR]

Les atteintes des articulations carpo-métacarpiennes ne se limitent pas aux rhizarthroses. Certains traumatismes sévères peuvent induire des luxations des articulations carpo-métacarpiennes II à V, et des impacts répétés peuvent aussi induire leur arthrose précoce avec (carpe bossu), mais aussi sans ostéophytose dorsale. Ces arthroses sont facilitées par des ossicules surnuméraires entre les carpo-métacarpiennes II et III. Les arthrites chroniques juvéniles et de l'adulte peuvent aussi induire des érosions précoces des carpo-métacarpiennes. Les travaux récents sur la pathogénie des rhizarthroses attribuent un rôle central à une instabilité acquise de la 1re carpo-métacarpienne dans la genèse des douleurs (d'origine surtout capsulaire, lors des mouvements de cisaillement). Les lésions osseuses semblent plus source de raideurs et malpositions. Ceci explique la nette prédominance féminine, et l'absence de corrélation fréquente entre douleurs et chondrolyse/ostéophytose. Cette instabilité peut résulter de dysplasies du trapèze, mais surtout de distensions de certains des 16 ligaments ceinturant l'articulation, dont le 'beak-ligament' intra-articulaire. Leur atteinte affecte aussi la qualité de verrouillage de la 1re carpo-métacarpienne par les muscles qui s'insèrent à la base du 1er métacarpien. Ceci explique que le traitement de référence non-chirurgical reste le port durable d'une attelle rigide. Les études randomisées versus placebo de corticoïdes ou d'acide hyaluronique n'ont pour l'instant pas démontré de nette efficacité. Du fait d'une évolution naturelle fréquente vers l'amélioration spontanée des rhizarthroses, il faut n'adresser au chirurgien que les patients au contexte psychologique favorable, et après un délai suffisant de traitement médical, mais plus tôt si une subluxation dorsale de la base du 1er métacarpien est durablement documentée. Carpometacarpal (CMCs) joints II to V can also be sources of pain, either following serious injuries with luxations of CMCs II to V, or chronic stresses leading to osteoarthritis, with (carpal boss) or without dorsal osteophytosis. These osteoarthritis can be fostered by surnumerous ossicles between CMC II and III. Early erosions of CMC II to V are frequently observed in juvenile chronic polyarthritis, whereas only chondrolysis occurs in most adult polyarthritis. Recent works on CMC-1 osteoarthritis point to a central role of instability, chondrolysis and osteophytosis being responsible for stiffness but poorly associated with pain, which seems to arise mostly from capsular stretching during shearing stresses. The CMC-1 instability can result from trapezal dysplasia and/or various lesions of the 16 ligaments stabilizing this joint, including the beak ligament (which also leads to less efficient thenar muscle contractions). Secretion of relaxin may account for such increased instability and the greater and earlier occurrence of CMC-1 osteoarthritis in females. A rigid cast of the thumb seems the most effective non-surgical treatment. Double-blind randomised studies versus placebo could not demonstrate the usefulness of either corticosteroids or hyaluronan. Since spontaneous improvement of pain and disability are often noticed, surgery should not be considered before several months, but may be even more appropriate in patients with chronic dorsal sub-luxation of the first metacarpal bone. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is a very important cereal worldwide, since it is the staple food for more than half of the world’s population. Iron (Fe) deficiency is among the most important agronomical concerns in calcareous soils where rice plants may suffer from this deficiency. Current production systems are based on the use of high-yielding varieties and the application of large quantities of agrochemicals, which can cause major environmental problems. The use of beneficial rhizosphere microorganisms is considered a relevant sustainable alternative to synthetic fertilizers. The main goal of this study was to determine the ability of the nonpathogenic strain Fusarium oxysporum FO12 to induce Fe-deficiency responses in rice plants and its effects on plant growth and Fe chlorosis. Experiments were carried out under hydroponic system conditions. Our results show that the root inoculation of rice plants with FO12 promotes the production of phytosiderophores and plant growth while reducing Fe chlorosis symptoms after several days of cultivation. Moreover, Fe-related genes are upregulated by FO12 at certain times in inoculated plants regardless of Fe conditions. This microorganism also colonizes root cortical tissues. In conclusion, FO12 enhances Fe-deficiency responses in rice plants, achieves growth promotion, and reduces Fe chlorosis symptoms.

Intrinsic improvement of iron (Fe) concentration in rice grains, called rice Fe biofortification, is a promising countermeasure against widespread human Fe deficiency. In this study, two novel rice Fe biofortification approaches are reported. The first approach (Y approach) involved the expression of maize YELLOW STRIPE 1 controlled by the HEAVY METAL ATPASE 2 promoter. The Y approach increased the polished grain Fe concentrations up to 4.8-fold compared with the non-transgenic (NT) line. The second approach (T approach) involved the expression of rice TRANSPORTER OF MUGINEIC ACID 1 controlled by the FERRIC REDUCTASE DEFECTIVE LIKE 1 promoter. The T approach increased the polished grain Fe concentrations by up to 3.2-fold. No synergistic increases in the polished grain Fe concentrations were observed when Y and T approaches were combined (YT approach). However, the polished grain Fe concentrations further increased by 5.1- to 9.3-fold compared with the NT line, when YT approach was combined with the endosperm-specific expression of FERRITIN (YTF approach), or when YTF approach was combined with the constitutive expression of NICOTIANAMINE SYNTHASE (YTFN approach). Total grain weight per plant in most Y, T, YT, and YTFN lines was comparable to that in the NT line, while it was significantly decreased in most YTF lines. The novel approaches reported in this study expand the portfolio of genetic engineering strategies that can be used for Fe biofortification in rice. [ABSTRACT FROM AUTHOR]

Iron is an essential element for all living organisms. The ability of plants to absorb inorganic iron from soil is important not only for plants but also for mammals, which ultimately rely on plants as their nutrient source. In contrast to most plant species, Poaceae plants, including rice, have developed a distinct chelation strategy to efficiently acquire insoluble soil iron using iron-chelating substances such as mugineic acid (MAs), called phytosiderophores. Genes involved in the biosynthesis and transport of MAs and their resulting iron(III)-MA complexes across membranes have been identified. On the other hand, an efficient short-step synthesis of the substrates MA and 2′-deoxymugineic acid (DMA) has enabled a sufficient supply of these compounds. Furthermore, owing to the chemical synthesis of proline-2′-deoxymugineic acid (PDMA), a cost-effective analog of DMA, the eff ectiveness of phytosiderophores in promoting rice growth in alkaline soil has been demonstrated at an experimental fi eld scale. Nicotianamine (NA), an MAs precursor essential for metal translocation within plant tissues, was recently shown to be absorbed as an iron(II) complex in the mouse small intestine by an amino acid transporter. The discovery of the biological role of NA in iron absorption by the small intestine not only highlights the biological significance of NA across the plant and animal kingdoms but also opens new possibilities for biofortification approaches. Here, we discuss the recent findings in MA research in terms of plant growth, application in agriculture, and the emerging nutraceutical value of NA in iron absorption in mammals. [ABSTRACT FROM AUTHOR]

Nicotianamine (NA) is one of the metal-chelating molecules found in higher plants in abundance. Synthesized by the enzyme nicotianamine synthase, NA has a major role in the transport of iron in plant tissues. This research paper deals with the coordination chemistry of the possible complexes of NA, [FeII (NA)]−, and [FeIII (NA)] in detail, from a theoretical standpoint. The chemical computations on the [FeII (NA)]− and [FeIII (NA)] complexes show that NA can bind with both Fe (+ 2) and Fe (+ 3) ions. The calculations confirm that the [FeIII (NA)] is thermodynamically more stable in comparison with [FeII (NA)]−, while [FeII (NA)]− is kinetically more stable than [FeIII (NA)]. Under the physiological conditions prevailing in plant tissues, [FeIII (NA)] can undergo reduction, but the auto-oxidation of [FeII (NA)]− to [FeIII (NA)] is prevented. In summary, NA can translocate Fe ions within plant tissues, wherever required, both as Fe (+ 2) and Fe (+ 3) complexes. [ABSTRACT FROM AUTHOR]

Background: Nicotianamine (NA), 2′-deoxymugineic acid (DMA), and mugineic acid (MA) are chelators required for iron uptake and transport in plants. Nicotianamine aminotransferase (NAAT), 2′-deoxymugineic acid synthase (DMAS), transporter of MAs (TOM), and efflux transporter of NA (ENA) are involved in iron uptake and transport in rice (Oryza sativa), wheat (Triticum aestivum), and barley (Hordeum vulgare); however, these families have not been fully identified and comprehensively analyzed in maize (Zea mays L.). Results: Here, we identified 5 ZmNAAT, 9 ZmDMAS, 11 ZmTOM, and 2 ZmENA genes by genome mining. RNA-sequencing and quantitative real-time PCR analysis revealed that these genes are expressed in various tissues and respond differently to high and low iron conditions. In particular, iron deficiency stimulated the expression of ZmDMAS1, ZmTOM1, ZmTOM3, and ZmENA1. Furthermore, we determined protein subcellular localization by transient expression of green fluorescent protein fusions in maize mesophyll protoplasts. ZmNAAT1, ZmNAAT-L4, ZmDMAS1, and ZmDMAS-L1 localized in the cytoplasm, whereas ZmTOMs and ZmENAs targeted to plasma and tonoplast membranes, endomembranes, and vesicles. Conclusions: Our results suggest that the different gene expression profiles and subcellular localizations of ZmNAAT, ZmDMAS, ZmTOM, and ZmENA family members may enable specific regulation of phytosiderophore metabolism in different tissues and under different external conditions, shedding light on iron homeostasis in maize and providing candidate genes for breeding iron-rich maize varieties. [ABSTRACT FROM AUTHOR]

Most plant species develop stress symptoms when exposed to high ammonium (NH4+) concentrations. The root is the first organ in contact with high NH4+ and therefore the first barrier to cope with ammonium stress. In this work, we focused on root adaptation to ammonium nutrition in the model plant Brachypodium distachyon. Proteome analysis revealed changes associated with primary metabolism, cell wall remodelling, and redox homeostasis. In addition, it showed a strong induction of proteins related to methionine (Met) metabolism and phytosiderophore (PS) synthesis in ammonium-fed plants. In agreement with this, we show how ammonium nutrition impacts Met/ S -adenosyl-Met and PS metabolic pathways together with increasing root iron content. Nevertheless, ammonium-fed plants displayed higher sensitivity to iron deficiency, suggesting that ammonium nutrition triggers impaired iron utilization and root to shoot transport, which entailed an induction in iron-related responses. Overall, this work demonstrates the importance of iron homeostasis during ammonium nutrition and paves a new way to better understand and improve ammonium use efficiency and tolerance. [ABSTRACT FROM AUTHOR]

This study investigates the influence of arsenic (As) and iron (Fe) on the molecular aspects of rice plants. The mRNA-abundance of As (OsLsi , OsPHT , OsNRAMP1 , OsABCC1) and Fe (OsIRT , OsNRAMP1 , OsYSL, OsFRDL1 , OsVIT2 , OsSAMS1 , OsNAS, OsNAAT1 , OsDMAS1 , OsTOM1 , OsFER) related genes has been observed in 12-d old As and Fe impacted rice varieties. Analyses of phytosiderophores synthesis and Fe-uptake genes affirm the existence of specialized Fe-uptake strategies in rice with varieties PB-1 and Varsha favouring strategy I and II, respectively. Expression of OsNAS3, OsVIT2, OsFER and OsABCC1 indicated PB-1′s tolerance towards Fe and As. Analysis of mitogen-activated protein kinase cascade members (OsMKK3 , OsMKK4 , OsMKK6 , OsMPK3 , OsMPK4 , OsMPK7 , and OsMPK14) revealed their importance in the fine adjustment of As/Fe in the rice system. A conditional network map was generated based on the gene expression pattern that unfolded the differential dynamics of both rice varieties. The mating based split ubiquitin system determined the interaction of OsIRT1 with OsMPK3, and OsLsi1 with both OsMPK3 and OsMPK4. In-silico tools also confirmed the binding affinities of OsARM1 with OsLsi1, OsMPK3 and OsMPK4, and of OsIDEF1/OsIRO2 with OsIRT1 and OsMPK3, supporting our hypothesis that OsARM1, OsIDEF1, OsIRO2 were active in the connections discovered by mbSUS. [Display omitted] • Iron (Fe) affects arsenic (As)-transporter gene's regulation in rice plants. • Studied rice varieties depicts variable Fe-uptake strategies. • MAPKs are responsive to the plant's As and Fe levels. • OsMPK3 interacts with both OsLsi1 and OsIRT1. [ABSTRACT FROM AUTHOR]

Phytosiderophores (PS) are root exudates released by grass species (Poaceae) that play a pivotal role in iron (Fe) plant nutrition. A direct determination of PS in biological samples is of paramount importance in understanding micronutrient acquisition mediated by PS. To date, eight plant-born PS have been identified; however, no analytical procedure is currently available to quantify all eight PS simultaneously with high analytical confidence. With access to the full set of PS standards for the first time, we report comprehensive methods to both fully characterize (IM-QTOFMS) and quantify (LC-ESI-MS/MS) all eight naturally occurring PS belonging to the mugineic acid family. The quantitative method was fully validated, yielding linear results for all eight analytes, and no unwanted interferences with soil and plant matrices were observed. LOD and LOQ values determined for each PS were below 11 and 35 nmol L−1, respectively. The method's precision under reproducibility conditions (intra- and inter-day) of measurement was less than 2.5% RSD for all analytes. Additionally, all PS were annotated with high-resolution mass spectrometric fragment spectra and further characterized via drift tube ion mobility-mass spectrometry. The collision cross-sections obtained for primary ion species yielded a valuable database for future research focused on in-depth PS studies. The new quantitative method was applied to analyse root exudates from Fe-controlled and deficient barley, oat, rye, and sorghum plants. All eight PS, including mugineic acid (MA), 3"-hydroxymugineic acid (HMA), 3"- epi -hydroxymugineic acid (epi -HMA), hydroxyavenic acid (HAVA), deoxymugineic acid (DMA), 3"-hydroxydeoxymugineic acid (HDMA), 3"- epi -hydroxydeoxymugineic acid (epi -HDMA) and avenic acid (AVA) were for the first time successfully identified and quantified in root exudates of various graminaceous plants using a single analytical procedure. These newly developed methods can be applied to studies aimed at improving crop yield and micronutrient grain content for food consumption via plant-based biofortification. [Display omitted] • Fully validated LC-ESI-MS/MS for PS quantification with internal standards. • Drift tube IM-QTOFMS characterization of PS. • MS library compilation including RT, fragment spectra, and DT CCS N2 for all analytes. • Quantification of PS in root exudates of graminaceous plants. [ABSTRACT FROM AUTHOR]

The major facilitator superfamily (MFS) is a large and diverse group of secondary transporters found across all kingdoms of life. Zinc-induced facilitator-like (ZIFL) transporters are the MFS family members that function as exporters driven by the antiporter-dependent processes. The presence of multiple ZIFL transporters was shown in various plant species, as well as in bryophytes. However, only a few ZIFLs have been functionally characterized in plants, and their localization has been suggested to be either on tonoplast or at the plasma membrane. A subset of the plant ZIFLs were eventually characterized as transporters due to their specialized role in phytosiderophores efflux and auxin homeostasis, and they were also proven to impart tolerance to micronutrient deficiency. The emerging functions of ZIFL proteins highlight their role in addressing important traits in crop species. This review aims to provide insight into and discuss the importance of plant ZIFL in various tissue-specific functions. Furthermore, a spotlight is placed on their role in mobilizing essential micronutrients, including iron and zinc, from the rhizosphere to support plant survival. In conclusion, in this paper, we discuss the functional redundancy of ZIFL transporters to understand their roles in developing specific traits in crop. [ABSTRACT FROM AUTHOR]