Explore the vast range of titles available.

Legumes control root nodule symbiosis (RNS) in response to environmental nitrogen availability. Despite the recent understanding of the molecular basis of external nitrate-mediated control of RNS, it remains mostly elusive how plants regulate physiological processes depending on internal nitrogen status. In addition, iron (Fe) acts as an essential element that enables symbiotic nitrogen fixation; however, the mechanism of Fe accumulation in nodules is poorly understood. Here, we focus on the transcriptome in response to internal nitrogen status during RNS in Lotus japonicus and identify that IRON MAN (IMA) peptide genes are expressed during symbiotic nitrogen fixation. We show that LjIMA1 and LjIMA2 expressed in the shoot and root play systemic and local roles in concentrating internal Fe to the nodule. Furthermore, IMA peptides have conserved roles in regulating nitrogen homeostasis by adjusting nitrogen-Fe balance in L. japonicus and Arabidopsis thaliana . These findings indicate that IMA-mediated Fe provision plays an essential role in regulating nitrogen-related physiological processes. The authors show IRON MAN peptides have an essential role in symbiotic nitrogen fixation during legume-rhizobium symbiosis. The peptides additionally function to regulate nitrogen homeostasis by controlling nitrogen-iron balance.

The endodermis acts as a “second skin” in plant roots by providing the cellular control necessary for the selective entry of water and solutes into the vascular system. To enable such control, Casparian strips span the cell wall of adjacent endodermal cells to form a tight junction that blocks extracellular diffusion across the endodermis. This junction is composed of lignin that is polymerized by oxidative coupling of monolignols through the action of a NADPH oxidase and peroxidases. Casparian strip domain proteins (CASPs) correctly position this biosynthetic machinery by forming a protein scaffold in the plasma membrane at the site where the Casparian strip forms. Here, we show that the dirigent-domain containing protein, enhanced suberin1 (ESB1), is part of this machinery, playing an essential role in the correct formation of Casparian strips. ESB1 is localized to Casparian strips in a CASP-dependent manner, and in the absence of ESB1, disordered and defective Casparian strips are formed. In addition, loss of ESB1 disrupts the localization of the CASP1 protein at the casparian strip domain, suggesting a reciprocal requirement for both ESB1 and CASPs in forming the casparian strip domain.

Biochemical reduction of nitrous oxide (N2O) to dinitrogen (N2) by N2O reductase (N2OR) is the only known sink to consume N2O. Copper (Cu) and pH are two key factors determining the activity of the enzyme N2OR. We hypothesized that changes in the Cu level could enhance the reduction of N2O to N2 in denitrifier strains and decrease the N2O emissions from agricultural soils. To test this hypothesis, Cu-modified culture medium was applied to denitrifier strains, and Cu-modified organic fertilizer was applied to both soil microcosms and fields. Of 46 denitrifier strains, 25 showed higher denitrifying activities and 30N2/(46N2O + 30N2) after the addition of Cu under pure culture conditions. Among 10 genera, Azospirillum and Herbaspirillum were the most responsive to the Cu level changes. The N2O flux was significantly reduced 4 or 8 days onwards after the application of 130 mM CuSO4-modified organic fertilizer (vol:wt = 1:1) into Andosol or Fluvisol, respectively, under soil microcosm conditions. In addition, the cumulative N2O emissions were significantly reduced after the application of 130 mM CuSO4-modified organic fertilizer. They were moderately reduced after the application of 130 mM CuSO4-modified organic fertilizer (vol:wt = 1:1) into a Fluvisol field. They were significantly lower in Azospirillum sp. UNPF1-inoculated soils after the application of 130 mM CuSO4-modified organic fertilizer when compared with that in dual non-inoculated and unmodified soils. Soils inoculated with Herbaspirillum sp. UKPF54 showed results similar to non-inoculated Fluvisol fields. These results suggest that Cu may enhance N2O conversion to N2 in denitrifiers and that Cu-modified organic fertilizer may enhance N2O consumption or decrease N2O emissions in agricultural soils.

The endodermis in roots acts as a selectivity filter for nutrient and water transport essential for growth and development. This selectivity is enabled by the formation of lignin-based Casparian strips. Casparian strip formation is initiated by the localization of the Casparian strip domain proteins (CASPs) in the plasma membrane, at the site where the Casparian strip will form. Localized CASPs recruit Peroxidase 64 (PER64), a Respiratory Burst Oxidase Homolog F, and Enhanced Suberin 1 (ESB1), a dirigent-like protein, to assemble the lignin polymerization machinery. However, the factors that control both expression of the genes encoding this biosynthetic machinery and its localization to the Casparian strip formation site remain unknown. Here, we identify the transcription factor, MYB36, essential for Casparian strip formation. MYB36 directly and positively regulates the expression of the Casparian strip genesCASP1, PER64,andESB1. Casparian strips are absent in plants lacking a functionalMYB36and are replaced by ectopic lignin-like material in the corners of endodermal cells. The barrier function of Casparian strips in these plants is also disrupted. Significantly, ectopic expression ofMYB36in the cortex is sufficient to reprogram these cells to start expressingCASP1–GFP, correctly localize the CASP1–GFP protein to form a Casparian strip domain, and deposit a Casparian strip-like structure in the cellwall at this location. These results demonstrate that MYB36 is controlling expression of the machinery required to locally polymerize lignin in a fine band in the cell wall for the formation of the Casparian strip.

Sustainable agriculture faces growing challenges in boosting food production while minimizing environmental impact, highlighting the need for innovative solutions. The \"plastics to fertilizers\" concept, which converts poly(isosorbide carbonate) (PIC) derived from plastic waste into urea and isosorbide, presents a promising approach, as we have previously reported (Abe in Green Chem 23:9030-9037, 2021). While urea’s role in plant nutrition is well established, the effect of isosorbide on plant growth and development remains largely unexplored. This study evaluates the impact of exogenous isosorbide treatment on Arabidopsis thaliana , aiming to unveil its potential as a biostimulant. Plants were grown in media with varying concentrations (0–10 mM) of isosorbide. Based on the optimal dose, determined by enhancements in shoot biomass and primary root length, we further analysed several parameters, including carbon and nitrogen content, carbon-to-nitrogen (C/N) ratio, nitrogen use efficiency (NUE), ionomic profiles, transcriptomic changes, and stress tolerance. Our results demonstrate that isosorbide treatment significantly promotes plant growth, with a significant increase in shoot biomass, improved C/N ratio, and enhanced NUE. Ionome analysis revealed altered distributions of essential elements in shoots and roots, indicating that isosorbide influence nutrient uptake and allocation. In addition, isosorbide enhanced plant growth under nitrogen deficiency and salt stress conditions. Transcriptomic analysis identified 447 differentially expressed genes in shoots and 327 in the roots, with significant enriched in pathways related to stress adaptation, metabolism, and hormonal regulation. Together, these findings provide novel insights into the biostimulant potential of isosorbide, highlighting its robust impact on plant growth and stress resilience while offering an innovative link between polymer recycling and sustainable agriculture.

The endodermis represents the main barrier to extracellular diffusion in plant roots, and it is central to current models of plant nutrient uptake. Despite this, little is known about the genes setting up this endodermal barrier. In this study, we report the identification and characterization of a strong barrier mutant, schengen3 (sgn3). We observe a surprising ability of the mutant to maintain nutrient homeostasis, but demonstrate a major defect in maintaining sufficient levels of the macronutrient potassium. We show that SGN3/GASSHO1 is a receptor-like kinase that is necessary for localizing CASPARIAN STRIP DOMAIN PROTEINS (CASPs)—major players of endodermal differentiation—into an uninterrupted, ring-like domain. SGN3 appears to localize into a broader band, embedding growing CASP microdomains. The discovery of SGN3 strongly advances our ability to interrogate mechanisms of plant nutrient homeostasis and provides a novel actor for localized microdomain formation at the endodermal plasma membrane. Plant roots forage in the soil for minerals and water, but they must also provide a barrier that stops these nutrients leaking back out of the plant and stops microbes invading and causing disease. The endodermis—an inner layer of cells that surrounds the veins that run along the middle of a root—acts as such a barrier in young roots. Polymers that repel water are deposited between the cells in the roots of almost all vascular plants—which include ferns, conifers, and flowering plants—to form a band around the endodermis called the ‘Casparian strip’. This strip seals off the young roots and stops water moving through the gaps between plant cells, but still allows minerals, nutrients, and water to be transported through the root cells and into the plant. However, the importance of this structure has yet to be tested due to the lack of mutant plants without a Casparian strip. Pfister et al. now report that deleting the gene that encodes a protein called SCHENGEN3 in the model plant Arabidopsis thaliana causes the Casparian strip to be interrupted by irregularly sized holes. This protein is normally found at high levels in the root endodermis, where it is embedded into the cell membranes. Pfister et al. also showed that without the SCHENGEN3 protein, other proteins called CASPs—that normally mark out a stripe around the root cells where the Casparian strip will form—only accumulated in discontinuous patches. Further experiments revealed that deleting the gene for SCHENGEN3 does not cause general problems in delivering the CASP proteins to the cell membrane; instead, it specifically stops the CASP proteins from forming a single, uninterrupted stripe. Unexpectedly, disrupting the Casparian strip did not appear to hinder many of the functions of a root. The mutant plants could still take up water and nutrients, and the leaves of mutant plants had normal levels of many essential minerals—with the exception of potassium. The level of this mineral was much lower in mutant plants without the SCHENGEN3 protein. Pfister et al. suggest that in plants that lack an intact Casparian strip, potassium is continuously leaked from the root into the soil. These findings reveal that in Arabidopsis, at least, the Casparian strip might not be as important as once thought for helping the plant to take up and accumulate water and nutrients. Further work is now needed to uncover the as yet unknown backup systems that might be able to compensate for the loss of this structure.

Accumulation of cadmium (Cd) in rice (Oryza sativa L.) grains poses a potential health problem, especially in Asia. Most Cd in rice grains accumulates through phloem transport, but the molecular mechanism of this transport has not been revealed. In this study, we identified a rice Cd transporter, OsLCT1, involved in Cd transport to the grains. OsLCT1-GFP was localized at the plasma membrane in plant cells, and OsLCT1 showed Cd efflux activity in yeast. In rice plants, strong OsLCT1 expression was observed in leaf blades and nodes during the reproductive stage. In the uppermost node, OsLCT1 transcripts were detected around large vascular bundles and in diffuse vascular bundles. RNAi-mediated knockdown of OsLCT1 did not affect xylem-mediated Cd transport but reduced phloem-mediated Cd transport. The knockdown plants of OsLCT1 accumulated approximately half as much Cd in the grains as did the control plants. The content of other metals in rice grains and plant growth were not negatively affected by OsLCT1 suppression. These results suggest that OsLCT1 functions at the nodes in Cd transport into grains and that in a standard japonica cultivar, the regulation of OsLCT1 enables the generation of \"low-Cd rice\" without negative effects on agronomical traits. These findings identify a transporter gene for phloem Cd transport in plants.

Molybdenum (Mo) is an essential micronutrient for plants, forming the Mo cofactor (Moco) necessary for molybdoenzyme activity. While only a single type of molybdate transporter (MOT) has been identified in plants, other Mo transporters remain unknown. In this study, we identified a novel Mo transporter gene, OsDISMO1 ( Oryza sativa Distributor of Molybdenum 1 ), through the characterization of a high Mo grain mutant in rice. Gene mapping of the mutant and the phenotype of knockout mutants demonstrated that OsDISMO1 is responsible for the observed mutant phenotype. Mo concentration analysis in various leaf tissues of three-week-old seedlings revealed higher Mo levels in the young leaves of the mutant compared to the wild type Hitomebore (HB), while the flag leaf of the mutant had lower Mo levels than the HB. OsDISMO1 promoter-GUS analysis indicated expression in the vascular bundles of shoots, particularly in the phloem. Additionally, a GFP-fused OsDISMO1 protein was localised to the endoplasmic reticulum (ER) membrane in rice protoplasts. The ability of OsDISMO1 to transport Mo was confirmed through heterologous expression in Saccharomyces cerevisiae . These findings suggest that OsDISMO1 is a Mo transporter, facilitating the movement of Mo from old to new or source tissues.

Efficient uptake of nutrients in both animal and plant cells requires tissue-spanning diffusion barriers separating inner tissues from the outer lumen/soil. However, we poorly understand how such contiguous three-dimensional superstructures are formed in plants. Here, we show that correct establishment of the plant Casparian Strip (CS) network relies on local neighbor communication. We show that positioning of Casparian Strip membrane domains (CSDs) is tightly coordinated between neighbors in wild-type and that restriction of domain formation involves the putative extracellular protease LOTR1. Impaired domain restriction in lotr1 leads to fully functional CSDs at ectopic positions, forming ‘half strips’. LOTR1 action in the endodermis requires its expression in the stele. LOTR1 endodermal expression cannot complement, while cortex expression causes a dominant-negative phenotype. Our findings establish LOTR1 as a crucial player in CSD positioning acting in a directional, non-cell-autonomous manner to restrict and coordinate CS positioning.

Cobalt (Co) and nickel (Ni) are beneficial and essential elements for plants, respectively, with the latter required for urease activity, which hydrolyzes urea into ammonium in plants. However, excess Co and Ni are toxic to plants and their transport mechanisms in rice are unclear. Here, we analyzed an ethyl methanesulfonate (EMS)-mutagenized rice mutant, 1187_n, with increased Co and Ni contents in its brown rice and shoots. 1187_n has a mutation in OsFPN1, which was correlated with a high Co and Ni phenotype in F2 crosses between the parental line and mutant. In addition, CRISPR/Cas9 mutants exhibited a phenotype similar to that of 1187_n, demonstrating that OsFPN1 is the causal gene of the mutant. In addition to the high Co and Ni in brown rice and shoots, the mutant also exhibited high Co and Ni concentrations in the xylem sap, but low concentrations in the roots, suggesting that OsFPN1 is involved in the root-to-shoot translocation of Co and Ni. The growth of 1187_n and CRISPR/Cas9 lines were suppressed under high Co and Ni condition, indicating OsFPN1 is required for the normal growth under high Co and Ni. An OsFPN1-green fluorescent protein (GFP) fusion protein was localized to the Golgi apparatus. Yeast carrying GFP-OsFPN1 increased sensitivity to high Co contents and decreased Co and Ni accumulation. These results suggest that OsFPN1 can transport Co and Ni and is vital detoxification in rice.