Detection of Cytosolic Ion Concentrations by the Trans-Golgi Network/Early Endosome is Important for Salt Tolerance.

Plant survival requires cellular sensing systems that detect and respond to nutrient and ion fluctuations. The ability to monitor and adjust solute concentrations is essential for managing environmental stresses, particularly salt stress, yet the molecular mechanisms underlying cellular ion sensing remain largely unknown. Here, we combine luminal pH measurements with mathematical modelling of ion transport to investigate the role of the Trans-Golgi Network/Early Endosome (TGN/EE) for cellular ion homeostasis.

Chloride transport and homeostasis in plants.

The micronutrient chloride (Cl) plays key roles in plant physiology, from photosystem II and vacuolar ATPase activity to osmoregulation, turgor maintenance and drought resilience, while also posing toxicity risks at high concentrations. This review examines Cl uptake, transport and homeostasis, focussing on adaptations balancing its dual roles as a nutrient and toxicant. Key transporters, including NPF, SLAH, ALMT, CLC and CCC families, mediate Cl fluxes to maintain ionic balance and prevent toxicity.

CLCf is an endosomal resident proton/chloride antiporter during salt stress.

CHLORIDE CHANNEL f (CLCf) has a role in maintaining -Golgi Network/Early Endosome function under all conditions and is unlikely to mediate plasma membrane chloride transport during salt stress.

The function of the Medicago truncatula ZIP transporter MtZIP14 is linked to arbuscular mycorrhizal fungal colonization.

Soil micronutrient availability, including zinc (Zn), is a limiting factor for crop yield. Arbuscular mycorrhizal (AM) fungi can improve host plant growth and nutrition through the mycorrhizal pathway of nutrient uptake. Although the physiology of Zn uptake through the mycorrhizal pathway is well established, the identity of the related molecular components are unknown.

Enhanced reactive oxygen detoxification occurs in salt-stressed soybean roots expressing GmSALT3.

Soybean (Glycine max) is an important crop globally for food and edible oil production. Soybean plants are sensitive to salinity (NaCl), with significant yield decreases reported under saline conditions. GmSALT3 is the dominant gene underlying a major QTL for salt tolerance in soybean.

Plant Trans-Golgi Network/Early Endosome pH regulation requires Cation Chloride Cotransporter (CCC1).

Plant cells maintain a low luminal pH in the trans-Golgi-network/early endosome (TGN/EE), the organelle in which the secretory and endocytic pathways intersect. Impaired TGN/EE pH regulation translates into severe plant growth defects. The identity of the proton pump and proton/ion antiporters that regulate TGN/EE pH have been determined, but an essential component required to complete the TGN/EE membrane transport circuit remains unidentified - a pathway for cation and anion efflux.

A single residue deletion in the barley HKT1;5 P189 variant restores plasma membrane localisation but not Na conductance.

Leaf Na exclusion, mediated by plasma membrane-localised Class 1 High-affinity potassium (K) Transporters (HKTs), is a key mechanism contributing to salinity tolerance of several major crop plants. We determined previously that the leucine to proline residue substitution at position 189 (L189P) in barley HvHKT1;5 disrupts its characteristic plasma membrane localisation and Na conductance. Here, we focus on a surprising observation that a single residue deletion of methionine at position 372 (M372del) within the conserved VMMYL motif in plant HKTs, restores plasma membrane localisation but not Na conductance in HvHKT1;5 P189.

Soybean CHX-type ion transport protein GmSALT3 confers leaf Na exclusion via a root derived mechanism, and Cl exclusion via a shoot derived process.

Soybean (Glycine max) yields are threatened by multiple stresses including soil salinity. GmSALT3 (a cation-proton exchanger protein) confers net shoot exclusion for both Na and Cl and improves salt tolerance of soybean; however, how the ER-localized GmSALT3 achieves this is unknown. Here, GmSALT3's function was investigated in heterologous systems and near isogenic lines that contained the full-length GmSALT3 (NIL-T; salt-tolerant) or a truncated transcript Gmsalt3 (NIL-S; salt-sensitive).

A single nucleotide substitution in TaHKT1;5-D controls shoot Na accumulation in bread wheat.

Improving salinity tolerance in the most widely cultivated cereal, bread wheat (Triticum aestivum L.), is essential to increase grain yields on saline agricultural lands. A Portuguese landrace, Mocho de Espiga Branca accumulates up to sixfold greater leaf and sheath sodium (Na ) than two Australian cultivars, Gladius and Scout, under salt stress in hydroponics.

Barley sodium content is regulated by natural variants of the Na transporter HvHKT1;5.

During plant growth, sodium (Na) in the soil is transported via the xylem from the root to the shoot. While excess Na is toxic to most plants, non-toxic concentrations have been shown to improve crop yields under certain conditions, such as when soil K is low. We quantified grain Na across a barley genome-wide association study panel grown under non-saline conditions and identified variants of a Class 1 HIGH-AFFINITY-POTASSIUM-TRANSPORTER (HvHKT1;5)-encoding gene responsible for Na content variation under these conditions.

The grapevine NaE sodium exclusion locus encodes sodium transporters with diverse transport properties and localisation.

Grapevine (Vitis vinifera L.) is a valuable crop for human consumption and wine production, and is prone to suffering from salinity stress in arid regions or when exposed to low quality irrigation water. A previous study identified a quantitative trait locus (QTL) NaE, containing six High-affinity Potassium Transporter 1 genes, that was associated with shoot Na exclusion in grapevine.

Roles of membrane transporters: connecting the dots from sequence to phenotype.

Background: Plant membrane transporters are involved in diverse cellular processes underpinning plant physiology, such as nutrient acquisition, hormone movement, resource allocation, exclusion or sequestration of various solutes from cells and tissues, and environmental and developmental signalling. A comprehensive characterization of transporter function is therefore key to understanding and improving plant performance.

Scope And Conclusions: In this review, we focus on the complexities involved in characterizing transporter function and the impact that this has on current genomic annotations.

Energy costs of salt tolerance in crop plants.

Agriculture is expanding into regions that are affected by salinity. This review considers the energetic costs of salinity tolerance in crop plants and provides a framework for a quantitative assessment of costs. Different sources of energy, and modifications of root system architecture that would maximize water vs ion uptake are addressed.

Root cell wall solutions for crop plants in saline soils.

The root growth of most crop plants is inhibited by soil salinity. Roots respond by modulating metabolism, gene expression and protein activity, which results in changes in cell wall composition, transport processes, cell size and shape, and root architecture. Here, we focus on the effects of salt stress on cell wall modifying enzymes, cellulose microfibril orientation and non-cellulosic polysaccharide deposition in root elongation zones, as important determinants of inhibition of root elongation, and highlight cell wall changes linked to tolerance to salt stressed and water limited roots.

Chloride: not simply a 'cheap osmoticum', but a beneficial plant macronutrient.

At macronutrient levels, chloride has positive effects on plant growth, which are distinct from its function in photosynthesis..