Nitrogen supply affects ion homeostasis by modifying root Casparian strip formation through the miR528-LAC3 module in maize

Although nitrogen(N)is known to affect mineral element homeostasis in plants,the molecular mechanisms of interactions between N and other nutrients remain largely unclear.Wereport here that N supply affects ion homeostasis inmaize.Berberine hemisulfate staining and a propidiumiodide penetration assay showed that N luxury significantly delayed Casparian strip(CS)formation in maize roots.We further demonstrated that N-mediated CS formation in maize was independent of RBOHF-activated H2O2 production.N luxury induced the expression of ZmmiR528 inwhole roots and root tips.Knockdown and loss-of-function ofZmmiR528 promoted CS formation under both N-luxury and N-deficient conditions.Both ZmMIR528a and ZmMIR528b contribute to early CS formation under different N conditions.RNA-seq and real-time RT-PCR analysis demonstrated that ZmLAC3,but not ZmLAC5,responded to N treatments.Consistent with results obtained with ZmmiR528 TM transgenic maize and mir528a/b loss-of-function mutants,transgenic maize overexpressing ZmLAC3 displayed early CS formation under different N conditions.Under field conditions,K,Ca,Mn,Cu,Mg,and Zn concentrations were greater in the ear leaf of ZmLAC3-overexpressing transgenicmaize than in the wild type.These results indicate that ZmmiR528 affects CS formation in maize by regulating the expression of ZmLAC3,and modification of CS formation has the potential to improve maize quality.

Regulation of lysosomal ion homeostasis by channels and transporters

Lysosomes are the major organelles that carry out degradation functions. They integrate and digest materials compartmental- ized by endocytosis, phagocytosis or autophagy. In addition to more than 60 hydrolases residing in the lysosomes, there are also ion channels and transporters that mediate the flux or transport of H＋, Ca2＋, Na＋, K＋, and C1- across the lysosomal mem- branes. Defects in ionic exchange can lead to abnormal lysosome morphology, defective vesicle trafficking, impaired autoph- agy, and diseases such as neurodegeneration and lysosomal storage disorders. The latter are characterized by incomplete lyso- somal digestion and accumulation of toxic materials inside enlarged intracellular vacuoles. In addition to degradation, recent studies have revealed the roles of lysosomes in metabolic pathways through kinases such as mechanistic target of rapamycin （mTOR） and transcriptional regulation through calcium signaling molecules such as transcription factor EB （TFEB） and cal- cineurin. Owing to the development of new approaches including genetically encoded fluorescence probes and whole endoly- sosomal patch clamp recording techniques, studies on lysosomal ion channels have made remarkable progress in recent years. In this review, we will focus on the current knowledge of lysosome-resident ion channels and transporters, discuss their roles in maintaining lysosomal function, and evaluate how their dysfunction can result in disease.

A neuromorphic device mimicking synaptic plasticity under different body fluid K^(+) homeostasis for artificial reflex path construction and pattern recognition

The ionic environment of body fluids influences nervous functions for maintaining homeostasis in organisms and ensures normal perceptual abilities and reflex activities.Neural reflex activities,such as limb movements,are closely associated with potassium ions(K+).In this study,we developed artificial synaptic devices based on ion concentration-adjustable gels for emulating various synaptic plasticities under different K+concentrations in body fluids.In addition to performing essential synaptic functions,potential applications in information processing and associative learning using short-and long-term plasticity realized using ion concentration-adjustable gels are presented.Artificial synaptic devices can be used for constructing an artificial neural pathway that controls artificial muscle reflex activities and can be used for image pattern recognition.All tests show a strong relationship with ion homeostasis.These devices could be applied to neuromorphic robots and human-machine interfaces.

Changes in Growth,Photosynthetic Pigments,Cell Viability,Lipid Peroxidation and Antioxidant Defense System in Two Varieties of Chickpea(Cicer arietinum L.)Subjected to Salinity Stress

Salinity is one of the most severe abiotic stresses for crop production.The present study investigates the salinityinduced modulation in growth indicators,morphology and movement of stomata,photosynthetic pigments,activity of carbonic anhydrase as well as nitrate reductase,and antioxidant systems in two varieties of chickpea(Pusa-BG5023,and Pusa-BGD72).On 20^(th) day of sowing,plants were treated with varying levels of NaCl(0,50,100,150 and 200 mM)followed by sampling on 45 days of sowing.Recorded observations on both the varieties reveal that salt stress leads to a significant decline in growth,dry biomass,leaf area,photosynthetic pigments,protein content,stomatal behavior,cell viability,activity of nitrate reductase and carbonic anhydrase with the rise in the concentration of salt.However,quantitatively these changes were less in Pusa-BG5023 as compared to Pusa-BGD72.Furthermore,salinity-induced oxidative stress enhanced malondialdehyde content,superoxide radicals,foliar proline content,and the enzymatic activities of superoxide dismutase,catalase,and peroxidase.The variety Pusa-BGD72 was found more sensitive than Pusa-BG5023 to salt stress.Out of different graded concentrations(50,100,150 and 200 mM)of sodium chloride,50 mM was least toxic,and 200 mM was most damaging.The differential behavior of these two varieties measured in terms of stomatal behavior,cell viability,photosynthetic pigments,and antioxidant defense system can be used as prospective indicators for selection of chickpea plants for salt tolerance and sensitivity.

Breaking Barriers:Selenium and Silicon-Mediated Strategies for Mitigating Abiotic Stress in Plants

Numerous plant species,particularly those that can accumulate selenium(Se)and silicon(Si),benefit from these essential micronutrients.Se and Si accumulation in plants profoundly affects several biochemical reactions in cells.Understanding how plants react to Se/Si enrichment is crucial for ensuring adequate dietary Se/Si intake for humans and animals and increasing plant tolerance to environmental stressors.Several studies have shown that Se/Si-enriched plants are more resistant to salinity,drought,extreme temperatures,UV radiation,and excess metalloids.The interplay between Se/Si in plants is crucial for maintaining growth and development under normal conditions while providing a critical defense mechanism against stressors like heavy metals and drought.Se and Si commonly stimulate antioxidant defense systems in plants exposed to environmental stressors,but the involved mechanisms are complex and not well understood.To ensure the positive effects of Se/Si fortification in plants,it is essential to consider the degree of accumulation,the chemical form of Se/Si used,the method of application,and the likelihood of interaction with other elements.In this review,we will discuss the effects of Se/Si bio-fortification on plants subjected to abiotic stressors.Plant responses to exogenous Se/Si will also be reviewed,emphasizing the influences of Se/Si in the modulation of enzymatic and non-enzymatic antioxidant defense mechanisms under various abiotic stress conditions.

Comparative Transcriptome Analysis of Salt-Stress-Responsive Genes in Rice Roots

Soil salinity greatly impairs plant growth and crop productivity.Rice(Oryza sativa L.)is a salt-sensitive crop.To better understand the molecular mechanisms of salt tolerance in roots,the BGISEQ-500 sequencing platform was employed to elucidate transcriptome changes in rice roots after 0,3,24,and 72 h of salt stress.The results showed that root K+content decreased and Na+content increased rapidly after the initial stage of salt stress,but that fresh and dry weight in root did not significantly reduce.Compared to the control(no salt stress),1,292,453,and 486 differentially expressed genes(DEGs)were upregulated,respectively,and 939,894,and 646 DEGs were downregulated,respectively,after 3,24,and 72 h of salt treatment.The number of DEGs was higher during the early stage of salt stress(3 h)than in later stages(24 and 72 h).A number of DEGs involved in the response and adaptation to salt stress were related to protein kinase and calcium-binding,plant hormone signaling and metabolism,transcriptional regulation,metabolic pathways,antioxidant activity,and ion transport.Many of these DEGs were activated during the early stage of salt stress(3 h).The present study reports candidate salt-stressresponsive genes with the potential to genetically improve salt tolerance in rice elsewhere.

Salt Tolerance Mechanisms and Approaches:Future Scope of Halotolerant Genes and Rice Landraces

All rice plant developmental stages are severely affected by soil salinity. Salinity-induced ionic and osmotic stresses affect stomata closure and gaseous exchange, and reduce transpiration and the rate of carbon assimilation, and hence decrease plant yield. Understanding the response of rice plants toward salinity stress at the genetic level and developing salt-tolerant varieties are the vital mandates for its effective management. This review described the present status of salt-tolerance achieved in rice by various mechanisms including the ion homeostasis(Na^+/H^+, OsNHX antiporters), compatible organic solutes(glycine betaine and proline), antioxidative genes(OsECS, OsVTE1, OsAPX and OsMSRA4.1), salt responsive regulatory elements(transcription factors, cis-acting elements and miRNAs) and genes ecoding protein kinases(MAPKs, SAPKs and STRKs). Further, the future perspective of developing salt-tolerant varieties lies in exploring halotolerant gene homologs from rice varieties, especially the landraces. Genetic diversity among rice landraces can serve as a valuable resource for future studies toward variety improvement through breeding and genome editing. Further, identification, multiplication, preservation and utilization of biodiversity among landraces are the urgent buffers to be saved as a heritage for future generations to come.

Thellungiella halophila ST5 improves salt tolerance in cotton

Background: Salinity is a major abiotic stress to global agriculture which hampers crop growth and development, and eventually reduces yield. Transgenic technology is an e ective and e cient approach to improve crop salt tolerance but depending on the availability of e ective genes. We previously isolated Salt Tolerance5(ThST5) from the halophyte Thellungiella halophila, an ortholog of Arabidopsis SPT4-2 which encodes a transcription elongation factor. However, SPT4-2-confered salt tolerance has not been evaluated in crops yet. Here we report the evaluation of Th ST5-conferred salt tolerance in cotton(Gossypium hirsutum L.).Results: The ThST5 overexpression transgenic cotton plants displayed enhanced tolerance to salt stress during seed germination and seedling stage compared with wild type. Particularly, the transgenic plants showed improved salinity tolerance as well as yield under saline field conditions. Comparative transcriptomic analysis showed that ThST5 improved salt tolerance of transgenic cotton mainly by maintaining ion homeostasis. In addition, ThST5 also orchestrated the expression of genes encoding antioxidants and salt-responsive transcription factors.Conclusion: Our results demonstrate that ThST5 is a promising candidate to improve salt tolerance in cotton.

Two ABCI family transporters,OsABCI15 and OsABCI16,are involved in grain-filling in rice

Seed development is critical for plant reproduction and crop yield,with panicle seed-setting rate,grain-filling,and grain weight being key seed characteristics for yield improvement.However,few genes are known to regulate grain filling.Here,we identify two adenosine triphosphate(ATP)-binding cassette(ABC)I-type transporter genes,OsABCI15 and OsABCI16,involved in rice grain-filling.Both genes are highly expressed in developing seeds,and their proteins are localized to the plasma membrane and cytosol.Interestingly,knockout of OsABCI15 and OsABCI16 results in a significant reduction in seed-setting rate,caused predominantly by the severe empty pericarp phenotype,which differs from the previously reported low seed-setting phenotype resulting from failed pollination.Further analysis indicates that OsABCI15 and OsABCI16 participate in ion homeostasis and likely export ions between filial tissues and maternal tissues during grain filling.Importantly,overexpression of OsABCI15 and OsABCI16 enhances the seed-setting rate and grain yield in transgenic plants and decreases ion accumulation in brown rice.Moreover,the OsABCI15/16 orthologues in maize exhibit a similar role in kernel development,as demonstrated by their disruption in transgenic maize.Therefore,ourfindings reveal the important roles of two ABC transporters in cereal grain filling,highlighting their value in crop yield improvement.

Seed Treatment with Auxins Modulates Growth and Ion Partitioning in Salt-stressed Wheat Plants

Experiments were performed to determine whether seed priming with different concentrations （100, 150, and 200 mg/L） of auxins （indoleacetic acid （IAA）, indolebutyric acid （IBA）, or their precursor tryptophane （Trp）） could alter salinity induced perturbances in salicylic acid and ion concentrations and, hence, growth in wheat （Triticum aestivum L.） cultivars, namely M.H.-97 （salt intolerant） and tnqtab-91 （salt tolerant）. Primed and non-primed seeds were sown in Petri dishes in a growth room, as well as in a field treated with 15 dS/m NaCl salinity. All priming agents, except IBA, increased the final germination percentage in both cultivars. The seedlings of either cultivar raised from Trp-treated seeds had greater dry biomass when under salt stress. In field experiments, Trp priming was much more effective in mediating the increase in grain yield, irrespective of the cultivar, under salt stress. The alleviatory effect of Trp was found to be associated with reduced uptake of Na^＋ in the roots and subsequent translocation to the shoots, as well as increased partitioning of Ca^＋ in the roots of salt-stressed wheat plants. Plants of both cultivars raised from Trp-and IAA-treated seeds accumulated free salicylic acid in their leaves when under salt stress. Overall, the Trp priming-induced improvement in germination and the subsequent growth of wheat plants could be related to ion homeostasis when under salt stress. The possible involvement of salicylic acid in the Trp priming-induced better growth under Conditions of salt stress is discussed.

Ion transporters: emerging agents for anticancer therapy

Natural ion channels are pore-forming proteins that allow ions to pass through biomembranes, playing pivotal roles in almost all facets of cellular physiological functions. Biomimetic ion transporters were initially investigated for the purpose of treating lifethreatening channelopathies. Recent studies have indicated that membrane-active synthetic ionophores possess desirable anticancer bioactivity against diverse cancer cell lines by disturbing intracellular ion homeostasis, triggering oxidative stress, and inducing apoptosis in tumors. Recent progress on ionophore-related antitumor therapeutics is comprehensively summarized in this review, including the molecular design principles, functional mechanisms, and characterization methods. Finally, we conclude this review by discussing the future opportunities and challenges in this field. It is anticipated that this review will provide an existing panoramic sketch and future directions toward the construction of novel ion transporters with simplified preparation procedures, enhanced biocompatibility, and desirable anti-proliferative activities, which may further accelerate their therapeutic applications in clinical treatments.

Salt Tolerance in Soybean

Soybean is an important cash crop and its productivity is significantly hampered by salt stress. High salt imposes negative impacts on growth, nodulation, agronomy traits, seed quality and quantity, and thus reduces the yield of soybean. To cope with salt stress, soybean has developed several tolerance mechanisms, including： （i） maintenance of ion homeostasis; （ii） adjustment in response to osmotic stress; （iii） restoration of osmotic balance; and （iv） other metabolic and structural adaptations. The regulatory network for abiotic stress responses in higher plants has been studied extensively in model plants such as Arabidopsis thaliana. Some homologous components involved in salt stress responses have been identified in soybean. In this review, we tried to integrate the relevant works on soybean and proposes a working model to describe its salt stress responses at the molecular level.

The Salt Overly Sensitive （SOS） Pathway： Established and Emerging Roles

Soil salinity is a growing problem around the world with special relevance in farmlands. The ability to sense and respond to environmental stimuli is among the most fundamental processes that enable plants to survive. At the cellular level, the Salt Overly Sensitive （SOS） signaling pathway that comprises SOS3, SOS2, and SOS1 has been proposed to mediate cellular signaling under salt stress, to maintain ion homeostasis. Less well known is how cellularly heterog- enous organs couple the salt signals to homeostasis maintenance of different types of cells and to appropriate growth of the entire organ and plant. Recent evidence strongly indicates that different regulatory mechanisms are adopted by roots and shoots in response to salt stress. Several reports have stated that, in roots, the SOS proteins may have novel roles in addition to their functions in sodium homeostasis. SOS3 plays a critical role in plastic development of lateral roots through modulation of auxin gradients and maxima in roots under mild salt conditions. The SOS proteins also play a role in the dynamics of cytoskeleton under stress. These results imply a high complexity of the regulatory networks involved in plant response to salinity. This review focuses on the emerging complexity of the SOS signaling and SOS protein functions, and highlights recent understanding on how the SOS proteins contribute to different responses to salt stress besides ion homeostasis.