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Background and aim Hydrocotyle bonariensis Comm ex Lamm (Araliaceae) is one of these plants sufficiently exploited in traditional African medicine for its hypotensive effect. However, the pharmacological effects of those plants on cardiac functions are not well known. The potassium currents IKs and IKr, responsible for the repolarization of cardiac cell action potential, strongly influence the human cardiac rhythm. Therefore, modulators of these currents have a beneficial or undesirable medical importance in relation to cardiac arrhythmias. In order to optimize the therapeutic use of this medicinal plant, we studied the effects of hydro-ethanolic leaf extract of Hydrocotyle bonariensis on both potassium currents. Experimental procedure The patch clamp experiments for IK currents recording were performed on the HEK 293 (Human Embryonic Kidney 293) cell line, stably transfected with either KCNQ1 and KCNE1 genes encoding the channel responsible for the "IKs" current (HEK293 IKs), or with hERG (human ether-a-go-go related gene) gene encoding "IKr" current (HEK293 IKr). Results and conclusion This study revealed that the hydro-ethanolic leaf extract of H. bonariensis significantly inhibits the slow potassium component (IKs) without altering the fast potassium component (IKr). The extract at 0.5 mg/ml decreases IKs conductance by 24 ± 4.1% (n = 6) without modifying its activation threshold suggesting a direct blockade of the slow potassium channel. This selective action of the extract on the IKs current reflects a class III anti-arrhythmic effect.

Chlorosis at leaf margins is a typical symptom of potassium (K) deficiency, but inappropriate application of K with other nutrients often masks symptoms of K deficiency. A two-year field experiment was conducted to measure the interactive effects of N and K on leaf photosynthesis and dry matter accumulation and the resulting growth dilution effect on K concentration and leaf K deficiency symptoms. N application aggravated the imbalance of N and K nutrients and further exacerbated K deficiency symptoms under K limitation. Synergistic effects of N and K promoted plant growth, amplified the growth dilution effect, and reduced the critical K concentration in leaves. Using 90% of the maximum shoot biomass as a threshold, the critical K concentration was 0.72% at the recommended N (N180) fertilization level. The critical K concentration increased by 62.5% owing to the reduced biomass under insufficient N (N90) supply. In contrast, high N (N270) reduced the critical K concentration (0.64%), accelerating chlorophyll decomposition and exacerbating K deficiency symptoms. The basis of changing the critical K concentration by magnifying growth dilution effect was the functional synergistic effect of N and K on photosynthetic characteristics. Under insufficient N, the low maximum carboxylation rate (Vcmax) limited the net photosynthetic rate (An) and necessitated more K to maintain high CO2 transmission capacity, to improve the total conductance gtot /Vcmax ratio. High N supply increased gtot and Vcmax, possibly mitigating the effect of K reduction on photosynthesis. In conclusion, it is unwise to judge K status of plants only by K concentration without accounting for crop mass (or dilution effect), critical K concentration and deficiency symptoms are affected by N fertilization, and the synergistic effect of N and K on leaf photosynthesis is the foundation of maximal growth of plants under diverse critical K concentrations.

To investigate the effect of potassium source and rate on soil K, growth and K uptake of spinach, a pots experiment was carried out during the winter season of 2020 at the greenhouse of the Faculty of Agriculture, Saba Basha, Alexandria, Egypt. The experiment was laid out in randomized complete block design (RCBD) with three replications. The treatments included applying 50% of recommended K in the form of potassium sulfate (PS50), 100% as potassium sulfate (PS100), 50% as potassium citrate (PC50), 100% as potassium citrate (PC100), 50% as potassium humate (PH50), 100% as potassium humate (PH100) and control (0% K). The obtained results showed that the application of potassium in the forms of potassium humate and potassium citrate improved spinach growth and K uptake compared to potassium sulfate. The application of potassium humate can minimize the potassium application rate and reduce the fertilizer requirements without significant influences on plant growth and potassium uptake.

KEY POINTS Zebrafish cardiac myocytes (CM) and vascular smooth muscle (VSM) express functional KATP channels of similar subunit composition, structure, and metabolic sensitivity to their mammalian counterparts. In contrast to mammalian cardiovascular KATP channels, zebrafish channels are insensitive to potassium channel opener drugs (pinacidil, minoxidil) in both chambers of the heart and in VSM. We provide a first characterization of the molecular properties of fish KATP channels and validate the use of such genetically modified fish as models of human Cantu Syndrome and ABCC9-related Intellectual disability and Myopathy Syndrome. ABSTRACT ATP-sensitive potassium channels (KATP channels) are hetero-octameric nucleotide-gated ion channels that couple cellular metabolism to excitability in various tissues. In the heart, KATP channels are activated during ischemia and potentially during adrenergic stimulation. In the vasculature, they are normally active at a low level, reducing vascular tone, but the ubiquitous nature of these channels leads to complex and poorly understood channelopathies as a result of gain- or loss-of-function mutations. Zebrafish (ZF) models of these channelopathies may provide insights to the link between molecular dysfunction and complex pathophysiology, but this requires understanding the tissue dependence of channel activity and subunit specificity. Thus far, direct analysis of ZF KATP expression and functional properties has only been performed in pancreatic β-cells. Using a comprehensive combination of genetically modified fish, electrophysiology, and gene expression analysis, we demonstrate that ZF cardiac myocytes (CM) and vascular smooth muscle (VSM) express functional KATP channels of similar subunit composition, structure, and metabolic sensitivity to their mammalian counterparts. However, in contrast to mammalian cardiovascular KATP channels, ZF channels are insensitive to potassium channel opener drugs (pinacidil, minoxidil) in both chambers of the heart and in VSM. The results provide a first characterization of the molecular properties of fish KATP channels and validate the use of such genetically modified fish as models of human Cantu Syndrome and ABCC9-related Intellectual disability and Myopathy Syndrome. This article is protected by copyright. All rights reserved.

Vonoprazan (VPZ), a new potassium-competitive acid blocker, has been approved and used for Helicobacter pylori eradication in Japan. To date, many studies, as well as several systematic reviews and meta-analyses (MAs), have compared VPZ-based 7-day triple therapy with proton pump inhibitor (PPI)-based therapy. An MA of randomized controlled trials (RCTs) comparing first-line VPZ- with PPI-based triple therapy, the latter featuring amoxicillin (AMPC) and clarithromycin (CAM), found that approximately 30% of patients hosted CAM-resistant H. pylori; however, the reliability was poor because of high heterogeneity and a risk of selection bias. VPZ-based triple therapy is superior to PPI-based triple therapy for patients with CAM-resistant H. pylori, but not for those with CAM-susceptible H. pylori. An MA of non-RCTs found that second-line VPZ-based triple therapies were slightly (~2.6%) better than PPI-based triple therapies (with AMPC and metronidazole). However, the reliability of that MA was also low because of selection bias, confounding variables and a risk of publication bias; in addition, it is difficult to generalize the results because of a lack of data on antibiotic resistance. VPZ-based triple therapy (involving AMPC and sitafloxacin) was more effective than PPI-based triple therapy in a third-line setting, but a confirmatory RCT is needed. Non-RCT studies indicated that VPZ-based triple therapy involving CAM and metronidazole may be promising. Any further RCTs must explore the antibiotic-resistance status when evaluating the possible superiority of a potassium-competitive acid blocker.

BACKGROUND AND PURPOSE Inward rectifier potassium (KIR ) channels are key effectors of vasodilatation in neurovascular coupling (NVC). KIR channels expressed by cerebral endothelial cells (EC) have been confirmed essential modulators of NVC. Alzheimer's disease (AD) and cerebrovascular disease (CVD) impact EC-KIR channel function, but whether oxidative stress or inflammation can explain this impairment remains elusive. EXPERIMENTAL APPROACH We evaluated KIR channel function in intact and EC-denuded pial arteries of wild-type (WT) and transgenic mice overexpressing a mutated form of the human amyloid precursor protein (APP mice, recapitulating amyloid β-induced oxidative stress seen in AD), or a constitutively active form of transforming growth factor-β1 (TGF mice, recapitulating inflammation seen in cerebrovascular pathology). Benefits of antioxidant (catalase) or anti-inflammatory (indomethacin) drugs were investigated. Vascular and neuronal components of NVC were also assessed in vivo. KEY RESULTS Our findings show that i) KIR channel-mediated maximal vasodilatation in APP and TGF mice reaches only 37% and 10%, respectively, of the response seen in WT mice, ii) KIR channel dysfunction results from KIR 2.1 subunit impairment; iii) about 50% of K+ -induced artery dilatation is mediated by EC-KIR channels; iv) oxidative stress and inflammation impair KIR channel function, which can be restored by antioxidant and anti-inflammatory drugs; and v) inflammation induces KIR 2.1 overexpression and impairs NVC in TGF mice. CONCLUSION AND IMPLICATIONS Therapies targeting both oxidative stress and inflammation are necessary for full recovery of KIR 2.1 channel function in cerebrovascular pathology caused by AD and CVD.

Background and Aim: The selection and proper application of disinfectants are crucial to the prevention of many diseases, so disinfectants must be evaluated before being used for the prevention of African swine fever (ASF). Three disinfectant products belonging to the group of potassium hydrogen peroxymonosulfates, product A and product B, and a quaternary ammonium compound called product C, were examined in vitro for host cell cytotoxicity and the efficacy of ASF virus inactivation. The study parameters included various concentrations, exposure times, temperatures, and degrees of cytotoxicity. Materials and Methods: Three disinfectant products were evaluated for cytotoxicity using primary porcine alveolar macrophage (PAM) cells at dilutions from 1:200 to 1:51,200. Disinfectants in concentrations of 1:200, 1:400, and 1:800 were prepared, the pH and the virucidal activity were tested. An equal volume of each dilution was mixed with the ASF virus and incubated at room temperature (20°C) or on ice (4°C) for 1 min, 5 min, or 30 min. Hemadsorption (HAD) or rosette formation was observed using an inverted microscope for 5 days after inoculation, and the virus titer was calculated as HAD50/mL. Each treatment and virus control were tested in triplicate, and the titers were reported as means and standard deviations. The reduction factor was used to measure inactivation. Results: Products A, B, and C at 1:400, 1:800, and 1:25,600 of dilution, respectively, did not show significant cytotoxic effects on PAM cells. Products A and B could inactivate ASF virus at 1:200 dilution within 5 min after exposure at 4°C. However, at 20°C, the exposure time had to be extended to 30 min to inactivate the virus. Product C could inactivate the virus at 1:400 dilution within 5 min under both temperature conditions, whereas at 1:800 dilution, the exposure time had to be extended to 30 min to completely inactivate the virus at 20°C. Conclusion: All disinfectants could inactivate ASF virus in various concentrations, under appropriate exposure times and reaction temperatures, and there was no evidence of host cell cytotoxicity. For the control of ASF in pig farms, the appropriate concentration, ambient temperature, and contact time of these disinfectants should be taken into account.

The steviol glycosides (SGs) in stevia (Stevia rebaudiana Bertoni) leaves are becoming increasingly valuable due to its high sweetness but low calorific value, which is driving the development of stevia commercial cultivation. Optimizing fertilization management can effectively increase SGs productivity, but knowledge on the relationship between potassium (K) fertilization and SGs production is still lacking. In this study, pot experiments were conducted in order to investigate the effect of K deficiency on SGs synthesis in stevia leaves, as well as the underlying mechanisms. Our results showed that when compared with standard K fertilization, K deficiency treatment has no significant effect on the biomass of stevia plant grown in a given soil with high K contents. However, K deficiency critically decreased leaf SGs contents as well as the expression of SGs synthesis-related genes. The contents of different sugar components decreased and the activities of sugar metabolism-related enzymes were inhibited under the K deficiency condition. Moreover, spraying sucrose on the leaves of stevia seedlings diminished the inhibitory effect caused by K deficiency. Our results also revealed the significant positive correlations between sucrose, glucose and SGs contents. Overall, our results suggest that K deficiency would suppress the synthesis of SGs in stevia leaves, and this effect may be mediated by the leaf sugar metabolism. Our findings provide new insights into the improvement of SGs production potential.

The presence of waters with high salt concentration stands out as a limiting factor for the quality of agricultural production. Thus, this study aimed to evaluate the fruit quality of West Indian cherry cv. Flor Branca, subjected to irrigation with water of different salinity levels and combinations of nitrogen-potassium fertilization, between 630 and 750 days after transplanting in the field. A randomized block design was used in a 5 × 4 factorial arrangement, with three replicates, whose treatments consisted of five values of electrical conductivies of irrigation water - ECw (0.3, 1.3, 2.3, 3.3 and 4.3 dS m-1) and four combinations of nitrogen and potassium fertilization (70-50, 100-75, 130-100 and 160-125% of recommendation of N and K2O, respectively). Electrical conductivity of irrigation water above 0.3 dS m-1 reduces the polar and equatorial diameters, hydrogen potential and flavonoid concentration and increases titratable acidity in West Indian cherry fruits. N-K2O combination of 70/50% of fertilizer recommendation reduces the effect of salt stress of irrigation water on the anthocyanin concentration in the fruits at ECw of 1.3 dS m-1 and ascorbic acid at ECw of 3.3 and 4.3 dS m-1.

Water resources are increasingly scarce, and in drought prone production systems, the capability of the plant to recover its adverse effects is important for yield stability. There is an urgent need to develop water-saving strategies for wheat production. Water stress at critical growth stages diminishes wheat production and has harmful effects on crop growth and development; however, regulated water deficit and potassium foliar application ameliorates its adverse effect up to a certain extent. Consequently, the water deficit effect at different growth stages of the crop with exogenous application of potassium was evaluated in a screenhouse experiment in a complete randomized design (CRD) having four repeats. Varieties of wheat, i.e. Lalma (drought resistant) and Pakhtunkhwa-2015 (drought susceptible), were sown. Water deficit, i.e. mild water stress (50% of water required for field capacity) and severe stress (no application of water), at different growth stages of the crop were imposed. Potassium (K) foliar spray (1%) from potassium sulfate (K2SO4) was applied at the respective stage subjected to water deficit levels. Internal water status, i.e. relative water content (RWC) and water retention capacity (WRC), were attained maximum at tillering stage under mild stress than the rest of the stages with maximum for Lalma. Conversely, water saturation deficit (WSD) and water uptake capacity (WUC) were higher under severe stress imposed at grain filling stage. Theses indices were maintained by foliar potassium application. Similarly, dry matter (DM) allocation varied for stress level imposition and translocation to other parts were improved under foliar K application. The chlorophyll indices, i.e., soil plant analysis development (SPAD) value, also decreased with the severity of water deficit. Grain yield was higher under stress imposition at grain filling stage than the rest of the stages, though severe water stress decreased yield significantly. The Potassium (K) foliar spray showed no prominent effect at grain filling. Canopy temperature increased with stress severity and was maintained under K foliar spray. Osmotic adjustment, water and turgor potential were affected by water stress and maintained with foliar K spray. Grain quality and biochemical traits of wheat were affected severely under water deficit. Potassium foliar spray was found to decrease the adverse effect of the water stress and hence maintained the quality and biochemical characters. It is concluded that application of foliar potassium decreases the adverse effects of water stress at any growth stage, minimises the stress indices drastic effect and maintains the internal water balance of the crop at different stages subjected to water deficit.

Background Inwardly rectifying potassium channels are essential for normal potassium homeostasis, maintaining the cellular resting membrane potential, and regulating electrical/electrolyte transportation. Mutations in Kir channels have been known to cause debilitating diseases ranging from neurological abnormalities to renal and cardiac failures. Many efforts have been made to understand their protein structures, physiological functions, and pharmacological modifiers. However, their expression and functions during embryonic development remain largely unknown. Results Using zebrafish as a model, we identified and renamed 31 kir genes. We also analyzed Kir gene evolution by phylogenetic and syntenic analyses. Our data indicated that the four subtypes of the Kir genes might have already evolved out in chordates. These vertebrate Kir genes most likely resulted from both whole-genome duplications and tandem duplications. In addition, we examined zebrafish kir gene expression during early embryogenesis. Each subgroup's genes showed similar but distinct gene expression domains. The gene expression of ohnologous genes from teleost-specific whole-genome duplication indicated subfunctionalization. Varied gene expression domains suggest that Kir channels may be needed for embryonic patterning or regulation. Conclusions Our phylogenetic and developmental analyses of Kir channels shed light on their evolutionary history and potential functions during embryogenesis related to congenital diseases and human channelopathies. This article is protected by copyright. All rights reserved.

AKT2 potassium (K+) channels are members of the plant Shaker family which mediate dual-directional K+ transport with weak voltage-dependency. Here we show that OsAKT2 of rice (Oryza sativa) functions mainly as an inward rectifier with strong voltage-dependency and acutely suppressed outward activity. This is attributed to the presence of a unique K191 residue in the S4 domain. The typical bi-directional leak-like property was restored by a single K191R mutation, indicating that this functional distinction is an intrinsic characteristic of OsAKT2. Furthermore, the opposite R195K mutation of AtAKT2 changed the channel to an inward-rectifier similar to OsAKT2. OsAKT2 was modulated by OsCBL1/OsCIPK23, evoking the outward activity and diminishing the inward current. The physiological relevance in relation to the rectification diversity of OsAKT2 was addressed by functional assembly in the Arabidopsis (Arabidopsis thaliana) akt2 mutant. Overexpression (OE) of OsAKT2 complemented the K+ deficiency in the phloem sap and leaves of the mutant plants but did not significantly contribute to the transport of sugars. However, the expression of OsAKT2-K191R overcame both the shortage of phloem K+ and sucrose of the akt2 mutant, which was comparable to the effects of the OE of AtAKT2, while the expression of the inward mutation AtAKT2-R195K resembled the effects of OsAKT2. Additionally, OE of OsAKT2 ameliorated the salt tolerance of Arabidopsis., The presence of a unique K191 residue retains the activity of rice potassium channel OsAKT2 mainly as an inward rectifier (Mode I) that emphasizes its in planta role of phloem K+ translocation.

BackgroundImproving the nutritional condition of grapevine in spring to regulate bloom, fruit set, and yield is among the management goals of vineyards.MethodsIn the present study, the early season spray of calcium sulfate (C; 0.00 and 2.00%), potassium sulfate (K; 0.00 and 3.00%), and agricultural grade mineral oil (V; 0.00 and 1.00%) on flower and fruit phenology, nutrient concentration, and cluster biophysical indices and yield of Sultana grapevine (Vitis viniferaL.) were investigated for two consecutive years.ResultsBased on the results, the spray of this nutrient combined with mineral oil significantly affected all the treatments except cluster length, berry length, and phosphorus concentration. The highest concentrations of potassium, calcium, and magnesium were obtained in the vines treated with V0K1C1, and the highest concentrations of zinc and iron were obtained only in the vines treated with mineral oil. In treatments containing mineral oil, especially in combination with the second level of calcium and potassium (V1K1C1), bloom time, berries pea-sized time, and harvest time were delayed by 3, 3, and 6 days compared with control vines. While in vines treated with a combination of the second level of potassium and calcium (V0K1C1), bloom time, berries pea-sized time, and harvest time were advanced by 5, 4, and 1.50 days, respectively, compared with control vines. Regarding the biophysical indices of the cluster, it was found that the vines treated with V1K1C1had higher cluster weight, berry weight, fruit, and raisins yield than other treatments. Also, the highest berry quality, including total soluble solids, titratable acidity, and total phenol content, were obtained in the vines treated with V0K1C1. However, the lowest berry quality was observed in the vines treated with mineral oil.ConclusionsTherefore, the combination of nutrients with mineral oil can alleviate the adverse effect of mineral oil solely on some phenological indices and berry quality-related traits in vineyards.

Dry rot caused by Macrophomina phaseolina was observed as a post-harvest infection during ginger storage. As the pathogen is infecting the crop in its growing stage, soil application of chemical/bioagent is required to manage the disease. Since silicates has been reported to have the ability to enhance resistance against root rot pathogens, the present study analyzed the in vitro, in planta and field level effect of potassium silicates on the growth of M. phaseolina. The study revealed that potassium silicate at 2.5 % concentration restricted the mycelial growth and also showed alteration in hyphal morphology with constrained growth of mycelia as observed by bright field and SEM analysis. The biochemical analysis of mycelia exposed to silicate revealed alteration in glycerol and EPS content which in turn resulted in the variation in the cell wall structure. The lipid peroxidation and the cell permeability was also higher for silicate treated mycelium. In planta and field studies showed an increase in the growth of potassium silicate treated plants besides reduction in dry rot disease incidence. The physicochemical analysis of soil depicted an increase in organic matter and nutrient availability in silicate treated soil. This is the first attempt to study the effect of potassium silicate molecule against M.phaseolina infection in ginger. These findings suggest the possibility of using potassium silicate as an alternative to fungicides against dry rot disease.

This study was conducted during two successive seasons (2019 and 2020) on cotton cultivar Giza 86 at El-Gemmeiza Agricultural Research Station, El-Gharbia Governorate, Egypt, to study the effect of foliar feeding withtwo compounds enriched with phosphorus and potassium [Agrophytex at two levels (2 and 4 cm3 /L) and potassium phosphate at two levels (2 and 4 g /L)] either alone or in combination at the low and high level compared to the control treatment (sprayed with tap water and fertilized with phosphorus and potassium at the recommended rates as soil application) on cotton productivity and quality. A randomized complete blocks design with 4 replicates was used. The obtained results revealed that foliar feeding with Agrophytexand potassium phosphate combination at the two levels examined significantly increased percentages of N, P, K and contents of chloroplast pigments in cotton leaves in 2019 season. Growth parameters, earliness measurements, seed cotton yield/feddan and its components in both seasons as well as micronaire reading and fiber strength in the second season were also increased. Whereas, boll shedding percentage decreased. Fiber length and uniformity index did not affected. It could be concluded that using combination of Agrophytexand potassium phosphate at the low level (2 cm3 Agrophytex+ 2 g potassium phosphate)/L four times (at seedling stage, squaring initiation, flowering start and peak of flowering stage) as alternative to soil P and K fertilization was recommended to reduce cost, overcome P and K fixation and obtain high productivity under conditions similar to El-Gemmeiza region.

Protein phosphatases play important roles in the regulation of various cellular processes in eukaryotes. The ascomycete Colletotrichum gloeosporioides is a causal agent of anthracnose disease on some important crops and trees. In this study, CgPPZ1, a protein phosphate gene and a homolog of yeast PPZ1, was identified in C. gloeosporioides. Targeted gene deletion showed that CgPpz1 was important for vegetative growth and asexual development, conidial germination, and plant infection. Cytological examinations revealed that CgPpz1 was localized to the cytoplasm. The ΔCgppz1 mutant was hypersensitive to osmotic stresses, cell wall stressors, and oxidative stressors. Taken together, our results indicated that CgPpz1 plays an important role in the fungal development and virulence of C. gloeosporioides and the multiple stress responses generated.

Improving potassium (K) use efficiency (KUE) is beneficial for the sustainable production of cereal crops. In this study, the effects of K input level on its uptake and agronomic trait of the winter wheat under deficit irrigation were investigated in K deprivation responses, using two cultivars contrasting (low-K tolerant cultivar Kenong 9204 and K deprivation sensitive one Jimai 120). Under sufficient-K treatment (K180, SK), the two cultivars showed similar K contents, and K accumulation, biomass, photosynthetic parameters in upper expanded leaves, including yield components. Under deficient-K (K60, DK) condition, both cultivars showed varied behaviors of the K-associated traits, physiological parameters, growth and agronomic traits; however, better response was observed in Kenong 9204 than Jimai 120. These results suggested the essential roles of low-K tolerant cultivars under the K-saving management together with deficit irrigation. Two genes of the potassium transporter (HAK) family, TaHAK3 and TaHAK5, showed expression of significantly upregulated upon K deprivation, with much more transcripts shown in the K-deprived Kenong 9204 plants than Jimai 120 ones. Transgene analysis on the HAK genes validated their positive roles in modulating the K accumulation and biomass production of plants under low-K condition. These results indicated that distinct HAK family genes are transcriptionally regulated underlying K deprivation signaling and contribute to plant K uptake and biomass production under low-K conditions. This study suggested the drastically genetic variation on K uptake and biomass production across winter wheat cultivars treated by K- and water-saving conditions, associated with transcription efficiency of the distinct HAK genes which modulate K uptake, growth and development of plants. © 2021 Friends Science Publishers

Inward rectifier K+ (Kir) channels have been studied extensively in mammals, where they play critical roles in health and disease. In insects, Kir channels have recently been found to be key regulators of diverse physiological processes in several tissues. The importance of Kir channels in insects has positioned them to serve as emerging targets for the development of insecticides with novel modes of action. In this article, we provide the first comprehensive review of insect Kir channels, highlighting the rapid progress made in understanding their molecular biology, physiological roles, pharmacology, and toxicology. In addition, we highlight key gaps in our knowledge and suggest directions for future research to advance our understanding of Kir channels and their roles in insect physiology. Further knowledge of their functional roles will also facilitate their exploitation as targets for controlling arthropod pests and vectors of economic, medical, and/or veterinary relevance. Expected final online publication date for the Annual Review of Entomology, Volume 67 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Since prehistory, human species have depended on plants for both food and medicine. Even in countries with ready access to modern medicines, alternative treatments are still highly regarded and commonly used. Unlike modern pharmaceuticals, many botanical medicines are in widespread use despite a lack of safety and efficacy data derived from controlled clinical trials and often unclear mechanisms of action. Contributing to this are the complex and undefined composition and likely multifactorial mechanisms of action and multiple targets of many botanical medicines. Here, we review the newfound importance of the ubiquitous KCNQ subfamily of voltage-gated potassium channels as targets for botanical medicines, including basil, capers, cilantro, lavender, fennel, chamomile, ginger, and Camellia, Sophora, and Mallotus species. We discuss the implications for the traditional use of these plants for disorders such as seizures, hypertension, and diabetes and the molecular mechanisms of plant secondary metabolite effects on KCNQ channels. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Combining a bulky bis(amide) and a reactive one-coordinate TMP (2,2,6,6-tetramethylpiperidide) ligand, a new mixed K/Zn heteroleptic base has been developed for regioselective zincation of fluoroarenes. This special ligand set allows for trapping and structural authentication of the first intermediates of direct Zn-H exchange of fluoroarenes obtained via deprotonative metallation, providing mechanistic insights of the processes involved.

The voltage-gated potassium channel, KV11.1, encoded by the humanEther-à-go-go- Related Gene (hERG) is expressed in cardiac myocytes, where it is crucial for the membrane repolarization of the action potential. Gating of hERG channel is characterized by rapid, voltage-dependent, C-type inactivation, which blocks ion conduction and is suggested to involve constriction of the selectivity filter. Mutations S620T and S641A/T within the selectivity filter region of hERG have been shown to alter the voltage- dependence of channel inactivation. Because hERG channel blockade is implicated in drug-induced arrhythmias associated with both the open and inactivated states, we used Rosetta to simulate effects of hERG S620T and S641A/T mutations to elucidate conformational changes associated with hERG channel inactivation and differences in drug binding between the two states. Rosetta modeling of the S641A fast-inactivating mutation revealed a lateral shift of F627 side chain in the selectivity filter into the central channel axis along the ion conduction pathway and formation of four lateral fenestrations in the pore. Rosetta modeling of the non-inactivating mutations S620T and S641T suggested a potential molecular mechanism preventing F627 side chain from shifting into the ion conduction pathway during the proposed inactivation process. Furthermore, we used Rosetta docking to explore the binding mechanism of highly selective and potent hERG blockers - dofetilide, terfenadine, and E4031. Our structural modeling correlate well with existing experimental evidence involving interactions of these drugs with key hERG residues Y652 and F656 inside the pore and reveal potential ligand binding interactions within fenestration region in an inactivated state.Significance StatementComputational models of hERG potassium channel provide structural insights into an inactivated state and associated drug interactions. Our computational approach will be useful to study ion channel modulation by small molecules.

Acute kidney injury (AKI), a common complication of sepsis, is characterized by a rapid loss of renal excretory function. A variety of etiologies and pathophysiological processes may contribute to AKI. Previously, mitogen-activated protein kinase 1 (MAPK1) was reported to regulate cellular processes in various sepsis-associated diseases. The current study aimed to further explore the biological function and regulatory mechanism of MAPK1 in sepsis-induced AKI. In our study, MAPK1 exhibited high expression in the serum of AKI patients. Functionally, knockdown of MAPK1 suppressed inflammatory response, cell apoptosis in response of lipopolysaccharide (LPS) induction in HK-2 cells. Moreover, MAPK1 deficiency alleviated renal inflammation, renal dysfunction, and renal injury in vivo. Mechanistically, MAPK1 could activate the downstream p38/NF-κB pathway. Moreover, long noncoding RNA potassium voltage-gated channel subfamily Q member 1 opposite strand/antisense transcript 1 (KCNQ1OT1) was identified to serve as a competing endogenous RNA for miR-212-3p to regulate MAPK1. Finally, rescue assays indicated that the inhibitory effect of KCNQ1OT1 knockdown on inflammatory response, cell apoptosis, and p38/NF-κB pathway was reversed by MAPK1 overexpression in HK-2 cells. In conclusion, KCNQ1OT1 aggravates acute kidney injury by activating p38/NF-κB pathway via miR-212-3p/MAPK1 axis in sepsis. Therefore, KCNQ1OT may serve as a potential biomarker for the prognosis and diagnosis of AKI patients.

Potassium (K) is an essential nutrient in plant metabolism, ionic balance, and stress resistance. In this study, the effects of K on agronomic attributes and on mineral and primary metabolite content in African potato were determined. K was administered hydroponically at four concentrations (4.00, 6.00, 8.00, and 10.00 meq·L−1) using Steiner’s universal nutrient solution. Chlorophyll content (CHL), leaf area (LA), fresh corm mass (FCM), number of roots (NR), root fresh weight (RFM), and root dry mass (RDM) were measured 18, 32, and 40 weeks after transplanting. Mineral analysis data were collected at 18 weeks, and primary metabolite data were collected at 32 weeks. Significant effects of K were observed after 18 weeks, and all test concentrations had a positive effect on yield. Calcium and boron significantly accumulated in the corm at 4.00 meq·L−1 K. Alanine and malic acid were the only metabolites affected by K concentrations. More minerals accumulated in the corm at 4.00 meq·L−1 K, whereas at 10.00 meq·L−1 K, more minerals clustered in the leaf. K applied at 4.00 meq·L−1 is recommended when growing African potato using a nutrient solution to improve corm mineral and metabolite accumulation.

The mosquito continues to be the most lethal animal to humans due to the devastating diseases that it carries and transmits. Controlling mosquito-borne diseases relies heavily on vector management using neurotoxic insecticides with limited modes of action. This has led to the emergence of resistance to pyrethroids and other neurotoxic insecticides in mosquitoes, which has reduced the efficacy of chemical control agents. Moreover, many neurotoxic insecticides are not selective for mosquitoes and negatively impact beneficial insects such as honeybees. Developing new mosquitocides with novel mechanisms of action is a clear unmet medical need; this review covers the efforts made toward this end by targeting the renal inward rectifier potassium channel (Kir) of the mosquito.

Epilepsy is a devastating neurological disorder characterized by recurrent seizures attributed to the disruption of the dynamic excitatory and inhibitory balance in the brain. Epilepsy has emerged as a global health concern affecting about 70 million people worldwide. Despite recent advances in pre-clinical and clinical research, its etiopathogenesis remains obscure, and there are still no treatment strategies modifying disease progression. Although the precise molecular mechanisms underlying epileptogenesis have not been clarified yet, the role of ion channels as regulators of cellular excitability has increasingly gained attention. In this regard, emerging evidence highlights the potential implication of inwardly rectifying potassium (Kir) channels in epileptogenesis. Kir channels consist of seven different subfamilies (Kir1-Kir7), and they are highly expressed in both neuronal and glial cells in the central nervous system. These channels control the cell volume and excitability. In this review, we discuss preclinical and clinical evidence on the role of the several subfamilies of Kir channels in epileptogenesis, aiming to shed more light on the pathogenesis of this disorder and pave the way for future novel therapeutic approaches.

Background: Catharanthus roseus (L.) G. Don is the main source of alkaloids anticancer drugs. Alkaloids are derived from amino acids and can lead to changes in these valuable compounds. Objective: This experiment evaluated the variation of amino acids under potassium and ascorbic acid treatments. Methods: Different concentrations (1.5, 3.16, 15 and 30 mM) and forms (K2SO4 and KNO3) of potassium (K+) were added to plants via Hoagland’s nutrient solution. Ascorbic acid (AsA) (750 mg L-1) was sprayed on the leaves surfaces on days 68 and 78. Amino acids were extracted from 90-day-old plant leaves, and different amino acids were determined by High-Performance Liquid Chromatography with fluorescence detection. Results: Amino acids increased in K+ deficiency (1.5 mM), but changes in negatively charged amino acids were lower. In contrast, N-rich amino acids showed the biggest change. In excessive K+, branched-chain and aromatic amino acids decreased, while the least amount of the other amino acids was observed in the plants treated with optimum K+. Conclusion: The exterior of AsA and excessive K+ cause branched-chain and aromatic amino acids, aspartic acid and glutamic acid to decrease.

A pot experiment was conducted during kharif season of 2019 to carry out the study on “Interactive effect of potash (K2O), potassium mobilizing bacteria (KMB) and FYM on forage yield, nutrient uptake by forage maize and soil fertility in a loamy sand soil of middle Gujarat”. Application of K2O @ 60 kg ha-1, KMB and FYM recorded significantly the highest plant height of forage maize at harvest over respective control. Crop fertilized with K2O @ 60 kg ha-1 and KMB gave significantly the highest green forage and dry matter yield. The results indicated that application of K2O @ 60 kg ha-1, potassium mobilizing bacteria recorded significantly the highest uptake of N, P, K, Fe and Zn by crop at harvest. Significantly the highest uptake of N, K and Cu were found with application of FYM @10 t ha-1. Significantly the highest K uptake by maize as well as higher P and Zn uptake by maize were observed due to interaction effect of K × KMB (60 kg K2O ha-1 with KMB). In case of N and Cu uptake by maize were noted the Significantly higher due to interaction effect of K × KMB (30 kg K2O ha-1 with KMB) and K × KMB × FYM (60 kg K2O ha-1 with KMB and FYM), respectively. The integrated use of potassium fertilizers along with KBM or in combination with FYM significantly improved the maize grain and nutrient uptake.

Aims: The present study aims to evaluate the effect of potassium carbonate (58 p.c) on agronomic and phytosanitary parameters in tomato crops. Place and Duration of Study: This study was carried out from May to September 2020 at N'gattakro, a village near the international airport in the city of Yamoussoukro, center region of Côte d’Ivoire. Methodology: Five doses of potassium carbonate (PC:T1= 2 Kg/ha; T2 = 3 Kg/ha; T3 = 4 Kg/ha; T4 = 5 Kg/ha; T5 = 6 Kg/ha), a reference control (TR1= IVORY (mancozeb 80%) and an untreated control were tested in a Fisher's complete block design with 4 replicates in a commercial garden plot. Results: As results T4 and T5 potassium carbonate improved the tomato yield. These doses promoted the yield of 5.02±0.09 and 6.92±0.16 t/ha compared to the control (3.405±0.1 t/ha). Moreover, at these doses, there was a low manifestation of toxicity. In addition, 6kg/ha of PC showed a fusarium wilt infection rate of 1.38±0.71% compared to 3.62±0.90% for the control. Conclusion: Potassium carbonate (58%) at 6 kg/ha can be an alternative solution to chemical control of fungal diseases in tomato cropping.

Potassium nutrition has been used in controlling fungal and bacterial diseases of plants. However, this has not yet been tested on control of Fusarium (Fusarium oxysporum f.sp. cubense -Foc), a major fungal disease constraining apple banana production. This study was set up with a general objective to investigate the effects of potassium on tolerance to Fusarium wilt in apple bananas using chlorophyll content, stomatal conductance and severity of Fusarium wilt symptoms as indicators. A screen house pot experiment was set up using tissue culture plantlets of apple bananas cv Ndiizi. Treatments comprised of different sources of potassium (Manure, inorganic K and potassium solubilizing bacteria -KSB) in a full factorial combination. Manure and Muriate of potash (MOP) were applied at rates equivalent to 150 kg K/ha and KSB (Frateuria auranta) at a rate of 1 l/ha. Fusarium wilt was inoculated in half the pots at 8 weeks after planting. Measurements on chlorophyll content and stomatal conductance as well as growth parameters were taken on weekly basis from the time of inoculation. Fusarium wilt significantly reduced stomatal conductance and chlorophyll content of the plants. Application of integrated potassium management (KSB x MOP x Manure) significantly reduced Fusarium wilt symptom expression. Key words: Chlorophyll content, stomatal conductance, Fusarium oxysporum sp. Cubense, manure, potassium.

Background: Anti-inflammatory role of Aloe vera gel is well established. Diclofenac is extensively used for acute and chronic inflammation. The present study was conducted to compare dried Aloe vera gel and diclofenac effects on sodium and potassium balance in hypertensive rats. Material and Methods: This experimental study was conducted at Sargodha Medical College from May to November 2016. Twenty-four healthy male Sprague Dawley rats 7-8 weeks of age were included in study. Any unhealthy-looking rat was excluded from the study. Rats were equally and randomly divided into four groups Normal control (group A), Model control (group B), Aloe vera (group C) & Diclofenac (group D). Hypertension was induced by a 20 % sucrose diet in all groups except group A in 8 weeks’ time. Group B, C & D received distilled water and Aloe vera dried gel 400 mg/kg & diclofenac powder 12 mg/kg body weight respectively orally between 8 to 10 weeks. Serum and urine analysis was performed for hematocrit, sodium, and potassium concentrations at zero, eight and ten weeks. Twenty-four-hour urinary sodium excretion was calculated. Data was analyzed using Graph Pad Prism version 6. Result: After 2-week administration of aloe vera and diclofenac powder, serum potassium significantly decreased in Group C (p

The monarch butterfly, Danaus plexippus L., has evolved to be insensitive to milkweed cardenolides via genetic modifications of Na+/K+-ATPase. There is concern for insecticide exposures near agriculture, with little information on monarch caterpillar toxicology. It is unclear how cardenolide insensitivity may affect the sensitivity of monarch caterpillars to pyrethroid insecticides. Additionally, potassium fertilizers may affect monarch caterpillar physiology and cardenolide sequestration. Here, we investigated the growth, survival, and development of caterpillars exposed to the cardenolide ouabain, bifenthrin, and potassium chloride (KCl) alone and in combination. Caterpillars were either exposed to 1) ouabain from third- to fifth-instar stage, 2) KCl at fifth-instar stage, 3) KCl and bifenthrin at fifth-instar stage, or 4) combinations of ouabain at third-instar stage + KCl + bifenthrin at fifth-instar stage. Caterpillar weight, diet consumption, frass, and survival were recorded for the duration of the experiments. It was observed that 1–3 mg ouabain/g diet increased body weight and diet consumption, whereas 50 mg KCl/g diet decreased body weight and diet consumption. Caterpillars feeding on KCl and treated with 0.2 µg/µl bifenthrin consumed significantly less diet compared to individuals provided untreated diet. However, there was no effect on survival or body weight. Combinations of KCl + ouabain did not significantly affect caterpillar survival or body weight following treatment with 0.1 µg/µl bifenthrin. At the concentrations tested, there were no effects observed for bifenthrin sensitivity with increasing cardenolide or KCl concentrations. Further studies are warranted to understand how milkweed-specific cardenolides, at increasing concentrations, and agrochemical inputs can affect monarch caterpillar physiology near agricultural landscapes.

Hepatocellular carcinoma (HCC) is a leading cause of cancer‐related death worldwide. Its high metastasis rate is significantly correlated with poor patient prognosis. Elucidating the molecular mechanism underlying HCC metastasis is essential for HCC treatment. Owing to their high conductance, large‐conductance calcium‐activated potassium channels (BK channels) play a critical role in the control of membrane potential and have repeatedly been proposed as potential targets for cancer therapy. Emerging evidence suggests that BK channels are involved in the progression of cancer malignancies. The present study investigated the role of BK channels in mediating the hypoxia‐stimulated migration of HCC cells both in vitro and in vivo in the absence and presence of various BK channels modulators. We found that BK channels were functionally expressed on the membranes of the SMMC‐7721 and Huh7 HCC cell lines. Furthermore, blockage or activation of BK channels on the surface of HCC cells correspondingly inhibited or promoted HCC cell proliferation, migration and invasion in hypoxia conditions, with altered expression and distribution of cell‐cell adhesion molecule E‐cadherin and typical marker of mesenchymal cells, Vimentin, but not N‐cadherin. Hypoxia conditions did not alter BK channels expression but increased its open probability. Moreover, BK channels blocker IbTX significantly inhibited HCC cell remote colonization in HCC cell xenografted mice. In conclusion, the results of this study suggest that blocking BK channels offers an attractive strategy for treating HCC.

Salt stress is one of the major abiotic stress, impedes plant photosynthetic processes, changes root architecture to impact leaf water status, and reduces potassium uptake and K+/Na+ ratio. Arbuscular mycorrhizal (AM) fungus and extra potassium promote plants tolerance of salt stress, respectively. However, little is known about the combined influence of AM fungus and extra potassium under salt stress. In current study, we analyzed the effects of AM fungus (Rhizophagus irregularis), potassium application (0, 1.6, and 6.4 mM K+), and salt stress (0 and 100 mM NaCl) on photosynthesis, leaf water status, root architecture, concentrations of Na+ and K+, shoot/root Na+, K+/Na+ homeostasis, and the relative expression of genes related to K+ uptake and transport (LbHAK, LbKT1, and LbSKOR) of Lycium barbarum. Under salt stress, inoculation of R. irregularis and application of potassium increased the net photosynthetic rate and stomatal conductance and reduced the intercellular CO2 concentration to improve photosynthesis. Inoculation of R. irregularis and application of potassium increased leaf relative water content and reduced water saturation deficit. Inoculation of R. irregularis and potassium application also modified root architecture, particularly in terms of root elongation and SRL reduction. Moreover, they increased K+ concentration, but evidently reduced Na+ transport to shoot. Regardless of salinity, AM plants had a significant decrease in shoot/root Na+ ratio compared with NM plants under each potassium condition. Additionally, R. irregularis and extra potassium upregulated the relative expressions of LbHAK, LbKT1, and LbSKOR, which are involved in K+/Na+ homeostasis. This study suggests that the beneficial effects of R. irregularis and extra potassium on photosynthetic capacity, root architecture, and K+/Na+ homeostasis improved the growth and salt tolerance of L. barbarum under salt stress.

Hymenaea stigonocarpa is anarboreal medicinal species used in the recovery of degraded areas. However, little is known about its nutritional requirements during the seedling phase, especially concerning to potassium. In this context, the aim of this study was to evaluate if potassium doses promote morphophysiological changes in Hymenaea stigonocarpa seedlings.A completely randomized design, consisting in six KCl doses (0, 50, 100, 150, 200 and 250 mg dm-3KCl) and four replications was applied. Biometric, biomass, physiological and potassium content variables were assessed. Hymenaea stigonocarpa displayed significant physiological and biometric responses to potassium fertilization, with the highest values observed at doses ranging from 150 to 200 mg dm-3 KCl. Moreover, concentration effects were noted regarding to potassium contents in seedling leaves and stems.

A field experiment was carried out at the Experimental Farm of El-Gemmeiza, Agric. Res. Station, El-Gharbeya Governorate, Egypt , during 2019 and 2020 summer seasons,to study the effects of different rates of potassium treatments at 48, 72 and 96 kg/fad. K2O as soil application and K2O concentration treatments at 0,0.5 and 1.0% as foliar application and their interactions on growth, yield and tuber quality of Jerusalem artichoke Fuseau cultivarunder clay soil.The interaction treatments of fertilizing Jerusalem artichoke with K2O at 72 kg /fad. as soil application (SA) and spraying plants with K2O at 1 % four times at 75, 90,105 and 120 days after planting had significantly increased on plant height , number of branches /plant,both fresh and dry weight of shoots/plant, N,P and K contents in shoots and its uptake, average tuber weight , yield / plant and total yield/faddan .While,the interaction treatment between K2O at 96 kg /fad. as soil application and spraying plants with K2O at 1% reflected a significant effect and increased total carbohydrates , inulin,K and dry matter percentages in tuber at harvest time compared with plants received K2O at 48 kg /fad. as SA only in both seasons. Finally, under the same conditions, fertilizing Jerusalem artichoke with K2O at72 kg/fad. as soil application and spraying plants with K2O at 1% reduced the using of potassium fertilizer by 25% and increases in total yield about 9.89 and 6.91 % over fertilizing with 96 kg /fad. K2O only in the 1st and 2nd seasons, respectively.

Cucumber (Cucumis sativus L.). was known for lowering blood pressure agents. Some researches show that Cucumber had a similar mechanism with a loop diuretic (Furosemide), exceeding sodium and potassium excretion. However, a part of Cucumber that gives a better effect on managing water and sodium balance remains unknown. This study was to explain the differences potential diuretic among parts of Cucumber (Cucumis sativus L.). This study was using a post-test only control group designed in animals. There were 44 male Mus musculus tested in this study. All of the animal testings was divided into 9 different treatment groups and 2 control groups. All Mus musculus got 1 mL methanol extract of Cucumber (Cucumis sativus L.) according to their group. The animal testing was put on metabolic cage to measure urine volume for 24 hours. The flesh and rind part of Cucumber (Cucumis sativus L.) showed a similar result with furosemide as diuretics agents. However, whole part of the fruit of Cucumber (Cucumis sativus L.) (flesh, rind, and seed) showed as natriuretic dan kaliuretic, Cucumber (Cucumis sativus L.) has a similar potential diuretic with Furosemide. Even in low concentrations of Cucumber extract, it led to having a potential diuretic, with natriuretic and kaliuretic effects in the whole part of the fruit. This could be suggested to people with chronic kidney diseases to prevent hyperkalemia.

BACKGROUND AND AIM The artificial sweetener acesulfame potassium (ACK) is officially approved as safe for intake and has been used in processed foods. However, ACKs have been reported to induce metabolic syndrome, along with alteration of the gut microbiota in mice. In recent years, studies have suggested that this artificial sweetener promotes myeloperoxidase reactivity in Crohn's disease-like ileitis. We aimed to investigate the effect of ACK on the intestinal mucosa and gut microbiota of normal mice. METHODS Acesulfame potassium was administered to C57BL/6J mice (8 weeks old) via free drinking. Intestinal damage was evaluated histologically, and messenger RNA (mRNA) levels of TNF-α, IFN-γ, IL1-β, MAdCAM-1, GLP1R, and GLP2R were determined with quantitative reverse transcription polymerase chain reaction (qRT-PCR). Immunohistochemistry was performed to examine the expression of MAdCAM-1 in the small intestine. The composition of gut microbiota was assessed using high-throughput sequencing. We performed intravital microscopic observation to examine if ACK altered lymphocyte migration to the intestinal microvessels. RESULTS Acesulfame potassium increased the expression of proinflammatory cytokines, decreased the expression of GLP-1R and GLP-2R, and induced small intestinal injury with an increase in intestinal permeability, and ACK treatment induced microbial changes, but the transfer of feces alone from ACK mice did not reproduce intestinal damage in recipient mice. ACK treatment significantly increased the migration of lymphocytes to intestinal microvessels. CONCLUSION Acesulfame potassium induces dysbiosis and intestinal injury with enhanced lymphocyte migration to intestinal mucosa. Massive use of non-caloric artificial sweeteners may not be as safe as we think.

Studying the ability of potassium solubilizing bacteria (KSB) inoculants to partially replace the convential potassium mineral fertilizer (KMF) in carrot fertilizing program, in addition to, clarifying their potential cytotoxicity on mitotic chromosomes division of carrot were conducted in the present investigation. According to field and laboratory experiment results, using the potassium solubilizing bacteria (KSB) as biofertilizer positively affected yield and quality of carrot especially, KSB3 inoculate. On the same direction, KSB and KMF combinations were more efficient than those of KSB and KMF alone. Regarding to the cytotoxic studies, data reveled that carrot root tips treated with KSB and their combinations improved cell division and exhibited low cytotoxicity on mitotic division than those treated with KMF alone. So, it could be concluded that potassium solubilizing bacteria (KSB) inoculants could be used alone or mixed with low doses of KMF as alternative of potassium mineral fertilizer (KMF) in carrot fertilizing programs. In addition, it had less cytotoxicity and ecologically safer than KMF.

The transition from mining to agriculture is hampered by a range of abiotic challenges to crop growth, including nutritional issues and heavy metal stress. Building on our previous work showing that potassium (K) limits legume growth in post-phosphate mining substrates on tropical Christmas Island, Australia, we undertook two field trials. The first compared the efficacy of controlled release K fertilisers (CRFs: KCl 2-month release, K2SO4 3-month and K2SO4 9-month) with immediately available potassium sulfate (K2SO4) fertiliser, on the legume Lablab purpureus. The second trial tested responses of L. purpureus to different rates of K2SO4 9-month CRF, and a combination treatment (CRF and K2SO4). Both trials were undertaken to determine how CRFs compare with immediately available K2SO4 in terms of increasing biomass, reducing cadmium (Cd) concentrations, maximising plant K concentrations and maintaining K soil retention. The first trial revealed that K2SO4 3-month and 9-month CRFs were similar to the 160 kg/ha K2SO4 treatment in significantly increasing L. purpureus biomass. Plant Cd and other heavy metal concentrations were significantly lower as plant biomass increased with increasing K, including with CRFs. The second trial showed no difference between various rates of K2SO4 9-month CRF and immediately available 160 kg/ha K2SO4 to increase biomass, reduce Cd or increase K concentrations. We have shown that although post-phosphate mining substrates can limit legume growth, high biomass can be attained with some CRFs, or K2SO4 at 160 kg/ha. Optimising nutrient input in post-mining agriculture is critical for developing safe, sustainable crops.

Two field experiments were carried out at the Vegetable Crops Farm in Baramoon Research Station, Dakahlia governorate, Egypt, during the two winter seasons, to investigate the effect of irrigation intervals under different sources of potassium combined with foliar application nano-K fertilizer on plant growth and productivity of garlic cv.Sids 40. The experiment includes 42 treatments which arranged in strip-split block design, as the interactions between three irrigation intervals (14, 21 and 28 days) as vertical plots, seven sources of potassium fertilization (100% K-mineral (150 kg Potassium Sulphate/fed.), 100% K-biofertilizer (2 L/fed., PSDB, Bacillus circulans), 100 % K-natural (700 kg Feldspar/fed.), 50 % K- mineral (75 kg/fed.) +50 % K-natural (350 kg/fed.), 50 % K- mineral (75 kg/fed.)+inoculated by PSDB, 50 % K-natural (350 kg/fed.)+inoculated by PSDB, and 33% K- mineral (50 kg/fed.)+33% K-natural (235 kg/fed.)+inoculated by PSDB as horizontal plots and two foliar applications (with nano-K and without) as split plots. Obtained results indicated that, the fertilization of plants with different sources of potassium as 33% K-mineral (50kg/fed.)+33% K-natural (235 kg/fed.) combined with inoculated by PSDB (2 L/fed), showed the best vegetative growth parameters and the highest yield productivity followed by the treatment of 50% K- mineral+50 % K-natural combined with foliar application by 3000 ppm nano-K particles under irrigation every 21 days Therefore, we recommend this treatment because it saves in the amount of mineral potassium and the amount of irrigation water and thus reduces the costs of garlic production and environmental pollution under the same conditions.

Zeolite is an abundant potassium (K)-rich silicate mineral that could increase K supply to plants. Potassium deficiency causes lodging problems and yield reductions in paddy fields in China. However, it is unknown whether zeolite amendments alleviate K deficiency or enhance lodging-related stem morphology characteristics in rice. A 2-year field experiment was conducted to evaluate the effect of zeolite amendment (0, 5 and 10 t ha–1) and K application (0, 30 and 60 kg ha–1) on rice grain yield, stem morphology, and K nutrient status in soil and plant tissues. In both years zeolite and K application, alone or in combination, significantly increased grain yield, mainly through increased number of panicles per plant with zeolite application and number of spikelets per panicle with K application. In the top 30 cm soil layer, zeolite amendment increased cation exchange capacity by up to 31% and available K by up to 38%. Zeolite or K application alone significantly increased stem, leaf and panicle K concentrations. Zeolite promoted K allocation to rice stems, and improved stem morphology associated with lodging index. In both years, zeolite or K application alone increased stem diameter, dry weight linear density and the breaking resistance moment by up to 7.0%, 8.3% and 16%, respectively, and decreased the stem lodging index by up to 6.7%. In summary, zeolite is an alternative source of K fertiliser and can alleviate K deficiency in paddy fields in China and elsewhere.

Marine algae survive in a high sodium environment, however, they experience potassium deprivation in cells as a consequence. Our previous study demonstrated that genes from the marine species of macroalgae, Pyropia yezoensis, including the ammonium transporter, PyAMT1, and a β-carbonic anhydrase, PyβCA1, could complement a potassium-uptake defective Escherichia coli mutant. In the present study, various Pyropia genes were expressed in Arabidopsis to determine if Pyropia genes could enhance potassium-deficiency tolerance in plants. Overexpression of PyAMT1, a nitrate transporter, PyNRT2.1, PyβCA1, and their Arabidopsis homologs in Arabidopsis, enhanced the tolerance of the transgenic plants to potassium starvation without altering potassium levels in the plants. A Pyropia coatomer gene, which is similar to the Arabidopsis coat protein complex I zeta subunit, also contributed to enhancing potassium deficiency tolerance and increasing potassium accumulation in Arabidopsis. The Pyropia PyC5 gene does not have any known homologues in higher plants and lacks any known motifs or domains. PyC5-overexpressing Arabidopsis plants grew much better under potassium deficiency conditions compared to control plants. Collectively, the results suggest that marine algae genes could be used as a novel source of genes to aid in the development of stress-tolerant plants.