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International audience; Arid/semi-arid and coastal agricultural areas of the world are especially vulnerable to climate change-driven soil salinity. Salinity tolerance in plants is a complex trait, with salinity negatively affecting crop yield. Plants adopt a range of mechanisms to combat salinity, with many transporter genes being implicated in Na+-partitioning processes. Within these, the high-affinity K+ (HKT) family of transporters play a critical role in K+ and Na+ homeostasis in plants. Among HKT transporters, Type I transporters are Na+-specific. While Arabidopsis has only one Na + -specific HKT (AtHKT1;1), cereal crops have a multiplicity of Type I and II HKT transporters. AtHKT1; 1 (Arabidopsis thaliana) and HKT1; 5 (cereal crops) ‘exclude’ Na+ from the xylem into xylem parenchyma in the root, reducing shoot Na+ and hence, confer sodium tolerance. However, more recent data from Arabidopsis and crop species show that AtHKT1;1/HKT1;5 alleles have a strong genetic association with ‘shoot sodium accumulation’ and concomitant salt tolerance. The review tries to resolve these two seemingly contradictory effects of AtHKT1;1/HKT1;5 operation (shoot exclusion vs shoot accumulation), both conferring salinity tolerance and suggests that contrasting phenotypes are attributable to either hyper-functional or weak AtHKT1;1/HKT1;5 alleles/ haplotypes and are under strong selection by soil salinity levels. It also suggests that opposite balancing mechanisms involving xylem ion loading in these contrasting phenotypes exist that require transporters such as SOS1 and CCC. While HKT1; 5 is a crucial but not sole determinant of salinity tolerance, investigation of the adaptive benefit(s) conferred by naturally occurring intermediate HKT1;5 alleles will be important under a climate change scenario.

Greenhouse horticulture (protected cropping) is essential in meeting increasing global food demand under climate change scenarios by ensuring sustainability, efficiency, and productivity. Recent advances in cover materials and photovoltaic technologies have been widely examined in greenhouses to improve light transmission and solar energy capture with promoting energy-saving. We review the studies on advanced greenhouse cover materials with variable light transmittance, the effects of which on leaf photosynthesis, physiology, and yield. We provide insights into the potential key biological processes of crops responding to these light changes, specifically light receptors, signal transduction, nutrient biosynthesis pathways (e.g., carotenoids, antioxidant compounds) during fruit development and ripening. A better understanding of greenhouse cover materials with a focus towards energy-efficient cover materials equipped in greenhouse is an opportunity for better yield and higher nutrient products production in vegetables in response to global climate challenges. Interdisciplinary research on the application of novel cover materials in greenhouses and biological investigation of light-induced physiology and nutrient formation in vegetables may promote yield and health attributes for protected cultivation of vegetables with energy use efficiency.

Optical films that alter light transmittance may reduce energy consumption in high-tech greenhouses, but their impact on crop physiology remains unclear. We compared the stomatal responses of Capsicum plants grown hydroponically under control glass (70% diffuse light) or the smart glass (SG) film ULR-80, which blocked >50% of short-wave radiation and ~9% of photosynthetically active radiation (PAR). SG had no significant effects on steady-state (gs) or maximal (gmax) stomatal conductance. In contrast, SG reduced stomatal pore size and sensitivity to exogenous abscisic acid (ABA), thereby increasing rates of leaf water loss, guard cell K+ and Cl– efflux, and Ca2+ influx. SG induced faster stomatal closing and opening rates on transition between low (100 µmol m–2 s–1) and high PAR (1500 µmol m–2 s–1), which compromised water use efficiency relative to control plants. The fraction of blue light (0% or 10%) did not affect gs in either treatment. Increased expression of stomatal closure and photoreceptor genes in epidermal peels of SG plants is consistent with fast stomatal responses to light changes. In conclusion, stomatal responses of Capsicum to SG were more affected by changes in light intensity than spectral quality, and re-engineering of the SG should maximize PAR transmission, and hence CO2 assimilation.

Ferns appear in the fossil record some 200 Myr before angiosperms. However, as angiosperm‐dominated forest canopies emerged in the Cretaceous period there was an explosive diversification of modern (leptosporangiate) ferns, which thrived in low, blue‐enhanced light beneath angiosperm canopies. A mechanistic explanation for this transformative event in the diversification of ferns has remained elusive. We used physiological assays, transcriptome analysis and evolutionary bioinformatics to investigate a potential connection between the evolution of enhanced stomatal sensitivity to blue light in modern ferns and the rise of angiosperm‐dominated forests in the geological record. We demonstrate that members of the largest subclade of leptosporangiate ferns, Polypodiales, have significantly faster stomatal response to blue light than more ancient fern lineages and a representative angiosperm. We link this higher sensitivity to levels of differentially expressed genes in blue‐light signaling, particularly in the cryptochrome (CRY) signaling pathway. Moreover, CRYs of the Polypodiales examined show gene duplication events between 212.9–196.9 and 164.4–151.8 Ma, when angiosperms were emerging, which are lacking in other major clades of extant land plants. These findings suggest that evolution of stomatal blue‐light sensitivity helped modern ferns exploit the shady habitat beneath angiosperm forest canopies, fueling their Cretaceous hyperdiversification.

Cold acclimation is crucial for the overwintering process of plants. Cold deacclimation is also important for plant survival in winter, which results in loss of freezing tolerance and initiation of growth. MicroRNAs (miRNAs) play crucial roles in regulating various physiological activities including cold response in plants. However, there is no study on miRNAs and their target genes in response to cold deacclimation in a cold-tolerant crop – barley (Hordeum vulgare L.). Here, we performed high-throughput sequencing of miRNAs of leaves during the cold deacclimation process using two barley cultivars with contrasting cold tolerance (Nure, tolerant and Tremois, sensitive). We found a total of 36 known and 267 novel miRNAs, including 12 known and 112 novel ones that are differentially expressed during cold deacclimation. The number of detected differentially expressed miRNAs was larger in Nure than that in Tremois, and the expression profile of miRNAs was dramatically different between Nure and Tremois. Moreover, we identified 13 known and 97 novel miRNAs, which have putative target genes during cold deacclimation. The putative targets of the novel miRNAs included genes encoding C-repeat binding factor (CBF) transcription factors, phytohormones, antioxidant, osmopretectant and flower development. Our results suggest that barley miRNAs respond quickly to cold deacclimation, and the larger number of miRNAs differentially expressed in the cold tolerant cv. Nure indicating that miRNAs might play an important role in the process of deacclimation. It sets a solid foundation for future studies and breeding programs on low temperature tolerance in barley.

This study aimed to reveal the mechanistic basis of the melatonin-mediated amelioration of salinity stress in plants. Electrophysiological experiments revealed that melatonin decreased salt-induced K+ efflux (a critical determinant of plant salt tolerance) in a dose- and time-dependent manner and reduced sensitivity of the plasma membrane K+-permeable channels to hydroxyl radicals. These beneficial effects of melatonin were abolished by NADPH oxidase blocker DPI. Transcriptome analyses revealed that melatonin induced 585 (448 up- and 137 down-regulated) and 59 (54 up- and 5 down-regulated) differentially expressed genes (DEGs) in the root tip and mature zone, respectively. The most noticeable changes in the root tip were melatonin-induced increase in the expression of several DEGs encoding respiratory burst NADPH oxidases (OsRBOHA and OsRBOHF), calcineurin B-like/calcineurin B-like-interacting protein kinase (OsCBL/OsCIPK), and calcium-dependent protein kinase (OsCDPK) under salt stress. Melatonin also enhanced the expression of potassium transporter genes (OsAKT1, OsHAK1, and OsHAK5). Taken together, these results indicate that melatonin improves salt tolerance in rice by enabling K+ retention in roots, and that the latter process is conferred by melatonin scavenging of hydroxyl radicals and a concurrent OsRBOHF-dependent ROS signalling required to activate stress-responsive genes and increase the expression of K+ uptake transporters in the root tip.

Extensive research on salinity tolerance in rice has been mostly carried out at the seedling stage in single experimental trials. Here, we aimed to understand the roles of ion transport and oxidative responses of leaf mesophyll in salinity tolerance of rice (Oryza sativa L.) at its reproductive stage using comparative investigations in both greenhouse and field trials. Two experimental trials were conducted to assess the salt tolerance of three rice cultivars at their reproductive stage in greenhouse and field. We employed agronomic, physiological, electrophysiological, molecular and cell imaging techniques to compare physiological response of control and salinity stressed rice plants. Salinity had the most severe effect to Koshihikari, followed by Doongara and Reiziq. We found that K+ retention and low recovery Cl− efflux in mesophyll cells confers salt tolerance in rice. Moderate to strong correlations were found between growth parameters and net K+ flux (r2 = 0.45–0.60), and net Cl− flux (r2 = 0.47–0.72). Also, dynamic ROS production and regulation of the NADPH oxidase gene, OsRBOHD, in mesophyll cells is crucial for salt tolerance of rice at the reproductive stage. OsRBOHD expression was significantly correlated to recovery ion fluxes (r2 = 0.45–0.64). This study brings together, for the first time, potential links between cellular ionic stress and oxidative stress components of salinity tolerance in rice at the reproductive stage in both greenhouse and field conditions. Our study will provide guidance to examine crop salinity tolerance at reproductive stages in controlled environments and natural climatic conditions in the future.

Potassium regulates a plethora of metabolic and developmental response in plants, and upon exposure to biotic and abiotic stresses a substantial K+ loss occurs from plant cells. The outward-rectifying potassium efflux GORK channels are central to this stress-induced K+ loss from the cytosol. In the mammalian systems, signaling molecules such as gamma-aminobutyric acid, G-proteins, ATP, inositol, and protein phosphatases were shown to operate as ligands controlling many K+ efflux channels. Here we present the evidence that the same molecules may also regulate GORK channels in plants. This mechanism enables operation of the GORK channels as a master switch of the cell metabolism, thus adjusting intracellular K+ homeostasis to altered environmental conditions, to maximize plant adaptive potential.

Summary Plant K+ uptake typically consists low—affinity mechanisms mediated by Shaker K+ channels (AKT/KAT/KC) and high‐affinity mechanisms regulated by HAK/KUP/KT transporters, which are extensively studied. However, the evolutionary and genetic roles of both K+ uptake mechanisms for drought tolerance are not fully explored in crops adapted to dryland agriculture. Here, we employed evolutionary bioinformatics, biotechnological and electrophysiological approaches to determine the role of two important K+ transporters HvAKT2 and HvHAK1 in drought tolerance in barley. HvAKT2 and HvHAK1 were cloned and functionally characterized using barley stripe mosaic virus‐induced gene silencing (BSMV‐VIGS) in drought‐tolerant wild barley XZ5 and agrobacterium‐mediated gene transfer in the barley cultivar Golden Promise. The hallmarks of the K+ selective filters of AKT2 and HAK1 are both found in homologues from strepotophyte algae, and they are evolutionarily conserved in strepotophyte algae and land plants. HvAKT2 and HvHAK1 are both localized to the plasma membrane and have high selectivity to K+ and Rb+ over other tested cations. Overexpression of HvAKT2 and HvHAK1 enhanced K+ uptake and H+ homoeostasis leading to drought tolerance in these transgenic lines. Moreover, HvAKT2‐ and HvHAK1‐overexpressing lines showed distinct response of K+, H+ and Ca2+ fluxes across plasma membrane and production of nitric oxide and hydrogen peroxide in leaves as compared to the wild type and silenced lines. High‐ and low‐affinity K+ uptake mechanisms and their coordination with H+ homoeostasis play essential roles in drought adaptation of wild barley. These findings can potentially facilitate future breeding programs for resilient cereal crops in a changing global climate.

Acid soil and the associated aluminum (Al) toxicity are one of major abiotic stresses, costing global agriculture significant production loss in major crops such as barley. Expansins are known as cell wall loosening proteins that regulate the loosening process of plant cell wall. However, the functional relationship between expansins and Al stress in barley was still poorly understood. In this study, we functionally characterized an Al inducible expansin gene, HvEXPA1, using a range of molecular and physiological approaches. There was a significant genotypic difference in Al-induced gene expression of HvEXPA1, where both Al-tolerant genotypes of Tibetan wild barley XZ16 and cv. Dayton showed significant upregulation but not in Al-sensitive wild barley XZ61. In XZ16, a significant upregulation of HvEXPA1 is exclusively induced by Al in low pH (4.3) at root tips, but not by low pH (4.3), normal apoplastic pH (5.8) or other metals ions such as Cr or La. Subcellular localization analysis indicated that HvEXPA1 is located in the plasma membrane. Bioinformatic analysis indicated that HvEXPA1 carried 3 domains and conserved 3D structure among seven genera. Barley stripe mosaic virus-induced gene silencing (BSMV-VIGS) of HvEXPA1 led to a significant decrease in root length and root dry weight under both of control and 200 μM Al treatments, but the inhibition in root cell length only recorded in control condition. Interestingly, reduced Al concentration via silencing of HvEXPA1 was recorded only in root cell wall but not in cell sap. Our results indicate that HvEXPA1 is an Al-inducible expansin gene, which participates in the root cell elongation and probably influences the Al content through regulating root cell wall loosening in barley.

Stomata are unique plant structures responsible for photosynthesis, transpiration and innate immunity to pathogens, and guard cells are one of the most studied cell types with respect to plant cell functioning, signalling, and stress responses. The ability to easily purify large quantities of high purity guard cell protoplasts (GCPs) would facilitate further studies, as current methods for GCP isolation are barely sufficient for omics research. Here, we report a new procedure for isolating high purity GCPs. For the isolation of GCPs, detached epidermal peels were used to extract GCPs instead of whole leaves. GCPs and mesophyll cell protoplasts (MCPs) were found to have diameters of 2.5–9.1 µm and 6.5–43.5 µm, respectively. The overlap in sizes of GCPs and MCPs suggests that blending and filtering of whole leaves used in previous methods may not necessarily avoid contamination with MCPs during GCP extraction. There were, on average, 8.4 ± 0.18 chloroplasts in GCPs and 34.6 ± 1.5 in MCPs. For MCPs and GCPs with similar sizes, there were fourfold more chloroplasts in MCPs, which made MCPs readily distinguishable from GCPs by microscopic inspection. The protocol enabled the isolation of over 1.44 × 106 GCPs from about 150 cm2Arabidopsis abaxial epidermis with over 97% purity. These protocols provide an advance in isolating sufficient, high purity, and viable protoplasts for RNA extraction and transcriptomic analysis. The application of this protocol to other plant species may accelerate the research and development of plant cell-type specific omics.

Active removal of Na+ from the cytosol into the vacuole plays a critical role in salinity tissue tolerance, but another, often neglected component of this trait is Na+ retention in vacuoles. This retention is based on an efficient control of Na+‐permeable slow‐ and fast‐vacuolar channels that mediate the back‐leak of Na+ into cytosol and, if not regulated tightly, could result in a futile cycle. This Tansley insight summarizes our current knowledge of regulation of tonoplast Na+‐permeable channels and discusses the energy cost of vacuolar Na+ sequestration, under different scenarios. We also report on a phylogenetic and bioinformatic analysis of the plant two‐pore channel family and the difference in its structure and regulation between halophytes and glycophytes, in the context of salinity tolerance.

Salinity stress in nature is often accompanied by soil waterlogging. The constraints imposed by this additional stress have a profound effect on Na+ and Cl− transport from roots to shoots, thus affecting homeostasis of some essential ions such as K+ or Ca2+ and influencing plant growth. The underlying mechanisms, however, remain largely unknown. In this study, we used a range of electrophysiological (ion flux measuring MIFE) and imaging (fluorescence dyes) techniques to investigate the role of Respiratory Burst Oxidase Homolog protein D (RBOHD) in Arabidopsis root responses to combined salinity and hypoxia stress. We found that combined stress causes more damage to plants than salinity stress alone, and the rbohD mutant is more sensitive to both treatments compared with wild type (WT). Mild hypoxia stress (root exposure to N2-bullbed solution for 48 h) reduced detrimental impact of salinity on the magnitude of NaCl-induced K+ loss from the root in wild type; this effect, however, was not observed in rbohD mutant. In salt-treated plants, onset of hypoxia led to increased uptake of Na+ and Cl− in plants lacking functional RBOHD protein but not in a wild type. The rbohD mutant lacked ability for stress-induced H2O2 production and accumulated more Ca2+ and Na+ than WT under both salinity and combined stress. These results suggested RBOHD plays an important role in the regulation of downstream Ca2+ signal and H2O2 production, thus affecting plant ionic homeostasis, and that the lack of functional RBOHD proteins compromises plant ability to minimise Na+ accumulation under salinity and combined stress.

Low-pH and Al3+ toxicity are the major factors causing the inhibition of root elongation and plant growth in acid soils. However, it is still unclear about the adaptive mechanisms for plant roots to cope with simultaneous low-pH and Al3+ toxicity in the acid soil. In this study, changes in root tip H+, K+, and Ca2+ fluxes and rhizospheric pH of three barley genotypes, including two Tibetan wild barley (XZ16, Al-tolerant; XZ61, Al-sensitive), and Al-tolerant cv Dayton, were investigated using microelectrode ion flux estimation (MIFE) technology. The results showed that Al-induced ion flux changes were mainly occurred at the elongation zone. Under low-pH treatment, at 24 h, the rhizosphere pH of low-pH tolerant XZ16 and Dayton were 0.7 and 0.3 units higher than low-pH sensitive XZ61, respectively. The H+ influx of tolerant XZ16 and Dayton was higher than that of sensitive XZ61 during the whole process of both low-pH and Al treatments. Furthermore, the Al stress significantly increased the Ca2+ efflux, inhibited the K+ efflux and ATPase activities, especially in the Al-sensitive XZ61. These results indicated that the higher low-pH tolerance in XZ16 was connected with the higher ability of H+ uptake and rhizospheric alkalization. The different mechanisms between low-pH and Al tolerance were probably tightly modulated by Al-induced increase of Ca2+ efflux and inhibition of ATPase activities.

Oxycodone or dexmedetomidine (DEX) alone are widely used in clinical practice. The aim of this study was to observe the effect of 2 oxycodone and DEX combinations on postoperative sleep quality.This was a prospective and randomized clinical study. A total of 99 patients underwent laparoscopic-assisted operations on stomach and intestines with general anesthesia were enrolled and randomly divided into 3 groups according to postoperative analgesic protocol (n=33 each). The analgesic protocols were as follows after the surgery. In group C, 0.6 mg/kg oxycodone alone was diluted to 100 mL in 0.9% saline. In group D1 or D2, 0.6 mg/kg oxycodone combined with 2.4 μg/kg or 4.8 μg/kg DEX was diluted to 100 mL in 0.9% saline, respectively. The intravenous patient-controlled analgesia device was set up to deliver a continuous infusion of 3 mL/h and a bolus of 1 mL, with a 12-minute lockout interval. The primary outcome was the percentage of stage 2 nonrapid eye movement (stage N2) sleep. Polysomnography was performed the night before operation (PSG-night0), the first (PSG-night1) and second (PSG-night2) nights after surgery.A total of 97 patients were included in the final analysis. Compared with group C, N2 sleep were higher in groups D1 and D2 on PSG-night1 (54±9% and 53±10%, respectively) and PSG-night2 (55±7% and 56±8%, respectively) (P0.001 for all comparisons). No differences were observed regarding N1 and N2 sleep between groups D1 and D2 on PSG-night1 and PSG-night2 (P0.05). Group C had higher percentage of N1 sleep on PSG-night1 (37±5%) and PSG-night2 (33±3%) when compared with groups D1 and D2 (P0.001 for the comparisons). Groups D1 and D2 required lower rates of rescue analgesia (5% and 4.7%, respectively; P=0.012) and effective pressing times (10.7±4.8 times and 9.9±2.6 times, respectively; P0.05) when compared with group C, whereas no statistical significance was found between groups D1 and D2. Furthermore, there were no significant difference about resting visual analogue scales at 4, 6, and 12 hours postoperatively between groups D1 and D2. In comparison with the other 2 groups, group D2 had a higher occurrence of postoperative hypotension (24.2%) (P0.05), though without significant sinus bradycardia.DEX combined with oxycodone can improve sleep quality and provide good visceral analgesia. However, larger doses of DEX does not further improve sleep but increases the risk of hypotension.

In recent years, research on wound healing has become increasingly in-depth, but therapeutic effects are still not satisfactory. Occasionally, pathological tissue repair occurs. Influencing factors have been proposed, but finding the turning point between normal and pathological tissue repair is difficult. Therefore, we focused our attention on the most basic level of tissue repair: fibroblasts. Fibroblasts were once considered terminally differentiated cells that represent a single cell type, and their heterogeneity was not studied until recently. We believe that subpopulations of fibroblasts play different roles in tissue repair, resulting in different repair results, such as the formation of normal scars in physiological tissue repair and fibrosis or ulcers in pathological tissue repair. It is also proposed that scarless healing can be achieved by regulating fibroblast subpopulations.

Wild rice Oryza rufipogon, a progenitor of cultivated rice Oryza sativa L., possesses superior salinity tolerance and is a potential donor for breeding salinity tolerance traits in rice. However, a mechanistic basis of salinity tolerance in this donor species has not been established. Here, we examined salinity tolerance from the early vegetative stage to maturity in O. rufipogon in comparison with a salt-susceptible (Koshihikari) and a salt-tolerant (Reiziq) variety of O. sativa. We assessed their phylogeny and agronomical traits, photosynthetic performance, ion contents, as well as gene expression in response to salinity stress. Salt-tolerant O. rufipogon exhibited efficient leaf photosynthesis and less damage to leaf tissues during the course of salinity treatment. In addition, O. rufipogon showed a significantly higher tissue Na+ accumulation that is achieved by vacuolar sequestration compared to the salt tolerant O. sativa indica subspecies. These findings are further supported by the upregulation of genes involved with ion transport and sequestration (e.g. high affinity K+ transporter 1;4 [HKT1;4], Na+/H+ exchanger 1 [NHX1] and vacuolar H+-ATPase c [VHA-c]) in salt-tolerant O. rufipogon as well as by the close phylogenetic relationship of key salt-responsive genes in O. rufipogon to these in salt-tolerant wild rice species such as O. coarctata. Thus, the high accumulation of Na+ in the leaves of O. rufipogon acts as a cheap osmoticum to minimize the high energy cost of osmolyte biosynthesis and excessive reactive oxygen species production. These mechanisms demonstrated that O. rufipogon has important traits that can be used for improving salinity tolerance in cultivated rice.

Epidermal fragments enriched in guard cells (GCs) were isolated from the halophyte quinoa (Chenopodium quinoa Wild.) species, and the response at the proteome level was studied after salinity treatment of 300 mM NaCl for 3 weeks. In total, 2147 proteins were identified, of which 36% were differentially expressed in response to salinity stress in GCs. Up and downregulated proteins included signaling molecules, enzyme modulators, transcription factors and oxidoreductases. The most abundant proteins induced by salt treatment were desiccation-responsive protein 29B (50-fold), osmotin-like protein OSML13 (13-fold), polycystin-1, lipoxygenase, alpha-toxin, and triacylglycerol lipase (PLAT) domain-containing protein 3-like (eight-fold), and dehydrin early responsive to dehydration (ERD14) (eight-fold). Ten proteins related to the gene ontology term &ldquo, response to ABA&rdquo, were upregulated in quinoa GC, this included aspartic protease, phospholipase D and plastid-lipid-associated protein. Additionally, seven proteins in the sucrose&ndash, starch pathway were upregulated in the GC in response to salinity stress, and accumulation of tryptophan synthase and L-methionine synthase (enzymes involved in the amino acid biosynthesis) was observed. Exogenous application of sucrose and tryptophan, L-methionine resulted in reduction in stomatal aperture and conductance, which could be advantageous for plants under salt stress. Eight aspartic proteinase proteins were highly upregulated in GCs of quinoa, and exogenous application of pepstatin A (an inhibitor of aspartic proteinase) was accompanied by higher oxidative stress and extremely low stomatal aperture and conductance, suggesting a possible role of aspartic proteinase in mitigating oxidative stress induced by saline conditions.

This study highlights the potential link between high light-induced canopy-level photosynthesis and mesophyll cell K+, Cl−, Ca2+, and H+ homeostasis in tomato. Light is a primary energy source for photosynthesis and a vital regulator of mineral nutrient uptake and distribution in plants. Plants need to optimize photosynthesis and nutrient balance in leaves for performance in fluctuating light conditions that are partially regulated by light-induced ion homeostatsis in the mesophyll cells. It is still elusive whether high light-induced leaf mesophyll ion fluxes affect leaf photosynthesis at different canopy levels in Solanum lycopersicum L. Leaf gas exchange and microelectrode ion flux (MIFE) measurements were employed to study the effects of prolonged light-induced canopy-level leaf physiological responses of tomato plants. High light resulted in a significant lowering in photosynthesis in the fully-exposed top canopy leaves of tomato, but not to mid- or low-canopy leaves. Leaf mesophyll K+ effluxes of all canopies were significantly decreased after three weeks of high light treatment. However, high light-induced leaf mesophyll Ca2+ effluxes were significantly enhanced only in the top and mid canopies. Moreover, we found that photosynthetic parameters were significantly correlated with leaf mesophyll ion fluxes. We thus propose that canopy-level significant Ca2+ efflux and K+ efflux of leaf mesophyll may serve as early indicators for light-induced regulation on photosynthesis. We conclude that light-induced differential photosynthetic performance and ion fluxes in leaves may implicate a requirement of more uniform light irradiance and spectra at different canopy levels of tall greenhouse tomato plants. This can be achieved through new innovative greenhouse lighting technologies and covering materials towards the enhancement of crop photosynthesis and yield.

Toxic heavy metals and metalloids in agricultural ecosystems are crucial factors that limit global crop productivity and food safety. Industrial toxic heavy metals and metalloids such as cadmium, lead, and arsenic have contaminated large areas of arable land in the world and their accumulation in the edible parts of crops is causing serious health risks to humans and animals. Plants have co-evolved with various concentrations of these toxic metals and metalloids in soil and water. Some green plant species have significant innovations in key genes for the adaptation of abiotic stress tolerance pathways that are able to tolerate heavy metals and metalloids. Increasing evidence has demonstrated that phytohormone abscisic acid (ABA) plays a vital role in the alleviation of heavy metal and metalloid stresses in plants. Here, we trace the evolutionary origins of the key gene families connecting ABA signaling with tolerance to heavy metals and metalloids in green plants. We also summarize the molecular and physiological aspects of ABA in the uptake, root-to-shoot translocation, chelation, sequestration, reutilization, and accumulation of key heavy metals and metalloids in plants. The molecular evolution and interaction between the ABA signaling pathway and mechanisms for heavy metal and metalloid tolerance are highlighted in this review. Therefore, we propose that it is promising to manipulate ABA signaling in plant tissues to reduce the uptake and accumulation of toxic heavy metals and metalloids in crops through the application of ABA-producing bacteria or ABA analogues. This may lead to improvements in tolerance of major crops to heavy metals and metalloids.

Drought and salinity are two of the most frequently co-occurring abiotic stresses. Despite recent advances in the elucidation of the effects of these stresses individually during the vegetative stage of plants, significant gaps exist in our understanding of the combined effects of these two frequently co-occurring stresses. Here, Tibetan wild barley XZ5 (drought tolerant), XZ16 (salt tolerant), and cultivated barley cv. CM72 (salt tolerant) were subjected to drought (D), salinity (S), or a combination of both treatments (D+S). Protein synthesis is one of the primary activities of the green part of the plant. Therefore, leaf tissue is an important parameter to evaluate drought and salinity stress conditions. Sixty differentially expressed proteins were identified by mass spectrometry (MALDI-TOF/TOF) and classified into 9 biological processes based on Gene Ontology annotation. Among them, 21 proteins were found to be expressed under drought or salinity alone, however, under D+S, 7 proteins, including S-adenosylmethionine synthetase 3 (SAMS3), were exclusively upregulated in drought-tolerant XZ5 but not in CM72. HvSAMS3 carries both N-terminal and central domains compared with Arabidopsis and activates the expression of several ethylene (ET)-responsive transcription factors. HvSAMS3 is mainly expressed in the roots and stems, and HvSAMS3 is a secretory protein located in the cell membrane and cytoplasm. Barley stripe mosaic virus-based virus-induced gene silencing (BSMV-VIGS) of HvSAMS3 in XZ5 severely compromised its tolerance to D+S and significantly reduced plant growth and K+ uptake. The reduced tolerance to the combined stress was associated with the inhibition of polyamines such as spermidine and spermine, polyamine oxidase, ethylene, biotin, and antioxidant enzyme activities. Furthermore, the exogenous application of ethylene and biotin improved the tolerance to D+S in BSMV-VIGS:HvSAMS3-inoculated plants. Our findings highlight the significance of HvSAMS3 in the tolerance to D+S in XZ5.

It has been increasingly important for breeding programs to be aimed at crops that are capable of coping with a changing climate, especially with regards to higher frequency and intensity of drought events. Grass stomatal complex has been proposed as an important factor that may enable grasses to adapt to water stress and variable climate conditions. There are many studies focusing on the stomatal morphology and development in the eudicot model plant Arabidopsis and monocot model plant Brachypodium. However, the comprehensive understanding of the distinction of stomatal structure and development between monocots and eudicots, especially between grasses and eudicots, are still less known at evolutionary and comparative genetic levels. Therefore, we employed the newly released version of the One Thousand Plant Transcriptome (OneKP) database and existing databases of green plant genome assemblies to explore the evolution of gene families that contributed to the formation of the unique structure and development of grass stomata. This review emphasizes the differential stomatal morphology, developmental mechanisms, and guard cell signaling in monocots and eudicots. We provide a summary of useful molecular evidences for the high water use efficiency of grass stomata that may offer new horizons for future success in breeding climate resilient crops.

Salinity stress affects global food producing areas by limiting both crop growth and yield. Attempts to develop salinity-tolerant rice varieties have had limited success due to the complexity of the salinity tolerance trait, high variation in the stress response and a lack of available donors for candidate genes for cultivated rice. As a result, finding suitable donors of genes and traits for salinity tolerance has become a major bottleneck in breeding for salinity tolerant crops. Twenty-two wild Oryza relatives have been recognized as important genetic resources for quantitatively inherited traits such as resistance and/or tolerance to abiotic and biotic stresses. In this review, we discuss the challenges and opportunities of such an approach by critically analyzing evolutionary, ecological, genetic, and physiological aspects of Oryza species. We argue that the strategy of rice breeding for better Na+ exclusion employed for the last few decades has reached a plateau and cannot deliver any further improvement in salinity tolerance in this species. This calls for a paradigm shift in rice breeding and more efforts toward targeting mechanisms of the tissue tolerance and a better utilization of the potential of wild rice where such traits are already present. We summarize the differences in salinity stress adaptation amongst cultivated and wild Oryza relatives and identify several key traits that should be targeted in future breeding programs. This includes: (1) efficient sequestration of Na+ in mesophyll cell vacuoles, with a strong emphasis on control of tonoplast leak channels; (2) more efficient control of xylem ion loading; (3) efficient cytosolic K+ retention in both root and leaf mesophyll cells; and (4) incorporating Na+ sequestration in trichrome. We conclude that while amongst all wild relatives, O. rufipogon is arguably a best source of germplasm at the moment, genes and traits from the wild relatives, O. coarctata, O. latifolia, and O. alta, should be targeted in future genetic programs to develop salt tolerant cultivated rice.

Soil salinity is a major environmental constraint affecting crop growth and threatening global food security. Plants adapt to salinity by optimizing the performance of stomata. Stomata are formed by two guard cells (GCs) that are morphologically and functionally distinct from the other leaf cells. These microscopic sphincters inserted into the wax-covered epidermis of the shoot balance CO2 intake for photosynthetic carbon gain and concomitant water loss. In order to better understand the molecular mechanisms underlying stomatal function under saline conditions, we used proteomics approach to study isolated GCs from the salt-tolerant sugar beet species. Of the 2088 proteins identified in sugar beet GCs, 82 were differentially regulated by salt treatment. According to bioinformatics analysis (GO enrichment analysis and protein classification), these proteins were involved in lipid metabolism, cell wall modification, ATP biosynthesis, and signaling. Among the significant differentially abundant proteins, several proteins classified as &ldquo, stress proteins&rdquo, were upregulated, including non-specific lipid transfer protein, chaperone proteins, heat shock proteins, inorganic pyrophosphatase 2, responsible for energized vacuole membrane for ion transportation. Moreover, several antioxidant enzymes (peroxide, superoxidase dismutase) were highly upregulated. Furthermore, cell wall proteins detected in GCs provided some evidence that GC walls were more flexible in response to salt stress. Proteins such as L-ascorbate oxidase that were constitutively high under both control and high salinity conditions may contribute to the ability of sugar beet GCs to adapt to salinity by mitigating salinity-induced oxidative stress.

Aluminum (Al) toxicity is the primary limiting factor of crop production on acid soils. Tibetan wild barley germplasm is a valuable source of potential genes for breeding barley with acid and Al tolerance. We performed microRNA and RNA sequencing using wild (XZ16, Al-tolerant; XZ61, Al-sensitive) and cultivated (Dayton, Al-tolerant) barley. A novel homeobox-leucine zipper transcription factor, HvHOX9, was identified as a target gene of miR166b and functionally characterized. HvHOX9 was up-regulated by Al stress in XZ16 (but unchanged in XZ61 and Dayton) and was significantly induced only in root tip. Phylogenetic analysis showed that HvHOX9 is most closely related to wheat TaHOX9 and orthologues of HvHOX9 are present in the closest algal relatives of Zygnematophyceae. Barley stripe mosaic virus-induced gene silencing of HvHOX9 in XZ16 led to significantly increased Al sensitivity but did not affect its sensitivity to other metals and low pH. Disruption of HvHOX9 did not change Al concentration in the root cell sap, but led to more Al accumulation in root cell wall after Al exposure. Silencing of HvHOX9 decreased H+ influx after Al exposure. Our findings suggest that miR166b/HvHOX9 play a critical role in Al tolerance by decreasing root cell wall Al binding and increasing apoplastic pH for Al detoxification in the root.

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. Energy requirements for transport of salt (NaCl) to leaf vacuoles for osmotic adjustment could be small if there are no substantial leaks back across plasma membrane and tonoplast in root and leaf. The coupling ratio of the H$^{+}$-ATPase also is a critical component. One proposed leak, that of Na$^{+}$ influx across the plasma membrane through certain aquaporin channels, might be coupled to water flow, thus conserving energy. For the tonoplast, control of two types of cation channels is required for energy efficiency. Transporters controlling the Na$^{+}$ and Cl$^{-}$ concentrations in mitochondria and chloroplasts are largely unknown and could be a major energy cost. The complexity of the system will require a sophisticated modelling approach to identify critical transporters, apoplastic barriers and root structures. This modelling approach will inform experimentation and allow a quantitative assessment of the energy costs of NaCl tolerance to guide breeding and engineering of molecular components.

Emerging evidence has demonstrated that the aberrant expression of histone-modifying enzymes such as histone demethylases contributes to gastric carcinogenesis and progression. The role of KDM4B in cancer progression has been gradually revealed. However, the underlying mechanisms regulating gastric cancer metastasis of KDM4B remain unclear. In the present study we determined KDM4B expression in gastric cancer and its biologic function in vitro and in vivo. We found that KDM4B expression was significantly increased in most gastric cancer tissues compared with the adjacent normal tissues. Upregulated expression of KDM4B in human gastric cancer was correlated with poor prognosis. In vitro, KDM4B overexpression in AGS cells promoted cell invasion, whereas knockdown of KDM4B inhibited cell invasion. Furthermore, KDM4B overexpression also promoted tumor metastasis in vivo. Mechanistically, KDM4B upregulated miR-125b expression and activated Wnt signaling pathway. More important, miR-125b partially mediated KDM4B-induced activation of Wnt signaling. Finally, we demonstrated that KDM4B promoted gastric cancer cell invasion in vitro and cancer metastasis in vivo, at least in part, by upregulating miR-125b expression. These data provided novel insights on the role of KDM4B-driven gastric cancer metastasis and indicated that KDM4B may be served as a potential target for gastric cancer.

Drought is one of the major abiotic stresses affecting crop yields. Understanding drought tolerance mechanism is pivotal for developing drought tolerant crop cultivars. Here, two Tibetan annual wild barley genotypes XZ5 (drought-tolerant) and XZ54 (drought-sensitive) were tested in this study. Gas exchange, stomatal parameters and yield analyses showed that XZ5 has superior drought tolerance than XZ54. Genome-wide transcriptome analysis with epidermal cell layer of XZ5 and XZ54 identified a total of 6,627 genes as drought-induced differentially expressed genes (DEGs) between the two genotypes. The key DEGs could be classified into abscisic acid, brassinosteroid, jasmonic acid, gibberellins, auxin indole-3-acetic acid pathways, reactive oxygen species signaling, Ca2+ signaling, nitric oxide signaling, stomatal development and membrane transport. Moreover, we discovered unique crosstalks among phytohormone pathways, cellular signaling and membrane transport, which are better regulated in the drought tolerant genotype XZ5. For instance, brassinosteroid may participate in co-regulation of stomatal movement with Abscisic acid through suppressing the expression of Brassinosteroid Insensitive 1-Associated Receptor Kinase (HvBAK) to release the interaction target Open Stomata 1 (HvOST1) in barley epidermal layers. This study provides some tissue-specific insights into the role of a crucial layer of cells—leaf epidermis for drought tolerance in the wild progenitors of cultivated barley.

We previously reported that expression and activity of acid invertases (AI) are increased in peach fruit under chilling stress. In order to determine which AI genes respond to chilling stress, seven AI genes, two vacuolar invertases (VINs) and five cell wall-bound invertases (CWINs), were identified and cloned. The predicted amino acid sequences of the genes contain conserved sites characteristic of plant AIs such as NDPNG/A, the sucrose-binding site, and MWECV/P, a cysteine catalytic motif. Using gene-specific primers, the expression of each gene was measured in ‘Baifeng’ and ‘Yulu’ peach fruits stored at 0, 5, 10 and 20 °C. Of the seven genes, expression of PpVIN2 was the most affected by chilling stress; the largest increases were in fruit stored at 5 °C, up to 17-fold in ‘Baifeng’ fruit, and up to 280-fold in ‘Yulu’ fruit. Overall, VIN activity was much higher than CWIN activity in stored peach fruit. In both cultivars reducing sugar content increased significantly and sucrose content decreased gradually during storage at 5 °C relative to other temperatures, and was accompanied by severe chilling injury symptoms. Thus, PpVIN2 appears to be induced by chilling and may play an important role in sucrose metabolism in peach fruit subjected to cold storage.

Our previous studies showed that high salt tolerance in Tibetan wild barley accessions was associated with HvHKT1;1, a member of the high-affinity potassium transporter family. However, molecular mechanisms of HvHKT1;1 for salt tolerance and its roles in K+/Na+ homeostasis remain to be elucidated. Functional characterization of HvHKT1;1 was conducted in the present study. NaCl-induced transcripts of HvHKT1;1 were significantly higher in the roots of Tibetan wild barley XZ16 relative to other genotypes, being closely associated with its higher biomass and lower tissue Na+ content under salt stress. Heterologous expression of HvHKT1;1 in Saccharomyces cerevisiae (yeast) and Xenopus laevis oocytes showed that HvHKT1;1 had higher selectivity for Na+ over K+ and other monovalent cations. HvHKT1;1 was found to be localized at the cell plasma membrane of root stele and epidermis. Knock-down of HvHKT1;1 in barley led to higher Na+ accumulation in both roots and leaves, while overexpression of HvHKT1;1 in salt-sensitive Arabidopsis hkt1-4 and sos1-12 loss-of-function lines resulted in significantly less shoot and root Na+ accumulation. Additionally, microelectrode ion flux measurements and root elongation assay revealed that the transgenic Arabidopsis plants exhibited a remarkable capacity for regulation of Na+, K+, Ca2+ and H+ homeostasis under salt stress. These results indicate that HvHKT1;1 is critical in radial root Na+ transport, which eventually reduces shoot Na+ accumulation. Additionally, HvHKT1;1 may be indirectly involved in retention of K+ and Ca2+ in root cells, which also improves plant salt tolerance.

Stronger Na+ extrusion and vacuolar sequestration are essential to confer better salt tolerance in bread wheat than in durum wheat. Removal of the root meristems increased salt sensitivity in wheat., The progress in plant breeding for salinity stress tolerance is handicapped by the lack of understanding of the specificity of salt stress signalling and adaptation at the cellular and tissue levels. In this study, we used electrophysiological, fluorescence imaging, and real-time quantitative PCR tools to elucidate the essentiality of the cytosolic Na+ extrusion in functionally different root zones (elongation, meristem, and mature) in a large number of bread and durum wheat accessions. We show that the difference in the root’s ability for vacuolar Na+ sequestration in the mature zone may explain differential salinity stress tolerance between salt-sensitive durum and salt-tolerant bread wheat species. Bread wheat genotypes also had on average 30% higher capacity for net Na+ efflux from the root elongation zone, providing the first direct evidence for the essentiality of the root salt exclusion trait at the cellular level. At the same time, cytosolic Na+ accumulation in the root meristem was significantly higher in bread wheat, leading to the suggestion that this tissue may harbour a putative salt sensor. This hypothesis was then tested by investigating patterns of Na+ distribution and the relative expression level of several key genes related to Na+ transport in leaves in plants with intact roots and in those in which the root meristems were removed. We show that tampering with this sensing mechanism has resulted in a salt-sensitive phenotype, largely due to compromising the plant’s ability to sequester Na+ in mesophyll cell vacuoles. The implications of these findings for plant breeding for salinity stress tolerance are discussed.

Significance Microsite evolution involving ecological divergence due to geological, edaphic, or climatic conditions requires adaptive complexes to environmental stresses. The higher drought tolerance of wild barley populations inhabiting Terra Rossa soil at the Tabigha Evolution Slope has been described, but the underlying genetic mechanisms remain unknown. Using genome resequencing and RNA-sequencing technologies of wild barley genotypes from contrasting Terra Rossa and basalt soil types, we identified genes in selection sweep regions on chromosomes 6H and 7H, showing divergence in the barley populations from Terra Rossa and basalt soils with significant roles in plant drought tolerance. Our results set a solid foundation for future work on gene discovery and on drought adaptation mechanisms in barley related to the rhizosphere environment., Ecological divergence at a microsite suggests adaptive evolution, and this study examined two abutting wild barley populations, each 100 m across, differentially adapted to drought tolerance on two contrasting soil types, Terra Rossa and basalt at the Tabigha Evolution Slope, Israel. We resequenced the genomes of seven and six wild barley genotypes inhabiting the Terra Rossa and basalt soils, respectively, and identified a total of 69,192,653 single-nucleotide variants (SNVs) and insertions/deletions in comparison with a reference barley genome. Comparative genomic analysis between these abutting wild barley populations involved 19,615,087 high-quality SNVs. The results revealed dramatically different selection sweep regions relevant to drought tolerance driven by edaphic natural selection within 2,577 selected genes in these regions, including key drought-responsive genes associated with ABA synthesis and degradation (such as Cytochrome P450 protein) and ABA receptor complex (such as PYL2, SNF1-related kinase). The genetic diversity of the wild barley population inhabiting Terra Rossa soil is much higher than that from the basalt soil. Additionally, we identified different sets of genes for drought adaptation in the wild barley populations from Terra Rossa soil and from wild barley populations from Evolution Canyon I at Mount Carmel. These genes are associated with abscisic acid signaling, signaling and metabolism of reactive oxygen species, detoxification and antioxidative systems, rapid osmotic adjustment, and deep root morphology. The unique mechanisms for drought adaptation of the wild barley from the Tabigha Evolution Slope may be useful for crop improvement, particularly for breeding of barley cultivars with high drought tolerance.

Larynx carcinoma (LC) is the most prevalent head and neck cancer among adults. LC xenograft mouse model was generated to verify the effect of VEGF on macrophage polarization and tumor growth in vivo. EdU assay was performed to measure the cell proliferation. Transwell assay was applied to assess cell migration. The expression of YAP and STAT3 was also significantly increased in LC tumor tissues. Moreover, both YAP and STAT3 overexpression in LC cells promoted the proliferation, migration, as well as the secretion of PD-L1 in M2-like TAMs. Mechanistically, the interaction between YAP and STAT3 facilitated the transcription of VEGF. Moreover, with a co-culture system, VEGF secretion in LC cells enhanced PD-L1 expression in M2-like TAMs via activating VEGFR1-TGFβ signaling pathway. Furthermore, VEGF secreted from LC cells also promoted the tumor growth of LC in vivo. We revealed that dysregulated YAP/STAT3 activity in LC cells could enhance the secretion of VEGF, which then functioned on M2-like TAMs via activating VEGFR1-TGFββ pathway to promote the expression of PD-L1 and immunosuppressive function of M2-like TAMs. Therefore, VEGF and PD-L1 might have a pivotal crosstalk between M2-like TAMs and LC cells, which provided a novel therapeutic target in regulating the metastasis of LC in future.

In plants, calcineurin B-like (CBL) proteins and their interacting protein kinases (CIPK) form functional complexes that transduce downstream signals to membrane effectors assisting in their adaptation to adverse environmental conditions. This study addresses the issue of the physiological role of CIPK9 in adaptive responses to salinity, osmotic stress, and K+ deficiency in rice plants. Whole-plant physiological studies revealed that Oscipk9 rice mutant lacks a functional CIPK9 gene and displayed a mildly stronger phenotype, both under saline and osmotic stress conditions. The reported difference was attributed to the ability of Oscipk9 to maintain significantly higher stomatal conductance (thus, a greater carbon gain). Oscipk9 plants contained much less K+ in their tissues, implying the role of CIPK9 in K+ acquisition and homeostasis in rice. Oscipk9 roots also showed hypersensitivity to ROS under conditions of low K+ availability suggesting an important role of H2O2 signalling as a component of plant adaptive responses to a low-K environment. The likely mechanistic basis of above physiological responses is discussed.

Summary Qingke, the local name of hulless barley in the Tibetan Plateau, is a staple food for Tibetans. The availability of its reference genome sequences could be useful for studies on breeding and molecular evolution. Taking advantage of the third‐generation sequencer (PacBio), we de novo assembled a 4.84‐Gb genome sequence of qingke, cv. Zangqing320 and anchored a 4.59‐Gb sequence to seven chromosomes. Of the 46,787 annotated ‘high‐confidence’ genes, 31 564 were validated by RNA‐sequencing data of 39 wild and cultivated barley genotypes with wide genetic diversity, and the results were also confirmed by nonredundant protein database from NCBI. As some gaps in the reference genome of Morex were covered in the reference genome of Zangqing320 by PacBio reads, we believe that the Zangqing320 genome provides the useful supplements for the Morex genome. Using the qingke genome as a reference, we conducted a genome comparison, revealing a close genetic relationship between a hulled barley (cv. Morex) and a hulless barley (cv. Zangqing320), which is strongly supported by the low‐diversity regions in the two genomes. Considering the origin of Morex from its breeding pedigree, we then demonstrated a close genomic relationship between modern cultivated barley and qingke. Given this genomic relationship and the large genetic diversity between qingke and modern cultivated barley, we propose that qingke could provide elite genes for barley improvement.

Over 17 million km2 of land is affected by soil flooding every year, resulting in substantial yield losses and jeopardizing food security across the globe. A key step in resolving this problem and creating stress-tolerant cultivars is an understanding of the mechanisms by which plants sense low-oxygen stress. In this work, we review the current knowledge about the oxygen-sensing and signaling pathway in mammalian and plant systems and postulate the potential role of ion channels as putative oxygen sensors in plant roots. We first discuss the definition and requirements for the oxygen sensor and the difference between sensing and signaling. We then summarize the literature and identify several known candidates for oxygen sensing in the mammalian literature. This includes transient receptor potential (TRP) channels; K+-permeable channels (Kv, BK and TASK); Ca2+ channels (RyR and TPC); and various chemo- and reactive oxygen species (ROS)-dependent oxygen sensors. Identified key oxygen-sensing domains (PAS, GCS, GAF and PHD) in mammalian systems are used to predict the potential plant counterparts in Arabidopsis. Finally, the sequences of known mammalian ion channels with reported roles in oxygen sensing were employed to BLAST the Arabidopsis genome for the candidate genes. Several plasma membrane and tonoplast ion channels (such as TPC, AKT and KCO) and oxygen domain-containing proteins with predicted oxygen-sensing ability were identified and discussed. We propose a testable model for potential roles of ion channels in plant hypoxia sensing.

While the role of the vacuolar NHX Na+/H+ exchangers in plant salt tolerance has been demonstrated on numerous occasions, their control over cytosolic ionic relations has never been functionally analysed in the context of subcellular Na+ and K+ homeostasis. In this work, PutNHX1 and SeNHX1 were cloned from halophytes Puccinellia tenuiflora and Salicornia europaea and transiently expressed in Arabidopsis wild type Col-0 and the nhx1 mutant. Phylogentic analysis, topological prediction, analysis of evolutionary conservation, the topology structure and analysis of hydrophobic or polar regions of PutNHX1 and SeNHX1 indicated that they are unique tonoplast Na+/H+ antiporters with characteristics for salt tolerance. As a part of the functional assessment, cytosolic and vacuolar Na+ and K+ in different root tissues and ion fluxes from root mature zone of Col-0, nhx1 and their transgenic lines were measured. Transgenic lines sequestered large quantity of Na+ into root cell vacuoles and also promoted high cytosolic and vacuolar K+ accumulation. Expression of PutNHX1 and SeNHX1 led to significant transient root Na+ uptake in the four transgenic lines upon recovery from salt treatment. In contrast, the nhx1 mutant maintained a prolonged Na+ efflux and the nhx1:PutNHX1 and nhx1:SeNHX1 lines started to actively pump Na+ out of the cell. Overall, our findings suggest that PutNHX1 and SeNHX1 improve Na+ sequestration in the vacuole and K+ retention in the cytosol and vacuole of root cells of Arabidopsis, and that they interact with other regulatory mechanisms to provide a highly orchestrated regulation of ionic relations among intracellular cell compartments.

Aluminium (Al) toxicity and phosphorus (P) deficiency often co-exist in acidic soils and limit plant growth and crop production. To investigate the alleviating effects of different levels of phosphorus on Al stress, greenhouse hydroponic experiments were conducted using two contrasting Tibetan wild barley genotypes XZ16 and XZ61 of Al tolerant and sensitive, respectively, and Al tolerant cv. Dayton. The results showed that Al stress induced reduction in P accumulation in plants; and stem and leaf P concentrations of the three genotypes, except of XZ16 under HP + Al (100 µM Al with high level of 360 µM P) which was close to the control level. XZ16 recorded significantly higher P accumulation in plants, compared with XZ61 and Dayton, and P concentrations in leaves under Al stress, and in stems under NP + Al (100 µM Al with normal level of 180 µM P) and HP + Al. Meanwhile, H+-, Ca2+Mg2+-, and Total- ATPase activities in XZ16 and Dayton under Al stress were markedly higher than in XZ61. Normal or high level of P under Al stress could relieve Al stress as enhanced plant biomass, with increased photosystem II photochemistry (Fv/Fm) and P content, relative to the low level of 90 µM P. Compared with XZ61, addition of high P concentration for XZ16 significantly increased the values of Gs and Tr, with higher root GPX and H+-ATPase activities, and such nutrient elements as P, Mg and Ca in stems and leaves, and induced more malate secretion, but less MDA accumulation.

Genotypic differences in cadmium (Cd) transport in developing grains of barley (Hordeum vulgare L.) were investigated using detached ears cultured in a nutrient solution containing 0.5 and 5 μM Cd. Cd concentration in each part of the ear in W6nk2 (a low-grain-Cd-accumulation genotype) was much less than in Zhenong8 (a high accumulator) with 0.5 μM Cd treatment. However, Cd concentration in W6nk2 grains increased with an increase in external Cd level and was similar to Zhenong8 with 5 μM Cd treatment. Awn removal, a high relative humidity (RH, 90%) and addition of sucrose markedly decreased grain Cd concentration in Zhenong8 but less affected Cd transport to grain in W6nk2. Stem girdling reduced Cd transport to developing grains with 5 μM Cd treatment, especially for W6nk2, whereas no effect was found in either genotype with low Cd treatment. Our results suggested that higher grain Cd in Zhenong8 is closely related to a larger capacity for xylem transport and is connected with Cd translocation in xylem and phloem sap.

Light is a vital regulator that controls physiological and cellular responses to regulate plant growth, development, yield, and quality. Light is the driving force for electron and ion transport in the thylakoid membrane and other membranes of plant cells. In different plant species and cell types, light activates photoreceptors, thereby modulating plasma membrane transport. Plants maximize their growth and photosynthesis by facilitating the coordinated regulation of ion channels, pumps, and co-transporters across membranes to fine-tune nutrient uptake. The signal-transducing functions associated with membrane transporters, pumps, and channels impart a complex array of mechanisms to regulate plant responses to light. The identification of light responsive membrane transport components and understanding of their potential interaction with photoreceptors will elucidate how light-activated signaling pathways optimize plant growth, production, and nutrition to the prevailing environmental changes. This review summarizes the mechanisms underlying the physiological and molecular regulations of light-induced membrane transport and their potential interaction with photoreceptors in a plant evolutionary and nutrition context. It will shed new light on plant ecological conservation as well as agricultural production and crop quality, bringing potential nutrition and health benefits to humans and animals.

Wild barley Hordeum spontaneum (WB) is the progenitor of a cultivated barley Hordeum vulgare (CB). Understanding efficient mechanisms evolved by WB to cope with abiotic stresses may open prospects of transferring these promising traits to the high yielding CB genotypes. This study aimed to investigate the strategies that WB plants utilise in regard to the control of stomatal operation and ionic homeostasis to deal with salinity stress, one of the major threats to the global food security. Twenty-six genotypes of WB and CB were grown under glasshouse conditions and exposed to 300 mM NaCl salinity treatment for 5 weeks followed by their comprehensive physiological assessment. WB had higher relative biomass than CB when exposed to salinity stress. Under saline conditions, WB plants were able to keep constant stomatal density (SD) while SD significantly decreased in CB. The higher SD in WB also resulted in a higher stomatal conductance (gs) under saline conditions, with gs reduction being 51% and 72% in WB and CB, respectively. Furthermore, WB showed faster stomatal response to light, indicating their better ability to adapt to changing environmental conditions. Experiments with isolated epidermal strips indicated that CB genotypes have the higher stomatal aperture when incubated in 80 mM KCl solution, and its aperture declined when KCl was substituted by NaCl. On the contrary, WB genotype had the highest stomatal aperture being exposed to 80 mM NaCl suggesting that WB plants may use Na+ instead of K+ for stomata movements. Overall, our data suggest that CB employ a stress-escaping strategy by reducing stomata density, to conserve water, when grown under salinity conditions. WB, on a contrary, is capable of maintaining relatively constant stomata density, faster stomatal movement and higher gs under saline conditions.

Halophytic Oryza coarctata is a good model system to examine mechanisms of salinity tolerance in rice. O. coarctata leaves show the presence of microhairs in adaxial leaf surface furrows that secrete salt under salinity. However, detailed molecular and physiological studies of O. coarctata microhairs are limited due to their relative inaccessibility. This work presents a detailed characterization of O. coarctata leaf features. O. coarctata has two types of microhairs on the adaxial leaf surface: longer microhairs (three morphotypes) lining epidermal furrow walls and shorter microhairs (reported first time) arising from bulliform cells. Microhair morphotypes include (i) finger-like, tubular structures, (ii) tubular hairs with bilobed and flattened heads and (iii) bi-or trifurcated hairs. The unicellular nature of microhairs was confirmed by propidium iodide (PI) staining. An efficient method for the isolation and enrichment of O. coarctata microhairs is presented (yield averaging ∼2 × 105/g leaf tissue). The robustness of the microhair isolation procedure was confirmed by subsequent viability staining (PI), total RNA isolation and RT-PCR amplification of O. coarctata trichome-specific WUSCHEL-related homeobox 3B (OcWox3B) and transporter gene-specific cDNA sequences. The present microhair isolation work from O. coarctata paves the way for examining genes involved in ion secretion in this halophytic wild rice model.

Significance The projected increase in drought severity and duration worldwide poses a significant threat to the health of terrestrial ecosystems. We reveal that unique genetic features of desiccation sensing and protection in streptophyte algae not only distinguish them from chlorophyte algae, but also represent a crucial evolutionary step that may have facilitated colonization and subsequent diversification of terrestrial habitats. We demonstrate the evolutionary significance of a molecular mechanism underlying how plants sense drought stress via the coordination of chloroplast retrograde signaling to trigger the closure of stomata, protecting vital photosynthetic tissue. Our findings constitute a significant step forward in understanding the evolution of plant drought tolerance, contributing to the diversification of terrestrial plant communities through past global climate transitions., Chloroplast retrograde signaling networks are vital for chloroplast biogenesis, operation, and signaling, including excess light and drought stress signaling. To date, retrograde signaling has been considered in the context of land plant adaptation, but not regarding the origin and evolution of signaling cascades linking chloroplast function to stomatal regulation. We show that key elements of the chloroplast retrograde signaling process, the nucleotide phosphatase (SAL1) and 3′-phosphoadenosine-5′-phosphate (PAP) metabolism, evolved in streptophyte algae—the algal ancestors of land plants. We discover an early evolution of SAL1-PAP chloroplast retrograde signaling in stomatal regulation based on conserved gene and protein structure, function, and enzyme activity and transit peptides of SAL1s in species including flowering plants, the fern Ceratopteris richardii, and the moss Physcomitrella patens. Moreover, we demonstrate that PAP regulates stomatal closure via secondary messengers and ion transport in guard cells of these diverse lineages. The origin of stomata facilitated gas exchange in the earliest land plants. Our findings suggest that the conquest of land by plants was enabled by rapid response to drought stress through the deployment of an ancestral SAL1-PAP signaling pathway, intersecting with the core abscisic acid signaling in stomatal guard cells.

Leaf shape is an important trait that influences the utilization rate of light, and affects quality and yield of pea (Pisum sativum). In the present study, a joint method of high-density genetic mapping using specific locus amplified fragment sequencing (SLAF-seq) and bulked segregant analysis (BSA) was applied to rapidly detect loci with leaf shape traits. A total of 7,146 polymorphic SLAFs containing 12,213 SNP markers were employed to construct a high-density genetic map for pea. We conducted quantitative trait locus (QTL) mapping on an F2 population to identify QTLs associated with leaf shape traits. Moreover, SLAF-BSA was conducted on the same F2 population to identify the single nucleotide polymorphism (SNP) markers linked to leaf shape in pea. Two QTLs (qLeaf_or-1, qLeaf_or-2) were mapped on linkage group 7 (LG7) for pea leaf shape. Through alignment of SLAF markers with Cicer arietinum, Medicago truncatula, and Glycine max, the pea LGs were assigned to their corresponding homologous chromosomal groups. The comparative genetic analysis showed that pea is more closely related to M. truncatula. Based on the sequencing results of two pools with different leaf shape, 179 associated markers were obtained after association analysis. The joint analysis of SLAF-seq and BSA showed that the QTLs obtained from mapping on a high-density genetic map are convincing due to the closely associated map region with the BSA results, which provided more potential markers related to leaf shape. Thus, the identified QTLs could be used in marker-assisted selection for pea breeding in the future. Our study revealed that joint analysis of QTL mapping on a high-density genetic map and BSA-seq is a cost-effective and accurate method to reveal genetic architecture of target traits in plant species without a reference genome.

To understand the adaptive strategies employed by plants to deal with saline conditions, two halophytic species [Chenopodium quinoa (quinoa) and Beta maritima (sea beet)] and their glycophytic relatives [Chenopodium album and Beta vulgaris (sugar beet)] were grown under 0−500 mM salt concentrations followed by the comprehensive assessment of their agronomical, ionic, gas exchange characteristics. Salinity levels up to 300 mM NaCl had no adverse effect on quinoa biomass and 200 mM NaCl stimulated sea beet growth. Stomatal conductance decreased in a dose-dependent manner in all species with increasing NaCl concentrations. However, CO2 assimilation rates remained constant or displayed higher values at the medium level of salinity (100−200 mM NaCl) in quinoa, sugar beet and sea beet. High maximum carboxylation rate of Rubisco (Vcmax) and higher rate of electron transport through photosystem II (J) were responsible for the high photosynthetic rates and biomass productions under these conditions. Both characteristics were much higher in halophytic species for the given external NaCl level. Stomatal densities were intrinsically lower in halophytic species (14–34%); these increased with increasing salinity levels in the sugar beet and sea beet while C. album and quinoa stomata remained less dense under saline conditions. Stomata responses to environmental stimuli were much faster in halophytes (16.6–49.7%), and substitution of K+ by Na+ resulted in promotion of stomatal opening under 50 mM NaCl and 50 mM KCl in quinoa. It is concluded that superior salinity tolerance in halophytes is achieved by significantly faster stomatal opening and closure, their ability to discriminate K+ over Na+, and uncoupling of CO2 assimilation from changes in stomatal aperture.

On the basis of endocrine therapy for patients with low burden metastatic prostate cancer (LBMP), the clinical efficacy and quality of life were compared between prostate-only directed radiotherapy (PODT) and prostate and metastasis radiotherapy (PMRT). From November 2009 to November 2015, total 91 patients newly diagnosed with LBMP were retrospectively analyzed, of which 52 patients received PODT and 39 patients received PMRT. The biochemical failure free interval (IBF), prostate specific survival (PCSS), and overall survival (OS) time were compared between the 2 groups, and expanded prostate cancer index composite (EPIC) scale was used to evaluate the difference in quality of life between the 2 groups. The median IBF of the PODT group was 31 months, which was significantly lower than the 39 months of the PMRT group (P .05); the side effects of acute radiotherapy in PMRT group were significantly higher than PODT group (P .05). Patients with LBMP receiving PMRT can improve IBF, but cannot increase PCSS and OS, and increase the incidence of acute radiation injury.

Knocking out GORK channels prevents K+ leak and increases waterlogging tolerance, while reduced RBOHD activity interferes with Ca2+ signalling, resulting in a hypoxia-sensitive phenotype., Regulation of root cell K+ is essential for acclimation to low oxygen stress. The potential roles of GORK (depolarization-activated guard cell outward-rectifying potassium) channels and RBOHD (respiratory burst oxidase homologue D) in plant adaptive responses to hypoxia were investigated in the context of tissue specificity (epidermis versus stele; elongation versus mature zone) in roots of Arabidopsis. The expression of GORK and RBOHD was down-regulated by 2- to 3-fold within 1 h and 24 h of hypoxia treatment in Arabidopsis wild-type (WT) roots. Interestingly, a loss of the functional GORK channel resulted in a waterlogging-tolerant phenotype, while rbohD knockout was sensitive to waterlogging. To understand their functions under hypoxia stress, we studied K+, Ca2+, and reactive oxygen species (ROS) distribution in various root cell types. gork1-1 plants had better K+ retention ability in both the elongation and mature zone compared with the WT and rbohD under hypoxia. Hypoxia induced a Ca2+ increase in each cell type after 72 h, and the increase was much less pronounced in rbohD than in the WT. In most tissues except the elongation zone in rbohD, the H2O2 concentration had decreased after 1 h of hypoxia, but then increased significantly after 24 h of hypoxia in each zone and tissue, further suggesting that RBOHD may shape hypoxia-specific Ca2+ signatures via the modulation of apoplastic H2O2 production. Taken together, our data suggest that plants lacking functional GORK channels are more capable of retaining K+ for their better performance under hypoxia, and that RBOHD is crucial in hypoxia-induced Ca2+ signalling for stress sensing and acclimation mechanism.

Chemical signals play a significant role in improving plant water use efficiency under drought stress. Hydroponic and pot experiments were conducted using three barley genotypes to study genotypic differences in K+, Ca2+ and H+ fluxes and physiological and biochemical traits of drought tolerant Tibetan wild barley XZ5 and cv Tadmor and drought sensitive cv ZJU9 in response to drought. Transient and steady-state ion fluxes were measured by noninvasive ion-selective microelectrode MIFE technique. We showed that exogenous PEG (polyethylene glycol 6000) and mannitol and soil drought stress all resulted in an immediate K+ uptake from root epidermis and leaf mesophyll, with much more uptake in XZ5. Long-term drought stress are more detrimental to root K+ homeostasis, and the degree of K+ uptake differed due to severity of drought stress and was less presented in XZ5. Barley subjected to drought stress caused a large H+ efflux in root epidermis and H+ influx in leaf mesophyll, with significantly less alteration in XZ5 and Tadmor than in ZJU9. Meanwhile a dramatic Ca2+ efflux was observed in root epidermis and leaf mesophyll under drought stress. PEG and mannitol treatments induced marked increases in H+-K+-ATPase in XZ5 and Tadmor. Our results demonstrate that K+ uptake, Ca2+ efflux and leaf H+ influx/alkalization of apoplastic pH could be a chemical signal in barley in response to drought stress, and that stimulated H+-K+-ATPase and K+ uptake, but less Ca2+ efflux and H+ alteration under drought, when concerning ionic mechanisms underlying drought tolerance, play an important role in drought tolerance in XZ5.

The substrate cocktail is frequently used to evaluate cytochrome P450 (CYP) enzyme-mediated drug interactions and potential interactions among the probe substrates. Here, we re-optimized the substrate cocktail method to increase the reliability and accuracy of screening for candidate compounds and expanded the method from a direct CYP inhibition assay to a time-dependent inhibition (TDI) assay. In the reaction mixtures containing human liver microsome (0.1 mg/mL), both the concentrations of a substrate cocktail (phenacetin for 1A2, coumarin for 2A6, bupropion for 2B6, diclofenac for 2C9, dextromethorphan for 2D6, and testosterone for 3A4) and the incubation time were optimized. Metabolites of the substrate probes were simultaneously analyzed by multiple-reaction monitoring (MRM) using a routine LC/MS/MS. Direct CYP inhibition was validated using 7 inhibitors (α-naphthoflavone, tranylcypromine, ticlopidine, fluconazole, quinidine, ketoconazole and 1-ABT). The time-dependent inhibition was partially validated with 5 inhibitors (ketoconazole, verapamil, quinidine, paroxetine and 1-ABT). The inhibition curve profiles and IC50 values of 7 CYP inhibitors were approximate when a single substrate and the substrate cocktail were tested, and were consistent with the previously reported values. Similar results were obtained in the IC50 shifts of 5 inhibitors when a single substrate and the substrate cocktail were tested in the TDI assay. The 6-in-1 substrate cocktail (for 1A2, 2A6, 2B6, 2C9, 2D6 and 3A) is reliable for assessing CYP inhibition and time-dependent inhibition of drug candidates.