Aquaporin Genes Research Articles

Growth Promotion and Salt-Tolerance Improvement of Gerbera jamesonii by Root Colonization of Piriformospora indica

Interaction of plants with beneficial microbes is one of the strategies for increasing growth and resistance under environmental stresses. In this study, the effects of a fungus, Piriformospora indica, on growth and salt resistance in gerbera (Gerbera jamesonii L.) seedlings were investigated. After co-cultivation with P. indica, the gerbera roots were colonized by the mature chlamydospores of P. indica. A large increase in plant biomass and enhanced photosynthesis were observed in the P. indica-colonized seedlings. Moreover, these seedlings also exhibited a strong tolerance to salt stress after the colonization. The wilting symptoms, the impairments in chlorophyll, carotenoids, and photosynthesis, and anthocyanin accumulation, that can be caused by salt stress, were alleviated in the P. indica-colonized plants. The malondialdehyde and hydrogen peroxide levels were lower in P. indica-colonized plants than in non-colonized plants under salt treatment, whereas both enzymatic and non-enzymatic antioxidants were not increased by P. indica colonization. Differential expressions of sodium transporter genes and aquaporin genes were found in gerbera plants after P. indica colonization. The P. indica colonization positively regulated the transcription level of genes involved in ionic homeostasis, such as NHX2 and SOS1, while most aquaporin genes were not induced in P. indica-colonized gerbera seedlings exposed to salt stress, except for NIP6;1 gene. These results demonstrate a strategy through plant–microbe interaction to promote Gerbera jamesonii performance under salt stress.

Effect of arbuscular mycorrhizal fungus, Funneliformis fasciculatum, on detoxification of Nickel and expression of TIP genes in Lolium perenne L.

Regarding to the super-beneficial effects of arbuscular mycorrhizal fungi (AMF) on host plant in response to environmental stresses, there is a great interest for understanding the mechanisms that enable mycorrhizal plant tolerate the stress conditions. In the present study, some physiological and molecular responses induced by arbuscular mycorrhizal fungus Funneliformis fasciculatum in Ni-stressed Lolium perenne were investigated. Since heavy-metal stress is reported to alter the water relations of plant, expression of two aquaporin (AQP)-coding genes (Lptip1;1 and Lptip1;2) were studied as a molecular mechanism which may be involved in Ni-stress tolerance. The results demonstrated a pronounced positive effect of AMF on Lolium growth, water content and photosynthetic pigments content under Ni stress condition, probably through an avoidance strategy which led to the decrease in Ni accumulation in plant tissues as well as decreasing Ni translocation to the shoots. The results also indicated the mycorrhizal-induced expression of both Lptip1;1 and Lptip1;2 genes in plant roots and shoots under Ni stress. Thus, it is concluded that these two genes could be considered as stress-inducible AQP genes.

Inhibition of aquaporins as a potential adjunct to breast cancer cryotherapy.

Cryoablation is an emerging type of treatment for cancer. The sensitization of tumors using cryosensitizing agents prior to treatment enhances ablation efficiency and may improve clinical outcomes. Water efflux, which is regulated by aquaporin channels, contributes to cancer cell damage achieved through cryoablation. An increase in aquaporin (AQP) 3 is cryoprotective, whereas its inhibition augments cryodamage. The present study aimed to investigate aquaporin (AQP1, AQP3 and AQP5) gene expression and cellular localization in response to cryoinjury. Cultured breast cancer cells (MDA-MB-231 and MCF-7) were exposed to freezing to induce cryoinjury. RNA and protein extracts were then analyzed using reverse transcription-quantitative PCR and western blotting, respectively. Localization of aquaporins was studied using immunocytochemistry. Additionally, cells were transfected with small interfering RNA to silence aquaporin gene expression and cell viability was assessed using the Sulforhodamine B assay. Cryoinjury did not influence gene expression of AQPs, except for a 4-fold increase of AQP1 expression in MDA-MD-231 cells. There were no clear differences in AQP protein expression for either cell lines upon exposure to frozen and non-frozen temperatures, with the exception of fainter AQP5 bands for non-frozen MCF-7 cells. The exposure of cancer cells to freezing temperatures altered the localization of AQP1 and AQP3 proteins in both MCF-7 and MDA-MD-231 cells. The silencing of AQP1, AQP3 and AQP5 exacerbated MDA-MD-231 cell damage associated with freezing compared with control siRNA. This was also observed with AQP3 and AQP5 silencing in MCF-7 cells. Inhibition of aquaporins may potentially enhance cryoinjury. This cryosensitizing process may be used as an adjunct to breast cancer cryotherapy, especially in the border area targeted by cryoablation where freezing temperatures are not cold enough to induce cellular damage.

Differential expression of aquaporin genes during ovary activation in the honeybee Apis mellifera (Hymenoptera: Apidae) queens.

Aquaporins are membrane proteins responsible for the rapid transport of water and solutes through the plasma membrane in almost all organisms including microorganisms, animals and plants. The knowledge about aquaporins in insects has advanced in the last years, especially in organs such as the gut and Malpighian tubules, but their roles in ovaries are poorly understood. This study reports the occurrence and the expression of gene profiles of predicted aquaporins in the ovaries of virgin and mated queens of the honeybee Apis mellifera. The expression of six aquaporin genes (Am-DRIP, Am-PRIP, Am-Eglp1, Am-Eglp2, Am-Eglp3 and Am-BIB) was investigated in the ovaries of queens of different ages and physiological status. The Am-Eglp3 has the higher level of transcript in newly emerged virgin queens. The Am-PRIP and Am-Eglp2 have a higher level of transcripts in 4days-old virgin queens, aged expected to mate. In mated queens, only the Am-Eglp2 show high level of transcripts. Aquaporin was immunolocalized in the follicular cells of both nurse and oocytic chambers of the previtellogenic and vitellogenic follicles. This is the first report for the presence of aquaporins in the ovaries of bees.

Meta-analysis of the effect of the overexpression of aquaporin family genes on the drought stress response

Aquaporin (AQP) plays an essential role in water uptake and transport in plants, especially in the response to drought stress, which suggests the use of AQP expression to regulate plant water-use efficiency. The overexpression of various AQP genes in a variety of plants has been reported, but inconsistencies in the experimental variables (such as stress type, gene donor, and recipient genus) and physiological parameters used to evaluate transgenic plants have made it difficult to elucidate the complex mechanisms by which AQPs affect drought tolerance. In this study, we performed a meta-analysis to categorize the responses of physiological parameters involved in drought tolerance in AQP-overexpressing plants and to evaluate the experimental variables that affect transgenic plant performance. The results of various studies indicated that two primary physiological processes (osmotic adjustment and alleviation of oxidative damage) were significantly affected by AQP overexpression. Among the examined experimental variables, treatment media (soil), stress type (no watering), stress duration (long-term), recipient genus (Nicotiana), donor species (Musaceae), and gene family (PIP2) had positive impacts on drought tolerance in transgenic plants. These findings may help to guide future studies investigating the function of AQPs in the response of plants to water deficit stress.

Computational prediction of microRNA targets of ion channels and aquaporins in Aedes aegypti

Background & objectives: Ion channels and water channel aquaporins are ubiquitous in most life forms and responsible for several physiological functions. Sanguivorous insects, like the mosquitoes also have ion channels which regulate many pivotal cellular processes. Alterations of ion channel/AQPs can have profound impact on mosquito physiology. The miRNAs, a newly discovered class of regulators in the gene network, can fine tune the expression of ion channel genes and this is of growing interest in research for the treatment of various channelopathies. In the present study, we tried to predict the miRNA targets of different types of ion channels and aquaporins of Aedes aegypti mosquito using in silico approaches. Methods: The list of Ae. aegypti ion channels and aquaporin genes and their sequences were retrieved from TransportDB and FlyBase databases. The miRNA sequences were retrieved from the miRBase. The miRNA targets of each channel gene were predicted using RNA22 v2 algorithm. Results: The miRNA targets of 198 ion channel genes (including potassium channels, sodium channels, calcium channels, chloride channels and several non-selective cation channels) and six aquaporin genes were predicted. Interpretation & conclusion: The results of the present study showed that each ion channel has many miRNA targets and a single miRNA can target multiple ion channel genes. Few miRNAs are specific for channel types, e.g. mir-31 targets most of the calcium ion channels; miR31 and mir-276-2 target multiple sodium channels. The present study can be considered as a leading step in the initiation of a miRNA database construction, exclusively for mosquito ion channels.

Genomic and expression characterization of aquaporin genes from Siniperca chuatsi

Aquaporins (AQPs) are major intrinsic proteins that form pores in the membranes of biological cells. We first cloned the full-length sequences of aqp0, 1, 3, 4, 7, 8, 9, 10, 11, and 12 genes in Siniperca chuatsi. The 10 S. chuatsi aqp (Sc-aqp) genes included complete open reading frames and exhibited different exon-intron organizations. Sc-aqp1, 3, 8, 9, 10, and 11 were mostly expressed in the gallbladder, gills, gastric cecum, liver, ovaries, and spleen, respectively; Sc-aqp0 and 4 were mostly expressed in larvae at 1 day after hatching and in gastrula; Sc-aqp7 and 12 were mostly expressed in 2K-cell embryos. The expression levels of Sc-aqp1, 3, 7, 8, 9, and 10 after 10 part per thousand (ppt) salt treatment had significantly changed compared with those after 0 ppt salt treatment. Real-time quantitative PCR analysis further showed that in the intestines, the mRNA levels of Sc-aqp1 and 10 significantly decreased by approximately 2.07- and 2.85-fold, respectively, whereas those of Sc-aqp8 and 9 significantly increased by approximately 7.08- and 4.14-fold, respectively. Sc-aqp1, 8, 9, and 10 showed no significant differences in the gills. Sc-aqp3 significantly decreased by approximately 1.51- and 1.67-fold in the gills and intestines, respectively. Sc-aqp7 significantly increased by approximately 4.18- and 7.04-fold in the gills and intestines, respectively. This study was the first to investigate the tissue expression profiles and response to salt stress of aqp genes in S. chuatsi. Moreover, altering diet and suffering from immune stress could cause changes in the expression level of aqps. This study provided valuable reference information for AQPs' roles in osmoregulation in freshwater fish.

Altered Iris Aquaporin Expression and Aqueous Humor Osmolality in Glaucoma.

PurposeAquaporins (AQPs) facilitate transmembrane osmotic water transport and may play a role in iris fluid conductivity, which is implicated in the pathophysiology of glaucoma. In this study, we compared the iris expression of AQPs and aqueous osmolality between primary angle closure glaucoma (PACG), primary open-angle glaucoma (POAG), and nonglaucoma eyes.MethodsAQP1-5 transcripts from a cohort of 36 PACG, 34 POAG and 26 nonglaucoma irises were measured by quantitative real-time PCR. Osmolality of aqueous humor from another cohort of 49 PACG, 50 POAG, and 50 nonglaucoma eyes were measured using an osmometer. The localization of AQP1 in both glaucoma and nonglaucoma irises was determined by immunofluorescent analysis.ResultsOf the five AQP genes evaluated, AQP1 and AQP2 transcripts were significantly upregulated in both PACG (3.48- and 8.07-fold, respectively) and POAG (3.12- and 11.58-fold, respectively) irises relative to nonglaucoma counterparts. The aqueous osmolalities of PACG (303.68 mmol/kg) and POAG (300.79 mmol/kg) eyes were significantly lower compared to nonglaucoma eyes (312.6 mmol/kg). There was no significant difference in expression of AQP transcripts or aqueous osmolality between PACG and POAG eyes.ConclusionsPACG and POAG eyes featured significant increase in AQP1 and AQP2 expression in the iris and reduced aqueous osmolality compared to nonglaucoma eyes. These findings suggest that the iris may be involved in altered aqueous humor dynamics in glaucoma pathophysiology. Because PACG did not differ from POAG in both properties studied, it is likely that they are common to glaucoma disease in general.

Identification of aquaporin members in Acacia auriculiformis and functional characterization of AaPIP1-2 involved in drought stress

Aquaporins (AQPs), which serve as water channel proteins, are linked to a plethora of processes related to plant growth and development, such as water transport and the acquisition of carbon, nitrogen, or micronutrients. However, little is known about Acacia auriculiformis AQPs. In this study, we present the first transcriptome-wide identification of the AQP gene family in A. auriculiformis. The total of 21 AQP genes that were identified were divided into four sub-families (NIPs, PIPs, SIPs, and TIPs) based on a phylogenetic analysis. Functional prediction based on NPA motifs, the ar/R selectivity filter, and Froger’s positions, suggested substrate specificity for these A. auriculiformis proteins. AQPs, which were globally expressed in all organs (roots, stems, nascent and mature leaves), as shown by gene expression profiles, were responsive to three environmental cues: elevated CO2, salt, and drought. Heterologous expression of AaPIP1-2 in Arabidopsis thaliana played a positive role in the response to PEG-treated drought stress by maintaining relative water content and enhancing the activities of enzymes that scavenge reactive oxygen species (ROS). Reduced ROS was likely associated with an increase in the activities of ROS-scavenging enzymes, and might be linked with the up-regulated expression of AaAQP genes. This study provides comprehensive bio-information on A. auriculiformis AQPs which would be helpful for additional gene function analyses.

Drought-Induced Root Pressure in Sorghum bicolor.

Root pressure, also manifested as profusive sap flowing from cut stems, is a phenomenon in some species that has perplexed biologists for much of the last century. It is associated with increased crop production under drought, but its function and regulation remain largely unknown. In this study, we investigated the initiation, mechanisms, and possible adaptive function of root pressure in six genotypes of Sorghum bicolor during a drought experiment in the greenhouse. We observed that root pressure was induced in plants exposed to drought followed by re-watering but possibly inhibited by 100% re-watering in some genotypes. We found that root pressure in drought stressed and re-watered plants was associated with greater ratio of fine: coarse root length and shoot biomass production, indicating a possible role of root allocation in creating root pressure and adaptive benefit of root pressure for shoot biomass production. Using RNA-Seq, we identified gene transcripts that were up- and down-regulated in plants with root pressure expression, focusing on genes for aquaporins, membrane transporters, and ATPases that could regulate inter- and intra-cellular transport of water and ions to generate positive xylem pressure in root tissue.

Response of spikelet water status to high temperature and its relationship with heat tolerance in rice

In rice, high-temperature stress (HT) during flowering results in decreased grain yield via a reduction in spikelet fertility; however, the effect of plant water status on spikelet fertility under HT remains unknown. To investigate the relationship between spikelet water status and spikelet fertility under HT, two experiments were performed under temperature-controlled conditions using four genotypes with varying tolerance to HT. Rice plants were exposed to HT for seven consecutive days during the flowering stage under three soil water treatments (soil water potential 0, −20, and −40 kPa), as well as under hydroponic conditions in a separate experiment. HT significantly decreased spikelet fertility, pollen fertility, and anther dehiscence under each of the three water treatments. HT significantly increased the spikelet transpiration rate, and this change was accompanied by a significant decrease in the internal temperature of the spikelets. HT decreased pollen grain diameter in heat-sensitive genotypes. HT had varying effects on the water potential of panicles and anthers but increased anther soluble-sugar concentration. Different aquaporin genes showed different expression profiles under HT, and the expression levels of PIPs for plasma membrane intrinsic proteins and TIPs for tonoplast intrinsic proteins increased in anthers but decreased in glumes. Correlation analyses showed that anther dehiscence and pollen (spikelet) fertility were tightly associated with anther water status, and the expression levels of almost all anther aquaporin genes were significantly correlated with anther dehiscence under HT. In summary, an increased spikelet transpiration rate and decreased internal spikelet temperature were associated with alleviation of the effects of HT in rice genotypes with varying degrees of heat tolerance, and the response of spikelet water status to HT, involving increased total expression of aquaporins and soluble sugar content, thereby improved pollen fertility, anther dehiscence, and spikelet fertility, especially in heat-resistant genotypes. The heat-resistant genotypes N22 and SY63 may adopt different approaches to reduce heat damage.

Plant aquaporins alleviate drought tolerance in plants by modulating cellular biochemistry, root-architecture, and photosynthesis.

Water is a vital resource for plants to grow, thrive, and complete their life cycle. In recent years, drastic changes in the climate, especially drought frequency and severity, have increased, which reduces agricultural productivity worldwide. Aquaporins are membrane channels belonging to the major intrinsic protein superfamily, which play an essential role in cellular water and osmotic homeostasis of plants under both control and water deficit conditions. A genome-wide search reveals the vast availability of aquaporin isoforms, phylogenetic relationships, different families, conserved residues, chromosomal locations, and gene structure of aquaporins. Furthermore, aquaporins gating and subcellular trafficking are commonly controlled by phosphorylation, cytosolic pH, divalent cations, reactive oxygen species, and stoichiometry. Researchers have identified their involvement in regulating hydraulic conductance, root system architecture, modulation of abiotic stress-related genes, seed viability and germination, phloem loading, xylem water exit, photosynthetic parameters, and post-drought recovery. Remarkable effects following the change in aquaporin activity and/or gene expression have been observed on root water transport properties, nutrient acquisition, physiology, transpiration, stomatal aperture, gas exchange, and water use efficiency. The present review highlights the role of different aquaporin homologs under water-deficit stress condition in model and crop plants. Moreover, the opportunity and challenges encountered to explore aquaporins for engineering drought-tolerant crop plants are also discussed here.

Glutamine and cystine-enriched diets modulate aquaporins gene expression in the small intestine of piglets.

The regulation of glycerol permeability in the gastrointestinal tract is crucial to control fat deposition, lipolysis and gluconeogenesis. Knowing that the amino acid glutamine is a physiological regulator of gluconeogenesis, whereas cystine promotes adiposity, herein we investigated the effects of dietary supplementation with glutamine and cystine on the serum biochemical parameters of piglets fed on amino acid-enriched diets, as well as on the transcriptional profile of membrane water and glycerol channels aquaporins (AQPs) in the ileum portion of the small intestine and its impact on intestinal permeability. Twenty male piglets with an initial body weight of 8.8 ± 0.89 kg were allocated to four dietary treatments (n = 5) and received, during a four week-period, a basal diet without supplementation (control) or supplemented with 8 kg/ton of glutamine (Gln), cystine (Cys) or the combination of the two amino acids in equal proportions (Gln + Cys). Most biochemical parameters were found improved in piglets fed Gln and Cys diet. mRNA levels of AQP3 were found predominant over the others. Both amino acids, individually or combined, were responsible for a consistent downregulation of AQP1, AQP7 and AQP10, without impacting on water permeability. Conversely, Cys enriched diet upregulated AQP3 enhancing basolateral membranes glycerol permeability and downregulating glycerol kinase (GK) of intestinal cells. Altogether, our data reveal that amino acids dietary supplementation can modulate intestinal AQPs expression and unveil AQP3 as a promising target for adipogenesis regulation.

Aquaporin-1 and aquaporin-9 gene variations in sudden infant death syndrome

Several studies have indicated that a vulnerability in the development and regulation of brain function is involved in sudden infant death syndrome (SIDS). The aim of this study was to investigate the genes encoding the brain aquaporins (AQPs) AQP1 and AQP9 in SIDS. The hypothesis was that specific variants of these genes are part of the genetic vulnerability predisposing infants to sudden unexpected death. The study included 168 SIDS cases with a median age of 15.5 (range 2–52) weeks and 372 adolescent/adult deceased controls with a median age of 44 (range 11–91) years. In the AQP1 gene, the rs17159702 CC/CT genotypes were found to be associated with SIDS (p = 0.02). In the AQP9 gene, the combination of a TT genotype of rs8042354, rs2292711 and rs13329178 was more frequent in SIDS cases than in controls (p = 0.03). In the SIDS group, an association was found between genetic variations in the AQP1 gene and maternal smoking and between the 3xTT combination in the AQP9 gene and being found lifeless in a prone position. In conclusion, this study adds further evidence to the involvement of brain aquaporins in SIDS, suggesting that specific variants of AQP genes constitute a genetic predisposition, making the infant vulnerable to sudden death together with external risk factors and probably other genetic factors.

Molecular Characterization and Expression of Four Aquaporin Genes in Impatiens walleriana During Drought Stress and Recovery.

Aquaporins comprise a large group of transmembrane proteins responsible for water transport, which is crucial for plant survival under stress conditions. Despite the vital role of aquaporins, nothing is known about this protein family in Impatiens walleriana, a commercially important horticultural plant, which is sensitive to drought stress. In the present study, attention is given to the molecular characterization of aquaporins in I. walleriana and their expression during drought stress and recovery. We identified four I. walleriana aquaporins: IwPIP1;4, IwPIP2;2, IwPIP2;7 and IwTIP4;1. All of them had conserved NPA motifs (Asparagine-Proline-Alanine), transmembrane helices (TMh), pore characteristics, stereochemical properties and tetrameric structure of holoprotein. Drought stress and recovery treatment affected the aquaporins expression in I. walleriana leaves, which was up- or downregulated depending on stress intensity. Expression of IwPIP2;7 was the most affected of all analyzed I. walleriana aquaporins. At 15% and 5% soil moisture and recovery from 15% and 5% soil moisture, IwPIP2;7 expression significantly decreased and increased, respectively. Aquaporins IwPIP1;4 and IwTIP4;1 had lower expression in comparison to IwPIP2;7, with moderate expression changes in response to drought and recovery, while IwPIP2;2 expression was of significance only in recovered plants. Insight into the molecular structure of I. walleriana aquaporins expanded knowledge about plant aquaporins, while its expression during drought and recovery contributed to I. walleriana drought tolerance mechanisms and re-acclimation.

Identification of a 1,274‐bp promoter of a Musa acuminata L. aquaporin gene (MaPIP1;1) which confers salinity stress inducibility in transgenic Arabidopsis

AbstractSalt stress will seriously influence alt stress in banana (Musa L.) induces MaPIP1;1, which enhances the salt resistance of transgenic Arabidopsis. The promoter pMaPIP1;1, located 13,62 bp upstream of the transcriptional start site, was isolated from the banana genome, and four pMaPIP1;1::GUS fusion constructs namely M‐P1, M‐P2, M‐P3, and M‐P4 were used to transform into Arabidopsis. In this work, in order to functionally verify the promoter responds to high salt stress, we used NaCl treatment for simulating salt terms. NaCl treatment is responded to by four transformants. M‐P2 (−1,274 bp to −1) showed the highest transcriptional activity among all transgenic Arabidopsis transformants. This area of the promoter endows high glucuronidase (GUS) enzyme activity according to NaCl treatment. These results will help us understand the transcriptional regulatory of MaPIP1;1, and promoter fragment M‐P2 will be an ideal candidate for overexpression of salt response genes to increase plant resistance.

Stem aquaporins and surfactant-related genes are differentially expressed in two Eucalyptus species in response to water stress

The regulation of water column tension in the xylem is essential to avoid embolism formation. Plants can actively reduce the hydraulic resistance in the xylem by moving water from the neighbourhood living cell, via aquaporins. They can also produce substances known as surfactants which stabilise nanobubbles avoiding embolism. Transcriptomic and proteomic data were used to test the presence of these two mechanisms in stems of Eucalyptus grandis and E. globulus grown at two temperature treatments (10–12°C and 33–35°C), thus at different vapour-pressure deficit (VPD) conditions. In both temperatures, plants were kept well-watered. Ten aquaporin genes (6 PIPs and 4 TIPs) and seven surfactant related genes (two phospholipid/glycerol acyltransferase and five lipid-transfer protein – LTP) were identified. Six aquaporins and two surfactant-related proteins identified in the proteomic analysis matched the transcriptome data. Seven aquaporin genes were up-regulated under 30°C, and high VPD in E. globulus (PIP1;2, PIP2;7, PIP1;4, TIP2;1, TIP1;3, TIP1;3(2), and TIP2;1(2)) and three were down-regulated (PIP2;5, PIP2;2, and PIP2;6). We also stressed plants of both species and analysed aquaporin and surfactant-related gene expression along with water stress development. The results showed that they also respond to water stress. Although we could not isolate the effect of temperature in the proteome and transcriptome experiments, our results suggest that aquaporins and surfactants can be involved in the reduction of embolism in eucalyptus under high xylem tension, by allowing radial transport of water in the stem and stabilising nanobubbles, respectively.

New insight into the mechanism of graphene oxide-enhanced phytotoxicity of arsenic species

Graphene oxide (GO) has exhibited significant potential to improve crop cultivation and yield. The application of GO in agriculture will inevitably result in interactions with conventional contaminants, causing potential changes to environmental behavior and toxicity of conventional contaminants. This study explored the joint phytotoxicity of GO and arsenic species (arsenite [As (III)], arsenate [As (V)]) to monocot (Triticum aestivum L.) and dicot (Solamun lycopersicum) plant species. Under the environmentally relevant concentrations, GO (1 mg/L) significantly increased the phytotoxicity of As (III) and As (V) (1 mg/L), with effects being both As- and plant species-specific. One mechanism of enhanced arsenic phytotoxicity could be GO-induced up-regulation of the aquaporin and phosphate transporter related genes expression, which would lead to the increased accumulation of As (III) and As (V) in plants. In addition, co-exposure with GO resulted in more severe oxidative stress than single As exposure, which could subsequently induce damage in root plasma membranes and compromise key arsenic detoxification pathways such as complexation with glutathione and efflux. Co-exposure to GO and As also led to more significant reduction in macro- and micronutrient content. The provided data highlight the high-impact of nanomaterials on the environmental risk of As in agricultural systems.

Zinc regulates the hydraulic response of maize root under water stress conditions

Zinc (Zn) is involved in plant growth and stress resistance and is known to increase crop yield. Here, we investigated the effect of Zn on water absorption in the roots of maize (Zea mays L.), a crop which is sensitive to Zn deficiency, during water stress conditions. Seedlings of the maize variety “Zhengdan 958” were cultivated with 0.1 or 6 μM ZnSO4·7H2O. To simulate drought stress, three-week-old seedlings were exposed to 15% polyethylene glycol (PEG). Root growth parameters, root antioxidant enzyme activity, root hydraulic conductivity, root aquaporin gene expression, root and leaf anatomy structure, leaf water potential, chlorophyll content, leaf area, and gas exchange parameters were measured. Under water stress, moderate Zn treatment promoted root growth; maintained root and leaf anatomy structural integrity. Moderate Zn significantly increased roots hydraulic conductivity (51%) and decreased roots antioxidant enzyme activity (POD: −11.1%, CAT: −35.1%, SOD: −3.1%) compared with low-level Zn under water stress. The expression of ZmPIP1;1, ZmPIP1;2, and ZmPIP2;2 was significantly higher with moderate Zn treatment than that of low-level Zn treatment. The leaf water potential, chlorophyll content, leaf area, and gas exchange parameters with moderate Zn treatment increased significantly under water stress compared with low-level Zn treatment. The moderate concentration of Zn improved root hydraulic conductivity in maize and increased resistance to simulated drought conditions by maintaining root structural integrity, decreasing antioxidant enzyme activity, and increasing aquaporin gene expression. Moderate Zn application increased root water absorption and leaf transpiration, thereby maintaining maize water balance under water stress conditions.

Genome-wide analysis of the aquaporin genes in melon (Cucumis melo L.)

Melon (Cucumis melo L.) is a very important crop throughout the world and has great economic importance, in part due to its nutritional properties. It prefers well-drained soil with low acidity and has a strong demand for water during fruit set. Therefore, a correct water balance—involving aquaporins—is necessary to maintain the plants in optimal condition. This manuscript describes the identification and comparative analysis of the complete set of aquaporins in melon. 31 aquaporin genes were identified, classified and analysed according to the evolutionary relationship of melon with related plant species. The individual role of each aquaporin in the transport of water, ions and small molecules was discussed. Finally, qPCR revealed that almost all melon aquaporins in roots and leaves were constitutively expressed. However, the high variations in expression among them point to different roles in water and solute transport, providing important features as that CmPIP1;1 is the predominant isoform and CmTIP1;1 is revealed as the most important osmoregulator in the tonoplast under optimal conditions. The results of this work pointing to the physiological importance of each individual aquaporin of melon opening a field of knowledge that deserves to be investigated.