Effects of Zinc Deficiency and Drought on Plant Growth and Metabolism of Reactive Oxygen Species in Maize (Zea mays L.)

The combinative effects of applied zinc （Zn） and soil moisture on the plant growth, Zn uptake, and the metabolism of reactive oxygen species （ROS） in maize （Zea mays L.） plants were examined through two pot experiments under greenhouse conditions. Maize variety Zhongdan 9409 was used. In experiment 1, maize plants were grown in cumulic cinnamon soil with five Zn treatments （0, 3.0, 9.0, 27.0, and 81.0 mg Zn kg^-1 soil）. Three treatments of soil moisture including serious drought, mild drought, and adequate water supply were set at 30-35%, 40-45%, and 70-75% （w/w） of soil saturated water content, respectively. Soil saturated water content was 36% （w/w）. The dry matter weights of shoots were enhanced by Zn application and adequate water supply. There was no apparent difference in plant growth among Zn application rates from 3.0 to 81.0 mg Zn kg^-1 soil. The increases of plant growth and Zn uptake due to Zn application were found more significant under well-watered condition than under drying condition. In experiment 2, two levels of Zn （0 and 5.0 mg Zn kg^-1 soil） and soil moisture regimen （40-45% and 70-75% of soil saturated water content, respectively） were set. Zn deficiency or water stress resulted in higher concentrations of O2^- and malondiadehyde in the first fully expanded leaves. Zn deficiency lowered the activity of superoxide dismutase （SOD, EC 1.15.1.1） in leaves. Drought stress increased SOD activity in leaves regardless of Zn supply. The activity of guaiacol peroxidase （POD, ECI.11.1.11） was found to be enhanced by Zn supply only in well-watered leaves. Zinc deficiency or water stress had little effect on the activity of catalase （CAT, EC 1.11.1.6）. The higher ROS level in early maize leaves due to water stress seemed not to be alleviated or lowered partially by Zn application. However, Zn fertilizer was recommended to apply to maize plants irrigated or supplied with adequate water, otherwise Zn deficiency would reduce the water use for plant biomass production.

Effects of dietary zinc deficiency on esophageal squamous cell proliferation and the mechanisms involved

BACKGROUND Dietary zinc deficiency has been shown to be associated with the development of esophageal cancer in humans,but the exact mechanism of action is not known AIM To observe the effects of dietary zinc deficiency on esophageal squamous cell proliferation.METHODS Thirty C57BL/6 mice were randomly divided into three groups:A zinc-sufficient(ZS)group,zinc-deficient(ZD)group,and zinc-replenished(ZR)group.For weeks 1–10,zinc levels in the mice diets were 30.66–30.89 mg/kg in the ZS group and 0.66–0.89 mg/kg in the ZD and ZR groups.During weeks 10–12,the ZR group was switched to the ZS diet;the other two groups had no changes in their diets.Changes in body weight,serum,and esophageal tissue zinc concentrations were assessed as well as differences in the expression of proliferating cell nuclear antigen(PCNA),mitogen-activated protein kinase p38(p38MAPK),nuclear factor kappa B(NF-κB)p105,NF-κB p65,and cyclooxygenase(COX)-2 proteins in the esophageal mucosa.RESULTS The body weight and zinc concentration in the serum and esophageal mucosa were significantly lower in the ZD and ZR groups than in the ZS group(P<0.05).In ZD mice,there was a marked proliferation of basal cells in the esophageal mucosa,resulting in a disturbance in the arrangement of basal cells in layers 2–4,a thickening of the squamous layer,and a significant increase in the expression of the above-mentioned five proteins involved in proliferation and inflammation in the esophageal mucosa.Two weeks after switching to the ZS diet,the serum zinc concentration in the ZR group increased,and the expression of PCNA,NF-κB p105,and COX-2 decreased,but the concentration of zinc in the esophageal mucosa and the structure of the esophageal mucosa did not display any significant changes CONCLUSION The ZD diet decreased the growth rate and promoted the proliferation of esophageal squamous cells in mice.The mechanism of proliferation was related to the induced overexpression of COX-2,P38,PCNA,and NF-κB(p105 and p65),and the ZR diet reduced the expression of PCNA,NF-κB p105,and COX-2,thereby reversing this process.

Identification of Potential Zinc Deficiency Responsive Genes and Regulatory Pathways in Rice by Weighted Gene Co-expression Network Analysis

Zinc(Zn)malnutrition is a major public health issue.Genetic biofortification of Zn in rice grain can alleviate global Zn malnutrition.Therefore,elucidating the genetic mechanisms regulating Zn deprivation response in rice is essential to identify elite genes useful for breeding high grain Zn rice varieties.Here,a meta-analysis of previous RNA-Seq studies involving Zn deficient conditions was conducted using the weighted gene co-expression network analysis(WGCNA)and other in silico prediction tools to identify modules(denoting cluster of genes with related expression pattern)of co-expressed genes,modular genes which are conserved differentially expressed genes(DEGs)across independent RNA-Seq studies,and the molecular pathways of the conserved modular DEGs.WGCNA identified 16 modules of co-expressed genes.Twenty-eight and five modular DEGs were conserved in leaf and crown,and root tissues across two independent RNA-Seq studies.Functional enrichment analysis showed that 24 of the 28 conserved modular DEGs from leaf and crown tissues significantly up-regulated 2 Kyoto Encyclopedia of Genes and Genomes(KEGG)pathways and 15 Gene Ontology(GO)terms,including the substrate-specific transmembrane transporter and the small molecule metabolic process.Further,the well-studied transcription factors(OsWOX11 and OsbHLH120),protein kinase(OsCDPK20 and OsMPK17),and miRNAs(OSA-MIR397A and OSA-MIR397B)were predicted to target some of the identified conserved modular DEGs.Out of the 24 conserved and up-regulated modular DEGs,19 were yet to be experimentally validated as Zn deficiency responsive genes.Findings from this study provide a comprehensive insight on the molecular mechanisms of Zn deficiency response and may facilitate gene and pathway prioritization for improving Zn use efficiency and Zn biofortification in rice.

Novel Sources of aus Rice for Zinc Deficiency Tolerance Identified Through Association Analysis Using High-Density SNP Array

Zinc （Zn） deficiency is a major soil constraint limiting rice crop growth and yield, yet the genetic control of tolerance mechanisms is still poorly understood. Here, we presented promising loci and candidate genes conferring tolerance to Zn deficiency and identified through association analysis using a 365 K single nucleotide polymorphism （SNP） marker array in a diverse aus （semi-wild type rice） panel. Tolerant accessions exhibited higher growth rate with relatively rare stress symptoms. Two loci on chromosomes 7 and 9 were strongly associated with plant vigor under Zn deficiency at a peak-stress stage. Based on previous microarray data from the same experimental plots, we highlighted four candidate genes whose expressions were accompanied by significant genotype and/or environment effects under Zn deficiency. Network-gene ontology supported known tolerance mechanisms, such as ascorbic acid pathway, and also suggested the importance of photosynthesis genes to overcome Zn deficiency symptoms.

Apoptosis Induced by Zinc Deficiency in Rat Osteoblast:Possible Involvement of Protein Kinase C

Ra ostcobasts were isolated from the 21-day fetal rat calvchas. The cells were grown in DMEM Plus 10% FBS, and were treated for 24 h. with 10 μmol/L TPEN or 10 μmol/L TPEN supplemented with 10 μmol/L Zn2+. Apoptosis of osteoblasts were measured by fiow cytometry, electron microscopy and DNA fragmentation analyzed by gel elecmphoresis. In addition, IP3 production and PKC activity were measmed in ordr to show whether they are involved in apoptosis in osteoblast induced by alnc deficiency. The results showed that 10 μmol/L TPEN could induce apoptosis in osteoblast in 24 h. But cells ed with 10μmol/L TPEN supplemented with 10 μmol/L Zn2+ showed no apoptotic changs in 24 h. TPEN significantly reduced the formation of IP3 and PKC activity after 24 h incubation. No differences were observed between the cells treated with TPEN supPlemented with Zn2+ simulaneosly and the untreated cells. It can be inferred that apoptosis induced by ainc deficiency may be due to the decreased activity of PKC which is impaired by reduced formation of IP3.

Integrated linkage mapping and genome-wide association study to dissect the genetic basis of zinc deficiency tolerance in maize at seedling stage

Zinc(Zn)deficiency is the most widespread micronutrient deficiency,affecting yield and quality of crops worldwide.Identifying genes associated with Zn-deficiency tolerance in maize is a basis for elucidating its genetic mechanism.A K22×CI7 recombinant inbred population consisting of 210 lines and an association panel of 508 lines were used to identify genetic loci influencing Zn-deficiency tolerance.Under-Zn and-Zn/CK conditions,15 quantitative trait loci(QTL)were detected,each explaining 5.7%-12.6%of phenotypic variation.Sixty-one significant single-nucleotide polymorphisms(SNPs)were identified at P<10^(-5)by genome-wide association study(GWAS),accounting for 5%-14%of phenotypic variation.Among respectively 198 and 183 candidate genes identified within the QTL regions and the 100-kb regions flanking these significant SNPs,12 were associated with Zn-deficiency tolerance.Among these candidate genes,four genes associated with hormone signaling in response to Zn-deficiency stress were co-localized with QTL or SNPs,including the genes involved in the auxin(ZmARF7),and ethylene(ZmETR5,ZmESR14,and ZmEIN2)signaling pathways.Three candidate genes were identified as being responsible for Zn transport,including ZmNAS3 detected by GWAS,ZmVIT and ZmYSL11 detected by QTL mapping.Expression of ZmYSL11 was up-regulated in Zn-deficient shoots.Four candidate genes that displayed different expression patterns in response to Zn deficiency were detected in the regions overlapping peak GWAS signals,and the haplotypes for each candidate gene were further analyzed.

Novel SLC30A2 mutations in the pathogenesis of transient neonatal zinc deficiency

Importance:Transient neonatal zinc deficiency(TNZD)occurs in breastfed infants due to abnormally low breast milk zinc levels.Mutations in the solute carrier family 30 member 2(SLC30A2)gene,which encodes the zinc transporter ZNT2,cause low zinc concentration in breast milk.Objective:This study aimed to provide further insights into TNZD pathophysiology.Methods:SLC30A2 sequencing was performed in three unrelated Japanese mothers,whose infants developed TNZD due to low-zinc milk consumption.The effects of the identified mutations were examined using cell-based assays and luciferase reporter analysis.Results:Novel SLC30A2 mutations were identified in each mother.One harbored a heterozygous missense mutation in the ZNT2 zinc-binding site,which resulted in defective zinc transport.The other two mothers exhibited multiple heterozygous mutations in the SLC30A2 promoter,the first mutations in the SLC30A2 regulatory region reported to date.Interpretation:This report provides new genetic insights into TNZD pathogenesis in breastfed infants.

Effect of Sulfur Fertilization on Productivity and Grain Zinc Yield of Rice Grown under Low and Adequate Soil Zinc Applications

This study aimed to investigate the responses in rice(Oryza sativa cv.Osmancik 97)production and grain zinc(Zn)accumulation to combined Zn and sulfur(S)fertilization.The experiment was designed as a factorial experiment with two Zn and three S concentrations applied to the soil in a completely randomized design with four replications.The plants were grown under greenhouse conditions at low(0.25 mg/kg)and adequate(5 mg/kg)Zn rates combined with S(CaSO_(4)·2H_(2)O)application(low,2.5 mg/kg;moderate,10 mg/kg,and adequate,50 mg/kg).The lowest rate of S at adequate soil Zn treatment increased grain yield by 68%compared with the same S rate at low Zn supply.Plants with the adequate S rate at low Zn and adequate Zn supply produced the highest grain yield,with increases of 247%and 143%compared with low S rate at low Zn and adequate Zn supply,respectively.The concentration of grain Zn and S responded differently to the applied S rates depending on the soil Zn condition.The highest grain Zn concentration,reaching 41.5 mg/kg,was observed when adequate Zn was supplied at the low S rate.Conversely,the adequate S rate at the low soil Zn conditions yielded the highest grain S concentration.The total grain Zn uptake per plant showed particular increases in grain Zn yield when adequate S rates were applied,showing increases of 208%and 111%compared with low S rate under low and adequate soil Zn conditions,respectively.The results indicated that the synergistic application of soil Zn and S improves grain production and grain Zn yield.These results highlight the importance of total grain Zn yield in addition to grain Zn concentration,especially under the growth conditions where grain yield shows particular increases as grain Zn is diluted due to increased grain yield by increasing S fertilization.

Effect of Zinc on Bone Metabolism in Fetal Mouse Limb Culture

Objective To determine the effects of zine-deficiency and zine-excess on hone metabolism. Methods We developed the culture model of fetal mouse limbs (16th day) cultivated in self-made rotator with continuing flow of mixed gas for six days in vitro. The cultured limbs were examined by the techniques of 45Ca tracer and X-roentgenography. Results The right limbs cultivated had longer bone length, higher bone density than the left limbs uncultivated from the same embryo; and histologically, the right limbs had active bone cell differentiation, proliferation, increased bone trabecula. clearly calcified cartilage matrix, and osteogenic tissue. Compared with the control group, the zinc-deficient group and zine-excess (Zn2+ l20) μmol/L) group contained less osteocalcin (BGP) and 45Ca content, and lower AKP activity; whereas zine-normal (Zn2+ 45 μmol/L and Zn2+ 70 μmol/L) groups contained more BGP and 45Ca contents, and higher AKP (alkaline phosphatase) activity. Conclusion Both zine-deficiency and zine-excess can alter bone growth and normal metabolism. The results indicate that the culture model of fetal mouse limbs (16th day) in vitro can be used as a research model of bone growth and development.

Improve Anthocyanin and Zinc Concentration in Purple Rice by Nitrogen and Zinc Fertilizer Application

Zinc(Zn)is an essential micronutrient for plant growth and development,and anthocyanin is a secondary metabolite compound generally produced under stress conditions;both have benefits to human health.Rice is a staple food crop for most of the world’s population,and purple rice is well known as a natural source of Zn and anthocyanins,but their stability depends upon many factors.This review focuses on the opportunity to increase Zn and anthocyanin compounds in purple rice grains via Zn and nitrogen(N)management during cultivation.Variation in grain Zn concentration and anthocyanin compounds is found among purple rice varieties,thus presenting a challenge for breeding programs aiming at high grain Zn and anthocyanin contents.Genetic engineering has successfully achieved a high-efficiency vector system comprising two regulatory genes and six structural anthocyanin-related genes driven by endosperm-specific promoters to engineer purple endosperm rice that can provide new high-anthocyanin varieties.Grain Zn and anthocyanin concentrations in rice can also be affected by environmental factors during cultivation,e.g.,light,temperature,soil salinity and nutrient(fertilizer)management.Applying N and Zn fertilizer is found to influence the physiological mechanisms of Zn absorption,uptake,transport and remobilization to promote grain Zn accumulation in rice,while N application can improve anthocyanin synthesis by promoting its biosynthesis pathway via the use of phenylalanine as a precursor.In summary,there is an opportunity to improve both grain Zn and anthocyanin in purple rice by appropriate management of Zn and N fertilizers during cultivation for specific varieties.

Zinc-deficient diet aggravates ventilation-induced lung injury in rats

We investigated the effects of zinc deficiency on acute lung injury （ALI） induced by mechanical ventilation. Male Sprague-Dawley rats were fed with a zinc-deficient or zinc-proficient diet for 4 weeks, and then received mechanical ventilation at normal frequency and pressure for 30 min. Total protein, cell count, the number of poly- morphonuclear neutrophil （PMN） in the bronchoalveolar lavage （BAL）, and vascular endothelial growth factor （VEGF） expression in the lung were determined. Activation of nuclear factor-t^B （NF-~cB） was detected by exam- ining the phosphorylation of NF-kB （pNF-kB p65） and the expression of inhibitor of NF-kB （pI-kBa）. Compared to the controls, total cell count and the number of PMNs were significantly increased to 160% and 140%, respec- tively, in zinc-deficient rats treated with ventilation. Activation of NF-kB was significantly increased and VEGF was also increased to three-folds. Zinc deficiency aggravated the inflammatory response in rats and was associated with the overexpression of VEGF in response to mechanical ventilation. Zinc supplementation may be beneficial to zinc-deficient patients during mechanical ventilation.

Biofortification of iron and zinc in rice and wheat

Iron and zinc are critical micronutrients for human health.Approximately two billion people suffer from iron and zinc deficiencies worldwide,most of whom rely on rice(Oryza sativa)and wheat(Triticum aestivum)as staple foods.Therefore,biofortifying rice and wheat with iron and zinc is an important and economical approach to ameliorate these nutritional deficiencies.In this review,we provide a brief introduction to iron and zinc uptake,translocation,storage,and signaling pathways in rice and wheat.We then discuss current progress in efforts to biofortify rice and wheat with iron and zinc.Finally,we provide future perspectives for the biofortification of rice and wheat with iron and zinc.