Delivery of WeChat-Based HIV Result e-Reports in Social Networks for Recruitment of High-Risk Population: Baseline Data From a Cluster Randomized Controlled Trial.

BACKGROUND: Disclosure of infectious disease status to social network peers can facilitate reaching and early detection among high-risk populations. In this era of social media, globally, HIV/AIDS represents a high burden of infectious disease. Thus, delivery of an HIV result e-report via social media presents a new approach that has the potential to improve contact with and enrollment of the high-risk population in research studies and routine practice. OBJECTIVE: This study explores the effectiveness and associated factors of a recruitment strategy (ie, WeChat-based HIV e-report delivery in social networks) on the enrollment of men who have sex with men (MSM) for an HIV testing intervention study. METHODS: This was an enrollment result analysis of an ongoing cluster randomized controlled trial (RCT) aiming to promote HIV testing among MSM. Recruitment of potential participants was based on the unit of an egocentric social network, which includes 1 core member (an offline tested ego as the recruiter) and several network members (online alters as network associates). Alters' enrollment and alters' transformation to ego-recruiters (alter-ego) were measured as outcomes. Recruitment outcomes were compared between the exchangeable and regular e-report groups of the RCT. Associated factors of both outcomes were also investigated, including sociodemographic characteristics, health behaviors, social network characteristics, e-report types, and online delivery information. Binary outcomes were modeled using logistic models, with Firth correction for rare events. Qualitative interviews were conducted to understand facilitators and barriers in detail for alter-ego as the subsequent wave's recruiter. RESULTS: The e-report of 1157 egos who tested offline were delivered to 5165 alters in 3 recruitment waves; eventually, 1162 eligible alters enrolled in this RCT (response rate: 22.5%). In the exchangeable e-report group, 544 egos recruited 467 alters, of which 35 alters transformed to alter-egos (7.5%), whereas in the regular e-report group, 613 egos recruited 695 alters, of which 40 alters transformed to alter-egos (5.8%). Alters' enrollment at first wave was associated with a higher number of e-reports being forwarded by the egos. Alters' transformation to alter-egos for the subsequent wave was associated with the exchangeable e-report, higher income, being a Guangzhou resident, unprotected anal intercourse, preferring self-testing, and viewing senders' e-reports frequently. Qualitative interviews revealed that the lack of awareness of e-reports' function and inadequate access to e-reports at offline testing facilities were major barriers to alters' transformation to offline ego-recruiters. CONCLUSIONS: The delivery of e-report was feasible in MSM social network, and the success and sustainability of online recruitment depended on high levels of familiarity among MSM with the digital tool. The HIV e-report exchange mechanism might promote MSM to test HIV offline to get their own e-report for exchange in the community. The e-report provides an innovative recruitment method with great potential to trace direct contacts for infectious diseases studies.

Correction: WeChat-Based HIV e-Report, a New Approach for HIV Serostatus Requests and Disclosures Among Men Who Have Sex With Men: Prospective Subgroup Analysis of a Randomized Controlled Trial.

[This corrects the article DOI: 10.2196/44513.].

WeChat-Based HIV e-Report, a New Approach for HIV Serostatus Requests and Disclosures Among Men Who Have Sex With Men: Prospective Subgroup Analysis of a Randomized Controlled Trial

BACKGROUND: Requesting and disclosing HIV serostatus is associated with a reduction in HIV transmission among men who have sex with men (MSM). However, the reliability of common methods for HIV serostatus request and disclosure is inadequate. Validated approaches for requesting and disclosing HIV serostatus are necessary. OBJECTIVE: The objective of this study was to investigate the use of the HIV e-report as authentic evidence of HIV serostatus among the MSM community in Guangzhou, China. Additionally, the study aimed to explore its correlation with HIV serostatus requesting and disclosure receiving behavior. METHODS: This study is a subgroup analysis of a cluster randomized controlled trial (RCT) that enrolled 357 participants during the first year. Participants in this RCT were recruited from the WeChat-based HIV testing service miniprogram developed by Guangzhou Center for Disease Control and Prevention, China. Participants completed web-based questionnaires at baseline and at the month 3 follow-up, which covered sociodemographic characteristics, HIV-related information, HIV serostatus requests, receiving HIV serostatus disclosures, and HIV e-report usage. Univariate and multivariate logistic regressions were used for data analysis. RESULTS: The WeChat-based HIV e-report was available in Guangzhou when the RCT project started. At the month 3 follow-up, 32.2% (115/357) of participants had their own HIV e-reports, and 37.8% (135/357) of them had received others' HIV e-reports. In all, 13.1% (27/205) and 10.5% (16/153) of participants started to use HIV e-reports to request the HIV serostatus from regular and casual male sex partners, respectively. Moreover, 27.3% (42/154) and 16.5% (18/109) of the regular and casual male sex partners, respectively, chose HIV e-reports to disclose their HIV serostatus. Compared to MSM who did not have HIV e-reports, those who had HIV e-reports and stated, "I had had my own HIV e-report(s) but hadn't sent to others" (multivariate odds ratio 2.71, 95% CI 1.19-6.86; P=.02) and "I had had my own HIV e-reports and had sent to others" (multivariate odds ratio 2.67, 95% CI 1.07-7.73; P=.048) were more likely to request HIV serostatus from their partners. However, no factor was associated with receiving an HIV serostatus disclosure from partners. CONCLUSIONS: The HIV e-report has been accepted by the MSM community in Guangzhou and could be applied as a new optional approach for HIV serostatus requests and disclosures. This innovative intervention could be effective in promoting infectious disease serostatus disclosure among the related high-risk population. TRIAL REGISTRATION: ClinicalTrials.gov NCT03984136; https://clinicaltrials.gov/show/NCT03984136. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.1186/s12879-021-06484-y.

OsNAR2.1 induced endogenous nitrogen concentration variation affects transcriptional expression of miRNAs in rice.

The studies of rice nitrogen concentration on the expression of miRNA so far are mostly limited to the exogenous nitrogen, leaving the effect of endogenous nitrogen largely unexplored. OsNAR2.1 is a high-affinity nitrate transporter partner protein which plays a central role in nitrate absorption and translocation in rice. The expression of OsNAR2.1 could influence the concentration of the endogenous nitrogen in rice. We showed that the expression and production of miRNA in rice can be influenced by manipulating the endogenous nitrogen concentration via OsNAR2.1 transgenic lines. The small RNA content, particularly 24 nucleotides small RNA, expressed differently in two transgenic rice lines (nitrogen efficient line with overexpression of OsNAR2.1 (Ov199), nitrogen-inefficient line with knockdown OsNAR2.1 by RNAi (RNAi)) compared to the wild-type (NP). Comparative hierarchical clustering expression pattern analysis revealed that the expression profiles of mature miRNA in both transgenic lines were different from NP. Several previously unidentified miRNAs were identified to be differentially expressed under different nitrogen concentrations, namely miR1874, miR5150, chr3-36147, chr4-27017 and chr5-21745. In conclusion, our findings suggest that the level of endogenous nitrogen concentration variation by overexpression or knockdown OsNAR2.1 could mediate the expression pattern and intensity of miRNA in rice, which is of high potential to be used in molecular breeding to improve the rice responses towards nitrogen utilization.

Phytoremediation of crude oil-contaminated sediment using Suaeda heteroptera enhanced by Nereis succinea and oil-degrading bacteria.

A 150-day experiment was performed to investigate the stimulatory effect of a promising phytoremediation strategy consisting of Suaeda heteroptera (S. heteroptera), Nereis succinea (N. succinea), and oil-degrading bacteria for cleaning up total petroleum hydrocarbons (TPHs) in spiked sediment. Inoculation with oil-degrading bacteria and/or N. succinea increased plant yield and TPH accumulation in S. heteroptera plants. The highest TPH dissipation (40.5%) was obtained in the combination treatment, i.e., S. heteroptera + oil-degrading bacteria + N. succinea, in which the sediment TPH concentration decreased from an initial value of 3955 to 2355 mg/kg in 150 days. BAF, BCF, and TF confirmed the role of N. succinea and oil-degrading bacteria in the amelioration and translocation of TPHs. In addition, TPH toxicity of S. heteroptera was alleviated by N. succinea and oil-degrading bacteria addition through the reduction of oxidative stress. Therefore, S. heteroptera could be used for cleaning up oil-contaminated sediment, particularly in the presence of oil-degrading bacteria + N. succinea. Field studies on oil-degrading bacteria + N. succinea may provide new insights on the rehabilitation and restoration of sediments contaminated by TPHs.

Our study attempted to investigate the stimulatory effect of a promising phytoremediation strategy consisting of Suaeda heteroptera (S. heteroptera), Nereis succinea (N. succinea), and oil-degrading bacteria for cleaning up TPH in spiked sediment. Planting S. heteroptera can greatly increase sediment TPH removal, and its removal was enhanced greater after inoculation with oil-degrading bacteria and/or N. succinea. Moreover, the promising phytoremediation strategy developed in the current work can serve as an efficient, novel approach to removal TPH in sediment/soil. In our opinions, these findings provide insights into the assessment of their ecological risks in the environments that are of interest to broad readership of International Journal of Phytoremediation.

High-temperature adaptation of an OsNRT2.3 allele is thermoregulated by small RNAs.

Climate change negatively affects crop yield, which hinders efforts to reach agricultural sustainability and food security. Here, we show that a previously unidentified allele of the nitrate transporter gene OsNRT2.3 is required to maintain high yield and high nitrogen use efficiency under high temperatures. We demonstrate that this tolerance to high temperatures in rice accessions harboring the HTNE-2 (high temperature resistant and nitrogen efficient-2) alleles from enhanced translation of the OsNRT2.3b mRNA isoform and the decreased abundance of a unique small RNA (sNRT2.3-1) derived from the 5' untranslated region of OsNRT2.3. sNRT2.3-1 binds to the OsNRT2.3a mRNA in a temperature-dependent manner. Our findings reveal that allelic variation in the 5' untranslated region of OsNRT2.3 leads to an increase in OsNRT2.3b protein levels and higher yield during high-temperature stress. Our results also provide a breeding strategy to produce rice varieties with higher grain yield and lower N fertilizer input suitable for a sustainable agriculture that is resilient against climate change.

Plant DNA Methylation Responds to Nutrient Stress.

Nutrient stress as abiotic stress has become one of the important factors restricting crop yield and quality. DNA methylation is an essential epigenetic modification that can effectively regulate genome stability. Exploring DNA methylation responses to nutrient stress could lay the foundation for improving plant tolerance to nutrient stress. This article summarizes the plant DNA methylation patterns, the effects of nutrient stress, such as nitrogen, phosphorus, iron, zinc and sulfur stress, on plant DNA methylation and research techniques for plant DNA methylation, etc. Our discussion provides insight for further research on epigenetics response to nutrient stress in the future.

The Comparison of Various Types of Health Insurance in the Healthcare Utilization, Costs and Catastrophic Health Expenditures among Middle-Aged and Older Chinese Adults.

Rapid aging in China is increasing the number of older people who tend to require health services for their poor perceived health. Drawing on the China Health and Retirement Longitudinal Study (CHARLS) 2018 data, we used two-part model and binary logistic regression to compare various types of health insurance in the healthcare utilization, costs and catastrophic health expenditures (CHE) among the middle-aged and older adults in China. Compared with uninsured, all types of health insurance promoted hospital utilization rate (ranged from 8.6% to 12.2%) and reduced out-of-pocket (OOP) costs (ranged from 64.9% to 123.6%), but had no significant association with total costs. In contrast, the association of health insurance and outpatient care was less significant. When Urban Employee Medical Insurance (UEMI) as reference, other types of insurance did not show a significant difference. Health insurance could not reduce the risk of CHE. The equity in healthcare utilization improved and healthcare costs had been effectively controlled among the elderly, but health insurance did not protect against CHE risks. Policy efforts should further focus on optimizing healthcare resource allocation and inclining toward the lower socio-economic and poor-health groups.

HUWE1 Causes an Immune Imbalance in Immune Thrombocytopenic Purpura by Reducing the Number and Function of Treg Cells Through the Ubiquitination Degradation of Ets-1.

Background: Immune thrombocytopenic purpura (ITP) is an autoimmune bleeding disorder and the decreased number and immunosuppressive dysfunction of Treg cells are key promoters of ITP. However, their mechanisms in ITP development have not been fully clarified. Methods: HUWE1 mRNA and protein levels in CD4+ T cells in peripheral blood from ITP patients were assessed by quantitative real-time PCR and Western blot. HUWE1 function in ITP was estimated using flow cytometry, enzyme-linked immunosorbent assay and immunosuppression assay. Besides, the HUWE1 mechanism in reducing the number and function of Treg cells in ITP was investigated by immunoprecipitation, cycloheximide-chase assay, ubiquitin experiment and immunofluorescence assay. Results: HUWE1 expression was elevated in CD4+ T cells in peripheral blood from ITP patients and HUWE1 mRNA level was negatively correlated with platelet counts and Treg cell percentage. Moreover, the interference with HUWE1 increased the number of Treg cells and enhanced its immunosuppressive function, and the HUWE1 overexpression produced the opposite results. For the exploration of mechanism, HUWE1 interacted with E26 transformation-specific-1 (Ets-1) and this binding was dependent on the negative regulation of the phosphorylation level of Ets-1 (Thr38) and HUWE1 facilitated the ubiquitin degradation of Ets-1 protein to restrain Treg cell differentiation and weaken their immunosuppressive functions. The in vivo assay confirmed that the HUWE1 inhibitor alleviated ITP in mice. Conclusion: HUWE1 induced the immune imbalance in ITP by decreasing the number and weakening the function of Treg cells through the ubiquitination degradation of Ets-1.

Gene Mapping, Cloning and Association Analysis for Salt Tolerance in Rice.

Soil salinization caused by the accumulation of sodium can decrease rice yield and quality. Identification of rice salt tolerance genes and their molecular mechanisms could help breeders genetically improve salt tolerance. We studied QTL mapping of populations for rice salt tolerance, period and method of salt tolerance identification, salt tolerance evaluation parameters, identification of salt tolerance QTLs, and fine-mapping and map cloning of salt tolerance QTLs. We discuss our findings as they relate to other genetic studies of salt tolerance association.

Increasing the HIV testing among MSM through HIV test result exchange mechanism: study protocol for a cluster randomized controlled trial.

BACKGROUND: HIV testing is an essential gateway to HIV prevention and treatment thus controlling the HIV epidemic. More innovative interventions are needed to increase HIV testing among men who have sex with men (MSM) since their testing rate is still low. We proposed an online HIV test results exchange mechanism whereby the one without a certified online HIV report will be asked to test HIV for exchanging HIV report with others. The exchange mechanism is developed as an extension to the existing online HIV testing service system. Through the extended system, MSM can obtain certified online HIV reports and exchange their reports with friends via WeChat. This study aims to assess effectiveness of the exchange mechanism to increase the HIV testing rate among MSM. METHODS: This study will use a cluster randomized controlled trial (RCT) design. Participants are recruited based on the unit of individual social network, the sender and the receivers of the HIV report. An individual social network is composed of one sender (ego) and one or more receivers (alters). In this study, MSM in an HIV testing clinic are recruited as potential egos and forwarded online reports to their WeChat friends voluntarily. Friends are invited to participate by report links and become alters. Ego and alters serve as a cluster and are randomized to the group using the certified online HIV report with exchange mechanism (intervention group) or without exchange mechanism (control group). Alters are the intervention targeting participants. The primary outcome is HIV testing rate. Other outcomes are sexual transmitted infections, sexual behaviors, HIV testing norms, stigma, risk perception and HIV report delivery. The outcomes will be assessed at baseline and follow-up questionnaires. Analysis will be according to intention to treat approach and using mixed-effect models with networks and individuals as random effects. DISCUSSION: This is the first study to evaluate the effectiveness of an HIV test result exchange mechanism to increase the HIV testing among MSM. This assessment of the intervention will also provide scientific evidence on other potential effects. Findings from this study will yield insights for sustainability driven by communities' intrinsic motivation. Trail registration: ClinicalTrials.gov NCT03984136. Registered 12 June 2019.

Plant DNA methylation is sensitive to parent seed N content and influences the growth of rice.

BACKGROUND: Nitrogen (N) is an important nutrient for plant growth, development, and agricultural production. Nitrogen stress could induce epigenetic changes in plants. In our research, overexpression of the OsNAR2.1 line was used as a testing target in rice plants with high nitrogen-use efficiency to study the changes of rice methylation and growth in respond of the endogenous and external nitrogen stress. RESULTS: Our results showed that external N deficiency could decrease seed N content and plant growth of the overexpression line. During the filial growth, we found that the low parent seed nitrogen (LPSN) in the overexpression line could lead to a decrease in the filial seed nitrogen content, total plant nitrogen content, yield, and OsNAR2.1 expression (28, 35, 23, and 55%, respectively) compared with high parent seed nitrogen (HPSN) in high nitrogen external supply. However, such decreases were not observed in wild type. Furthermore, methylation sequencing results showed that LPSN caused massive gene methylation changes, which enriched in over 20 GO pathways in the filial overexpression line, and the expression of OsNAR2.1 in LPSN filial overexpression plants was significantly reduced compared to HPSN filial plants in high external N, which was not shown in wild type. CONCLUSIONS: We suggest that the parent seed nitrogen content decreased induced DNA methylation changes at the epigenetic level and significantly decreased the expression of OsNAR2.1, resulting in a heritable phenotype of N deficiency over two generations of the overexpression line.

Extracellular vesicles derived from miR-199a-5p-modified adipose-derived mesenchymal stem cells alleviate immune thrombocytopenia by inhibiting T helper 17 differentiation.

The abnormal differentiation of T helper 17 (Th17) cells is considered a vital promoter of immune thrombocytopenia (ITP) progression. Therefore, this study investigated the role of miR-199a-5p in Th17 differentiation and determined whether extracellular vesicles (EVs) derived from miR-199a-5p-modified adipose-derived mesenchymal stem cells (ADSCs) could relieve ITP by inhibiting Th17 differentiation. The miR-199a-5p level was lessened in the spleen tissues of mice with ITP, while the signal transducer and activator of transcription 3 (STAT3) expression and the population of Th17 in CD4+T cells were boosted. Functionally, miR-199a-5p overexpression lowered IL-17 secretion and the proportion of Th17/CD4+T cells. Further investigation showed that miR-199a-5p directly targeted STAT3 mRNA, and negatively modulated its expression. STAT3 overexpression was found to facilitate Th17 differentiation, which was subsequently abolished by miR-199a-5p overexpression. EVs isolated from miR-199a-5p-modified ADSCs (miR-199a-5p-EVs) highly expressed miR-199a-5p and could restrain CD4+T cells polarized toward a Th17 phenotype in vitro. Administering of miR-199a-5p-EVs elevated platelet counts and decreased the proportion of Th17/CD4+T cells in mice with ITP. Taken together, EVs derived from miR-199a-5p-modified ADSCs vividly repressed Th17 differentiation by transferring miR-199a-5p to CD4+T cells, thus ameliorating experimental ITP.

Co-Overexpression of OsNAR2.1 and OsNRT2.3a Increased Agronomic Nitrogen Use Efficiency in Transgenic Rice Plants.

The NO3 - transporter plays an important role in rice nitrogen acquisition and nitrogen-use efficiency. Our previous studies have shown that the high affinity systems for nitrate uptake in rice is mediated by a two-component NRT2/NAR2 transport system. In this study, transgenic plants were successful developed by overexpression of OsNAR2.1 alone, OsNRT2.3a alone and co-overexpression of OsNAR2.1 and OsNRT2.3a. Our field experiments indicated that transgenic lines expressing p35S:OsNAR2.1 or p35S:OsNAR2.1-p35S:OsNRT2.3a constructs exhibited increased grain yields of approximately 14.1% and 24.6% compared with wild-type (cv. Wuyunjing 7, WT) plants, and the agricultural nitrogen use efficiency increased by 15.8% and 28.6%, respectively. Compared with WT, the 15N influx in roots of p35S:OsNAR2.1 and p35S: OsNAR2.1-p35S:OsNRT2.3a lines increased 18.9%­27.8% in response to 0.2 mM, 2.5 mM 15NO3 -, and 1.25 mM 15NH4 15NO3, while there was no significant difference between p35S:OsNAR2.1 and p35S:OsNAR2.1-p35S:OsNRT2.3a lines; only the 15N distribution ratio of shoot to root for p35S:OsNAR2.1-p35S:OsNRT2.3a lines increased significantly. However, there were no significant differences in nitrogen use efficiency, 15N influx in roots and the yield between the p35S:NRT2.3a transgenic lines and WT. This study indicated that co-overexpression of OsNAR2.1 and OsNRT2.3a could increase rice yield and nitrogen use efficiency.

miR-106b-5p induces immune imbalance of Treg/Th17 in immune thrombocytopenic purpura through NR4A3/Foxp3 pathway.

BACKGROUND: Immune imbalance of regulatory T cells (Treg)/T helper 17 cells (Th17) contributes to the development of immune thrombocytopenic purpura (ITP). The dysregulation of miRNAs is important in the development of ITP. However, the role of miR-106b-5p in Treg/Th17 imbalance remains unknown in ITP. MATERIALS AND METHODS: Peripheral blood was collected from patients with ITP and healthy controls, and CD4 + T cells were further isolated. miR-106b-5p, nuclear receptor subfamily 4 group A member 3 (NR4A3), forkhead box protein 3 (Foxp3), IL-17A, and TGF-ß expressions were detected by qRT-PCR, western blot, or ELISA. The effect of miR-106b-5p on NR4A3 was detected by dual-luciferase reporter gene assay. RESULTS: Compared with healthy controls, miR-106b-5p was elevated in peripheral blood of patients with ITP, and NR4A3 expression was decreased. sh-NR4A3 significantly decreased Foxp3 and TGF-ß expressions, indicating that NR4A3 may regulate Treg differentiation via Foxp3. Additionally, NR4A3 was identified to be a target of miR-106b-5p, and miR-106b-5p was able to negatively modulate NR4A3 expression. Moreover, we found miR-106b-5p induced immune imbalance of Treg/Th17 through NR4A3. In vivo experiments revealed that silencing miR-106b-5p promoted Treg differentiation and increased the number of platelets, suggesting the relief of ITP. CONCLUSION: miR-106b-5p regulated immune imbalance of Treg/Th17 in ITP through the NR4A3/Foxp3 pathway.

Genetic and Global Epigenetic Modification, Which Determines the Phenotype of Transgenic Rice?

Transgenic technologies have been applied to a wide range of biological research. However, information on the potential epigenetic effects of transgenic technology is still lacking. Here, we show that the transgenic process can simultaneously induce both genetic and epigenetic changes in rice. We analyzed genetic, epigenetic, and phenotypic changes in plants subjected to tissue culture regeneration, using transgenic lines expressing the same coding sequence from two different promoters in transgenic lines of two rice cultivars: Wuyunjing7 (WYJ7) and Nipponbare (NP). We determined the expression of OsNAR2.1 in two overexpression lines generated from the two cultivars, and in the RNA interference (RNAi) OsNAR2.1 line in NP. DNA methylation analyses were performed on wild-type cultivars (WYJ7 and NP), regenerated lines (CK, T0 plants), segregation-derived wild-type from pOsNAR2.1-OsNAR2.1 (SDWT), pOsNAR2.1-OsNAR2.1, pUbi-OsNAR2.1, and RNAi lines. Interestingly, we observed global methylation decreased in the T0 regenerated line of WYJ7 (CK-WJY7) and pOsNAR2.1-OsNAR2.1 lines but increased in pUbi-OsNAR2.1 and RNAi lines of NP. Furthermore, the methylation pattern in SDWT returned to the WYJ7 level after four generations. Phenotypic changes were detected in all the generated lines except for SDWT. Global methylation was found to decrease by 13% in pOsNAR2.1-OsNAR2.1 with an increase in plant height of 4.69% compared with WYJ7, and increased by 18% in pUbi-OsNAR2.1 with an increase of 17.36% in plant height compared with NP. This suggests an absence of a necessary link between global methylation and the phenotype of transgenic plants with OsNAR2.1 gene over-expression. However, epigenetic changes can influence phenotype during tissue culture, as seen in the massive methylation in CK-WYJ7, T0 regenerated lines, resulting in decreased plant height compared with the wild-type, in the absence of a transformed gene. We conclude that in the transgenic lines the phenotype is mainly determined by the nature and function of the transgene after four generations of transformation, while the global epigenetic modification is dependent on the genetic background. Our research suggests an innovative insight in explaining the reason behind the occurrence of transgenic plants with random and undesirable phenotypes.

OsNAR2.1 Positively Regulates Drought Tolerance and Grain Yield Under Drought Stress Conditions in Rice.

Drought is an important environmental factor that severely restricts crop production. The high-affinity nitrate transporter partner protein OsNAR2.1 plays an essential role in nitrate absorption and translocation in rice. Our results suggest that OsNAR2.1 expression is markedly induced by water deficit. After drought stress conditions and irrigation, compared with wild-type (WT), the survival rate was significantly improved in OsNAR2.1 over-expression lines and decreased in OsNAR2.1 RNAi lines. The survival rate of Wuyunjing7 (WYJ), OsNRT2.1 over-expression lines and OsNRT2.3a over-expression lines was not significantly different. Compared with WT, overexpression of OsNAR2.1 could significantly increase nitrogen uptake in rice, and OsNAR2.1 RNAi could significantly reduce nitrogen uptake. Under drought conditions, the expression of OsNAC10, OsSNAC1, OsDREB2a, and OsAP37 was significantly reduced in OsNAR2.1 RNAi lines and increased substantially in OsNAR2.1 over-expression lines. Also, the chlorophyll content, relative water content, photosynthetic rate and water use efficiency were decreased considerably in OsNAR2.1 RNAi lines and increased significantly in OsNAR2.1 over-expression lines under drought conditions. Finally, compared to WT, grain yield increased by about 9.1 and 26.6%, in OsNAR2.1 over-expression lines under full and limited irrigation conditions, respectively. These results indicate that OsNAR2.1 regulates the response to drought stress in rice and increases drought tolerance.

Plant nitrate transporters: from gene function to application.

We summarize nitrate transporters and discuss their potential in breeding for improved nitrogen use efficiency and yield.

pOsNAR2.1:OsNAR2.1 expression enhances nitrogen uptake efficiency and grain yield in transgenic rice plants.

The nitrate (NO3-) transporter has been selected as an important gene maker in the process of environmental adoption in rice cultivars. In this work, we transferred another native OsNAR2.1 promoter with driving OsNAR2.1 gene into rice plants. The transgenic lines with exogenous pOsNAR2.1:OsNAR2.1 constructs showed enhanced OsNAR2.1 expression level, compared with wild type (WT), and 15 N influx in roots increased 21%-32% in response to 0.2 mm and 2.5 mm 15NO3- and 1.25 mm 15 NH415 NO3 . Under these three N conditions, the biomass of the pOsNAR2.1:OsNAR2.1 transgenic lines increased 143%, 129% and 51%, and total N content increased 161%, 242% and 69%, respectively, compared to WT. Furthermore in field experiments we found the grain yield, agricultural nitrogen use efficiency (ANUE), and dry matter transfer of pOsNAR2.1:OsNAR2.1 plants increased by about 21%, 22% and 21%, compared to WT. We also compared the phenotypes of pOsNAR2.1:OsNAR2.1 and pOsNAR2.1:OsNRT2.1 transgenic lines in the field, found that postanthesis N uptake differed significantly between them, and in comparison with the WT. Postanthesis N uptake (PANU) increased approximately 39% and 85%, in the pOsNAR2.1:OsNAR2.1 and pOsNAR2.1:OsNRT2.1 transgenic lines, respectively, possibly because OsNRT2.1 expression was less in the pOsNAR2.1:OsNAR2.1 lines than in the pOsNAR2.1:OsNRT2.1 lines during the late growth stage. These results show that rice NO3- uptake, yield and NUE were improved by increased OsNAR2.1 expression via its native promoter.