ZmGI2 regulates flowering time through multiple flower development pathways in maize.

GIGANTEA (GI) encodes a component of the circadian clock core oscillator and has been identified as a regulatory pathway of the circadian rhythm and photoperiodic flowering in model plants. However, the regulatory pathway of GI affecting flowering time is unknown in maize. Here, we identified that the zmgi2 mutant flowered earlier than the wild type under long day (LD) conditions, whereas the difference in flowering time was not apparent under short day (SD) conditions. The 24 h optimal expression of the gene in the stem apex meristems (SAM) appeared at 9 h after dawn under LD conditions and at 11 h after dawn under SD conditions. DAP-Seq and RNA-Seq further revealed that ZmGI2 delays flowering by directly binding to the upstream regions of ZmVOZs, ZmZCN8 and ZmFPF1 to repress the expression of these genes and by directly binding to the upstream regions of ZmARR11, ZmDOF and ZmUBC11 to promote the expression of these genes. The genetic and biochemical evidence suggests a model for the potential role of ZmGI2 in regulating the flowering time-dependent photoperiodic pathway. This study provides novel insights into the function of ZmGIs in maize and further demonstrates their potential importance for floral transition. These results contribute to a comprehensive understanding of the molecular mechanisms and regulatory networks of GI transcription factors in regulating flowering time in maize.

On correlation between canopy vegetation and growth indexes of maize varieties with different nitrogen efficiencies.

Studying the canopy spectral reflection characteristics of different N-efficient maize varieties and analyzing the relationship between their growth indicators and spectral vegetation indices can help the breeding and application of N-efficient maize varieties. To achieve the optimal management of N fertilizer resources, developing N-efficient maize varieties is necessary. In this research, maize varieties, i.e., the low-N-efficient (Zhengdan 958, ZD958), the high-N efficient (Xianyu 335, XY335), the double-high varieties (Qiule 368, QL368), and the double inefficient-type varieties (Yudan 606 YD606), were used as materials. Results indicate that nitrogen fertilization significantly increased the vegetation indices NDVI, GNDVI, GOSAVI, and RVI of maize varieties with different nitrogen efficiencies. These findings were consistent with the performance of yield, dry matter mass, and leaf nitrogen content and were also found highest under both medium and high nitrogen conditions in the double-high variety QL368. The correlations of dry matter quality, leaf nitrogen content, yield, and vegetation indices (NDVI, GNDVI, RVI, and GOSAVI) at the filling stage of different N-efficient maize varieties were all highly significant and positive. In this relationship, the best effect was found at the filling stages, with correlation coefficients reaching 0.772-0.942, 0.774-0.970, 0754-0.960, and 0.800-0.960. The results showed that the yield, dry matter weight, and leaf nitrogen content of maize varieties with different nitrogen efficiencies increased first and then stabilized with the increase in the nitrogen application level in different periods, and the highest nitrogen application level of maize yield should be between 270 and 360 kg/hm2. At the filling stage, canopy vegetation index of maize varieties with different nitrogen efficiencies was positively correlated with yield, dry matter weight, and leaf nitrogen content, especially GNDVI and GOSAVI on the leaf nitrogen content. It can be used as a means to predict its growth index.

ZmDWF1 regulates leaf angle in maize.

Leaf angle (LA) is a critical agronomic trait enhancing grain yield under high-density planting in maize. A number of researches have been conducted in recent years to investigate the quantitative trait loci/genes responsible for LA variation, while only a few genes were identified through map-based cloning. Here we cloned the ZmDWF1 gene, which was previously reported to encode Δ24-sterol reductase in the brassinosteroids (BRs) biosynthesis pathway. Overexpression of ZmDWF1 resulted in enlarged LA, indicating that ZmDWF1 is a positive regulator of LA in maize. To reveal the regulatory framework of ZmDWF1, we conducted RNA-Sequencing and yeast-two hybrid (Y2H) screening analysis. RNA-Sequencing analyzing results indicate ZmDWF1 mainly affected expression level of genes involved in cell wall associated metabolism and hormone metabolism including BR, gibberellin, and auxin. Y2H screening with Bi-FC assay confirmed three proteins (ZmPP2C-1, ZmROF1, and ZmTWD1) interacting with ZmDWF1. We revealed a new regulatory network of ZmDWF1 gene in controlling plant architecture in maize.

In-Hospital Mortality Risk Model of Gastric Cancer Surgery: Analysis of a Nationwide Institutional-Level Database With 94,277 Chinese Patients.

Background: The objective of this study is to identify independent risks and protective factors and to construct a mortality prediction model for gastrectomy in the Chinese population. Study design: This is a population-based prospective cohort at an institutional level. Seventy-two participating hospitals reported their annual gastrectomy data between 2014 and 2016, while 44 variables covering the institution and surgical information were included in the analysis. We used R software to encode and complete data pre-processing. The first difference model was applied to build the risk model. Data from 2014 and 2015 were assigned to risk model development, while data from 2016 was used for validation. Results: In the included centers with 94,277 gastric cancer cases, the in-hospital mortality rate was 0.32%. The regression model revealed that provinces with low-middle GDP, hospitals with annual gastrectomy volume between 100 and 500, greater volume of urgent surgeries performed, larger proportion of males, and a higher proportion of liver metastasis were independent risk factors for mortality following gastric surgeries, while higher laparoscopic resection volume, greater volume of distal gastrectomy with B2 reconstruction, and larger proportion of palliative surgery were independent protective factors (p < 0.05, respectively). In the prediction test, the mean square error of the training set was 0.948, while that of the test set was 0.728, demonstrating the effectiveness of this model. Conclusions: We constructed the first mortality risk prediction model for gastric cancer surgery in the Chinese population. The identified risk factors will help with the therapy selection, while further informing Chinese medical policy decision-makers.

Proteomics analysis reveals that nitric oxide regulates photosynthesis of maize seedlings under water deficiency.

Nitric oxide (NO) is an important bioactive molecule that functions in regulating diverse abiotic stresses in plants, whereas its molecular mechanism remains obscure. In this study, treatment with 0.1 mM NO donor (sodium nitroprusside, SNP) significantly alleviated the inhibited growth induced by 15% polyethyleneglycol (PEG)-stimulated water deficiency (WD) for 3 days in maize seedlings, manifested by less decreased plant total fresh weight and dry weight. Comprehensive proteome analysis was further used to measure the expression profiles of leaf proteins of SNP-pretreated maize seedlings under WD conditions to explore the molecular mechanisms of NO-induced WD tolerance. Using 2-DE method, 135 protein spots showed significantly enhanced or reduced abundance, of which 102 spots were successfully identified MALDI-TOF/TOF MS. The identified protein species were associated with diverse functions, and most (52/83, 62.7%) of known protein species were related to photosynthetic processes. Compared to alone PEG treatment, the abundance of 25 identified protein species in SNP + PEG treatment were enhanced among the identified photosynthesis-related protein species. In addition, exogenous SNP application dramatically regulated chlorophyll α fluorescence kinetics e.g. the increase of maximum quantum yield of PSII (Fv/Fm), photosynthetic performance index (PI), and IP phase, whereas it remarkably reduced the polyphasic OJIP fluorescence transient, the accumulation of reactive oxygen species (H2O2 and O2•-) and malondialdehyde (MDA). These findings suggest that the NO-induced WD tolerance could be associated with improved photosynthetic capability in higher plants.

Physiological and proteomic analysis of maize seedling response to water deficiency stress.

Low water availability is a major abiotic factor limiting photosynthesis and the growth and yield of crops. Maize (Zea mays) is among the most drought-sensitive cereal crops. Herein, the physiological and proteomic changes of maize seedlings caused by polyethylene-glycol-induced water deficit were analyzed. The results showed that malondialdehyde and proline contents increased continuously in the treated seedlings. Soluble sugar content and superoxide dismutase activity were upregulated initially but became downregulated under prolonged water deficit. A total of 104 proteins were found to be differentially accumulated under water stress. The identified proteins were mainly involved in photosynthesis, carbohydrate metabolism, stress defense, energy production, and protein metabolism. Interestingly, substantial incongruence between protein and transcript levels was observed, indicating that gene expression in water-stressed maize seedlings is controlled by complex mechanisms. Finally, we propose a hypothetical model that includes the different molecular, physiological, and biochemical changes that occurred during the response and tolerance of maize seedlings to water deficiency. Our study provides valuable insight for further research into the overall mechanisms underlying drought response and tolerance in maize and other plants.

Perception of recovery of households affected by 2008 Wenchuan earthquake: A structural equation model.

Much of the literature on recovery focuses on the economy, the physical environment and infrastructure at a macro level, which may ignore the personal experiences of affected individuals during recovery. This paper combines internal factors at a micro level and external factors at a macro level to model for understanding perception of recovery (PoR). This study focuses on areas devastated by the 2008 Wenchuan earthquake in China. With respect to three recovery-related aspects (house recovery condition (HRC), family recovery power (FRP) and reconstruction investment (RI)), structural equation modeling (SEM) was applied. It was found that the three aspects (FRP, HRC and RI) effectively explain how earthquake affected households perceive recovery. Internal factors associated with FRP contributed the most to favourable PoR, followed by external factors associated with HRC. Findings identified that for PoR the importance of active recovery within households outweighed an advantageous house recovery condition. At the same time, households trapped in unfavourable external conditions would invest more in housing recovery, which result in wealth accumulation and improved quality of life leading to a high level of PoR. In addition, schooling in households showed a negative effect on improving PoR. This research contributes to current debates around post-disaster permanent housing policy. It is implied that a one-size-fits-all policy in disaster recovery may not be effective and more specific assistance should be provided to those people in need.

The Vulnerability of People to Landslides: A Case Study on the Relationship between the Casualties and Volume of Landslides in China.

The lack of a detailed landslide inventory makes research on the vulnerability of people to landslides highly limited. In this paper, the authors collect information on the landslides that have caused casualties in China, and established the Landslides Casualties Inventory of China. 100 landslide cases from 2003 to 2012 were utilized to develop an empirical relationship between the volume of a landslide event and the casualties caused by the occurrence of the event. The error bars were used to describe the uncertainty of casualties resulting from landslides and to establish a threshold curve of casualties caused by landslides in China. The threshold curve was then applied to the landslide cases occurred in 2013 and 2014. The validation results show that the estimated casualties of the threshold curve were in good agreement with the real casualties with a small deviation. Therefore, the threshold curve can be used for estimating potential casualties and landslide vulnerability, which is meaningful for emergency rescue operations after landslides occurred and for risk assessment research.

Quantitative iTRAQ-based proteomic analysis of phosphoproteins and ABA-regulated phosphoproteins in maize leaves under osmotic stress.

Abscisic acid (ABA) regulates various developmental processes and stress responses in plants. Protein phosphorylation/dephosphorylation is a central post-translational modification (PTM) in ABA signaling. However, the phosphoproteins regulated by ABA under osmotic stress remain unknown in maize. In this study, maize mutant vp5 (deficient in ABA biosynthesis) and wild-type Vp5 were used to identify leaf phosphoproteins regulated by ABA under osmotic stress. Up to 4052 phosphopeptides, corresponding to 3017 phosphoproteins, were identified by Multiplex run iTRAQ-based quantitative proteomic and LC-MS/MS methods. The 4052 phosphopeptides contained 5723 non-redundant phosphosites; 512 phosphopeptides (379 in Vp5, 133 in vp5) displayed at least a 1.5-fold change of phosphorylation level under osmotic stress, of which 40 shared common in both genotypes and were differentially regulated by ABA. Comparing the signaling pathways involved in vp5 response to osmotic stress and those that in Vp5, indicated that ABA played a vital role in regulating these pathways related to mRNA synthesis, protein synthesis and photosynthesis. Our results provide a comprehensive dataset of phosphopeptides and phosphorylation sites regulated by ABA in maize adaptation to osmotic stress. This will be helpful to elucidate the ABA-mediate mechanism of maize endurance to drought by triggering phosphorylation or dephosphorylation cascades.

Abscisic acid refines the synthesis of chloroplast proteins in maize (Zea mays) in response to drought and light.

To better understand abscisic acid (ABA) regulation of the synthesis of chloroplast proteins in maize (Zea mays L.) in response to drought and light, we compared leaf proteome differences between maize ABA-deficient mutant vp5 and corresponding wild-type Vp5 green and etiolated seedlings exposed to drought stress. Proteins extracted from the leaves of Vp5 and vp5 seedlings were used for two-dimensional electrophoresis (2-DE) and subsequent matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). After Coomassie brilliant blue staining, approximately 450 protein spots were reproducibly detected on 2-DE gels. A total of 36 differentially expressed protein spots in response to drought and light were identified using MALDI-TOF MS and their subcellular localization was determined based on the annotation of reviewed accession in UniProt Knowledgebase and the software prediction. As a result, corresponding 13 proteins of the 24 differentially expressed protein spots were definitely localized in chloroplasts and their expression was in an ABA-dependent way, including 6 up-regulated by both drought and light, 5 up-regulated by drought but down-regulated by light, 5 up-regulated by light but down-regulated by drought; 5 proteins down-regulated by drought were mainly those involved in photosynthesis and ATP synthesis. Thus, the results in the present study supported the vital role of ABA in regulating the synthesis of drought- and/or light-induced proteins in maize chloroplasts and would facilitate the functional characterization of ABA-induced chloroplast proteins in C(4) plants.

[Shade-tolerance indices of maize: selection and evaluation].

A field experiment was conducted to study the morphological, physiological, and yield traits of 24 maize cultivars under 50% shading. Comparing with the control, 50% shading decreased the plant height, stem diameter, leaf net photosynthetic rate (Pn), specific leaf weight (SLW), aboveground dry matter accumulation, ear length and diameter, axis diameter, and kernels per row. The interval from anthesis to silking (ASI) was prolonged, and the grain yield was decreased significantly. The percent changes of ASI, Pn, SLW, and kernels per row were significantly correlated with aboveground dry matter accumulation and grain yield, being able to be used as the indices to evaluate the maize shade-tolerance in field. Cluster analysis using comprehensive shade-tolerance traits as evaluation parameters indicated that 14 maize cultivars including Zhengdan 958, Xundan 20, and Denghai 602, etc. were of shade-tolerance type, and 10 cultivars (Anyu 12 and Yuyu 22, etc. ) were of shade-sensitive type. It was suggested that adopting the morphological, physiological and yield traits as the indices to evaluate the shade-tolerance of maize would be more objective, simple and practical.

Effects of osmotic stress on the kinds, forms and levels of polyamines in wheat coleoptiles.

The changes in levels and forms of polyamine (Pa) in the coleoptiles of two wheat (triticum aestivum L.) cultivars differing in drought tolerance were investigated under osmotic stress. The drought-tolerant 'Yumai 18' showed marked increases in free spermidine (Spd) and spermine (Spm) levels in coleoptiles after being treated with polyethylene glycol (PEG)-6000 for 2 d in the dark, while drought-sensitive 'Yangmai 9' showed a significant increase in free putrescine (Put) content. Treatment of coleoptiles with methylglyoxal-bis (guanylhydrazone) (MGBG), an S-adenosylmethionine decarboxylase (S-AMDC) inhibitor, resulted in reduction of free Spd and free Spm levels in coleoptiles and aggravation of PEG-induced injury to 'Yumai 18' coleoptile, while exogenous Spd treatment resulted in an increase in free Spd + free Spm content of coleoptiles, and an alleviation of PEG-induced injury to 'Yangmai 9' coleoptile. Osmotic stress induced significant increases in perchloric acid-soluble conjugated PA (PS conjugated PA) and perchloric acid-insoluble conjugated PA (PIS conjugated PA) levels in coleoptiles of 'Yumai 18' whereas osmotic stress affected only slightly the PS-conjugated PA and PIS-conjugated PA levels in 'Yangmai 9' coleoptiles. Treatment of coleoptiles with phenanthroline (o-Phen), an inhibitor of transglutaminase (TGase), also aggravated the PEG-induced injury to 'Yumai 18' coleoptiles, accompanied by the decreases in the level of PIS-conjugated PA. These results suggest that free Spd, free Spm and conjugated PA enhance the osmotic stress tolerance of wheat coleoptiles.