Response of root endosphere bacterial communities of typical rice cultivars to nitrogen fertilizer reduction at the jointing stage.

Root endosphere bacterial communities play an essential role in regulating plant growth and resisting nutrient stress. However, there is still a lack of knowledge on the response of root endosphere bacterial communities of rice (Oryza sativa L.) to reduced nitrogen (N). We investigated endosphere bacterial communities and quantified the abundance of functional genes involved in N conversion and ethylene synthesis in the roots of hybrid rice and japonica rice at the jointing stage under the traditional high-yielding N fertilization (THYN) and reduced N fertilization (RN). Results showed different selection preferences of root endosphere bacterial communities of two rice cultivars under THYN treatment. Specifically, δ-proteobacteria and Firmicutes were enriched in the root endosphere of hybrid rice, while γ-proteobacteria and α-proteobacteria were enriched in the root endosphere of japonica rice. Root endosphere bacterial communities of two rice cultivars showed different tolerance to RN, but showed commonalities in the selection of bacteria taxon, such as the massive enrichment of Burkholderia-Caballeronia-Paraburkholderia in the root endosphere. Additionally, the relative abundances of nifH, amoA-archaea, nirS, nirK, and acdS genes in japonica rice roots were higher than those in roots of hybrid rice under THYN treatment. RN significantly increased the relative abundance of acdS gene in roots of hybrid rice, alleviating the decline in above-ground dry matter weight. Our study revealed potential microbiological strategies for rice to cope with insufficient N supply.

Possible effects of temperature on bacterial communities in the rhizosphere of rice under different climatic regions.

Global warming is an indisputable fact. However, the effect of warming on the rhizosphere bacterial community of crops is not well understood. Therefore, we carried out pot experiments with three rice (Oryza sativa L.) varieties in black soil across three climatic regions of northeast China to simulate temperature change, and analyzed the response of the rhizosphere bacterial community to different temperatures. Results showed that climate had stronger effects on rhizosphere bacterial communities than rice variety. The rhizosphere bacterial diversity differed significantly among the three climatic regions and positively correlated with the mean daily average temperature (MAveT), mean daily maximum temperature (MMaxT), and mean daily minimum temperature (MMinT), and negatively correlated with the daily temperature range (DTR). Principal co-ordinate analysis revealed that bulk soil bacterial communities maintained a high similarity across the three climatic regions, while rhizosphere bacterial communities notably varied. This change was significantly correlated with MAveT, MMaxT, MMinT, and DTR. Compared with bulk soil, Proteobacteria and Bacteroidetes were enriched in the rhizosphere, while Actinobacteria was depleted. Moreover, these changes were strengthened by increasing the temperature and decreasing DTR. Additionally, correlation analysis revealed that changes in rhizosphere bacterial communities were closely related to the formation of rice yields. Our study revealed that the increasing temperature indirectly reshapes the rhizosphere bacterial community that may promote rice production in areas with lower temperatures.

Effects of late-stage nitrogen fertilizer application on the starch structure and cooking quality of rice.

BACKGROUND: With the rapid development of modern agriculture, high-quality rice production and consumption has become the current urgent demand for the development of rice production. In this paper, the effects of late-stage nitrogen fertilizer application on rice quality were studied under the same genetic background. Wx near-isogenic lines were used as test materials to study the starch composition, amylopectin structure and cooking quality of rice. RESULTS: Results showed that rice amylose content and gel consistency significantly differed when different Wx genes were tranformed into waxy rice. The law of apparent amylose content in rice is Wxa > Wxin > Wxb > wx at the same nitrogen level, while the trend of gel consistency was opposite to that of apparent amylose content, presenting obvious characteristics of Indica and Japonica varieties. As the amount of fertilizer application increased, apparent amylose content increased, gel consistency decreased, breakdown and peak viscosities dropped and setback viscosity and peak time increased. Moreover, the cooking quality of rice significantly decreased with the use of nitrogen fertilizer, especially under low-level nitrogen fertilizer application. Amylopectin structure varied significantly in different genotypes of the Wx gene, and the degree of branching was as follows: wx > Wxb > Wxin > Wxa . This result indicated that the closer to Indica rice, the fewer short chains of amylopectin. Starch crystallinity and swelling potential were negatively correlated with amylose content but significantly positively correlated with amylopectin branching degree, decreasing with the increase of late-stage nitrogen fertilization. CONCLUSION: Late-stage nitrogen fertilization reduced the cooking quality of rice by increasing amylose content and reducing amylopectin branching degree, which decreased starch crystallinity and aggravated pasting properties. Obviously, controlling late nitrogen application is essential to optimize rice quality. © 2017 Society of Chemical Industry.

Changes in mineral elements and starch quality of grains during the improvement of japonica rice cultivars.

BACKGROUND: The improvement of rice cultivars plays an important role in yield increase. However, little is known about the changes in starch quality and mineral elements during the improvement of rice cultivars. This study was conducted to investigate the changes in starch quality and mineral elements in japonica rice cultivars. RESULTS: Twelve typical rice cultivars, applied in the production in Jiangsu province during the last 60 years, were grown in the paddy fields. These cultivars were classified into six types according to their application times, plant types and genotypes. The nitrogen (N), phosphorus (P) and, and potassium (K) were mainly distributed in endosperm, bran and bran, respectively. Secondary and micromineral nutrients were distributed throughout grains. With the improvement of cultivars, total N contents gradually decreased, while total P, K and magnesium contents increased in grains. Total copper and zinc contents in type 80'S in grains were highest. The improvement of cultivars enhanced palatability (better gelatinisation enthalpy and amylose content), taste (better protein content) and protein quality (better protein components and essential amino acids). Correlation analysis indicated the close relationship between mineral elements and starch quality. CONCLUSION: The mineral elements and starch quality of grains during the improvement of japonica rice cultivars are improved. © 2017 Society of Chemical Industry.

A predictive model for secondary central nervous system infection after craniotomy based on machine learning.

To analyze the risk factors of secondary Central nervous system infections (CNSIs) after craniotomy, and to establish an individualized predictive model for CNSIs risk. The independent risk factors were screened by univariate and multivariate logistic regression analysis. Logistic regression, naive bayes, random forest, light GBM and adaboost algorithms were used to establish predictive models for secondary CNSIs after craniotomy. The predictive model based on the Adaboost algorithm demonstrated superior prediction performance compared to the other four models. Under 5-fold cross validation, the accuracy was 0.80, the precision was 0.69, the recall was 0.85, the F1-score was 0.76, the area under the ROC curve was 0.897,and the average precision was 0.880. The top 5 variables of importance in Adaboost model were operation time, indwelling time of lumbar drainage tube, indwelling lumbar drainage tube during operation, indwelling epidural drainage tube during operation, and GCS score. In addition, Adaboost model with the best prediction performance was used for clinical verification, and the prediction results were compared with the actual occurrence of CNSIs after surgery. The results showed that the accuracy of Adaboost model in predicting CNSIs was 60%, the accuracy of Adaboost model in predicting non-CNSIS was 92%, and the overall prediction accuracy was 76%.

Effects of Salt Stress on Grain Yield and Quality Parameters in Rice Cultivars with Differing Salt Tolerance.

Rice yield and grain quality are highly sensitive to salinity stress. Salt-tolerant/susceptible rice cultivars respond to salinity differently. To explore the variation in grain yield and quality to moderate/severe salinity stress, five rice cultivars differing in degrees of salt tolerance, including three salt-tolerant rice cultivars (Lianjian 5, Lianjian 6, and Lianjian 7) and two salt-susceptible rice cultivars (Wuyunjing 30 and Lianjing 7) were examined. Grain yield was significantly decreased under salinity stress, while the extent of yield loss was lesser in salt-tolerant rice cultivars due to the relatively higher grain filling ratio and grain weight. The milling quality continued to increase with increasing levels. There were genotypic differences in the responses of appearance quality to mild salinity. The appearance quality was first increased and then decreased with increasing levels of salinity stress in salt-tolerant rice but continued to decrease in salt-susceptible rice. Under severe salinity stress, the protein accumulation was increased and the starch content was decreased; the content of short branched-chain of amylopectin was decreased; the crystallinity and stability of the starch were increased, and the gelatinization temperature was increased. These changes resulted in the deterioration of cooking and eating quality of rice under severe salinity-stressed environments. However, salt-tolerant and salt-susceptible rice cultivars responded differently to moderate salinity stress in cooking and eating quality and in the physicochemical properties of the starch. For salt-tolerant rice cultivars, the chain length of amylopectin was decreased, the degrees of order of the starch structure were decreased, and pasting properties and thermal properties were increased significantly, whereas for salt-susceptible rice cultivars, cooking and eating quality was deteriorated under moderate salinity stress. In conclusion, the selection of salt-tolerant rice cultivars can effectively maintain the rice production at a relatively high level while simultaneously enhancing grain quality in moderate salinity-stressed environments. Our results demonstrate specific salinity responses among the rice genotypes and the planting of salt-tolerant rice under moderate soil salinity is a solution to ensure rice production in China.

To Systematically Evaluate and Analyze the Efficacy and Safety of Transcatheter Arterial Chemoembolization (TACE) in the Treatment of Primary Liver Cancer.

The efficacy and safety of transcatheter arterial chemoembolization (TACE) are systematically evaluated in the treatment of primary liver cancer, which provides a reference for clinical practice and more in-depth research. Cochrane Library, PubMed, EMbase, CBM, CNKI, VIP, and WanFang Data, supplemented by other searches, collected all randomized controlled trials (RCT) comparing TACE combined with TACE alone for HCC. The meta-analysis, after selecting the literature, extracting data, and evaluating the methodological quality of the included studies following the inclusion criteria, was performed using RevMan 5.1 software. There was statistical difference in 3-year survival rate of TACE combined with heat treatment for advanced hepatocellular carcinoma (OR = 1.72,95%CI (1.22,2.41), P=0.002, I2 = 0%, and Z = 3.12), total effective rate (OR = 1.91,95%CI (1.31,2.78), P=0.0008, I2 = 0%, and Z = 3.37), quality-of-life improvement rate (OR = 2.29,95%CI (1.62,3.23), P < 0.00001, I2 = 83%, and Z = 3.37), and complication rate (OR = 2.29,95%CI (1.62,3.23), P < 0.00001, I2 = 83%, and Z = 3.37). Compared with TACE alone, TACE combined with hyperthermia can significantly improve the survival rate and recent efficacy of patients, improve the quality of life, and have a trend to reduce the incidence of toxicity. However, its long-term efficacy and more comprehensive safety need to be verified by more sample and high-quality RCT.

Ethylenediurea reduces grain chalkiness in hybrid rice cultivars under ambient levels of surface ozone in China.

High concentration of tropospheric ozone (O3) causes crop yield losses, which could be reduced by foliar application of ethylenediurea (EDU). Rice grain appearance is a major quality trait that determines the milling quality, white rice productivity and the market value. Grain chalkiness is one of the common defects that deteriorate the grain appearance in rice due to its negative effects on palatability and milling yield. Whether EDU could reduce grain chalkiness in rice which was usually increased by high concentration of O3 is not clarified. We report the grain chalkiness in 19 rice cultivars (CVs) of three types: indica (6 CVs), japonica (5 CVs) and hybrids (8 CVs), observed in an EDU application experiment in the field in China. The ambient O3 level as expressed by accumulated hourly O3 concentration over the threshold of 40 ppb (AOT40) for 80 days until maturity reached 12.8 ppm h at a near-by monitoring station. Fraction of the chalky grains (FCG) in the hybrid cultivars was 8% lower in EDU than that in the control treatments, whereas no significant effect of EDU on FCG was found in japonica or indica cultivars. The reduction of FCG due to EDU treatment in hybrid cultivars was attributed to the significant reduction of milky white grains followed by that of white belly grains. Thus, the application of EDU could ameliorate the decline of grain appearance quality in hybrid rice by decreasing the FCG and enhancing the fraction of perfect grains (FPG). Moreover, there were significant interactions between the EDU application and rice cultivars, indicating varietal difference in the protection of grain appearance quality by EDU. These results suggest the need for further studies on the mechanisms of the effects of EDU on grain chalkiness.

High Leaf Vein Density Promotes Leaf Gas Exchange by Enhancing Leaf Hydraulic Conductance in Oryza sativa L. Plants.

Six cultivated rice genotypes showing different stomatal conductance (g s) values were used to investigate the influence of leaf vein traits on leaf gas exchange and leaf hydraulics. The results showed that g s was the main determinant of the varietal difference in the net photosynthetic rate (P N), whereas the area-based leaf nitrogen content (Narea) and mesophyll conductance (g m) were not main factors. g s and P N were both positively correlated with leaf hydraulic conductance (K leaf). A high density of leaf veins (vein length per leaf area, VLA), especially minor leaf veins (VLAminor), was of benefit for improving the K leaf. The proportion of the minor leaf vein length to the total leaf vein length did not impact the leaf hydraulics or leaf gas exchange. Overall, these findings suggested that a high density of leaf veins, especially minor leaf veins, enhances K leaf and promotes g s and P N in cultivated rice genotypes and a high VLA can be regarded as a high photosynthetic capacity trait in rice plants.

Ethylenediurea (EDU) protects inbred but not hybrid cultivars of rice from yield losses due to surface ozone.

The rising concentration of ground-level ozone (O3) reduces crop yield via increased oxidative stress. Application of ethylenediurea (EDU) protects plants from O3 and could thereby serve as a means to estimate the crop yield losses due to ambient O3 (AO3). However, no study but a few exceptions has ever compared the yield loss estimates from EDU application with those from O3 elevation experiments. Here, we estimated yield loss to AO3 in rice cultivars across the 3 types, indica, japonica, and hybrid, by an EDU application in the field, and compared the yield losses with those estimated with dose-response relationships based on O3 elevation experiments. Relative yield loss (RYL) in the EDU application was estimated at 16% across the rice types on an assumption of a 100% efficiency for protection of crop yield by EDU. This estimate of RYL was close to the 15% RYL estimated from the O3 elevation experiments when a common sensitivity to O3 is assumed across the cultivars. The rice yield loss due to AO3 was thus consistent between the two approaches supporting the idea of EDU application for the yield loss estimation. When only hybrids are focused, however, the RYL from EDU application (16%) was much lower than the 34% RYL from the O3 elevation experiments, which indicates only a 37% yield protection by EDU in the hybrid rice. The incomplete protection by EDU and its genetic variability indicates the need to quantify the efficiency of protection from AO3-induced yield loss as estimated with O3 manipulating experiments.

Disruption of a gene for rice sucrose transporter, OsSUT1, impairs pollen function but pollen maturation is unaffected.

Sucrose transporters (SUTs) are known to play critical roles in the uptake of sucrose from the apoplast in various steps of sugar translocation. Because developing pollen is symplastically isolated from anther tissues, it is hypothesized that SUTs are active in the uptake of apoplastic sucrose into pollen. To investigate this possibility, a comprehensive expression analysis was performed for members of the SUT gene family in the developing pollen of rice (Oryza sativa L.) using real-time RT-PCR combined with a laser microdissection technique. Among the five SUT genes, OsSUT1 and OsSUT3 were found to be preferentially expressed and had temporal expression patterns that were distinct from each other. Expression of OsSUT1 in pollen was confirmed by a promoter-GUS fusion assay. The physiological function of OsSUT1 in pollen was further investigated using retrotransposon insertion mutant lines. While the homozygote of disrupted OsSUT1 (SUT1-/-) could not be obtained, heterozygote plants (SUT1+/-) showed normal grain filling. Their progeny segregated into SUT1+/- and SUT1+/+ with the ratio of 1:1, suggesting that the pollen disrupted for OsSUT1 is dysfunctional. This hypothesis was reinforced in vivo by a backcross of SUT1+/- plants with wild-type plants and also by in vitro pollen germination on the artificial media. However, starch accumulation during pollen development was not affected by disruption of OsSUT1, suggesting that the sugar(s) required for starch biosynthesis is supplied by other sugar transporters.

miR-210 is a Serological Biomarker for Predicting Recurrence and Prognosis of Colon Carcinoma Patients with Liver Metastases After Radiofrequency Ablation Treatment.

PURPOSE: Hepatic metastasis of colon carcinoma seriously affects the prognosis of patients, and miRNA has attracted much attention in predicting hepatic metastasis of colon carcinoma (CC). This research aimed to explore the predictive role of miR-210 in serum for recurrence and prognosis of CC patients with hepatic metastasis. METHODS: Altogether, 150 patients with liver metastases of CC (research group, RG) and 130 patients with non-metastatic of CC (control group, CG) admitted to People's Hospital of Deyang City from March 2012 to March 2015 were obtained and their serum was collected. miR-210 in the RG and the CG, and miR-210 in the RG after radiofrequency ablation treatment were detected, the relationship between miR-210 and pathological parameters of CC patients with hepatic metastasis was analyzed, and patients in the RG were followed up for 5 years to analyze the recurrence, overall survival (OS) and disease-free survival (DFS). The area under the curve (AUC) of receiver operating characteristic curve (ROC) was applied to test the predictive value of miR-210. Cox regression was applied to analyze the independent prognostic factors of patients. RESULTS: miR-210 in the RG was evidently higher than that in the CG, and AUC for distinguishing hepatic metastasis of CC was 0.907. miR-210 had a close correlation with lymph node metastasis, distant metastasis and pathological differentiation. After treatment, miR-210 in the RG was evidently reduced, and the serum was higher in patients with recurrence and with poor prognosis. AUC for predicting recurrence was 0.858, and AUC for predicting poor prognosis was 0.843. High miR-210 was closely related to lower 5-year OS and DFS and is also an independent prognostic factor affecting patients' 5-year OS. CONCLUSION: miR-210 is enhanced in hepatic metastasis of CC, which is a serological biomarker for predicting recurrence and prognosis of patients with hepatic metastasis of CC after radiofrequency ablation, and has great clinical application value.

Introgression of qPE9-1 allele, conferring the panicle erectness, leads to the decrease of grain yield per plant in japonica rice (Oryza sativa L.).

Panicle architecture is closely related to yield formation. The qPE9-1 gene has been proved to be widely used in high-yield rice cultivar developments, conferring erect panicle character in japonica rice. Recently, qPE9-1 has been successfully cloned; however, the genetic effect on grain yield per plant of the erect panicle allele qPE9-1 is controversial yet. In the present study, a drooping panicle parent Nongken 57, carrying qpe9-1 allele, was used as recurrent parent to successively backcross to a typical erect panicle line from the double haploid (DH) population (Wuyunjing 8/Nongken 57), which was previously shown to carry qPE9-1 allele. Thus a pair of near-isogenic lines (NILs) was developed. The comparison of agronomic traits between the NILs showed that, when qpe9-1 was replaced by qPE9-1, the panicle architecture was changed from drooping to erect; moreover, the panicle length, plant height, 1000-grain weight and the tillers were significantly decreased, consequently resulting in the dramatic decrease of grain yield per plant by 30%. Therefore, we concluded that the qPE9-1 was a major factor controlling panicle architecture, and qPE9-1 had pleiotropic nature, with negative effects on grain yield per plant. This result strongly suggests that the erect panicle allele qPE9-1 should be used together with other favorable genes in the high-yield breeding practice. In addition, the effect of qPE9-1 on eating and cooking quality was also discussed in the present study.

[Effects of water stress during grain-filling period on rice grain yield and its quality under different nitrogen levels].

To examine the effects of nitrogen (N) supply and water stress on rice grain yield and its quality, a pot experiment was conducted at Yangzhou University. Three rice cultivars were grown under two N levels (high N and normal N) from initial heading, and two water conditions (well watering and water stress) were installed for each of the two N levels from flowering to maturity. The results showed that when the plants of test cultivars were grown under normal N level, water stress markedly reduced the grain-filling percentage and grain weight, resulting in a significant decrease of grain yield by 11.6% to approximately 14.7%. Though the head-milled rice had a slight increase, the percentage of chalkiness was significantly increased by 18.7% to approximately 33.1%, which resulted in an inferior performance in grain-apparent quality. In contrast, when the plants were grown under high N level, water stress increased the grain yield by 18. 8% to approximately 22.2% because of the increase of grain-filling percentage and grain weight. As compared with well watering, water stress decreased the percentages of chalky grain and chalkiness by 15.3% to approximately 37.2% and 13.7% to 29.9%, respectively, which improved the performance of grain-apparent quality. The pronounced effects of N application and water treatment were observed on the RVA profile and cooked quality. Under both two N levels, water stress decreased the peak viscosity and breakdown (except for Yangdao 6) while increased the setback. According to the performance in the indices of cooked quality, the palatability became poor when subjected to water stress under normal N level, as the result of the increase of hardness and cohesiveness. In contrast, under high N level, water stress availed the ascending of viscosity at the early stage when rice flours were pasting, peak viscosity and breakdown were increased, and setback was decreased, suggesting that the palpability got well. It was concluded that mild water stress during grain-filling period was benefit for the development of high quality grain when rice plants were grown under high N level.

[Difference of lead uptake and distribution in rice cultivars and its mechanism].

In order to investigate the uptake of lead by rice plant and the distribution of lead in different parts of rice, pot experiment was conducted with 20 rice cultivars of different genotypes by adding lead to soil. The results showed that there existed significant differences among the cultivars in the lead uptake and distribution by rice plants, but the differences had no obvious relationship with rice genotypes. The lead concentrations decreased rapidly from roots to grains along rice plants, so the concentrations of lead were very low in grains compared with other parts of rice plants. The regression analysis showed that there were significant negative correlations between adjacent organs of rice plant, but positive correlations, mostly significant, between disconnected organs, for the lead concentrations in them. Lead concentration in the leaf of heading stage showed a significant positive correlation with that in the grain of ripening stage. Lead was not distributed uniformly in different parts of grain structure, and the lead accumulation in polished rice was only 32.88% of the total lead accumulation in grain.