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Phosphorus (P) and potassium (K) stress significantly affect the growth, physiological characteristics, and nutrient uptake of rice plants. This study investigated the photosynthetic nitrogen (N) metabolism, N uptake, and N utilization of plants under varied P and K supplies. Two local conventional high-yield rice varieties (Shennong 265 and Liaojing 294) were used. These varieties were subjected to the following hydroponic experimental treatments: HPHK (normal P and K concentrations), HPLK (normal P and 1/20 normal K concentration), LPHK (normal K and 1/20 normal P concentration), and LPLK (1/20 normal P and K concentrations). The results showed that the mesophyll cells had a relatively complete nuclear and chloroplast structures, and the antioxidant enzymes of the plants were significantly reduced under the HPHK treatment. Compared to the LP treatments (LPHK and LPLK), the HPHK treatment was found to have the following potential effects: effectively optimize plant configuration; promote leaf development (Pn, E, Ci, and Tr, chlorophyll, and leaf area index); significantly increase the N-metabolism-related enzyme activity of leaves and roots and the accumulation of N in the plant in the main growth stages; and significantly increase the rice yield and N-related efficiency. In conclusion, the HPHK treatment was found to be beneficial in improving the plant configuration, promoting photosynthetic N metabolism, and increasing grain yield and N-related utilization efficiency. [ABSTRACT FROM AUTHOR]

Northeast China is an important commercial grain base for China, but also the largest japonica rice production area. However, N, and K fertilizer application and unreasonable application times are prominent contradictions that restrict the development of japonica rice. This study aimed to investigate how to rationally apply N and K fertilizers to affect grain filling and ultimately increase the quality of the rice. In this field study, two N application levels and three K application ratios were set in 2020 and 2021 using Shennong 265 (SN265) and Meifengdao 61 (MF61). We found that the final seed growth and filling rate of SN265 were higher than those of MF61, and their filling characteristics were slow in the early stage and fast in the later stage, with large fluctuations. Appropriate reductions and increases of N and K fertilizer applications, respectively, in the early stage could improve grain filling. Compared with SN265, MF61 had a 3.2% increase in head rice rate, lower amylose and protein content, a decrease of chalkiness degree and chalkiness percentage by 23.96 and 34.00%, respectively, and more reasonable protein components. With the N application increase, the processing quality improved, the amylose and protein content and chalkiness increased, the protein components increased except for the milled rice glutelin, and the rice taste value decreased. At low N levels, increasing the proportion of K application was consistent with the effect of increasing N. The taste value of SN265 decreased linearly with the increase in the ratio of N application to pre-application of K, the highest taste value was obtained when the N fertilizer was applied at a rate of 180 kg ha−1, and the ratio of before and after K fertilizer application was about 1:2. The taste value of MF61 decreased linearly with the N application increase and showed a trend of increasing and then decreasing with the K application increase in the early stage. The taste peak gradually shifted back with the N application increase, and the highest taste value was obtained when N fertilizer was applied at 180 kg ha−1; the ratio of before and after K fertilizer application was about 3:2. By constructing the grain-filling quality evaluation system, the characteristic parameters of superior and inferior grains at the early and late stages of grain filling, respectively, greatly affected the rice taste value. Additionally, the percentage of the rice grain weight at the maximum grain-filling rate to the final rice grain weight (I) of superior grains, glutelin content, and value of the RVA profile characteristics were all critical reference indicators for rice taste quality. [ABSTRACT FROM AUTHOR]

The tiller angle, which is an important agronomic trait, determines plant architecture and greatly influences the grain yield of rice. In this study, a population of chromosome segment substitution lines derived from a cross between a japonica variety with a compact plant architecture—Koshihikari—and an indica variety with a spread-out plant architecture—Nona Bokra—was used to investigate the genetic basis of the tiller angle. Five quantitative trait loci (qTA1, qTA5, qTA9-1, qTA9-2, and qTA11) for the tiller angle were detected on chromosomes 1, 5, 9, 9, and 11 in two different environments. The phenotypic variation in these QTLs ranged from 3.78% to 8.22%. Two pairs of digenic epistatic QTLs were detected in Lingshui. The epistatic interaction explained 15.19% and 13.60% of the phenotypic variance, respectively. Among the five QTLs, qTA9-2 was detected in both environments. An F2 mapping population containing the qTA9-2 QTL was established. The location of qTA9-2 was narrowed down to a 187 kb region between InDel markers M9 and M10 on chromosome 9. Thirty open reading frames (ORFs), including TAC1, a gene known to regulate the tiller angle, were identified in this region. The gene sequencing results suggested that a base substitution from G to A at position 1557 in the 3′-untranslated region led to a difference in the expression of qTA9-2 in Koshihikari and Nona Bokra. These findings provide a potential gene resource for the improvement of rice plant architecture. [ABSTRACT FROM AUTHOR]

Nitrogen is a crucial element that impacts rice yields, and effective tillering is a significant agronomic characteristic that can influence rice yields. The way that reduced nitrogen affects effective tillering is a complex quantitative trait that is controlled by multiple genes, and its genetic basis requires further exploration. In this study, 469 germplasm varieties were used for a genome-wide association analysis aiming to detect quantitative trait loci (QTL) associated with effective tillering at low (60 kg/hm2) and high (180 kg/hm2) nitrogen levels. QTLs detected over multiple years or under different treatments were scrutinized in this study, and candidate genes were identified through haplotype analysis and spatio-temporal expression patterns. A total of seven genes (NAL1, OsCKX9, Os01g0690800, Os02g0550300, Os02g0550700, Os04g0615700, and Os04g06163000) were pinpointed in these QTL regions, and were considered the most likely candidate genes. These results provide favorable information for the use of auxiliary marker selection in controlling effective tillering in rice for improved yields. [ABSTRACT FROM AUTHOR]

Objective: microRNA‐450b (miR‐450b) plays an important role in cancer progression; however, its function in oral squamous cell carcinoma (OSCC) remains largely unknown. This study aimed to investigate the action mechanisms of miR‐450b in OSCC. Materials and Methods: OSCC animal model was established via continuous induction with single‐drug 7, 12‐dimethylbenzo[a]anthracene (DMBA). Animal tissue samples were pathologically typed using haematoxylin–eosin (HE) staining. The Cancer Genome Atlas (TCGA) database was used to predict miR‐450b and SERPINB2 expression in head and neck squamous cell carcinoma (HNSCC). qRT‐PCR and Western blotting were used to detect gene and protein expression in OSCC tissue and cells, respectively. OSCC cell proliferation, growth, migration and invasion were detected using CCK‐8, colony formation, transwell migration and matrigel invasion assays, respectively. Bioinformatic tools were used to predict miR‐450b target genes. Dual‐luciferase reporter assay was used to verify targeting between miR‐450b and SERPINB2. Finally, small interfering RNA (siRNA) was used to reduce SERPINB2 expression to detect its effect on tumourigenesis. Results: Four stages of OSCC carcinogenesis (normal oral epithelium, simple epithelial hyperplasia, dysplasia and OSCC) were identified. miR‐450b was found to be overexpressed in OSCC animal samples, HNSCC samples and human OSCC cells. Upregulation of miR‐450b significantly promoted OSCC cell proliferation, colony formation, migration and invasion, while its downregulation had the opposite effect. SERPINB2 was found to be a miR‐450b target gene, and its expression was negatively correlated with miR‐450b expression. Altering SERPINB2 expression effectively inhibited OSCC cell invasion, metastasis and epithelial‐mesenchymal transition (EMT). Conclusions: miR‐450b plays a key role in OSCC tumourigenesis by regulating OSCC cell migration, invasion and EMT via SERPINB2. [ABSTRACT FROM AUTHOR]

Based on the data of indexed papers from Inspec database, scientometrics and statistics‐related analysis methods are used to study the overall development trend of international cooperation in advanced manufacturing, the characteristics and evolution of major countries in four dimensions of cooperation scale, cooperation intensity, cooperation dominance rate, cooperation impact, and cooperation network from 2011 to 2020, and this article focuses on the changing trend of China and the differences existing with other countries. The study shows that cooperation in advanced manufacturing has an upward trend, with China and the US having a clear lead in cooperation scale and intensity. China leads the most in the aspect of international cooperation in the field of advanced manufacturing, while the US. is at the heart of a network of cooperation across the field. [ABSTRACT FROM AUTHOR]

Brown rice traits are critical to both grain yield and quality. In the present study, the chromosome segment substitution lines (CSSLs) population derived from a cross between japonica Koshihikari and indica Nona Bokra was used to analyze the brown rice length (BRL), brown rice width (BRW), length–width ratio of brown rice (BLWR), brown rice thickness (BRT), brown rice perimeter (BRP), brown rice area (BRA), thousand-grain weight of brown rice (BRGW), brown rice ratio (BRR), taste value of brown rice (BTV), and water content of brown rice (BWC). Correlations analysis showed that most of the brown rice traits had significant correlations with each other, except for BRR, BTV, and BWC. A total of sixty-one QTLs for these traits were identified under three environments, which mapped to chromosomes 1, 2, 3, 5, 6, 7, 8, 10, 11, and 12, with the LOD ranging from 2.52 to 16.68 and accounting for 2.60 to 25.38% of the total phenotypic variations. Moreover, thirty pairs of epistatic interactions for BRL, BRW, BLWR, BRP, and BRA were estimated and distributed on all chromosomes except 10. These findings will provide a further understanding of the genetic basis of brown rice traits and facilitate the genetic improvement of rice yield and quality through breeding. [ABSTRACT FROM AUTHOR]

Background: The CRISPR/Cas9 system is widely used for genome editing in human, rat and mouse cells. In this study, we established Fzd6 mutant mice using CRISPR/Cas9 technology, and obtained Fzd6 homozygous mutant (Fzd6Q152E) mice through breeding. Fzd6 plays a role in depression, but there are few related reports. We used this model to investigate the mechanism of Fzd6 involved in depression, and build a solid foundation for subsequent in-depth studies. Methods and Results: The target of Fzd6 mutation was obtained by CRISPR/Cas9 technology and hippocampal tissue was collected for Nissl staining and histological analysis. Blood was collected for enzyme linked immunosorbent assay (ELISA); The gene expression of Fzd6 and the related genes expression in wnt pathway was quantified by quantitative real-time PCR (qRT-PCR), and then expression of Fzd6 and proteins in the Wnt pathway were identified by western blotting. ELISA results showed that the expression levels of brain derived neurotrophic factor (BDNF), 5-hydroxytryptamine (5-HT), and Noradrenaline (NE) in serum were significantly decreased in Fzd6Q152E mice, whereas the mRNA expression of Lrp5, Lrp6, and Dkk2 is increased. The western blotting revealed that the expression of Fzd6 and Lrp6 is decreased, although the expression of Dkk2 and Gsk-3β increased. Conclusion: Our study successfully established homozygous Fzd6 mutant mice model. The relationship between Fzd6-Wnt and depression was preliminarily clarified, which provides an ideal animal model for subsequent research on diseases induced by the Fzd6 mutation. [ABSTRACT FROM AUTHOR]

Light, simple, and high-efficiency fertilization is currently an effective method used to improve quality and increase yield. Most research has only focused on the yield or quality of rice, and no effective or in-depth studies exist on the key stage of panicle, which is essential for these two aspects. This study aimed to determine the effect of applying Nitrogen (N) and Potassium (K) fertilizers on the yield and quality at different leaf ages. The rice cultivar, Shennong 265, was grown in the field-tube condition at the 5-leaf age with K fertilizer at different panicle stages. Five K fertilizer and four N fertilizer levels were applied simultaneously during two growing seasons in 2020–2021. The application of K fertilizer at different panicle stages significantly affected the yield and quality. The application of K and N fertilizers at the 12th-leaf-age increased the number of panicles and grains per panicle, thereby increasing the yield with an average increase of 23.20% over local farmer's fertilization model (CK) in two years. Application at the 10th-leaf age reduced the starch and protein content of the rice and improved the nutritional quality and taste, with an average increase of 11.08 points compared to CK in two years. The processing quality was the best at the panicle K fertilizer application rate of 47.81–64.69 kg ha−1, and the starch and protein contents were the lowest at the panicle K fertilizer application rate of 56.25 kg ha−1. Under different panicle K fertilizer application rates, N fertilizers had great differences in processing quality but had slight differences in nutritional quality; that is, the starch and protein content (total protein and four protein components) significantly increased. The application of panicle N fertilizer mainly affected starch pasting viscosity (RVA profile characteristics). When panicle K fertilizer was applied after panicle N fertilizer, the yield and quality showed a trend of synergistic improvement. Although this improvement was a low-level synergy, it can still be a direction used to explore the synergistic improvement of output and quality. [ABSTRACT FROM AUTHOR]

Sugar allocation between vegetative and reproductive tissues is vital to plant development, and sugar transporters play fundamental roles in this process. Although several transcription factors have been identified that control their transcription levels, the way in which the expression of sugar transporter genes is controlled at the posttranscriptional level is unknown. In this study, we showed that OsRRM, an RNA-binding protein, modulates sugar allocation in tissues on the source-to-sink route. The OsRRM expression pattern partly resembles that of several sugar transporter and transcription factor genes that specifically affect sugar transporter gene expression. The messenger RNA levels of almost all of the sugar transporter genes are severely reduced in the osrrm mutant, and this alters sugar metabolism and sugar signaling, which further affects plant height, flowering time, seed size, and starch synthesis. We further showed that OsRRM binds directly to messenger RNAs encoded by sugar transporter genes and thus may stabilize their transcripts. Therefore, we have uncovered the physiological function of OsRRM, which sheds new light on sugar metabolism and sugar signaling. [ABSTRACT FROM AUTHOR]

Product innovation and service upgrades are effective measures for firms to improve their competitiveness. Considering the upgrading of the installed customers (IU), the upgrade strategy of a platform firm usually follows two principles, namely, the derived principle (i.e., the basic product still operates when the new derived product is released) or updated principle (i.e., the basic product stops operating when the new product is released). This study investigates whether an upgraded strategy considering IU is beneficial to the platform and which upgrade principle is preferred by platforms in a two-sided market. To explore the optimal upgrade strategy of a platform, we set up a monopoly model and propose three upgraded strategies: the traditional strategy (which does not consider IU), the updated strategy and the derived strategy. The updated strategy can be seen as a discrimination price between the installed and potential buyers. However, the derived strategy helps the platform to classify the buyers into low- and high-end ones. Compared to the traditional strategy, the platform will get higher commission profit and lower membership profit by using the strategies considering IU. [ABSTRACT FROM AUTHOR]

High temperature (HT) has an adverse effect on rice grain filling by inhibiting the accumulation of storage materials. However, the regulatory mechanism of this inhibition remains unknown. Here, we report that Opaque2 like transcription factor OsbZIP58 is a key factor regulating storage material accumulation under HT. The OsbZIP58 gene promotes expression of many seed storage protein genes and starch synthesis genes while inhibits expression of some starch hydrolyzing α‐amylase genes under HT. The loss of OsbZIP58 function leads to floury and shrunken endosperms and dramatically reduced storage materials in the seeds under HT. HT is found to affect alternative splicing of OsbZIP58, promoting the formation of the truncated OsbZIP58β protein form over the full‐length OsbZIP58α protein form. The OsbZIP58β form has a lower transcriptional activity than the OsbZIP58α form, especially under HT condition. Interestingly, rice varieties with less heat sensitivity have reduced alternative splicing of OsbZIP58. Therefore, OsbZIP58 is a crucial gene in regulating storage material accumulation under HT and lower alternative splicing of OsbZIP58 may contribute to heat tolerance during grain filling. High temperature (HT) can harm rice grain quality by significantly reducing the storage materials accumulation. Here we found the alternative splicing of OsbZIP58 can be induced by HT and the lower activity of OsbZIP58β encoded by alternative spliced transcript might account for the decrease of storage materials accumulation and seed quality control in rice under HT. [ABSTRACT FROM AUTHOR]

During conventional fertilization, N is applied before or during the early growth stages of rice (Oryza sativa L.), usually resulting in N loss and waste. Therefore, developing effective N management practices to reduce N losses and increase rice yield and N use efficiency (NUE) will be beneficial to farmers and the environment. Here, the effects of delayed timing and reduced N fertilizer on the yield and NUE of japonica rice grown in Shenyang, China, were investigated in 2016 and 2017. Fertilization during the early tillering stage had no significant effect on the leaf area index (LAI), amount of bleeding sap, dry matter accumulation, or N accumulation by the mid‐tillering (nine‐leaf) stage. After the jointing stage, compared with conventional N treatment, delayed timing of tillering fertilization from 5.5‐leaf stage (7 d after transplanting) to the nine‐leaf stage increased root activity and enhanced nitrate reductase and glutamine synthetase activities in rice leaves. Greater N accumulation from the jointing to grain‐filling stages increased LAI and dry matter accumulation. Average grain yield as a result of delayed N fertilization was 8.6 and 30.7% higher than conventional N treatment. Given the results, optimizing N application rates and timing improved NUE and decreased the amount of N fertilizer needed for maintaining and increasing yield. Collectively, these results indicate that the delayed timing of tillering N fertilizer improves rice yield and NUE. [ABSTRACT FROM AUTHOR]

The response of rice to nitrogen (N) was compared between three rice cultivars and three N treatments: 1:0, 0:1, and 1:1 NH4+:NO3−. The three rice cultivars used were: Shennong1401 (SN1401, erect panicle rice cultivar) and Habataki and Sasanishiki (curved panicle rice cultivars). At the booting stage, higher gene expression and enzyme activity associated with N metabolism of rice in the including-NO3− solutions effected the secondary assimilation of N metabolism, and ultimately increased grain development. During the tillering stage, lower NO3− uptake rates and glutamine synthetase and NADH-dependent glutamate synthase activity in Habataki and Sasanishiki under the NO3− treatments resulted in lower effective panicle number per plant. However, no significant differences were observed in the grain yield per plant of SN1401 between NH4+ and NO3− treatments. Our results indicate that the erect panicle rice cultivar can grow better under the including-NO3− treatment. [ABSTRACT FROM AUTHOR]

Japonica rice is widely planted in north-eastern China because of its superior food quality and stable grain yields. Nitrogen (N) is an essential element for rice growth, and development and its availability directly impacts on rice yields. The knowledge of N uptake and its utilization characteristics in japonica are thus important areas of research. Three japonica rice cultivars, SN265, SN1401, and SN9816, which are planted across large areas of north-eastern China, were used here to evaluate the uptake and utilization along the life cycle of both ammonium (N H 4 +) and nitrate (N O 3 −) in hydroponically grown plants. The plants were grown in one of three different solutions with varying N H 4 + : N O 3 − ratios: 1:0, 0:1, and 1:1 (The total N content was 40 mg L−1 for each treatment). At the tillering stage, when only N O 3 − was provided, lower rates of N uptake and enzyme activities of three rice plants resulted in reduced tiller numbers. During the reproductive stage, the N H 4 + and (N H 4 +) uptake rates in SN1401 were consistently maintained at high levels, whereas the rates in SN265 and SN9816 were significantly lower, across all three treatments. At the booting stage, when only N O 3 − was provided, SN1401 plants had significantly higher expression levels of OsNRT2.1 and OsNRT2.2 , higher activity of nitrate reductase in the roots, and higher activity levels of glutamine synthetase and glutamate synthase in the leaves, compared with the SN265 and SN9816 plants. The higher enzyme activity was beneficial to the secondary assimilation of N, which ultimately promoted panicle development in SN1401. Consequently, the grain yield per plant of SN1401 was the highest with solutions of both N H 4 + and N O 3 − . These results indicate that selecting a rice cultivar with higher utilization of N O 3 − is beneficial for increasing the number of grains per panicle, grain yield, and N use efficiency. [ABSTRACT FROM AUTHOR]

Concerns regarding rising population levels and the impacts of atmospheric greenhouse gas (GHG) emissions on world climate have encouraged effective alternative methods to increase agricultural production while mitigating climate change. Soil GHG emissions from maize ( Zea mays L.) fields treated with stover and a stover-derived biochar amendment during two consecutive maize growing seasons were studied in a brown earth soil type in Liaoning, China. We considered three treatments: CK (basal application of mineral NPK fertilizer; 120 kg N ha, 60 kg PO ha, and 60 kg KO ha, respectively), ST (maize stover application; 7.5 t ha), and BC (7.5 t ha of maize stover was charred, with a yield of 35% of the original biomass; 2.63 t ha). Both ST and BC treatments received the same fertilization as CK. Soil GHG emissions were monitored using the static chamber-gas chromatography method. The mean CO emissions of the two-year experiment indicated that ST and BC were significantly higher than CK by 131.0 and by 21.3%, respectively, and there was a striking difference between ST and BC treatments. The NO-N emissions decreased in the following order, BC < ST < CK, and cumulative reduced CH emissions in BC and ST were 1.58 and 2.21 times higher than observations in CK, respectively. The total global warming potential (GWP) in 2013 and 2014 decreased in the following order: BC < ST < CK. For the yield average data of two-year experiment, compared to CK and BC treatments, ST treatment showed 7.9 and 4.5% reduction, respectively. The C gains in BC treatment were significantly higher than that observed in ST treatment by 7.3%. Compared with the stover incorporating, biochar application significantly decreased the total CO emissions and GHG intensity (GHGI), and it enhanced C-sequestration. [ABSTRACT FROM AUTHOR]

Impacts of biochar on greenhouse gas emissions and C sequestration in agricultural soils have been considered as the key to mitigate climate change. There is limited knowledge regarding the effects of rice straw-derived biochar and interaction with N fertilization on soil C sequestration and rice productivity in fertile paddy fields. A 2-year (2013 and 2014) consecutive field trial was performed using straw treatment (5.05 t ha − 1 ) and biochar amendment (0, 1.78, 14.8 and 29.6 t ha − 1 ) with or without urea application in a rice paddy in Northeast China. A super high yielding rice variety ( Oryza sativa L. subsp. Japonica cv. ‘Shennong 265’) was cultivated with permanent flooding. Results showed that biochar amendments significantly decreased CH 4 emissions relative to straw treatment irrespective of N fertilization, especially in N-fertilized soils with 1.78 t ha − 1 biochar. There were no differences in CO 2 emissions with respect to biochar amendments, except for 14.8 t ha − 1 biochar with N fertilization. Straw treatment had the highest global warming potential over a 100-year time frame, which was nearly 1.5 times that of 14.8 t ha − 1 biochar amendment without N fertilization. Biochar addition increased total soil C by up to 5.75 mg g − 1 and 11.69 mg g − 1 (with 14.8 and 29.6 t ha − 1 biochar, respectively), whereas straw incorporation increased this value by only 3.92 mg g − 1 . The aboveground biomass of rice in biochar-amended soils increased to varying degrees compared with that in straw-treated soils. However, biochar application had no effects on rice yield, regardless of N fertilization. This study indicated that transforming straw to biochar was more stabilized and more suitable to mitigate greenhouse gas emissions and increase C storage in agriculture soils in Northeast China. [ABSTRACT FROM AUTHOR]

An understanding of the leaf and root traits associated with high nitrogen (N) absorption and utilization is very important in the development of N-efficient varieties in crop breeding programs. However, in rice, the relations between these traits and nitrogen use efficiencies (NUEs) have yet to be identified. Therefore, the responses of leaf and root traits and yields of the three main japonica rice cultivars in northern China were examined at a range of N application rates. The rice cultivars, Shennong 265 (SN265), Tiejing 11 (TJ11), and Fengjing (FJ), were grown in the field at six N rates (0, 60, 120, 180, 240, and 300 kg ha−1) applied during two growing seasons (2018 and 2019). With the increase in N rate, the grain yield of SN265 and TJ11 increased, whereas the grain yield of FJ first increased and then decreased. The grain yield of FJ was higher than that of SN265 and TJ11 at lower N rates, whereas the grain yields of SN265 and TJ11 were higher than that of FJ at higher N rates. The NUEs decreased with the increase in N rates. At lower N rates, the ability of rice to obtain N was the main limitation on rice yield, but with the increase in N rates, the limitation on yield due to N absorption capacity gradually weakened. However, at higher N rates, rice yields were restricted by the ability to utilize N. Compared with TJ11 or FJ, SN265 had higher N utilization capacity primarily because of its higher Rubisco activity, NR activity, GS activity, and ROA. Compared with SN265 or TJ11, FJ had a higher N absorption capacity that was attributed to its larger root architecture, which might have also been one of the reasons for lower N utilization. Therefore, by improving N absorption and utilization-related leaf and root traits, high yields and NUEs can be achieved in rice production at different N application rates. [ABSTRACT FROM AUTHOR]

Although nitrogen (N), phosphorus (P), and potassium (K) co-application improves crop growth, yield, and N use efficiency (NUE) of rice, few studies have investigated the mechanisms underlying these interactions. To investigate root morphological and physiological characteristics and determine yield and nitrogen use parameters, rhizo-box experiments were performed on rice using six treatments (no fertilizer, PK, N, NK, NP, and NPK) and plants were harvested at maturity. The aboveground biomass at the elongating stage and grain yield at maturity for NPK treatment were higher than the sum of PK and N treatments. N, P, and K interactions enhanced grain yield due to an increase in agronomic N use efficiency (NAE). The co-application of N, P, and K improved N uptake and N recovery efficiency, exceeding the decreases in physiological and internal NUE and thereby improving NAE. Increases in root length and biomass, N uptake per unit root length/root biomass, root oxidation activity, total roots absorption area, and roots active absorption area at the elongating stage improved N uptake via N, P, and K interactions. The higher total N uptake from N, P, and K interactions was due to improved root characteristics, which enhanced the rice yield and NUE. [ABSTRACT FROM AUTHOR]

Nitrogen is an essential nutrient for plant growth and basic metabolic processes. Root systems play an important role in the ability of plants to obtain nutrients from the soil, and are closely related to the growth and development of above-ground plants. Root morphology analysis showed that root growth was induced under low-nitrogen conditions and inhibited under high-nitrogen conditions. To better understand the molecular mechanisms and metabolic basis underlying the rice root response to nitrogen availability, an integrated analysis of the rice root transcriptome and metabolome under three environmental conditions (low-, control, and high-nitrogen conditions) was conducted. A total of 262 and 262 differentially level metabolites were identified under low- and high-nitrogen conditions, respectively. A total of 696 and 808 differentially expressed genes were identified under low- and high-nitrogen conditions, respectively. For both the differentially expressed genes and metabolites, KEGG pathway analysis indicated that amino acid metabolism, carbon and nitrogen metabolism, phenylpropanoid metabolism, and phytohormones' signal transduction were significantly affected by nitrogen availability. Additionally, variable levels of 65 transcription factors (TFs) were identified in rice leaves exposed to high and low nitrogen, covering 22 TF families. These results also indicate that there is a significant difference in the transcriptional regulation mechanisms of rice roots between low and high nitrogen. In summary, our study provides new information for a further understanding of the response of rice roots to low-nitrogen and high-nitrogen conditions. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is an extremely important macronutrient for plant growth and development. It is the main limiting factor in most agricultural production. However, it is well known that the nitrogen use efficiency (NUE) of rice gradually decreases with the increase of the nitrogen application rate. In order to clarify the underlying metabolic and molecular mechanisms of this phenomenon, we performed an integrated analysis of the rice transcriptome and metabolome. Both differentially expressed genes (DEGs) and metabolite Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that carbon and nitrogen metabolism is significantly affected by nitrogen availability. Further analysis of carbon and nitrogen metabolism changes in rice under different nitrogen availability showed that high N inhibits nitrogen assimilation and aromatic metabolism pathways by regulating carbon metabolism pathways such as the tricarboxylic acid (TCA) cycle and the pentose phosphate pathway (PPP). Under low nitrogen, the TCA cycle is promoted to produce more energy and α-ketoglutarate, thereby enhancing nitrogen transport and assimilation. PPP is also inhibited by low N, which may be consistent with the lower NADPH demand under low nitrogen. Additionally, we performed a co-expression network analysis of genes and metabolites related to carbon and nitrogen metabolism. In total, 15 genes were identified as hub genes. In summary, this study reveals the influence of nitrogen levels on the regulation mechanisms for carbon and nitrogen metabolism in rice and provides new insights into coordinating carbon and nitrogen metabolism and improving nitrogen use efficiency in rice. [ABSTRACT FROM AUTHOR]

A correction to the article "Effect of volatile organic compounds absorbedto fresh biochar on survival of Bacillus mucilaginosus and structure of soil microbial communities" that was published in the December 14, 2014 issue is presented.