Peanut kernels rich in oil, particularly those with oleic acid as their primary fatty acid, are in high demand among consumers, the food industry, and farmers due to their superior nutritional content, extended shelf life, and health benefits.  The oil content and fatty acid composition are governed by multiple genetic factors.  Identifying the quantitative trait loci (QTLs) related to these attributes will facilitate marker-assisted selection and genomic selection, thus enhancing quality-focused peanut breeding programs.  For this purpose, we developed a population of 521 recombinant inbred lines (RILs) and tested their kernel quality traits across five different environments.  We identified two major and stable QTLs for oil content, qOCAh12.1 and qOCAh16.1.  The markers linked to these QTLs were designed by Kompetitive allele-specific PCR (KASP) and subsequently validated.  Moreover, we found that the superior haplotype of oil content in the qOCAh16.1 region was conserved within the plant introduction (PI) germplasm cluster, as evidenced by a diverse peanut accession panel.  In addition, we determined that qAh09 and qAh19.1, which harbor the key gene encoding fatty acid desaturase 2 (FAD2), influence all seven fatty acids, palmitic, stearic, oleic, linoleic, arachidic, gadoleic, and behenic acids.  Regarding the protein content and the long-chain saturated fatty acid behenic acid, qAh07 emerged as the major and stable QTL, accounting for over 10% of the phenotypic variation explained (PVE).  These findings can enhance marker-assisted selection in peanut breeding, with the aim of improving the oil content, and deepen our understanding of the genetic mechanisms that shape fatty acid composition. 

Enhancing host immunity is an effective way to reduce morbidity in chickens.  Heterophil to lymphocyte ratio (H/L) is associated with host disease resistance in birds.  Chickens with different H/L levels show different disease resistances.  However, the utility of the H/L as an indicator of immune function needs to be further analyzed.  In this study, a H/L directional breeding chicken line (Jingxing yellow chicken) was constructed, which has been bred for 12 generations.  We compared the function of heterophils, and combined statistical analysis to explore the candidate genes and pathways related to H/L.  The oxidative burst function of the heterophils isolated from the H/L selection line (G12) was increased (P=0.044) compared to the non-selection line (NS).  The 22.44 Mb genomic regions which annotated 300 protein-coding genes were selected in the genome of G9 (n=92) compared to NS (n=92) based on a genome-wide selective sweep.  Several selective regions were identified containing genes like interferon induced with helicase C domain 1 (IFIH1) and moesin (MSN) associated with the intracellular receptor signaling pathway, C–C motif chemokine receptor 6 (CCR6), dipeptidyl peptidase 4 (DPP4) and hemolytic complement (HC) associated with the negative regulation of leukocyte chemotaxis and tight junction protein 1 (TJP1) associated with actin cytoskeleton organization.  In addition, 45 genome-wide significant indels containing 29 protein-coding genes were also identified as associated with the H/L based on genome-wide association study (GWAS).  The expression of protein tyrosine phosphatase non-receptor type 5 (PTPN5) (r=0.75, P=0.033) and oxysterol binding protein like 5 (OSBPL5) (r=0.89, P=0.0027) were positively correlated with H/L.  Compared to the high H/L group, the expressions of PTPN5 and OSBPL5 were decreased (P<0.05) in the low H/L group of Beijing you chicken.  The A/A allelic frequency of indel 5_13108985 (P=3.85E–06) within OSBPL5 gradually increased from the NS to G5 and G9, and the individuals with A/A exhibited lower H/L than individuals with heterozygote A/ATCT (P=4.28E–04) and homozygous ATCT/ATCT (P=3.40E–05).  Above results indicated oxidative burst function of heterophils were enhanced, and 22.44 Mb genomic regions were selected with the directional selection of H/L.  In addition, PTPN5 and OSBPL5 genes were identified as H/L-related candidate genes.  These findings revealed the complex genetic mechanism of H/L related to immunity and will allow selection for improving chicken immunity based on the H/L

The accurate prediction of soybean yield is of great significance for agricultural production, monitoring and early warning.  Although previous studies have used machine learning algorithms to predict soybean yield based on meteorological data, it is not clear how different models can be used to effectively separate soybean meteorological yield from soybean yield in various regions.  In addition, comprehensively integrating the advantages of various machine learning algorithms to improve the prediction accuracy through ensemble learning algorithms has not been studied in depth.  This study used and analyzed various daily meteorological data and soybean yield data from 173 county-level administrative regions and meteorological stations in two principal soybean planting areas in China (Northeast China and the Huang–Huai region), covering 34 years.  Three effective machine learning algorithms (K-nearest neighbor, random forest, and support vector regression) were adopted as the base-models to establish a high-precision and highly-reliable soybean meteorological yield prediction model based on the stacking ensemble learning framework.  The model’s generalizability was further improved through 5-fold cross-validation, and the model was optimized by principal component analysis and hyperparametric optimization.  The accuracy of the model was evaluated by using the five-year sliding prediction and four regression indicators of the 173 counties, which showed that the stacking model has higher accuracy and stronger robustness.  The 5-year sliding estimations of soybean yield based on the stacking model in 173 counties showed that the prediction effect can reflect the spatiotemporal distribution of soybean yield in detail, and the mean absolute percentage error (MAPE) was less than 5%.  The stacking prediction model of soybean meteorological yield provides a new approach for accurately predicting soybean yield.

Photosynthesis occurs mainly in chloroplasts, whose development is regulated by proteins encoded by nuclear genes.  Among them, pentapeptide repeat (PPR) proteins participate in organelle RNA editing.  Although there are more than 450 members of the PPR protein family in rice, only a few affect RNA editing in rice chloroplasts.  Gene editing technology has created new rice germplasm and mutants, which could be used for rice breeding and gene function study.  This study evaluated the functions of OsPPR9 in chloroplast RNA editing in rice.  The osppr9 mutants were obtained by CRISPR/Cas9, which showed yellowing leaves and a lethal phenotype, with suppressed expression of genes associated with chloroplast development and accumulation of photosynthetic-related proteins.  In addition, loss of OsPPR9 protein function reduces the editing efficiency of rps8-C182, rpoC2-C4106, rps14-C80, and ndhB-C611 RNA editing sites, which affects chloroplast growth and development in rice.  Our data showed that OsPPR9 is highly expressed in rice leaves and encodes a DYW-PPR protein localized in chloroplasts.  Besides, the OsPPR9 protein was shown to interact with OsMORF2 and OsMORF9.  Together, our findings provide insights into the role of the PPR protein in regulating chloroplast development in rice. 

Salinity severely affects plant growth and development. Thus, it is crucial to identify the genes functioning in salt stress response and unravel the mechanism by which plants against salt stress. This study used the phosphoproteomic assay and found that 123 of the 4 000 quantitative analyzed phosphopeptides were induced by salt stress. The functional annotation of the non-redundant protein database (NR) showed 23 differentially expressed transcription factors, including a phosphopeptide covering the Serine 31 in the RAV (related to ABI3/VP1) transcription factor (named SiRAV1). SiRAV1 was located in the nucleus. Phenotypic and physiological analysis showed that overexpressing SiRAV1 in foxtail millet enhanced salt tolerance and alleviated the salt-induced increases of H₂O₂ accumulation, malondialdehyde (MDA) content, and percent of electrolyte leakage. Further analysis showed that SiRAV1 positively regulated SiCAT expression to modulate the catalase (CAT) activity by directly binding to the SiCAT promoter in vivo and in vitro. Moreover, we found that phosphorylation of SiRAV1 at the Ser31 site positively regulated salt tolerance in foxtail millet via enhancing its binding ability to SiCAT promoter but did not affect its subcellular localization. Overall, our results define a mechanism for SiRAV1 function in salt response where salt-triggered phosphorylation of SiRAV1 at Ser31 enhances its binding ability to SiCAT promoter, and the increased SiCAT expression contributes to salt tolerance in foxtail millet.

The red coloring of pear fruits is mainly caused by anthocyanin accumulation.  Red sport, represented by the green pear cultivar ‘Bartlett’ (BL) and the red-skinned derivative ‘Max Red Bartlett’ (MRB), is an ideal material for studying the molecular mechanism of anthocyanin accumulation in pear.  Genetic analysis has previously revealed a quantitative trait locus (QTL) associated with red skin color in MRB.  However, the key gene in the QTL and the associated regulatory mechanism remain unknown.  In the present study, transcriptomic and methylomic analyses were performed using pear skin for comparisons between BL and MRB.  These analyses revealed differential PcHY5 DNA methylation levels between the two cultivars; MRB had lower PcHY5 methylation than BL during fruit development, and PcHY5 was more highly expressed in MRB than in BL.  These results indicated that PcHY5 is involved in the variations in skin color between BL and MRB.  We further used dual luciferase assays to verify that PcHY5 activates the promoters of the anthocyanin biosynthesis and transport genes PcUFGT, PcGST, PcMYB10 and PcMYB114, confirming that PcHY5 not only regulates anthocyanin biosynthesis but also anthocyanin transport.  Furthermore, we analyzed a key differentially methylated site between MRB and BL, and found that it was located in an intronic region of PcHY5.  The lower methylation levels in this PcHY5 intron in MRB were associated with red fruit color during development, whereas the higher methylation levels at the same site in BL were associated with green fruit color.  Based on the differential expression and methylation patterns in PcHY5 and gene functional verification, we hypothesize that PcHY5, which is regulated by methylation levels, affects anthocyanin biosynthesis and transport to cause the variations in skin color between BL and MRB.

Nitrogen (N) is unevenly distributed throughout the soil and plant roots proliferate in N-rich soil patches.  However, the relationship between the root response to localized N supply and maize N uptake efficiency among different genotypes is unclear.  In this study, four maize varieties were evaluated to explore genotypic differences in the root response to local N application in relation to N uptake.  A split-root system was established for hydroponically-grown plants and two methods of local N application (local banding and local dotting) were examined in the field.  Genotypic differences in the root length response to N were highly correlated between the hydroponic and field conditions (r>0.99).  Genotypes showing high response to N, ZD958, XY335 and XF32D22, showed 50‒63% longer lateral root length and 36‒53% greater root biomass in N-rich regions under hydroponic conditions, while the LY13 genotype did not respond to N.  Under field conditions, the root length of the high-response genotypes was found to increase by 66‒75% at 40‒60 cm soil depth, while LY13 showed smaller changes in root length.  In addition, local N application increased N uptake at the post-silking stage by 16‒88% in the high-response genotypes and increased the grain yield of ZD958 by 10‒12%.  Moreover, yield was positively correlated with root length at 40‒60 cm soil depth (r=0.39).  We conclude that local fertilization should be used for high-response genotypes, which can be rapidly identified at the seedling stage, and selection for “local-N responsive roots” can be a promising trait in maize breeding for high nitrogen uptake efficiency.  

High-yield rice varieties with a suitable growth duration are required for mechanical transplanting in multiple cropping systems.  Daily yield is an appropriate criterion for the selection of machine-transplanted rice varieties.  The aim of this study was to investigate the growth characteristics and grain production in machine-transplanted medium indica hybrid rice with a high daily yield.  We conducted a field experiment on 20 medium indica hybrid rice varieties in 2017 and 2018.  Grain yield decreased significantly with growth duration between jointing and heading, but it increased with dry matter accumulation, growth rate between jointing and heading, dry matter partitioning to the stem plus sheath at heading, daily yield, and number of spikelets per panicle.  Compared with the medium and low daily yield variety types, the high daily yield variety type increased shoot biomass by improving crop growth rate and dry matter accumulation amount between jointing and heading and after heading.  The high daily yield variety type decreased the growth duration pre-heading and the proportions of dry matter partitioned to the leaf lamina at heading and maturity, but it also increased the post-heading accumulated dry matter in the grain and the remobilization of dry matter stored in the vegetative organs.  Furthermore, the high daily yield variety type significantly increased the occurrence rate of tillers, which is beneficial for the formation of a larger panicle size and an increase in the grain-filling rate.  These changes contributed to a 6.51–23.16% relative increase in grain yield of the high daily yield variety type.  In conclusion, the selection of high daily yield indica hybrid rice varieties with shorter pre-heading growth duration, greater tiller occurrence rate and spikelet numbers per panicle, higher post-jointing growth rates and stem plus sheath dry matter accumulation at heading is suitable for machine-transplanted rice.

High-moisture extrusion technology should be considered one of the best choices for producing plant-based meat substitutes with the rich fibrous structure offered by real animal meat products.  Unfortunately, the extrusion process has been seen as a “black box” with limited information about what occurs inside, causing serious obstacles in developing meat substitutes.  This study designed a high-moisture extrusion process and developed 10 new plant-based meat substitutes comparable to the fibrous structure of real animal meat.  The study used the Feature-Augmented Principal Component Analysis (FA-PCA) method to visualize and understand the whole extrusion process in three ways systematically and accurately.  It established six sets of mathematical models of the high-moisture extrusion process based on 8 000 pieces of data, including five types of parameters.  The FA-PCA method improved the R² values significantly compared with the PCA method.  The Way 3 was the best to predict product quality (Z), demonstrating that the gradually molecular conformational changes (Yⁿ´) were critical in controlling the final quality of the plant-based meat substitutes.  Moreover, the first visualization platform software for the high-moisture extrusion process has been established to clearly show the “black box” by combining the virtual simulation technology.  Through the software, some practice work such as equipment installation, parameter adjustment, equipment disassembly, and data prediction can be easily achieved.

Salmonella is one of the most common food-borne pathogens and its resistance in chicken can be improved through genetic selection.  The heterophils/lymphocytes (H/L) ratio in the blood reflects the immune system status of chicken.  We compared the genome data and spleen transcriptomes between the H/L ratio-selected and non-selected chickens, after Salmonella infection, aiming to identify the key genes participating in the antibacterial activity in the spleen.  The results revealed that, the selected population had stronger (P<0.05) liver resistance to Salmonella typhimurium (ST) than the non-selected population.  In the selected and non-selected lines, the identified differentiation genes encode proteins involved in biological processes or metabolic pathways that included the TGF-beta signaling pathway, FoxO signaling pathway, and Salmonella infection pathway.  The results of the analysis of all identified differentially expressed genes (DEGs) of spleen revealed that the G protein-coupled receptor (GPCR) and insulin-like growth factor (IGF-I) signaling pathways were involved in the Salmonella infection pathway.  Integrated analysis of DEGs and F_ST (fixation index), identified candidate genes involved in Salmonella infection pathway, such as GPR39, NTRK2, and ANXA1.  The extensive genomic changes highlight the polygenic genetic of the immune response in these chicken populations.  Numerous genes related to the immune performance are differentially expressed in the selected and non-selected lines and the selected lines has a higher resistance to Salmonella. 

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive diseases on wheat worldwide.  Wudubaijian, a wheat landrace released from Gansu Province in China since 1950, exhibits adult-plant resistance to stripe rust for several decades.  To elucidate the genetic basis of stripe rust resistance, Wudubaijian was crossed with the high susceptible cultivar Mingxian 169, and stripe rust tests of both parents and the F_2:3 lines were conducted in four environments of Yangling and Tianshui in 2015 and 2016, respectively.  The relative area under disease progress curve (rAUDPC) of Mingxian 169/Wudubaijian F_2:3 lines showed that the resistance of Wudubaijian was controlled by quantitative trait loci (QTL).  Combined with phenotypic data and molecular markers, two stable QTLs were identified in Wudubaijian.  QYrwdbj.nwafu-5A with the phenotypic variance of 15.02–40.26% was located between 5AS1–0.40–0.75 and 5AS3–0.75–0.98 of chromosome 5AS, and QYrwdbj.nwafu-2B.1 with the phenotypic variance of 9.54–10.40% was located in the bin C-2BS1–0.53 of chromosome 2BS.  Through the location of flanking markers and epistasis analysis, QYrwdbj.nwafu-5A may be a new major QTL that can be used in conjunction with other stripe rust resistance genes (QTLs).

Monoclonal antibodies (mAbs) are widely used in virus research and disease diagnosis.  The nucleoprotein (NP) of influenza A virus (IAV) plays important roles in multiple stages of the virus life cycle.  Therefore, generating conserved mAbs against NP and characterizing their properties will provide useful tools for IAV research.  In this study, two mAbs against the NP protein, 10E9 and 3F3, were generated with recombinant truncated NP proteins (NP-1 and NP-2) as immunogens.  The heavy-chain subclass of both 10E9 and 3F3 was determined to be IgG2α, and the light-chain type was κ.  Truncation and site-specific mutation analyses showed that the epitopes of mAbs 10E9 and 3F3 were located in the N terminal 84–89 amino acids and the C terminal 320–324 amino acids of the NP protein, respectively.  We found that mAbs 10E9 and 3F3 reacted well with the NP protein of H1–H15 subtypes of IAV.  Both 10E9 and 3F3 can be used in immunoprecipitation assay, and 10E9 was also successfully applied in confocal microscopy.  Furthermore, we found that the 10E9-recognized ₈₄SAGKDP₈₉ epitope and 3F3-recognized ₃₂₀ENPAH₃₂₄ epitope were highly conserved in NP among all avian and human IAVs.  Thus, the two mAbs we developed could be used as powerful tools in the development of diagnostic methods of IAV, and also surely promote the basic research in understanding the replication mechanisms of IAV.

Grain water relations play an important role in grain filling in maize.  The study aimed to gain a clear understanding of the changes in grain dry weight and water relations in maize grains by using hybrids with contrasting nitrogen efficiencies under differing nitrogen levels.  The objectives were: 1) to understand the changes in dry matter and percent moisture content (MC) during grain development in response to different nitrogen application rates and 2) to determine whether nitrogen application affects grain filling by regulating grain water relations.  Two maize hybrids, high N-efficient Zhenghong 311 (ZH311) and low N-efficient Xianyu 508 (XY508), were grown in the field under four levels of N fertilizer: 0, 150, 300, and 450 kg N ha^–1 during three growing seasons.  Dry weight, percent MC and water content (WC) of basal–middle and apical grains were investigated.  The difference in the maximum WC and filling duration of basal–middle and apical grains in maize ears resulted in a significant difference in final grain weight.  Grain position markedly influenced grain drying down; specifically, the drying down rate of apical grains was faster than that of basal–middle grains.  Genotype and grain position both influenced the impact of nitrogen application rate on grain filling and drying down.  Nitrogen rate determined the maximum grain WC and percent MC loss rate in the middle and the late grain-filling stages, thus affecting final grain weight.  The use of high N-efficient hybrids, combined with the reduction of nitrogen application rate, can coordinate basal–middle and apical grain drying down to ensure yield.  This management strategy could lead to a win–win situation in which the maximum maize yield, efficient mechanical harvest and environmental safety are all achieved. 

Soil organic carbon (SOC) and nitrogen (N) are two of the most important indicators for agricultural productivity.  The primary objective of this study was to investigate the changes in SOC and N in the deep soil profile (up to 100 cm) and their relationships with crop productivity under the influence of long-term (since 1990) fertilization  in the wheat-maize cropping system.  Treatments included CK (control), NP (inorganic N and phosphorus (P) fertilizers), NPK (inorganic N, P and potassium fertilizers), NPKM (NPK plus manure), and M (manure).  Crop yield and the properties of topsoil were measured yearly from 2001 to 2009.  C and N contents were measured at five different depths in 2001 and 2009.  The results showed that wheat and maize yields decreased between 2001 and 2009 under the inorganic fertilizer (NP and NPK) treatments.  The average yield between 2001 and 2009 under the NP, NPK, NPKM, and M treatments (compared with the CK treatment) increased by 38, 115, 383, and 381%, respectively, for wheat and 348, 891, 2 738, and 1 845%, respectively, for maize.  Different long-term fertilization treatments significantly changed coarse free particulate (cfPOC), fine free particulate (ffPOC), intramicroaggregate particulate (iPOC), and mineral-associated (mSOC) organic carbon fractions.  In the experimental years of 2001 and 2009, soil fractions occurred in the following order for all treatments: mSOC>cfPOC>iPOC>ffPOC.  All fractions were higher under the manure application treatments than under the inorganic fertilization treatments.  Compared to the inorganic fertilization treatments, manure input enhanced the stocks of SOC and total N in the surface layer (0–20 cm) but decreased SOC and N in the deep soil layer (80–100 cm).  This reveals the efficiency of manure in increasing yield productivity and decreasing risk of vertical loss of nutrients, especially N, compared to inorganic fertilization treatments.  The findings provide opportunities for understanding deep soil C and N dynamics, which could help mitigate climate change impact on agricultural production and maintain soil health.

Winter jujube (Ziziphus jujuba ‘Dongzao’) is an excellent late maturing variety of fresh-eating jujube in China.  Fruit texture is an important indicator of sensory quality.  To investigate the correlations among texture indices and establish an evaluation system for winter jujube texture, we used the TMS-Touch instrument to perform a texture profile analysis (TPA) on 1 150 winter jujubes from three major producing areas in China.  Eight indices and their best-fit distribution were obtained, including fracture (Pearson), hardness (InvGauss), adhesive force (Weibull), adhesiveness (LogLogistic), cohesiveness (LogLogistic), springiness (BetaGeneral), gumminess (InvGauss), and chewiness (InvGauss).  Based on the best-fit distribution curves, each index was divided into five grades (lower, low, medium, high and higher) by the 10th, 30th, 70th and 90th percentiles.  Among the texture indices, 82% of the correlation coefficients were highly significant (P<0.01); meanwhile, chewiness was significantly (P<0.01) and positively correlated with springiness and gumminess, of which the correlation coefficients were up to 0.8692 and 0.8096, respectively.  However, adhesiveness was significantly (P<0.01) and negatively related to adhesive force with a correlation coefficient of –0.7569.  Among hardness, cohesiveness, springiness, gumminess, and chewiness, each index could be well fitted by a multiple linear regression with the remaining four indices, with the coefficients above 0.94 and the mean fitting error and mean prediction error lower than 10%.  A comprehensive evaluation model was consequently established based on factor analysis to evaluate the texture quality of winter jujube.  The results demonstrated that winter jujube with higher comprehensive scores generally exhibited higher springiness and chewiness, but had lower adhesive force and adhesiveness.  We used factor analysis and clustering analysis to divide the eight studied texture into four groups (cohesive factor, adhesive-soft factor, tough-hard factor, and crispness factor), whose representative indices were springiness, adhesiveness, hardness, and fracture, respectively.  Overall, this study investigated the variation in each index of winter jujube texture, explored the association among these indices, screened the representative indices, and established a texture evaluation system.  The results provide a methodological basis and technical support for evaluating winter jujube texture.

As a critical food crop, sweetpotato (Ipomoea batatas (L.) Lam.) is widely planted all over the world, but it is deeply affected by Sweetpotato Virus Disease (SPVD).  The present study utilized short tandem target mimic (STTM) technology to effectively up-regulate the expression of laccase (IbLACs) by successfully inhibiting the expression of miR397.  The upstream genes in the lignin synthesis pathway were widely up-regulated by feedback regulation, including phenylalanine ammonialyase (PAL), 4-coumarate-CoAligase (4CL), hydroxycinnamoyl CoA:shikimatetransferase (HTC), caffeicacid O-methyltransferase (COMT), and cinnamyl alcohol dehydrogenase (CAD).  Meanwhile, the activities of PAL and LAC increased significantly, finally leading to increased lignin content.  Lignin deposition in the cell wall increased the physical defence ability of transgenic sweetpotato plants, reduced the accumulation of SPVD transmitted by Bemisia tabaci (Gennadius), and promoted healthy sweetpotato growth.  The results provide new insights for disease resistance breeding and green production of sweetpotato. 

The wheat aphid, Sitobion miscanthi, is one of the most destructive pests of wheat plants in the temperate regions of China.  Little is known about the genetic structure evolution of  the different geographic populations of S. miscanthi with its migration.  In this study, we investigated the population genetic structure and demographic history of S. miscanthi by analysing 18 geographical populations across China using one mitochondrial gene, COI; one nuclear gene, EF-1α; and two endosymbiont Buchnera genes, gnd and trpA.  Analysis of data from the various groups showed high haplotype diversity and low nucleotide variation.  SAMOVA analysis did not find a correlation between genetic distance and geographic distance.  However, areas with high population diversity exhibited high haplotype diversity.  Therefore, we speculate that there are two main natural migration pathways of S. miscanthi in China.  One is from Yunnan to the Sichuan Basin, and the other is from Wuhan, Xinyang and Jiaodong Peninsula areas to the northwest.  Based on this hypothesis, we inferred that these aphid populations appear first in the southwestern and southern regions and spread to the north with the help of the southeastern and southwestern monsoons, which occur in spring and summer.  In autumn, the aphids spread southward with the northeastern and northwestern monsoons.

The panicle architecture and grain size of rice affect not only grain yield but also grain quality, especially grain appearance. The erect-panicle (EP) trait controlled by the qpe9-1/dep1 allele has been widely used in high-yielding japonica rice breeding, but usually accompanied with moderate appearance of milled rice. The null gs9 allele shows a good potential for improving grain shape and appearance. However, GS9 and qPE9-1/DEP1 loci are tightly linked, and their interaction is unclear, which obviously restricts their utilization in modern rice breeding. In the present study, comparative analyses of protein and mRNA levels revealed that GS9 and qPE9-1 function independently. Three near-isogenic lines (NILs) carrying various allelic combinations of these two loci, NIL (gs9/qpe9-1), NIL (GS9/qPE9-1) and NIL (gs9/qPE9-1), in the EP japonica cultivar 2661 (GS9/qpe9-1) background were developed for genetic interaction analysis. GS9 and qPE9-1 had additive effects on determining grain size, and the null gs9 allele could decrease grain chalkiness and improve grain appearance without affecting plant and panicle architecture in EP japonica cultivars. Additionally, introgression lines (ILs) developed in another released EP japonica cultivar Wuyujing 27 (WYJ27) background showed the same additive effect and the feasibility of utilizing the gs9 allele to improve grain appearance quality in high-yielding EP cultivars. This study provides an effective strategy for rice breeders to improve rice grain appearance in EP japonica and related cultivars.

Under the limited cultivated land area and the pursuit of sustainable agricultural development, it is essential for the safety of grain production to study agricultural management approaches on narrowing the winter wheat yield gap and improving nitrogen use efficiency (NUE) in China. In this study, DSSAT-CERES-Wheat Model is used to simulate winter wheat yield under different agricultural treatments, and we analyze yield gaps and NUE with different management scenarios at regional scales and evaluate the suitable approaches for reducing yield gap and increasing NUE. The results show that, the potential of narrowing yield gap ranges 300–900 kg ha^–1 with soil nutrients increase, 400–1 200 kg ha^–1 with sowing date adjustment and 0–400 kg ha^–1 with planting density increase as well as 700–2 200 kg ha^–1 with adding nitrogen fertilizer. Contribution rates of management measures of soil nutrients, sowing date adjusting, planting density, and nitrogen fertilizers are 5–15%, 5–15%, 0–4%, and 10–20%, respectively. Difference in nitrogen partial productivity ranges 3–10 kg kg^–1 for soil nutrients, 1–10 kg kg^–1 for sowing date adjusting, 1–5 kg kg^–1 for planting density increase, and –12–0 kg kg^–1 for adding nitrogen fertilizers, respectively. It indicates that four treatments can narrow yield gap and improve the NUE in varying degrees, but increasing nitrogen fertilizer leads to the decrease of NUE.

 

Nitrogen (N) is a critical element for plant growth and productivity that influences photosynthesis and chlorophyll fluorescence. We investigated the effect of low-N stress on leaf photosynthesis and chlorophyll fluorescence characteristics of maize cultivars with difference in tolerance to low N levels. The low-N tolerant cultivar ZH311 and low-N sensitive cultivar XY508 were used as the test materials. A field experiment (with three N levels: N0, 0 kg ha^–1; N1, 150 kg ha^–1; N2, 300 kg ha^–1) in Jiyanyang, Sichuan Province, China, and a hydroponic experiment (with two N levels: CK, 4 mmol L^–1; LN, 0.04 mmol L^–1) in Chengdu, Sichuan Province, China were conducted. Low-N stress significantly decreased chlorophyll content and rapid light response curves of the maximum fluorescence under light (F_m´), fluorescence instable state (F_s), non-photochemical quenching (q_N), the maximum efficiency of PSII photochemistry under dark-adaption (F_v/F_m), potential activity of PSII (F_v/F_o), and actual photochemical efficiency of PSII (ΦPSII) of leaves. Further, it increased the chlorophyll (Chl) a/Chl b values and so on. The light compensation point of ZH311 decreased, while that of XY508 increased. The degree of variation of these indices in low-N tolerant cultivars was lower than that in low-N sensitive cultivars, especially at the seedling stage. Maize could increase Chl a/Chl b, apparent quantum yield and light saturation point to adapt to N stress. Compared to low-N sensitive cultivars, low-N tolerant cultivars maintained a higher net photosynthetic rate and electron transport rate to maintain stronger PSII activity, which further promoted the ability to harvest and transfer light. This might be a photosynthetic mechanism by which low-N tolerant cultivar adapt to low-N stress.