Low-affinity nitrate transporter genes have been identified in subfamilies 4–8 of the rice nitrate transporter 1 (NRT1)/peptide transporter family (NPF), but the OsNPF3 subfamily responsible for nitrate and phytohormone transport and rice growth and development remains unknown.  In this study, we described OsNPF3.1 as an essential nitrate and phytohormone transporter gene for rice tillering and nitrogen utilization efficiency (NUtE).  OsNPF3.1 possesses four major haplotypes of its promoter sequence in 517 cultivars, and its expression is positively associated with tiller number.  Its expression was higher in the basal part, culm, and leaf blade than in other parts of the plant, and was strongly induced by nitrate, abscisic acid (ABA) and gibberellin 3 (GA₃) in the root and shoot of rice.  Electrophysiological experiments demonstrated that OsNPF3.1 is a pH-dependent low-affinity nitrate transporter, with rice protoplast uptake assays showing it to be an ABA and GA₃ transporter.  OsNPF3.1 overexpression significantly promoted ABA accumulation in the roots and GA accumulation in the basal part of the plant which inhibited axillary bud outgrowth and rice tillering, especially at high nitrate concentrations.  The NUtE of OsNPF3.1-overexpressing plants was enhanced under low and medium nitrate concentrations, whereas the NUtE of OsNPF3.1 clustered regularly interspaced short palindromic repeats (CRISPR) plants was increased under high nitrate concentrations.  The results indicate that OsNPF3.1 transports nitrate and phytohormones in different rice tissues under different nitrate concentrations.  The altered OsNPF3.1 expression improves NUtE in the OsNPF3.1-overexpressing and CRISPR lines at low and high nitrate concentrations, respectively.

The use of hybrid wheat is one way to improve the yield in the future.  However, greater plant heights increase lodging risk to some extent.  In this study, two hybrid combinations with differences in lodging resistance were used to analyze the stem-related traits during the filling stage, and to investigate the mechanism of the difference in lodging resistance by analyzing lignin synthesis of the basal second internode (BSI).  The stem-related traits such as the breaking strength, stem pole substantial degree (SPSD), and rind penetration strength (RPS), as well as the lignin content of the lodging-resistant combination (LRC), were significantly higher than those of the lodging-sensitive combination (LSC).  The phenylpropanoid biosynthesis pathway was significantly and simultaneously enriched according to the transcriptomics and metabolomics analysis at the later filling stage.  A total of 35 critical regulatory genes involved in the phenylpropanoid pathway were identified.  Moreover, 42% of the identified genes were significantly and differentially expressed at the later grain-filling stage between the two combinations, among which more than 80% were strongly up-regulated at that stage in the LRC compared with LSC.  On the contrary, the LRC displayed lower contents of lignin intermediate metabolites than the LSC.  These results suggested that the key to the lodging resistance formation of LRC is largely the higher lignin synthesis at the later grain-filling stage.  Finally, breeding strategies for synergistically improving plant height and lodging resistance of hybrid wheat were put forward by comparing the LRC with the conventional wheat applied in large areas.

The seed storage materials accumulate during seed development, and are essential for seed germination and seedling establishment.  Here we employed two bi-parental populations of an F_2:3 population developed from a cross of improved 220 (I220, small seeds with low starch) and PH4CV (large seeds with high starch), as well as recombinant-inbred lines (RILs) of X178 (high starch) and its improved introgression line I178 (low starch), to identify the genes that control seed storage materials.  We identified a total of 12 QTLs for starch, protein and oil, which explained 3.44–10.79% of the phenotypic variances.  Among them, qSTA2-1 identified in F_2:3 and qSTA2-2 identified in the RILs partially overlapped at an interval of 7.314–9.554 Mb, and they explained 3.44–10.21% of the starch content variation, so they were selected for further study.  Fine mapping of qSTA2-2 with the backcrossed populations of I220/PH4CV in each generation narrowed it down to a 199.7 kb interval that contains 14 open reading frames (ORFs).  Transcriptomic analysis of developing seeds from the near-isogenic lines (NILs) of I220/PH4CV (BC₅F₂) showed that only 11 ORFs were expressed in 20 days after pollination (DAP) seeds.  Five of them were upregulated and six of them were downregulated in NIL^I220, and the differentially expressed genes (DEGs) between NIL^I220 and NIL^PH4CV were enriched in starch metabolism, hormone signal transduction and glycosaminoglycan degradation.  Of the eleven NIL^I220 differential expressed ORFs, ORF4 (Zm00001d002260) and ORF5 (Zm00001d002261) carry 75% protein sequence similarity, both encodes an glycolate oxidase, were the possible candidates of qSTA2-2.  Further analysis and validation indicated that mutation of the qSTA2-2 locus resulted in the dysfunction of ABA accumulation, the embryo/endosperm ratio and the starch and hormone levels.

Phosphorus (P) is essential for living plants, and P deficiency is one of the key factors limiting the yield in rapeseed production worldwide.  As the most important organ for plants, root morphology traits (RMTs) play a key role in P absorption.  To investigate the genetic variability of RMT under low P availability, we dissected the genetic structure of RMTs by genome-wide association studies (GWAS), linkage mapping and candidate gene association studies (CGAS).  A total of 52 suggestive loci were associated with RMTs under P stress conditions in 405 oilseed rape accessions.  The purple acid phosphatase gene BnPAP17 was found to control the lateral root number (LRN) and root dry weight (RDW) under low P stress.  The expression of BnPAP17 was increased in shoot tissue in P-efficient cultivars compared to root tissue and P-inefficient cultivars in response to low P stress.  Moreover, the haplotype of BnPAP17^Hap3 was detected for the selective breeding of P efficiency in oilseed rape.  Over-expression of the BnPAP17^Hap3 could promote the shoot and root growth with enhanced tolerance to low P stress and organic phosphorus (Po) utilization in oilseed rape.  Collectively, these findings increase our understanding of the mechanisms underlying BnPAP17-mediated low P stress tolerance in oilseed rape.

Biaxial rotary tillage in dryland (DBRT) can complete biaxial rotary tillage with straw incorporation, secondary suppression, and ditching, and it has been previously studied in direct-seeded rice and wheat.  However, the effects of DBRT on the mechanically transplanted rice yield and greenhouse gas emissions remain unclear.  To evaluate the effects of DBRT on improving the food security of mechanically transplanted rice and reducing the greenhouse gas emissions, we conducted an experiment for two years with wheat straw incorporation.  Three tillage methods were set up: DBRT, uniaxial rotary tillage in dryland and paddy (DPURT), and uniaxial rotary tillage in paddy (PURT).  The results showed that compared with DPURT and PURT, DBRT increased the yield of machine-transplanted rice by 7.5–11.0% and 13.3–26.7%, respectively, while the seasonal cumulative CH₄ emissions were reduced by 13.9–21.2% and 30.2–37.0%, respectively, and the seasonal cumulative N₂O emissions were increased by 13.5–28.6% and 50.0–73.1%, respectively.  Consequently, DBRT reduced the global

Ratoon rice, which refers to a second harvest of rice obtained from the regenerated tillers originating from the stubble of the first harvested crop, plays an important role in both food security and agroecology while requiring minimal agricultural inputs.  However, accurately identifying ratoon rice crops is challenging due to the similarity of its spectral features with other rice cropping systems (e.g., double rice).  Moreover, images with a high spatiotemporal resolution are essential since ratoon rice is generally cultivated in fragmented croplands within regions that frequently exhibit cloudy and rainy weather.  In this study, taking Qichun County in Hubei Province, China as an example, we developed a new phenology-based ratoon rice vegetation index (PRVI) for the purpose of ratoon rice mapping at a 30 m spatial resolution using a robust time series generated from Harmonized Landsat and Sentinel-2 (HLS) images.  The PRVI that incorporated the red, near-infrared, and shortwave infrared 1 bands was developed based on the analysis of spectro-phenological separability and feature selection.  Based on actual field samples, the performance of the PRVI for ratoon rice mapping was carefully evaluated by comparing it to several vegetation indices, including normalized difference vegetation index (NDVI), enhanced vegetation index (EVI) and land surface water index (LSWI).  The results suggested that the PRVI could sufficiently capture the specific characteristics of ratoon rice, leading to a favorable separability between ratoon rice and other land cover types.  Furthermore, the PRVI showed the best performance for identifying ratoon rice in the phenological phases characterized by grain filling and harvesting to tillering of the ratoon crop (GHS-TS2), indicating that only several images are required to obtain an accurate ratoon rice map.  Finally, the PRVI performed better than NDVI, EVI, LSWI and their combination at the GHS-TS2 stages, with producer’s accuracy and user’s accuracy of 92.22 and 89.30%, respectively.  These results demonstrate that the proposed PRVI based on HLS data can effectively identify ratoon rice in fragmented croplands at crucial phenological stages, which is promising for identifying the earliest timing of ratoon rice planting and can provide a fundamental dataset for crop management activities.

Adjusting agronomic measures to alleviate the kernel position effect in maize is important for ensuring high yields.  In order to clarify whether the combined application of organic fertilizer and chemical fertilizer (CAOFCF) can alleviate the kernel position effect of summer maize, field experiments were conducted during the 2019 and 2020 growing seasons, and five treatments were assessed: CF, 100% chemical fertilizer; OFCF1, 15% organic fertilizer+85% chemical fertilizer; OFCF2, 30% organic fertilizer+70% chemical fertilizer; OFCF3, 45% organic fertilizer+55% chemical fertilizer; and OFCF4, 60% organic fertilizer+40% chemical fertilizer.  Compared with the CF treatment, the OFCF1 and OFCF2 treatments significantly alleviated the kernel position effect by increasing the weight ratio of inferior kernels to superior kernels and reducing the weight gap between the superior and inferior kernels.  These effects were largely due to the improved filling and starch accumulation of inferior kernels.  However, there were no obvious differences in the kernel position effect among plants treated with CF, OFCF3, or OFCF4 in most cases.  Leaf area indexes, post-silking photosynthetic rates, and net assimilation rates were higher in plants treated with OFCF1 or OFCF2 than in those treated with CF, reflecting an enhanced photosynthetic capacity and improved post-silking dry matter accumulation (DMA) in the plants treated with OFCF1 or OFCF2.  Compared with the CF treatment, the OFCF1 and OFCF2 treatments increased post-silking N uptake by 66.3 and 75.5%, respectively, which was the major factor driving post-silking photosynthetic capacity and DMA.  Moreover, the increases in root DMA and zeatin riboside content observed following the OFCF1 and OFCF2 treatments resulted in reduced root senescence, which is associated with an increased post-silking N uptake.  Analyses showed that post-silking N uptake, DMA, and grain yield in summer maize were negatively correlated with the kernel position effect.  In conclusion, the combined application of 15–30% organic fertilizer and 70–85% chemical fertilizer alleviated the kernel position effect in summer maize by improving post-silking N uptake and DMA.  These results provide new insights into how CAOFCF can be used to improve maize productivity.

The application of a male-sterile line is an ideal approach for hybrid seed production in non-heading Chinese cabbage (Brassica rapa ssp. chinensis).  However, the molecular mechanisms underlying male sterility in B. rapa are still largely unclear.  We previously obtained the natural male sterile line WS24-3 of non-heading Chinese cabbage and located the male sterile locus, Bra2Ms, on the A2 chromosome.  Cytological observations revealed that the male sterility of WS24-3 resulted from disruption of the meiosis process during pollen formation.  Fine mapping of Bra2Ms delimited the locus within a physical distance of about 129 kb on the A2 chromosome of B. rapa.  The Bra039753 gene encodes a plant homeodomain (PHD)-finger protein and is considered a potential candidate gene for Bra2Ms.  Bra039753 was significantly downregulated in sterile line WS24-3 compared to the fertile line at the meiotic anther stage.  Sequence analysis of Bra039753 identified a 369 bp fragment insertion in the first exon in male sterile plants, which led to an amino acid insertion in the Bra039753 protein.  In addition, the 369 bp fragment insertion was found to cosegregate with the male sterility trait.  This study identified a novel locus related to male sterility in non-heading Chinese cabbage, and the molecular marker obtained in this study will be beneficial for the marker-assisted selection of excellent sterile lines in non-heading Chinese cabbage and other Brassica crops.

Identification of the S genotype of Malus plants will greatly promote the discovery of new genes, the cultivation and production of apple, the breeding of new varieties, and the origin and evolution of self-incompatibility in Malus plants.  In this experiment, 88 Malus germplasm resources, such as Aihuahong, Xishuhaitang, and Reguanzi, were used as materials.  Seven gene-specific primer combinations were used in the genotype identification.  PCR amplification using leaf DNA produced a single S-RNase gene fragment in all materials.  The results revealed that 70 of the identified materials obtained a complete S-RNase genotype, while only one S-RNase gene was found in 18 of them.  Through homology comparison and analysis, 13 S-RNase genotypes were obtained: S₁S₂ (Aihuahong, etc.), S₁S₂₈ (Xixian Haitang, etc.), S₁S₅₁ (Hebei Pingdinghaitang), S₁S₃ (Xiangyangcun Daguo, etc.), S₂S₃ (Zhaiyehaitang, etc.), S₃S₅₁ (Xishan 1), S₃S₂₈ (Huangselihaerde, etc.), S₂S₂₈ (Honghaitang, etc.), S₄S₂₈ (Bo 11), S₇S₂₈ (Jiuquan Shaguo), S₁₀S_e (Dongchengguan 13), S₁₀S₂₁ (Dongxiangjiao) and S_eS₅₁ (Xiongyue Haitang).  Simultaneously, the frequency of the S gene in the tested materials was analyzed.  The findings revealed that different S genes had varying frequencies in Malus resources, as well as varying frequencies between intraspecific and interspecific.  S₃ had the highest frequency of 68.18%, followed by S₁ (42.04%).  In addition, the phylogenetic tree and origin evolution analysis revealed that the S gene differentiation was completed prior to the formation of various apple species, that cultivated species also evolved new S genes, and that the S₅₀ gene is the oldest S allele in Malus plants.  The S₁, S₂₉, and S₃₃ genes in apple-cultivated species, on the other hand, may have originated in M. sieversii, M. hupehensis, and M. kansuensis, respectively.  In addition to M. sieversii, M. kansuensis and M. sikkimensis may have also played a role in the origin and evolution of some Chinese apples.

Pyrus pyrifolia Nakai ‘Whangkeumbae’ is a sand pear fruit with excellent nutritional quality and taste.  However, the industrial development of pear fruit is significantly limited by its short shelf life.  Salicylic acid (SA), a well-known phytohormone, can delay fruit senescence and improve shelf life.  However, the mechanism by which SA regulates CONSTANS-LIKE genes (COLs) during fruit senescence and the role of COL genes in mediating fruit senescence in sand pear are poorly understood.  In this study, 22 COL genes were identified in sand pear, including four COLs (PpCOL8, PpCOL9a, PpCOL9b, and PpCOL14) identified via transcriptome analysis and 18 COLs through genome-wide analysis.  These COL genes were divided into three subgroups according to the structural domains of the COL protein.  PpCOL8, with two B-box motifs and one CCT domain, belonged to the first subgroup.  In contrast, the other three PpCOLs, PpCOL9a, PpCOL9b, and PpCOL14, with similar conserved protein domains and gene structures, were assigned to the third subgroup.  The four COLs showed different expression patterns in pear tissues and were preferentially expressed at the early stage of fruit development.  Moreover, the expression of PpCOL8 was inhibited by exogenous SA treatment, while SA up-regulated the expression of PpCOL9a and PpCOL9b.  Interestingly, PpCOL8 interacts with PpMADS, a MADS-box protein preferentially expressed in fruit, and SA up-regulated its expression.  While the production of ethylene and the content of malondialdehyde (MDA) were increased in PpCOL8-overexpression sand pear fruit, the antioxidant enzyme (POD and SOD) activity and the expression of PpPOD1 and PpSOD1 in the sand pear fruits were down-regulated, which showed that PpCOL8 promoted sand pear fruit senescence.  In contrast, the corresponding changes were the opposite in PpMADS-overexpression sand pear fruits, suggesting that PpMADS delayed sand pear fruit senescence.  The co-transformation of PpCOL8 and PpMADS also delayed sand pear fruit senescence.  The results of this study revealed that PpCOL8 can play a key role in pear fruit senescence by interacting with PpMADS through the SA signaling pathway.

Fusarium head blight (FHB), mainly caused by the fungal pathogen Fusarium graminearum, is one of the most destructive wheat diseases.  Besides directly affecting the yield, the mycotoxin residing in the kernel greatly threatens the health of humans and livestock.  Xinong 979 (XN979) is a widely cultivated wheat elite with high yield and FHB resistance.  However, its resistance mechanism remains unclear.  In this study, we studied the expression of genes involved in plant defense in XN979 by comparative transcriptomics.  We found that the FHB resistance in XN979 consists of two lines of defense.  The first line of defense, which is constitutive, is knitted via the enhanced basal expression of lignin and jasmonic acid (JA) biosynthesis genes.  The second line of defense, which is induced upon F. graminearum infection, is contributed by the limited suppression of photosynthesis and the struggle of biotic stress-responding genes.  Meanwhile, the effective defense in XN979 leads to an inhibition of fungal gene expression, especially in the early infection stage.  The formation of the FHB resistance in XN979 may coincide with the breeding strategies, such as selecting high grain yield and lodging resistance traits.  This study will facilitate our understanding of wheat–F. graminearum interaction and is insightful for breeding FHB-resistant wheat.

Developing and excavating new agrochemicals with highly active and safe is an important tactic for protecting crop health and food safety.  In this paper, to discover the new bactericide candidates, we designed, prepared a new type of 1,2,3,4-tetrahydro-β-carboline (THC) derivatives and evaluated the in vitro and in vivo bioactivities against the Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas axonopodis pv. citri (Xac), and Pseudomonas syringae pv. actinidiae (Psa).  The in vitro bioassay results exhibited that most title molecules possessed good activity toward the three plant pathogenic bacteria, the compound A₁₇ showed the most active against Xoo and Xac with EC₅₀ values of 7.27 and 4.89 mg mL^–1 respectively, and compound A₈ exhibited the best inhibitory activity against Psa with EC₅₀ value of 4.87 mg mL^–1.  Pot experiments showed that compound A₁₇ exhibited excellent in vivo antibacterial activities to manage rice bacterial leaf blight and citrus bacterial canker, with protective efficiencies of 52.67 and 79.79% at 200 mg mL^–1, respectively.  Meanwhile, compound A₈ showed good control efficiency (84.31%) against kiwifruit bacterial canker at 200 mg mL^–1.  Antibacterial mechanism suggested that these compounds could interfere with the balance of the redox system, damage the cell membrane, and induce the apoptosis of Xoo cells.  Taken together, our study revealed that tetrahydro-β-carboline derivatives could be a promising candidate model for novel broad-spectrum bactericides.

The Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathway play a pivotal role in innate immunity.  Among invertebrates, Domeless receptors serve as the key upstream regulators of this pathway.  In our study on Bactrocera dorsalis, we identified three cytokine receptors: BdDomeless1, BdDomeless2, and BdDomeless3.  Each receptor encompasses five fibronectin-type-III-like (FN III) extracellular domains and a transmembrane domain.  Furthermore, these receptors exhibit the increased responsiveness to diverse pathogenic challenges.  Notably, only BdDomeless3 is upregulated during symbiont-like viral infections.  Moreover, silencing BdDomeless3 enhanced the infectivity of Bactrocera dorsalis cripavirus (BdCV) and B. dorsalis picorna-like virus (BdPLV), underscoring BdDomeless3’s crucial role in antiviral defense of B. dorsalis.  Following the suppression of Domeless3 expression, six antimicrobial peptide genes displayed decreased expression, potentially correlating with the rise in viral infectivity.  To our knowledge, this is the first study identifying cytokine receptors associated with the JAK/STAT pathway in tephritid flies, shedding light on the immune mechanisms of B. dorsalis.

Wings are an important flight organ of insects.  Wing development is a complex process controlled by a series of genes.  The flightless wing pad transforms into a mature wing with the function of migratory flight during the nymph-to-adult metamorphosis.  However, the mechanism of wing morphogenesis in locusts is still unclear.  This study analyzed the microstructures of the locust wing pads at pre-eclosion and the wings after eclosion and performed the comparative transcriptome analysis.  RNA-seq identified 25,334 unigenes  and 3,430 differentially expressed genes (DEGs) (1,907 up-regulated and 1,523 down-regulated).  The DEGs mainly included cuticle development (LmACPs), chitin metabolism (LmIdgf4), lipid metabolism-related genes, cell adhesion (Integrin), zinc finger transcription factors (LmSalm, LmZF593 and LmZF521), and others.  Functional analysis based on RNA interference and hematoxylin and eosin (H&E) staining showed that the three genes encoded zinc finger transcription factors are essential for forming wing cuticle and maintaining morphology in Locusta migratoria.  Finally, the study found that the LmSalm regulates the expression of LmACPs in the wing pads at pre-eclosion, and LmZF593 and LmZF521 regulate the expression of LmIntegrin/LmIdgf4/LmHMT420 in the wings after eclosion.  This study revealed that the molecular regulatory axis controls wing morphology in nymphal and adult stages of locusts, offering a theoretical basis for the study of wing development mechanisms in hemimetabolous insects.

The invasive fall armyworm Spodoptera frugiperda (J. E. Smith) invaded Asia in 2018, colonizing the tropical and southern subtropical regions as well as migrating with the monsoons into Northeast Asia during spring and summer.  This has resulted in widespread infestations, with significant impacts on maize production in various Asian countries.  Previous studies have shown that the invasion of this pest can alter the species relationships of maize pests, but the actual impact on maize pest management is still unclear.  This study investigated the changes in maize pest occurrence and pesticide use in the annual breeding areas of S. frugiperda in Yunnan Province and the Guangxi Zhuang Autonomous Region of China during 2017–2021, based on surveys and interviews with small farmers in maize production.  The results showed that S. frugiperda has emerged as the dominant species among maize pests after invasion and colonization, replacing traditional pests such as Ostrinia furnacalis, Spodoptera litura, Agrotis ypsilon, and Rhopalosiphum maidis.  The variety of pesticides used for maize pest control has changed from chlorpyrifos, lambda-cyhalothrin, and acetamiprid to emamectin benzoate-based pesticides with high effectiveness against S. frugiperda.  Furthermore, the frequency of maize pest chemical applications has increased from an average of 5.88 to 7.21 times per season, with the amounts of pesticides used in summer and autumn maize being significantly higher than in winter and spring maize, thereby increasing application costs by more than 35%.  The results of this study clarified the impact of S. frugiperda invasion on maize pest community succession and chemical pesticide use in tropical and south subtropical China, thereby providing a baseline for modifying the regional control strategies for maize pests after the invasion of this relatively new pest.

Ovarian follicle development is associated with the physiological functions of granulosa cells (GCs), including proliferation and apoptosis.  The level of miR-24-3p in ovarian tissue of high-yielding Yorkshire×Landrace sows was significantly higher than that of low-yielding sows.  However, the functions of miR-24-3p on GCs are unclear.  In this study, using flow cytometry, 5-ethynyl-2´-de-oxyuridine (EdU) staining, and cell count, we showed that miR-24-3p promoted the proliferation of GCs increasing the proportion of cells in the S phase and upregulating the expression of cell cycle genes, moreover, miR-24-3p inhibited GC apoptosis.  Mechanistically, on-line prediction, bioinformatics analysis, a luciferase reporter assay, RT-qPCR, and Western blot results showed that the target gene of miR-24-3p in proliferation and apoptosis is cyclin-dependent kinase inhibitor 1B (P27/CDKN1B).  Furthermore, the effect of miR-24-3p on GC proliferation and apoptosis was attenuated by P27 overexpression.  These findings suggest that miR-24-3p regulates the physiological functions of GCs.

This study aimed to investigate the dose-effect of iron on growth performance, antioxidant function, intestinal morphology, and mRNA expression of jejunal tight junction protein in 1- to 21-d-old yellow-feathered broilers.  A total of 720 1-d-old yellow-feathered male broilers were allocated to 9 treatments with 8 replicate cages of 10 birds per cage.  The dietary treatments were consisted of a basal diet (contained 79.6 mg Fe kg^–1) supplemented with 0, 20, 40, 60, 80, 160, 320, 640, and 1,280 mg Fe kg^–1 in the form of FeSO₄·7H₂O.  Compared with the birds in the control group, birds supplemented with 20 mg Fe kg^–1 had higher average daily gain (ADG) (P<0.0001).  Adding 640 and 1,280 mg Fe kg^–1 significantly decreased ADG (P<0.0001) and average daily feed intake (ADFI) (P<0.0001) compared with supplementation of 20 mg Fe kg^–1.  Malondialdehyde (MDA) concentration in plasma and duodenum increased linearly (P<0.0001), but MDA concentration in liver and jejunum increased linearly (P<0.05) or quadratically (P<0.05) with increased dietary Fe concentration.  The villus height (VH) in duodenum and jejunum, and the ratio of villus height to crypt depth (V/C) in duodenum decreased linearly (P˂0.05) as dietary Fe increased.  As dietary Fe increased, the jejunal relative mRNA abundance of claudin-1 decreased linearly (P=0.001), but the jejunal relative mRNA abundance of zona occludens-1 (ZO-1) and occludin decreased linearly (P˂0.05) or quadratically (P˂0.05).   Compared with the supplementation of 20 mg Fe kg^–1, the supplementation of 640 mg Fe kg^–1 or higher increased (P˂0.05) MDA concentrations in plasma, duodenum, and jejunum, decreased VH in the duodenum and jejunum, and the addition of 1,280 mg Fe kg^–1 reduced (P˂0.05) the jejunal tight junction protein (claudin-1, ZO-1, occludin) mRNA abundance.  In summary, 640 mg of supplemental Fe kg^–1 or greater was associated with decreased growth performance, increased oxidative stress, disrupted intestinal morphology, and reduced mRNA expression of jejunal tight junction protein.

Streptococcus suis serotype 2 (S. suis 2) is a zoonotic pathogen that clinically causes severe swine and human infections (such as meningitis, endocarditis, and septicemia).  In order to cause widespread diseases in different organs, S. suis 2 must colonize the host, break the blood barrier, and cause exaggerated inflammation.  In the last few years, most studies have focused on a single virulence factor and its influences on the host.  Membrane vesicles (MVs) can be actively secreted into the extracellular environment contributing to bacteria-host interactions.  Gram-negative bacteria-derived outer membrane vesicles (OMVs) were recently shown to activate host Caspase-11-mediated non-canonical inflammasome pathway via deliverance of OMV-bound lipopolysaccharide (LPS), causing host cell pyroptosis.  However, little is known about the effect of the MVs from S. suis 2 (Gram-positive bacteria without LPS) on cell pyroptosis.  Thus, we investigated the molecular mechanism by which S. suis 2 MVs participate in endothelial cell pyroptosis.  In this study, we used proteomics, electron scanning microscopy, fluorescence microscope, Western blotting, and bioassays, to investigate the MVs secreted by S. suis 2.  First, we demonstrated that S. suis 2 secreted MVs with an average diameter of 72.04 nm, and 200 proteins in MVs were identified.  Then, we showed that MVs were transported to cells via mainly dynamin-dependent endocytosis.  The S. suis 2 MVs activated NLRP3/Caspase-1/GSDMD canonical inflammasome signaling pathway, resulting in cell pyroptosis, but it did not activate the Caspase-4/-5 pathway.  More importantly, endothelial cells produce large amounts of reactive oxygen species (ROS) and lost their mitochondrial membrane potential under induction by S. suis 2 MVs.  The results in this study suggest for the first time that MVs from S. suis 2 were internalized by endothelial cells via mainly dynamin-dependent endocytosis and might promote NLRP3/Caspase-1/GSDMD pathway by mitochondrial damage, which produced mtDNA and ROS  under induction, leading to the pyroptosis of endothelial cells.

Pseudorabies (PR) is an acute infectious disease of pigs caused by the PR virus (PRV) and results in great economic losses to the pig industry worldwide.  PRV glycoprotein E (gE)-based enzyme-linked immunosorbent assay (ELISA) has been used to distinguish gE-deleted vaccine-immunized pigs from wild-type virus-infected pigs to eradicate PR in some countries.  Nanobody has the advantages of small size and easy genetic engineering and has been a promising diagnostic reagent.  However, there were few reports about developing nanobody-based ELISA for detecting anti-PRV-gE antibodies.  In the present study, the recombinant PRV-gE was expressed with a bacterial system and used to immunize the Bactrian camel.  Then, two nanobodies against PRV-gE were screened from the immunized camel by phage display technique.  Subsequently, two nanobody-HRP fusion proteins were expressed with HEK293T cells.  The PRV-gE-Nb36-HRP fusion protein was selected as the probe for developing the blocking ELISA (bELISA) to detect anti-PRV-gE antibodies.  Through optimizing the conditions of bELISA, the amount of coated antigen was 200 ng per well, and dilutions of the fusion protein and tested pig sera were separately 1:320 and 1:5.  The cut-off value of bELISA was 24.20%, and the sensitivity and specificity were 96.43 and 92.63%, respectively.  By detecting 233 clinical pig sera with the developed bELISA and a commercial kit, the results showed that the coincidence rate of two assays was 93.99%.  Additionallly, epitope mapping showed that PRV-gE-Nb36 recognized a conserved conformational epitope in different reference PRV strains.  Simple, great stability and low-cost nanobody-based bELISA for detecting anti-PRV-gE antibodies were developed.  The bELISA could be used for monitoring and eradicating PR.

Achieving high maize yields and efficient phosphorus (P) use with limited environmental impacts is one of the greatest challenges in sustainable maize production.  Increasing plant density is considered an effective approach for achieving high maize yields.  However, the low mobility of P in soils and the scarcity of natural P resources have hindered the development of methods that can simultaneously optimize P use and mitigate the P-related environmental footprint at high plant densities.  In this study, meta-analysis and substance flow analysis were conducted to evaluate the effects of different types of mineral P fertilizer on maize yield at varying plant densities and assess the flow of P from rock phosphate mining to P fertilizer use for maize production in China.  A significantly higher yield was obtained at higher plant densities than at lower plant densities.  The application of single super-phosphate, triple super-phosphate, and calcium magnesium phosphate at high plant densities resulted in higher yields and a smaller environmental footprint than the application of diammonium phosphate and monoammonium phosphate.  Our scenario analyses suggest that combining the optimal P type and application rate with a high plant density could increase maize yield by 22%.  Further, the P resource use efficiency throughout the P supply chain increased by 39%, whereas the P-related environmental footprint decreased by 33%.  Thus, simultaneously optimizing the P type and application rate at high plant densities achieved multiple objectives during maize production, indicating that combining P management with cropping techniques is a practical approach to sustainable maize production.  These findings offer strategic, synergistic options for achieving sustainable agricultural development.

The accurate simulation of regional-scale winter wheat yield is important for national food security and the balance of grain supply and demand in China.  Presently, most remote sensing process models use the “biomass×harvest index (HI)” method to simulate regional-scale winter wheat yield.  However, spatiotemporal differences in HI contribute to inaccuracies in yield simulation at the regional scale.  Time-series dry matter partition coefficients (Fr) can dynamically reflect the dry matter partition of winter wheat.  In this study, Fr equations were fitted for each organ of winter wheat using site-scale data.  These equations were then coupled into a process-based and remote sensing-driven crop yield model for wheat (PRYM-Wheat) to improve the regional simulation of winter wheat yield over the North China Plain (NCP).  The improved PRYM-Wheat model integrated with the fitted Fr equations (PRYM-Wheat-Fr) was validated using data obtained from provincial yearbooks.  A 3-year (2000–2002) averaged validation showed that PRYM-Wheat-Fr had a higher coefficient of determination (R²=0.55) and lower root mean square error (RMSE=0.94 t ha^–1) than PRYM-Wheat with a stable HI (abbreviated as PRYM-Wheat-HI), which had R² and RMSE values of 0.30 and 1.62 t ha^–1, respectively.  The PRYM-Wheat-Fr model also performed better than PRYM-Wheat-HI for simulating yield in verification years (2013–2015).  In conclusion, the PRYM-Wheat-Fr model exhibited a better accuracy than the original PRYM-Wheat model, making it a useful tool for the simulation of regional winter wheat yield.

Rapid and accurate acquisition of soil organic matter (SOM) information in cultivated land is important for sustainable agricultural development and carbon balance management.  This study proposed a novel approach to predict SOM with high accuracy using multiyear synthetic remote sensing variables on a monthly scale.  We obtained 12 monthly synthetic Sentinel-2 images covering the study area from 2016 to 2021 through the Google Earth Engine (GEE) platform, and reflectance bands and vegetation indices were extracted from these composite images.  Then the random forest (RF), support vector machine (SVM) and gradient boosting regression tree (GBRT) models were tested to investigate the difference in SOM prediction accuracy under different combinations of monthly synthetic variables.  Results showed that firstly, all monthly synthetic spectral bands of Sentinel-2 showed a significant correlation with SOM (P<0.05) for the months of January, March, April, October, and November.  Secondly, in terms of single-monthly composite variables, the prediction accuracy was relatively poor, with the highest R² value of 0.36 being observed in January.  When monthly synthetic environmental variables were grouped in accordance with the four quarters of the year, the first quarter and the fourth quarter showed good performance, and any combination of three quarters was similar in estimation accuracy.  The overall best performance was observed when all monthly synthetic variables were incorporated into the models.  Thirdly, among the three models compared, the RF model was consistently more accurate than the SVM and GBRT models, achieving an R² value of 0.56.  Except for band 12 in December, the importance of the remaining bands did not exhibit significant differences.  This research offers a new attempt to map SOM with high accuracy and fine spatial resolution based on monthly synthetic Sentinel-2 images.

Rapidly expanding studies investigate the effects of e-commerce on company operations in the retail market.  However, the interaction between agri-food e-commerce (AEC) and the traditional agri-food wholesale industry (AWI) has not received enough attention in the existing literature.  Based on the provincial panel data from 2013 to 2020 in China, this paper examines the effect of AEC on AWI, comprising three dimensions: digitalization (DIGITAL), agri-food e-commerce infrastructure and supporting services (AECI), and agri-food e-commerce economy (AECE).  First, AWI and AEC are measured using an entropy-based combination of indicators.  The results indicate that for China as a whole, AWI has remained practically unchanged, whereas AEC exhibits a significant rising trend.  Second, the findings of the fixed-effect regression reveal that DIGITAL and AECE tend to raise AWI, whereas AECI negatively affects AWI.  Third, threshold regression results indicate that AECI tends to diminish AWI with three-stage inhibitory intensity, which manifests as a first increase and then a drop in the inhibition degree.  These results suggest that with the introduction of e-commerce for agricultural product circulation, digital development will have catfish effects that tend to stimulate the vitality of the conventional wholesale industry and promote technical progress.  Furthermore, the traditional wholesale industry benefits financially from e-commerce even while it diverts part of the traditional wholesale circulation for agricultural products.

This paper examines the impacts of information about COVID-19 on pig farmers’ production willingness by using endorsement experiments and follow-up surveys conducted in 2020 and 2021 in China.  Our results show that, first, farmers were less willing to scale up production when they received information about COVID-19.  The information in 2020 that the second wave of COVID-19 might occur without a vaccine reduced farmers’ willingness to scale up by 13.4%, while the information in 2021 that COVID-19 might continue to spread despite the introduction of vaccine reduced farmers’ willingness by 4.4%.  Second, farmers whose production was affected by COVID-19 were considerably less willing to scale up, given the access to COVID-19 information.  Third, farmers’ production willingness can predict their actual production behavior.