Avian infectious bronchitis (IB) is a highly contagious infectious disease caused by infectious bronchitis virus (IBV), which is prevalent in many countries worldwide and causes serious harm to the poultry industry. At present, many commercial IBV vaccines have been used for the prevention and control of IB; however, IB outbreaks occur frequently. In this study, two new strains of IBV, SX/2106 and SX/2204, were isolated from two flocks which were immunized with IBV H120 vaccine in central China. Phylogenetic and recombination analysis indicated that SX/2106, which was clustered into the GI-19 lineage, may be derived from recombination events of the GI-19 and GI-7 strains and the LDT3-A vaccine. Genetic analysis showed that SX/2204 belongs to the GVI-1 lineage, which may have originated from the recombination of the GI-13 and GVI-1 strains and the H120 vaccine. The virus cross-neutralization test showed that the antigenicity of SX/2106 and SX/2204 was different from H120. Animal experiments found that both SX/2106 and SX/2204 could replicate effectively in the lungs and kidneys of chickens and cause disease and death, and H120 immunization could not provide effective protection against the two IBV isolates. It is noteworthy that the pathogenicity of SX/2204 has significantly increased compared to the GVI-1 strains isolated previously, with a mortality rate up to 60%. Considering the continuous mutation and recombination of the IBV genome to produce new variant strains, it is important to continuously monitor epidemic strains and develop new vaccines for the prevention and control of IBV epidemics.
Aphis gossypii has become increasingly difficult to manage due to its strong insecticide resistance. In the laboratory, we established sulfoxaflor-resistant and acetamiprid-resistant strains in two A. gossypii populations with different basal insecticide resistance levels, and evaluated the effects of basal insecticide resistance on the resistance development and cross-resistance, as well as differences in fitness. Under the same selection pressure, Yarkant A. gossypii (with low basal insecticide resistance) evolved resistance to sulfoxaflor and acetamiprid more quickly than Jinghe A. gossypii (with high basal insecticide resistance), and the evolution of A. gossypii resistance to sulfoxaflor developed faster than acetamiprid in both Yarkant and Jinghe, Xingjiang, China. The sulfoxaflor-resistant strains selected from Yarkant and Jinghe developed significant cross-resistance to acetamiprid, imidacloprid, thiamethoxam and pymetrozine; while the acetamiprid-resistant strains developed significant cross-resistance to sulfoxaflor, imidacloprid, thiamethoxam, pymetrozine, and chlorpyrifos. The relative fitness of A. gossypii decreased as the resistance to sulfoxaflor and acetamiprid developed. The relative fitness levels of the sulfoxaflor-resistant strains (Yarkant-SulR and Jinghe-SulR) were lower than those of the acetamiprid-resistant strains (Yarkant-AceR and Jinghe-AceR). In addition, the relative fitness levels of sulfoxaflor- and acetamiprid-resistant strains were lower in Jinghe than in Yarkant. In summary, basal insecticide resistance of A. gossypii and insecticide type affected the evolution of resistance to insecticides in A. gossypii, as well as cross-resistance to other insecticides. The sulfoxaflor- and acetamiprid-resistant A. gossypii strains had obvious fitness costs. The results of this work will contribute to the insecticide resistance management and integrated management of A. gossypii.
Application of organic manure as a potential strategy to alleviate the limitation of microbial resources in soybean rhizospheric and bulk soils
The development and vigor of soil microorganisms in terrestrial ecosystems are frequently constrained by the limited availability of essential elements such as carbon (C), nitrogen (N), and phosphorus (P). In this study, we investigated the impact of long-term application of varying levels of organic manure, low (7.5 Mg ha−1 yr−1), moderate (15.0 Mg ha−1 yr−1), and high (22.5 Mg ha−1 yr−1), on the stoichiometry of enzymes and the structures of the microbial communities in soybean rhizospheric and bulk soils. The main goal of this research was to examine how soil microbial resource limitations in the rhizosphere respond to different long-term fertilization strategies. The soil enzymatic activities were quantified, and the structure of the microbial community was assessed by analyzing phospholipid fatty acid profiles. When compared to the bulk soil, the rhizospheric soil had significant increases in microbial biomass carbon (MBC), nitrogen (MBN), and phosphorus (MBP), with MBC increasing by 54.19 to 72.86%, MBN by 47.30 to 48.17%, and MBP by 17.37 to 208.47%. Compared with the unfertilized control (CK), the total microbial biomasses of the rhizospheric (increased by 22.80 to 90.82%) and bulk soils (increased by 10.57 to 60.54%) both exhibited increases with the application of organic manure, and the rhizospheric biomass was higher than that of bulk soil. Compared with bulk soil, the activities of C-, N- and P-acquiring enzymes of rhizospheric soil increased by 22.49, 14.88, and 29.45% under high levels of organic manure, respectively. Analyses of vector length, vector angle, and scatter plots revealed that both rhizospheric and bulk soils exhibited limitations in terms of both carbon (C) and phosphorus (P) availability. The results of partial least-squares path modelling indicated that the rhizospheric soil exhibited a more pronounced response to the rate of manure application than the bulk soil. The varying reactions of rhizospheric and bulk soils to the extended application of organic manure underscore the crucial function of the rhizosphere in mitigating limitations related to microbial resources, particularly in the context of different organic manure application rates.
Straw mulching alters the composition and loss of dissolved organic matter in farmland surface runoff by inhibiting the fragmentation of soil small macroaggregates
Straw mulching is a widespread practice for reducing the soil carbon loss caused by erosion. However, the effects of straw mulching on dissolved organic matter (DOM) runoff loss from black soil are not well studied. How straw mulching affects the composition and loss of runoff DOM by changing soil aggregates remains largely unclear. Here, a straw mulching treatment was compared to a no mulching treatment (as a control) on sloping farmland with black soil erosion in Northeast China. We divided the soil into large macroaggregates (>2 mm), small macroaggregates (0.25–2 mm), and microaggregates (<0.25 mm). After five rain events, the effects of straw mulching on the concentration (characterized by dissolved organic carbon (DOC)) and composition (analyzed by fluorescence spectroscopy) of runoff and soil aggregate DOM were studied. The results showed that straw mulching reduced the runoff amount by 54.7%. Therefore, although straw mulching increased the average DOC concentration in runoff, it reduced the total runoff DOM loss by 48.3%. The composition of runoff DOM is similar to that of soil, as both contain humic-like acid and protein-like components. With straw mulching treatment, the protein-like components in small macroaggregates accumulated and the protein-like components in runoff declined with rain events. Fluorescence spectroscopy technology may help in understanding the hydrological paths of rain events by capturing the dynamic changes of runoff and soil DOM characteristics. A variation partitioning analysis (VPA) indicated that the DOM concentration and composition of microaggregates explained 68.2% of the change in runoff DOM from no mulching plots, while the change in runoff DOM from straw mulching plots was dominated by small macroaggregates at a rate of 55.1%. Taken together, our results demonstrated that straw mulching reduces the fragmentation of small macroaggregates and the loss of microaggregates, thus effecting DOM compositions in soil and reducing the DOM loss in runoff. These results provide a theoretical basis for reducing carbon loss in sloping farmland.
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.
The role of cAMP-dependent protein kinase A in the formation of long-term memory in Bactrocera dorsalis
The cAMP-dependent protein kinase A (PKA) signaling pathway has long been considered critical for long-term memory (LTM) formation. Previous studies have mostly focused on the role of PKA signaling in LTM induction by multiple spaced conditioning with less attention to LTM induction by a single conditioning. Here, we conducted behavioral-pharmacology, enzyme immunoassay and RNA interference experiments to study the role of the PKA signaling pathway in LTM formation in the agricultural pest Bactrocera dorsalis, which has a strong memory capacity allowing it to form a two-day memory even from a single conditioning trial. We found that either blocking or activating PKA prior to conditioning pretreatment affected multiple spaced LTM, and conversely, they did not affect LTM formed by single conditioning. This was further confirmed by enzyme-linked immunosorbent assay (ELISA) and silencing of the protein kinase regulatory subunit 2 and catalytic subunit 1. Taken together, these results suggest that activating PKA during memory acquisition helps to induce the LTM formed by multiple spaced conditioning but not by a single conditioning. Our findings challenge the conserved role of PKA signaling in LTM, which provides a basis for the greater diversity of molecular mechanisms underlying LTM formation across species, as well as possible functional and evolutionary implications.
Wheat is a staple cereal crop that is crucial for food security and human health. Improving wheat quality has become an essential task for breeders to meet escalating market demand. In this study, a set of wheat-Aegilops tauschii introgression lines was developed from a cross between the high-yielding wheat variety Jimai 22 and Ae. tauschii Y215. A high-density genetic map containing 2,727 single nucleotide polymorphisms (SNPs) was constructed using a 55K SNP array to conduct quantitative trait loci (QTL) analysis for grain quality-related traits. Eight QTL were identified for grain protein content (GPC), starch content, and wet gluten content in the two environments. Among them, a major and environmentally stable QTL, qGPC4D, for GPC was identified, with favorable alleles contributed by Ae. tauschii Y215. Subsequently, qGPC4D was narrowed down to a 9.88 Mb physical interval through further fine mapping utilizing the introgression lines. Additionally, three linked SNP of qGPC4D were converted into high-throughput kompetitive allele-specific PCR (KASP) markers and validated in the introgression population. These findings offer promising candidate genes, elite introgression lines, and KASP markers for wheat high-quality breeding.
Mycotoxins are the most widely present pollutants in both dietary provisions and livestock feed, and they pose a series of hazards for humans and animals. Deoxynivalenol (DON) is a prevalent mycotoxin that is primarily produced by Fusarium spp. and commonly found in various cereal products. Feeding swine diets contaminated with trichothecene DON can lead to major adverse effects, including reduced feed intake, diminished weight gains, and compromised immune function. Among all animal species tested, swine were the most sensitive to DON. Here we explored the disruption of gut health by DON, considering aspects such as intestinal histomorphology, epithelial barrier functions, the intestinal immune system, microflora, and short-chain fatty acid production in the intestines. Numerous additives have been documented for their potential in the detoxification of DON. These additives can alleviate the toxic effects of DON on pigs by modulating the Nrf2-Keap1, mitogen-activated protein kinases (MAPKs) and Nuclear factor kappa-B (NF-κB) signaling pathways. Additionally, there are additives capable of mitigating the toxicity of DON through adsorption or biotransformation. This update has novel potential for advancing our comprehension of the mechanisms linked to DON intestinal toxicity and facilitating the formulation of innovative strategies to mitigate the impact of DON.
Asian citrus psyllid (ACP) is a significant pest of citrus crops that can transmit citrus Huanglongbing (HLB) by feeding on the phloem sap of citrus plants, which poses a significant threat to citrus production. Volatile signal chemicals with plant communication functions can effectively enhance the resistance of recipient plants to herbivorous insects with minimal impacts on plant growth. While (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), (E,E)-4,8,12-trimethyl-1,3,7,11-tridecene (TMTT), (E)-β-caryophyllene, and dimethyl disulfide (DMDS), are known as signaling molecules in guava-sweet orange communication, whether these four chemical signals can enhance the resistance of Citrus sinensis to feeding by ACP adults with no apparent costs in terms of plant growth remains unclear. Therefore, this study measured the effect of non-damaging induction by DMNT, TMTT, (E)-β-caryophyllene, and DMDS on the ability of C. sinensis to resist feeding by ACP, as well as their impacts on the defensive phytochemicals, defensive enzymes, functional nutrients, Photosystem II's utilization and allocation of light energy, photosynthetic pigments, growth conditions, and leaf stomatal aperture in C. sinensis. The results indicate that non-damaging induction by these four chemicals can enhance the activity of the defensive enzyme polyphenol oxidase (PPO) and increase the contents of total phenols, tannins, and terpenoid defensive phytochemicals within C. sinensis, thereby enhancing the resistance of C. sinensis to ACP feeding. Specifically, DMNT and DMDS exhibit more significant effects in inducing resistance compared to TMTT and (E)-β-caryophyllene. The characteristics of chlorophyll fluorescence parameters and changes in photosynthetic pigments in C. sinensis during different post-exposure induction periods revealed these chemicals can maintain the stability of the photosynthetic system in C. sinensis and regulate its capacity to capture, transmit, and distribute light energy, which significantly enhances the non-photochemical quenching ability (Y(NPQ)) of C. sinensis. In addition, detailed measurements of the water content, specific leaf mass (LMA), functional nutrients (soluble protein, soluble sugar, and amino acids), and stomatal parameters in C. sinensis leaves further indicated that the non-destructive induction by these chemicals can optimize the levels of functional nutrients in C. sinensis, primarily manifesting as the upregulation of soluble sugars, proline, or soluble proteins, and reduction of stomatal area and aperture, which maintains a stable leaf water content and LMA, thereby enhancing resistance to ACP while sustaining the healthy growth of C. sinensis. These results fully substantiate that the non-damaging induction by the signal chemicals DMNT, TMTT, (E)-β-caryophyllene, and DMDS can enhance the resistance of C. sinensis to ACP feeding while maintaining the balance between pest resistance and growth. This balance prevents any catastrophic effects on the growth of C. sinensis, so these agents can potentially be integrated with other pest management strategies for the collective protection of crops. This study provides theoretical support and assistance for the development of signal chemical inducers for the prevention and management of ACP in agricultural systems.
Maize (Zea mays L.) is a crucial global crop, serving as a primary source of food and feed. However, its kernels are susceptible to infection by Aspergillus flavus, a fungus known for producing aflatoxins- highly carcinogenic compounds harmful to human and animal health. Identifying quantitative trait loci (QTLs) for aflatoxin resistance and developing aflatoxin-resistant maize varieties are essential for mitigating aflatoxin contamination. In this study, we conducted a genome-wide association study (GWAS) using an enlarged genotypic panel of 311 maize inbred lines to identify genetic loci associated with A. flavus resistance. Phenotypic data on A. flavus resistance were collected through controlled inoculation experiments conducted under controlled conditions. The results revealed that the resistance traits to A. flavus follow a normal distribution. Additionally, temperate inbreds exhibited stronger resistance to A. flavus than tropical/subtropical materials. This study identified 15 novel QTLs encompassing 47 high-expressed genes, with each QTL explaining 8.22-27.71% of the phenotypic variation, indicating that increased marker density improved statistical power. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that these genes are related to fatty acid synthesis, glycoside decomposition, and root growth and development. One specific gene, Zm00001d021197, located on ZmAFR16, displayed clustered peaks and accounted for an average of 10.21% of the phenotypic variation. This gene was found to play a role in cell membrane formation and possess alpha-L-fucosidase activity, promoting glycoside metabolism and contributing to polysaccharide degradation. Haplotype analysis showed significant differences in resistance to A. flavus among different haplotypes of the Zm00001d033637 and Zm00001d021197. Inbreds carrying the favorable haplotype combination of these two genes exhibited strong resistance to A. flavus. By select sweep analysis, it was found that Zm00001d021197 was selected during the domestication of teosinte (Zea mays ssp. mexicana) to modern maize, as well as during the adaptation from tropical/subtropical maize to temperate maize. Importantly, we developed molecular markers in the promoter region of Zm00001d021197 to efficiently identify maize germplasm with beneficial haplotypes for resistance to A. flavus. These findings not only enhance our understanding of the genetic factors influencing maize kernel resistance to A. flavus but also offer valuable insights for improving existing germplasm and developing new maize varieties with enhanced resistance to this pathogen.