The yellow seed trait is preferred by breeders for its potential to improve the seed quality and commercial value of Brassica napus.  In the present study, we produced yellow seed mutants using a CRISPR/Cas9 system when the two BnPAP2 homologs were knocked out.  Histochemical staining of the seed coat demonstrated that proanthocyanidin accumulation was significantly reduced in the pap2 double mutants and decreased specifically in the endothelial and palisade layer cells of the seed coat.  Transcriptomic and metabolite profiling analysis suggested that disruption of the BnPAP2 genes could reduce the expression of structural and regulated genes in the phenylpropanoid and flavonoid biosynthetic pathways.  The broad suppression of these genes might hinder proanthocyanidin accumulation during seed development, and thereby causing the yellow seed trait in B. napus.  These results indicate that BnPAP2 might play a vital role in the regulatory network controlling proanthocyanidin accumulation.

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.

Sugarcane/soybean intercropping with reduced nitrogen addition is an important sustainable agricultural pattern that can alter soil ecological functions, thereby affecting straw decomposition in the soil.  However, the mechanisms underlying changes in soil organic carbon (SOC) composition and microbial communities during straw decomposition under long-term intercropping with reduced nitrogen addition remain unclear.  In this study, we conducted an in-situ microplot incubation experiment with 13C-labeled soybean straw residue addition in a two-factor (cropping pattern: sugarcane monoculture (MS) and sugarcane/soybean intercropping (SB); nitrogen addition levels: reduced nitrogen addition (N1) and conventional nitrogen addition (N2)) long-term experimental field plot.  The results showed that the SBN1 treatment significantly increased the residual particulate organic carbon (POC) and residual microbial biomass carbon (MBC) contents during straw decomposition, and the straw carbon in soil was mainly conserved as POC.  Straw addition changed the structure and reduced the diversity of the soil microbial community, but microbial diversity gradually recovered with decomposition time.  During straw decomposition, the intercropping pattern significantly increased the relative abundances of Firmicutes and Ascomycota.  In addition, straw addition reduced microbial network complexity in the sugarcane/soybean intercropping pattern but increased it in the sugarcane monoculture pattern.  Nevertheless, microbial network complexity remained higher in the SBN1 treatment than in the MSN1 treatment.  In general, the SBN1 treatment significantly increased the diversity of microbial communities and the relative abundance of microorganisms associated with organic matter decomposition, and the changes in microbial communities were mainly driven by the residual labile SOC fractions.  These findings suggest that more straw carbon can be sequestered in the soil under sugarcane/soybean intercropping with reduced nitrogen addition to maintain microbial diversity and contribute to the development of sustainable agriculture.

The biological chemistry would be responsible for the meat quality. This study tried to investigate the transcript expression profile and explain the characteristics of differentially expressed genes between the Wujin and Landrace pigs. The results showed that 526 differentially expressed genes were found by comparing the transcript expression profile of muscle tissue between Wujin and Landrace pigs. Among them, 335 genes showed up-regulations and 191 genes showed down-regulations in Wujin pigs compared with the Landrace pigs. Gene ontology (GO) analysis indicated that the differentially expressed genes were clustered into three groups involving in protein synthesis, energy metabolism and immune response. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis found that these differentially expressed genes participated in protein synthesis metabolism, energy metabolism and immune response pathway. The Database for Annotation, Visualization and Integrated Discovery (DAVID) analysis of protein function and protein domains function also confirmed that differentially expressed genes belonged to protein synthesis, energy metabolism and immune response. Genes related protein synthesis metabolism pathway in Landrace was higher than in Wujin pigs. However, differentially expressed genes related energy metabolism and immune response was up-regulated in Wujin pigs compared with Landrace pigs. Quantitative real-time RT-PCR on selected genes was used to confirm the results from the microarray. These suggested that the genes related to protein synthesis, energy metabolism and immune response would contribute to the growth performance, meat quality as well as anti-disease capacity.

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.

To ensure the reliability of learned information, most insects require multiple intervals of experience before storing the information as Long-term memory (LTM), and this requirement has been validated in insects from the behavioral to the molecular level. Recent studies have shown that some insects can form LTM after a single experience, although the mechanisms underlying one-trial LTM formation are not well understood. Therefore, understanding the mechanisms underlying rapid learning and subsequent preference formation in insects is crucial. Here we show that the agricultural pest Bactrocera dorsalis can rapidly form LTM, which is dependent on protein synthesis, and that the formation of LTM requires high energy support at the cost of reduced survival. Furthermore, based on a liquid chromatography-mass spectrometry (LC-MS) metabolomics approach, we found that LTM-related processes are sequentially coupled to two processes for energy generation, the TCA cycle and oxidative phosphorylation. This was further confirmed by blocking these energy generation processes. Our results provide a theoretical basis for the development of behavioral modulators in oriental fruit flies that target energy generation intermediate metabolites, as well as a new perspective on the rapid formation of LTM in insects.

Apple fruit firmness is a crucial index for measuring the internal quality of apples, influencing palatability and determining storage and transportation capacity. The primary cause of decreased firmness during fruit development is the hydrolysis of cell wall polysaccharides. Xyloglucan endotransglycosylase/hydrolase (XTH) is a key enzyme involved in the depolymerization of cell wall polysaccharides, but its mechanism in the formation of fruit firmness remains unclear. Here, we identified the gene MdXTH2 by integrating metabolomic and transcriptomic data, and further analyzed its function and molecular mechanism in the formation of apple fruit firmness. The results showed a downward trend in both fruit firmness and cell wall components throughout fruit development. The contents of cell wall material, cellulose, and hemicellulose in various apple varieties exhibited significant positive correlations with firmness, with total correlation coefficients of 0.862, 0.884, and 0.891, respectively. Overexpression of MdXTH2 significantly increased fruit firmness in apple and tomato, inhibited fruit ripening, and significantly suppressed calli growth. The upstream transcription factor MdNAC72 of the MdXTH2 gene can promote the expression of fruit ripening-related genes. Furthermore, dual-luciferase, yeast one-hybrid, and electrophoretic mobility shift assay assays demonstrated that MdNAC72 down-regulated the transcription of MdXTH2 by binding to its promoter. In summary, these results provide a strategy for studying fruit quality regulation and a theoretical basis for breeding apple varieties with moderate firmness through genetic improvement.