The aim of this study was to investigate the effects of dietary fat on energy and nitrogen (N) metabolism efficiency, rumen fermentation, and microbiota in twin suckling lambs. Thirty pairs of twin male lambs were randomly divided into two groups with one group receiving a high-fat diet (HF) and the other a normal-fat diet (NF). Two diets (milk replacer and starter) of equal protein and different fat levels. The metabolism test was conducted when the lambs were 50–60 days old, and nine pairs of twin lambs were randomly selected for slaughter to collect rumen fluid at 60 days old. The result showed that fat addition increased the final body weight (BW), ruminal ammonia nitrogen (NH3-N) content, proportion of propionic acid, and estimated methane production (CH4e) (P<0.05). The high fat diet tended to improve digestive energy (DE), metabolism energy (ME), DE/ME, utilisation of N (0.05<P<0.1). However, microbial crude protein (MCP) content, total volatile fatty acids (VFA), acetic acid ratio, and the ratio of acetate to propionate (A:P) were lower than that in the NF group (P<0.05). Regardless of whether fat is added or not, no different were observed in blood metabolites between the treatment. High-throughput sequencing revealed that fat addition before weaning increased phyla Proteobacteria and genera of Succinivibrio, but decreased the relative abundance of Clostridium IV, Dialister, Roseburia, Acidaminococcus, and Megasphaera genera. These findings indicated that high fat diet improved body weight, energy and nitrogen utilization may by shifting the rumen toward propionate fermentation via the enrichment of Succinivibrio.
Genome wide association analysis identifies candidate genes for fruit quality and yield in Actinidia eriantha
Quality and yield are the primary concerns in kiwifruit breeding, but research on the genetic mechanisms of fruit size, shape, and ascorbic acid (ASA) content is currently very limited, which restricts the development of kiwifruit molecular breeding. In this study, we obtained a total of 8.88 million highly reliable single nucleotide polymorphism (SNP) markers from 140 individuals from the natural hybrid offspring of Actinidia eriantha cv. ‘White’ using whole genome resequencing technology. A genome-wide association study was conducted on eight key agronomic traits, including single fruit weight, fruit shape, ASA content, and the number of inflorescences per branch. A total of 59 genetic loci containing potential functional genes were located, and candidate genes related to single fruit weight, fruit length, ASA content, number of inflorescences per branch and other traits were identified within the candidate interval, such as AeWUSCHEL, AeCDK1 (cell cycle dependent kinase), AeAO1 (ascorbic oxidase) and AeCO1 (CONSTANS-like 4). After constructing an RNAi vector for AeAO1 and injecting it into the fruit of cv. ‘Midao 31’ to interfere with the expression of the AeAO1 gene, the results showed that the activity of ascorbic oxidase in the fruit of ‘Midao 31’ significantly decreased, while the content of ASA significantly increased. This study provides valuable insights into the genetic basis of variation in A. eriantha fruit traits, which may benefit molecular marker-assisted breeding efforts.
Strigolactones modulate cotton fiber elongation and secondary cell wall thickening
Cotton is one of the most important economic crops in the world, and it is a major source of fiber in the textile industry. Strigolactones (SLs) are a class of carotenoid-derived plant hormones involved in many processes of plant growth and development, although the functions of SL in fiber development remain largely unknown. Here, we found that the endogenous SLs were significantly higher in fibers at 20 days post-anthesis (DPA). Exogenous SLs significantly increased fiber length and cell wall thickness. Furthermore, we cloned three key SL biosynthetic genes, namely GhD27, GhMAX3, and GhMAX4, which were highly expressed in fibers, and subcellular localization analyses revealed that GhD27, GhMAX3, and GhMAX4 were localized in the chloroplast. The exogenous expression of GhD27, GhMAX3, and GhMAX4 complemented the physiological phenotypes of d27, max3, and max4 mutations in Arabidopsis, respectively. Knockdown of GhD27, GhMAX3, and GhMAX4 in cotton resulted in increased numbers of axillary buds and leaves, reduced fiber length, and significantly reduced fiber thickness. These findings revealed that SLs participate in plant growth, fiber elongation, and secondary cell wall formation in cotton. These results provide new and effective genetic resources for improving cotton fiber yield and plant architecture.
Rice false smut, caused by Ustilaginoidea virens, is a devastating disease that greatly reduces rice yield and quality. However, controlling rice false smut disease is challenging due to the unique infection mode of U. virens. Therefore, there is a need for early diagnosis and monitoring techniques to prevent the spread of this disease. Lateral flow strip-based recombinase polymerase amplification (LF-RPA) overcomes the limitations of current U. virens detection technologies, which are time-consuming, require delicate equipment, and have a high false-positive rate. In this study, we used a comparative genomics approach to identify Uv_3611, a specific gene of U. virens, as the target for the LF-RPA assay. The designed primers and probe efffectively detected the genomic DNA (gDNA) of U. virens and demonstrated no cross-reactivity with related pathogens. Under optimal conditions, the LF-RPA assay demonstrated a sensitivity of 10 pg of U. virens gDNA. Additionally, by incorporating a simplified PEG-NaOH method for plant DNA extraction, the LF-RPA assay enabled the detection of U. virens in rice spikelets within 30 min, without the need for specialized equipment. Furthermore, the LF-RPA assay successfully detected U. virens in naturally infected rice and seed samples in the field. Therefore, the LF-RPA assay is sensitive, efficient, and convenient, and could be developed as a kit for monitoring rice false smut disease in the field.
The lodging issue is a significant factor that hinders the enhancement of oil flax production efficiency in northern China. Crop lodging or not, and lignin content in the stems are closely related, and how nitrogen fertilizer and potassium fertilization interaction regulate lignin biosynthesis in the stems of oil flax requires further in-depth study. Therefore, the research aims to enhance the lodging resistance and facilitate an increased yield of oil flax. We are examined the interaction of different nitrogen fertilizers (75, 150, and 225 kg N ha-1) and potassium fertilizers (60 and 90 kg K2O ha-1) on oil flax lignin metabolism, lodging resistance, and grain yield in 2022 and 2023 growing seasons. The results indicated that nitrogen and potassium fertilizer levels and their interaction treatments are facilitated lignin accumulation, achievement of lodging resistance and high yield. Compared to CK, the 75-150 kg N ha-1 in combination with 60 kg K2O ha-1 treatments significantly enhanced the enzyme activities (TAL, PAL, POD, and CAD) and the gene expressions (4CL1 and F5H3) for lignin syntheses, lignin content dramatically increased 29.63-43.30%, improved stem bending strength and lodging resistance index, and grain yield increased 23.27-32.34%. Correlation analysis indicated that nitrogen and potassium fertilizer positively regulated the relative enzyme activities and genes expression for lignin to facilitated lignin biosynthesis and accumulation, and enhanced stem bending strength and lodging resistance index. Positive correlations were found among the relative enzyme activities and gene expressions for lignin, lodging resistance and grain yield. To summarize, 75-150 kg N ha-1 in conjunction with 60 kg K2O ha-1 treatment was promoted to lignin biosynthesis and accumulation, enhanced the lodging resistance and grain yield of oil flax in the dryland farming region of central Gansu. Furthermore, it served as a technical guide for cultivating stress tolerance and high-yield oil flax in the dryland farming region.
The role of β-hydroxybutyric acid (BHBA) includes providing energy, regulating signaling pathways, and ameliorating the gut microbiota in the host, while its nutrient mechanism to improve rumen epithelium development in young ruminants is still unclear. In this study, a total of 12 female Haimen goats with 30 days of age were chosen and divided into two groups. One group was fed with basic diet (CON), and the other group was fed a basal diet supplemented with 6 g d-1 dietary β-hydroxybutyrate sodium (BHBA-Na). The experimental period was 30 days, and all goats were slaughtered at 60 days of age. The joint analysis of multi-omics, including rumen microbiota, rumen epithelial transcriptome and rumen epithelial metabolomics in young goat model, was performed to systematically investigate the effect of dietary BHBA-Na on rumen development in young goats. As the results, we found that dietary BHBA-Na improved the growth performance of young goat including body weight, average daily gain (ADG) and dry matter intake (DMI) (P<0.05). Dietary BHBA-Na also increased the weight of rumen, and promoted the growth of rumen epithelium development (P < 0.05). The abundance of several beneficial bacteria was increased (Fibrobacter, Succinivibrio, Clostridiales, etc.,). The rumen epithelium transcriptome and metabolomics indicated that BHBA-Na supplementation showed a remarkable effect on the nutrient metabolism of the rumen epithelium. Specifically, the pathways of “fatty acid metabolism”, “cholesterol homeostasis”, “reactive oxygen species (ROS) pathway” and “peroxisome” were activated in response to BHBA-Na addition (P < 0.05). Moreover, the genes (HMGCS2, ECSH1, ACAA2, ECH1, ACADS etc.) and metabolites (succinic acid, alpha-ketoisovaleric acid, etc.) involved in these pathways were also regulated positively (P < 0.05). The rumen epithelium obtained the energy for its development from the process of volatile fatty acids (VFAs) decomposition. Finally, we observed the close correlations among the phenotypes, ruminal microbiota, host genes and epithelial metabolites. Overall, our results revealed that the BHBA-Na promoted the growth and rumen development of young goats possibly by enhancing DMI and regulating the rumen microbiota and the metabolisms of VFA and amino acid in the rumen epithelium.
Hydraulic theory predicts a positive coupling between leaf hydraulic conductance (Kleaf) and stomatal conductance (gs); however, this theory has not been fully supported by observations, and the underlying mechanisms remain unclear. Currently, subdividing Kleaf into leaf hydraulic conductance inside xylem (Kx) and outside xylem (Kox) offers a new perspective for elucidating the regulatory mechanism of Kleaf on gs. Optimal planting density can enhance water use efficiency (WUE) by optimizing gs; however, the changes in leaf hydraulic properties during this process and its regulation of gs and WUE remain unclear. We examined the relationships between Kx and Kox with gs, photosynthetic rate (AN), and WUE, and investigated the structural basis determining Kox in cotton under eight planting densities of 12, 18, 24, 36, 48, 60, 72, and 84 plant m-². The results showed that as the increase of planting density, Kleaf and AN remained consistent while Kox and gs decreased significantly. Kox was significantly influenced by leaf thickness and the volume fraction of inter-cellular air space. Kleaf and Kx showed no correlation with AN or gs, but Kox exhibited a significant positive correlation with gs. Furthermore, Kox is significantly negatively correlated with WUE. These findings suggest that Kox modulates gs to reduce water loss while maintaining AN, thereby enhancing WUE in cotton under various planting densities.
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.
Plastic film mulching (PFM) increases crop yields in semi-arid regions by reducing water losses and increasing soil temperature, while crop production in these areas also serves as a significant source of ammonia (NH3) emissions. The effects of PFM on NH3 emissions are nearly unknow because of interactions between larger N mineralization at higher temperature and film cover preventing NH3 diffusion. Therefore, our objectives were to (1) evaluate the effects of PFM on NH3 emissions under field conditions, and (2) identify the maize yield and NH3 emissions under climate change and atmospheric N deposition using the DeNitrification-DeComposition (DNDC) model. The experimental treatments included four treatments: (1) no plastic film mulching without N fertilization (control), (2) plastic film mulching without N fertilization (PFM), (3) N fertilization without plastic film mulching (N), and (4) plastic film mulching with N fertilization (PFM+N). The PFM increased maize yields by 211% and yield stability across the years when combined with N fertilization. PFM reduced NH3 emissions by 35% through three mechanisms: i) high water content under PFM saturates soil pores, hindering NH3 gas movement to atmosphere, ii) the hot and wet conditions under PFM accelerates nitrification rate, thus increasing pH buffering capacity during urea hydrolysis, and iii) the physical barrier created by PFM reduced NH3 exchange between soil and air. Daily NH3 emissions increased with soil temperature, NH4+ content, and pH, but declined with soil moisture under N fertilization. The NH3 emissions under PFM+N increased with NH4+ content. The parameterised DNDC model simulated very well the yield and daily NH3 emissions. PFM+N increased yield and reduced NH3 emissions under the shared socioeconomic pathway (SSP) scenario and the N deposition. Yield under PFM+N increased with increasing N deposition, while NH3 emissions under N deposition increased under the high radiative forcing scenario (SSP5-8.5). Concluding, PFM increase yields and mitigate NH3 emissions, and it also has the potential to achieve similar benefits under future conditions.
Leaf rolling is an important morphological trait in wheat (Triticum aestivum L.), strongly correlating to photosynthesis, transpiration, and respiration, especially in abiotic stress conditions. Identification of quantitative trait loci (QTLs)/genes underling rolling leaf is essential for wheat breeding. In this study, one EMS-induced mutant Y536 was isolated in Nongda3753 background with extreme abaxial rolling leaf. The F2 and F2:3 populations derived from a cross between Jing411 and mutant Y536 with contrasting leaf rolling morphology were developed to map locus controlling leaf rolling. A public SSR marker was isolated on chromosome 6DL that held a high linkage level with leaf rolling index (LRI). Quantitative trait locus (QTL) analysis revealed a stable QTL associated with LRI, named QLRI.cau-6D, which explained 7.69 to 10.86% of the total phenotypic variation and had LOD scores ranging from 10.00 to 13.32. TraesCS6D02G237000 (TaHDZIV-D1) was the priority candidate gene according to coding sequence differences between two parents and gene functional annotations. Consistently, knockout of TaHDZIV-A1/B1/D1 in common wheat line ‘JW1’ significantly increased LRI compared to the wild type, as well as overexpression of TaHDZIV-D1 in ‘JW1’ significantly decreased LRI until opposite direction. Moreover, genetic evidence suggested that a dose-dependent manner in TaHDZIV-A1/B1/D1 affects leaf rolling. Collectively, these findings provide a novel and recent insight into the genetic base of leaf rolling in common wheat.