【Objective】This study aimed to explore the differences in genome-wide DNA methylation patterns and their relationships with associated gene expression in different heat-tolerant sesame varieties under high temperature stress, in order to gain a deeper understanding of the regulatory mechanisms of DNA methylation in sesame's response to high temperature stress, and to provide a theoretical basis for heat tolerance breeding in sesame. 【Method】Two sesame varieties, Zhengtaizhi 3 (heat-tolerant) and Shandong White Sesame (heat-sensitive), were selected as experimental materials and cultivated under high temperature (41 ℃) and control (30 ℃) conditions for 10 days. Nanopore sequencing technology was used to conduct methylation sequencing of the genomic DNA of these two sesame varieties, and transcriptome sequencing was performed to analyze changes in the expression of associated genes. Minimap 2 software was utilized for reference genome sequence alignment, and Tombo software was employed to detect 5mC, CpG, and 6mA methylation sites. Differentially methylated regions (DMRs) were identified based on a genome segmentation approach. Finally, functional annotation and pathway analysis of DMR-associated differentially expressed genes (DMR-DEGs) were conducted using GO, COG, and KEGG databases. 【Result】Under high temperature stress, significant changes were observed in the genome-wide DNA methylation patterns of both Zhengtaizhi 3 and Shandong White Sesame. Specifically, the m6A and cytosine methylation (mC) contents of Zhengtaizhi 3 increased, while those of Shandong White Sesame decreased. A total of 621 DMRs (Zhengtaizhi 3) and 374 DMRs (Shandong White Sesame) were identified across the entire genome, mainly distributed in promoter and intergenic regions. Further analysis revealed that these DMRs were significantly associated with 113 DMR-DEGs (Zhengtaizhi 3) and 56 DMR-DEGs (Shandong White Sesame), respectively, and that demethylated DMRs were closely related to upregulated gene expression. Functional annotation results indicated that these DMR-DEGs were primarily involved in biological processes such as carbohydrate transport and metabolism, posttranslational modification, protein turnover, signal transduction, and secondary metabolite biosynthesis. 【Conclusion】This study revealed the differences in genome-wide DNA methylation patterns and their relationships with associated gene expression in different heat-tolerant sesame varieties under high temperature stress. Zhengtaizhi 3, a heat-tolerant sesame variety, regulated the expression of related genes by increasing DNA methylation levels under high temperature stress, while Shandong White Sesame, a heat-sensitive variety, exhibited a decreasing trend in methylation levels. In particular, the dynamic changes in CpG site methylation played a crucial role in regulating sesame's response to high temperature stress. These findings provide new insights and theoretical support for understanding the mechanisms of sesame heat tolerance and for heat tolerance breeding.
【Objective】CEP (C-terminal encoded peptides) is a gene that encodes hormone-like peptides secreted by roots and serves as a key regulator of plant root growth and development. To provide a molecular theoretical basis for further elucidating the function of MsCEP genes in root growth and development, members of the Medicago sativa MsCEP gene family, basic characteristics, expression differences in different tissues, and their roles in root growth were identified and analyzed. 【Method】Based on the genomic information of the alfalfa cultivar Xinjiang Daye, the MsCEP gene family members of alfalfa were accurately identified using local Blast analysis in TBtools and feature domain by referring to MtCEP family protein of Medicago truncatula sequence. The fundamental genetic and protein characteristics and the phylogenetic relationship of the MsCEP genes were analyzed by bioinformatics methods. The expression patterns of alfalfa MsCEP gene family members in various tissues were assessed using transcriptome data and real-time fluorescence quantitative PCR. The functional roles of mature MsCEP peptides in root growth and development were analyzed by exogenous application experiments. 【Result】A total of 35 MsCEP family members were identified in the genome of alfalfa Xinjiang Daye, and these genes are distributed across 18 chromosomes, lack introns, and all possess an N-terminal signal peptide and one or two conserved domains of the CEP family. The MsCEP members displayed predicted amino acid length ranging from 59 to 150, with molecular weights spanning 6.7 to 16.2 kDa, the isoelectric points varying from 5.80 to 10.41, instability indices ranging from 30.63 to 89.93, aliphatic indices ranging from 54.41 to 134.88, and the grand average of hydropathicity ranging from -1.110 to 0.377. Subcellular localization predictions indicated that the MsCEP protein predominantly localizes to the nucleus, plasma membrane, chloroplast, and Golgi apparatus. Cluster analysis delineated three distinct branches within the family, aligning with counterparts from Arabidopsis thaliana and Medicago truncatula. The largest branch encompassed 48 CEP members. Collinearity analysis highlighted a collinear relationship between the MsCEP genes in alfalfa and those in Arabidopsis thaliana and Medicago truncatula. Tissue expression analysis revealed that members of the MsCEP family exhibit distinct tissue-specific expression patterns, with higher expression levels in roots and lower or no expression detected in leaves. Among them, 22 members exhibited higher expression levels in roots compared to other tissues. The exogenous application of synthetic mature MsCEP2 peptide suppressed the growth of primary and lateral roots, reduced the number of lateral roots, and decreased the density of lateral roots. 【Conclusion】In conclusion, our investigation identified a total of 35 MsCEP members from the alfalfa 'Xinjiangdaye' genome database, which are revealed to be highly conserved. The MsCEP genes are primarily expressed in roots, and the exogenous application of synthetic mature MsCEP peptides can regulate root morphology, indicating that MsCEP peptides play important roles in root growth and development of alfalfa.
With the continuous improvement in rice cultivation techniques, China has maintained a high rice production level of about 210 million tons over the past decade. Direct-seeding rice cultivation technology, recognized for its efficiency and simplicity, has been favored by Chinese farmers. However, controversies persist regarding direct-seeding rice compared to transplanted rice in national-scale production. Thus, this study employed meta-analysis techniques to quantify disparities in grain yield, economic benefit, rice quality, lodging characteristic, and greenhouse gas emissions between direct-seeding rice and transplanted rice. Our results indicated that direct-seeding rice significantly reduced grain yield by an average of 6.3% relative to transplanted rice, which was main due to the reduced total spikelet (-3.8%) and filled-grain percentage (-1.8%). In different planting systems in China, the yield of direct-seeding rice had significantly decreased compared to transplanted rice, and the direct-seeding rice-induced reductions in yield of single rice (-10.9%) and late rice (-13.1%) were higher than those of middle rice (-4.8%) and early rice (-4.4%). The grain yield reductions for direct-seeding rice were from 10% to 20% in Jilin, Liaoning, Xinjiang, Ningxia, Shandong, Jiangsu, and Zhejiang provinces, meanwhile Heilongjiang and Jiangxi provinces saw reductions of 5% to 10%, but it had no significant effect in other provinces. Direct-seeding rice resulted in comparable net economic return relative to transplanted rice (p> 0.05). Direct-seeding rice reduced milled rice rate (-3.1%) and gel consistency (-3.5%), improved appearance quality (chalkiness percentage and chalkiness degree, which decreased by 25.3% and 22.5%, respectively), whereas no significant effects were observed on nutrition quality and taste value. Direct-seeding rice increased lodging index at base of the first (+12.4%) and third (+10.3%) internodes, but not at the second internode, indicating an increase in risk of lodging relative to transplanted rice. In terms of greenhouse gas emissions, direct-seeding rice fields showed reductions in methane emissions (-42.8%), global warming potential (-36.2%), and greenhouse gas intensity (-41.1%) compared to transplanted rice fields, while promoting nitrous oxide emissions (+29.1%). In addition, a review was recounted on nitrogen utilization and its loss, water and energy use efficiency, and weed incidence. Finally, the recommendations for the future advancement of direct-seeding rice were proposed, main focusing on rice variety breeding, rice cultivation technique optimization, rice planting area layout, as well as policies and services with the goal of technological innovation and regionalized application of direct-seeding rice cultivation technology in China.
【Objective】This study aimed to explore the physiological mechanism of silicon alleviating aluminum toxicity in plants, to study the effect of biomineralization structure constructed on rice root border cells and root tips on aluminum stress, so as to provide the theoretical and practical guidance for acid soil mineralization to alleviate aluminum toxicity of plants in southern China. 【Method】Employing rice (Oryza.Sativa L.) as the experimental materials, using root tips and root border cells as the research object, under 100 μmol·L-1 aluminum stress treatment, polyethylenimine induced nano silica to form biomineralization structure on the surface of root tips and root border cells. Four treatments are administered: bare cells without aluminum stress (-Si-Al), bare cells with aluminum stress (-Si+Al), silica-coated cells without aluminum stress (+Si-Al), and silica-coated cells with aluminum stress (+Si+Al). The study examined the cell viability, levels of active oxygen species, and localization of active aluminum in root border cells, as well as the relative elongation of the root tips, levels of active oxygen species, callose content and localization of active aluminum in the root tips. 【Result】Under aluminum stress, compared with non biomineralization, polyethylenimine induced nano silica deposition on the cell wall of root border cells, so the survival rate of root border cells increased by 21.04%, the level of reactive oxygen species decreased by 87.65%, and the relative fluorescence value increased by 77.09% after Morin staining, and then effectively improved cell survival rate, reduced ROS production, and slowed down the programmed cell death; after polyethylenimine induced nano silica deposition in root tip, the relative growth rate of root tip increased by 26.95%, the level of reactive oxygen species decreased by 27.73%, the content of callose increased by 55.29%, and the relative fluorescence value increased by 55.45% after Morin staining, hematoxylin staining also showed that more Al3+ was deposited in the meristematic and transitional zones of root tip, and this indicated that the biomineralization deposition could adsorb more Al3+ on the surface of root tip, prevent Al3+ from entering the root tip to protect, and then alleviate the toxic effect of aluminum on root tip. 【Conclusion】Polyethylenimine induced nano silica deposition on the cell wall endows rice root border cells and root tips with aluminum tolerance, and reduced aluminum accumulation in rice, thus ensuring food safety and human health.
【Objective】The objective of this study is to determine differentially expressed proteins in Locusta migratoria before and after Paranosema locustae infection by using tandem mass tag (TMT) quantitative proteomics techniques, screen differentially expressed immune and metabolic related proteins, and to explore the pathogenic mechanism of P. locustae, so as to provide a scientific basis for better use of P. locustae to control locusts in the future. 【Method】The healthy nymphs obtained by laboratory incubation were inoculated with 5 µL of 1×106 spores/mL P. locustae. The uninfected nymphs were used as the control group and fed under the same conditions as the infected group. The hemolymph of L. migratoria was taken as a sample. TMT technique was used to analyze the quantitative proteomics of the L. migratoria hemolymph in the infected group and the control group, and the differential proteins were identified. The biological process, molecular function and cellular component of differential proteins were analyzed by the Gene Ontology (GO) method. The differential proteins metabolic pathways were annotated by the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway website. 【Result】A total of 128 proteins were significantly different in abundance between the infected group and the control group, of which 66 proteins were up-regulated and 62 proteins were down-regulated in the infected group. GO analysis showed that the differential proteins were mainly involved in metabolic processes and were mainly distributed in cells. KEGG analysis showed that 16 proteins were significantly enriched in five pathways. Immune-related proteins, including six glutathione S-transferases (GSTs), one superoxide dismutase (SOD), four heat shock proteins (HSPs) and two peroxide dismutases (PODs), were significantly changed. Besides, metabolism-related proteins, including six glycometabolism-related proteins, two amino acids and one lipid metabolism-related proteins, were significantly changed. 【Conclusion】There were significant differences in the protein levels of L. migratoria before and after infection with P. locustae. Several differentially expressed proteins with different functions were screened, which were mainly distributed in cells. Immune-related proteins such as GST, HSP, SOD and POD were significantly up-regulated, indicating that immune and stimulus response-related proteins play an important role in the immune defense of locust hosts. The significant increase in metabolism-related proteins suggests that P. locustae infection promotes L. migratoria metabolism and provides energy for its proliferation.
【Objective】To provide significant references for revealing the role of non-classic OBP gene in the olfactory recognition mechanism of Bactrocera minax, an in-depth study on the molecular characteristics of B. minax Minus-C OBP (BminMinusOBP1) and Plus-C OBP (BminPlusOBP1) and ligand binding properties of its heterologous expressed proteins was conducted.【Method】Based on the B. minax transcriptome database, BminMinusOBP1 and BminPlusOBP1 were analyzed, identified, and cloned. The sequence characteristics and tissue expression patterns of BminMinusOBP1 and BminPlusOBP1 were analyzed by bioinformatics software and RT-qPCR, respectively. Recombinant expression vectors pET32a/BminMinusOBP1 and pET32a/BminPlusOBP1 were constructed, and the recombinant expression vectors were transferred into prokaryotic cell BL21 (DE3) for heterologous expression. The binding ability of the bacterially expressed BminMinusOBP1 and BminPlusOBP1 proteins to 12 host plant volatiles was investigated by the fluorescence competitive binding assay using 1-NPN as the fluorescent probe.【Result】Sequence analysis indicated that BminMinusOBP1 contains an open reading frame (ORF) of 426 bp that encodes 141 amino acid residues, and there is a signal peptide composed of 16 amino acid residues at its N-terminus. The predicted molecular weight of the mature protein is 14.39 kDa and the isoelectric point is 4.86. The four conserved cysteine residues were found in BminMinusOBP1 amino acid sequence, which is a typical feature of Minus-C OBP of insects. The ORF of BminPlusOBP1 is 765 bp, encoding 254 amino acid residues, and 18 amino acid residues at its N-terminus are signal peptide sequences. The predicted molecular weight of BminPlusOBP1 mature protein is 27.29 kDa and the isoelectric point is 5.75. The sequence contains conserved cysteine residues and proline residues specific to Plus-C OBP. The tissue expression patterns of BminMinusOBP1 and BminPlusOBP1 demonstrated that the expression of these two genes was not high in the antennae, the main olfactory organ, but high in the head tissue where the antennae had been removed. The results of fluorescence competitive binding experiments showed that both BminMinusOBP1 and BminPlusOBP1 exhibited broad ligand binding spectra. BminMinusOBP1 can bind to eight of the 12 tested odor ligands, including methyl eugenol, linalool, acetoin, (1s)-(-)-α-pinene, methyl salicylate, benzaldehyde, 1-octanol and citral, with Ki values ranging from 9.02 to 22.13 μmol·L-1. BminPlusOBP1 can bind to all 12 tested odor ligands, with Ki values ranging from 7.40 to 16.74 μmol·L-1. 【Conclusion】BminMinusOBP1 showed medium or strong binding affinity for seven host plant volatile components such as linalool, acetoin, citral, etc. BminPlusOBP1 showed medium or strong binding affinity for 12 host plant volatile components such as methyl eugenol, raspberry ketone, methyl phenylacetate, etc. Information from this study can provide an important reference for a comprehensive understanding of the functional characteristics of each member of the odorant binding protein family in B. minax.
【Objective】The analysis of rice yield, nitrogen use efficiency and the quantitative relationship between apparent nitrogen balance and soil alkali-hydrolyzed nitrogen under different nitrogen fertilizer management conditions could provide a more comprehensive understanding of the effects of long-term fertilization on soil fertility, so as to provide the theoretical guidance for efficient production and scientific nitrogen management of red soil paddy fields. 【Method】Based on the red soil double cropping rice long-term fertilization positioning experiment (started in 1981, located in Jinxian County, Jiangxi Province), five treatments were selected: no fertilizer (CK), nitrogen and phosphorus fertilizer (NP), nitrogen and potassium fertilizer (NK), nitrogen, phosphorus and potassium fertilizer (NPK), nitrogen, phosphorus and organic fertilizer (NPKM), and then the grain and straw yield and nitrogen uptake of rice in each season were investigated and analyzed, and the soil alkali-hydrolyzed nitrogen content was analyzed after late rice. The nitrogen uptake, nitrogen utilization rate, nitrogen apparent balance and the changes of soil alkali-hydrolyzed nitrogen were calculated and analyzed on a 10-year basis. 【Result】During the 40 years of experiment (1981-2020), the rice yield and nitrogen uptake under NPKM treatment were the highest, increased by 65.9%-108.4% and 85.1%-132.5% compared with CK, respectively, and increased by 19.3%-92.1% and 19.4%-99.8% compared with fertilizer treatments (NPK, NK and NP), respectively, showing significant differences. With the increase of the experimental period, the nitrogen use efficiency of fertilizer treatment gradually decreased, and the NPKM treatment also showed a decreasing trend in the first 30 years (1981-2010), but the rate was slower than that of fertilizer treatment, and increased in the recent 10 years (2011-2020), and from the lowest in the first 10 years (1981-1990) to the highest in the recent 10 years, increased by 25.3%-271.2% compared with fertilizer treatment. The nitrogen surplus was the highest under NPKM treatment during the 40 years of experiment, with an increase of 137.1%-577.2% compared with fertilizer treatment, but in the last 30 years (1991-2020), the nitrogen surplus gradually decreased with the increase of the experimental period. The soil alkaline hydrolyzed nitrogen content was the highest under NPKM treatment during the 40 years of experiment, increased by 7.1%-24.4% compared with CK, but the difference was not significant in the first 10 years, and increased by 11.0%-35.2% compared with fertilizer treatment, while there was no significant difference between fertilizer treatment and CK. Correlation analysis showed that the nitrogen surplus was significantly positively correlated with the soil alkaline hydrolyzed nitrogen content in the last 20 years (2001-2020). 【Conclusion】In the red soil double-cropping rice system, with the increase of fertilization years, the combined application of organic and inorganic fertilizers had better effects on rice yield, nitrogen uptake, nitrogen uptake and utilization, and soil alkali-hydrolyzed nitrogen content. Meanwhile, the increase of nitrogen surplus caused by long-term fertilization also further increased the soil alkali-hydrolyzed nitrogen content in the topsoil. The contribution capacity of nitrogen surplus to soil alkali-hydrolyzed nitrogen increased gradually.
【Objective】This study aimed to explore the dynamic change of soil texture and nutrients resulting from 60 years of agricultural cultivation subsequent to the conversion of grassland to cropland in the typical steppe of Xilingol County. It also evaluated whether the 18 years cropland afforestation had effectively mitigated the negative impacts of long-term cultivation on soil particle size distribution and soil nutrients. The research sought to enhance understanding of soil quality evolution during ecological restoration processes in this region and provided a scientific basis for assessing the actual effectiveness of ecological restoration measures. 【Method】Five sites within 60 km2 of the study area as replicates were chosen to investigate the particle size distribution, bulk density, and nutrient characteristics within the 0-30 cm soil layer across four land use types, including grassland (GL), cropland (CL) and afforestation land with row spacing of 2 m (AL-2) and 5 m (AL-5). 【Result】(1) The soil particle composition across various land use types included sand (61%-82%), silt (16%-35%) and clay (less than 4%). Notably, the content of silt (2-50 μm) in cropland and afforestation land was significantly lower than that in grassland, whereas the proportion of sand (>50 μm) was markedly higher in comparison to grassland. Further, compared with natural grassland, the cultivation has resulted in a reduction of soil particles smaller than 120 μm and an increase in soil particles larger than 120 μm. However, the afforestation for 18 years has not alleviated the decrease in fine particles (≤120 μm) caused by cultivation. (2) In 0-30 cm soil layer, the composition of soil particle size in each land use type showed uniformity along the soil depth, which reflected poor sorting characteristics and a negative to extremely negative particle size distribution pattern and sharp kurtosis. Among them, the grassland had the smallest mean particle size and the highest fractal dimension. (3) The soil bulk density gradually increased with the increase in soil depth. Nutrient changes were primarily concentrated in the shallow soil layer of 0-10 cm, where cultivation activities led to significantly decrease in soil organic carbon (OC), total nitrogen (TN) and total phosphorus (TP) content. Compared with cropland, the shrubland formed after afforestation did not significantly alter the content of organic carbon and total nitrogen, but significantly reduced the total phosphorus content. (4) It A highly significant positive correlation between soil particle components smaller than 120 μm and soil organic carbon, total nitrogen and total phosphorus was found, which indicated that the decline in soil nutrients was closely linked to the loss of fine soil particles. 【Conclusion】In summary, the long-term conversion of grassland to cropland has led to the degradation of soil physical structure, with the loss of soil fine particles has affected the enrichment of nutrients. Moreover, the effects of afforestation after 18 years on improving soil texture and restoring nutrient levels were not significant.
【Objective】Chilling stress is a significant abiotic factor that leads to reduction in yield and quality of cucumber plants cultivated in solar greenhouse during winter. Cold-induced stress memory, as a flexible behavior in response to environmental changes, plays an important role in plant acclimation to adverse conditions. To elucidate the regulatory mechanism of cold circulation-induced stress memory on the chilling tolerance in cucumber, and provide technical guidance for enhancing the adaptation of cucumber to low temperature in solar-greenhouse. 【Method】Jinyou 35 cucumber plants were used as experimental materials, and were treated in an artificial climate chamber. There were four treatments: No cold induction treatment (C0R0), single cold induction (C1R1: 24 h treatment at a day/night temperature of 8 ℃/8 ℃ followed by a recovery period of 48 h at 25 ℃/18 ℃), repeated cold circulation induction twice (C2R2: same conditions as C1R1, cycle twice), and repeated cold circulation induction three times (C3R3: same conditions as C1R1 treatment, cycle three times). Subsequently, the seedlings were exposed to chilling stress condition (8 ℃/5 ℃). The C0R0 treatment at normal temperature (25 ℃/18 ℃) was used as the control. Following a 48 h exposure to chilling stress, the functional leaves were sampled for analysis. 【Result】The results showed that cold circulation induction significantly alleviated the symptoms of chilling injury, markedly reduced the levels of malondialdehyde (MDA), electrolyte leakage (EL), chilling injury index (CI), as well as the accumulation of hydrogen peroxide (H2O2) and superoxide anion ($\mathrm{O}_2^{\bar{.}}$) in cucumber seedlings, compared with the C0R0. The cold circulation induction treatments exhibited a significant increase in the activities of superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX) and glutathione reductase (GR) and their mRNA expression levels, relative to the C0R0 treatment under chilling stress. Among the cold circulation induction treatments, C2R2 exhibited the mildest symptoms of chilling injury. After exposure to 8 ℃/5 ℃ for 48 h, the CI of C2R2 seedlings decreased by 30.6% compared to that of the C0R0. Moreover, the MDA content, EL, as well as the accumulation of H2O2 and $\mathrm{O}_2^{\bar{.}}$ in C2R2 seedlings were lower by 39.4%, 29.8%, 34.0% and 48.0%, respectively compared with those observed in C0R0 seedlings. However, the activities of SOD, POD, APX and GR of C2R2 treatment were 48.3%, 185.1%, 34.8% and 50.4% higher, with corresponding increases in mRNA expression by 0.94-, 3.45-, 1.76- and 1.17-fold, respectively, compared to the C0R0 seedlings. The induction of cold circulation also significantly upregulated the expression levels of cold- responsive genes CsICE1, CsCBF1, CsCOR47 and heat shock protein CsHSPs. Overexpression of CsHSP26.5 and CsHSP17.6C distinctly enhanced the chilling tolerance of cucumber induced by cold circulation induction. 【Conclusion】Stress memory induced by cold circulation can enhance the chilling tolerance of cucumber seedlings, with the most optimal effect observed after two cycles. The main mechanisms are: (1) Cold circulation induction increase the activity of antioxidant system and decrease the accumulation of reactive oxygen species (ROS) under chilling stress, and consequently alleviate the oxidative damage in cucumber caused by chilling stress; (2) Cold circulation induction upregulate the expression of cold- responsive genes and activates of their function, thereby improving the chilling tolerance of cucumber seedlings; (3) CsHSPs are involve in the regulation of stress memory induced by cold circulation to the chilling tolerance in cucumber. The stress memory induced following two cycles of cold circulation in cucumber plants was between 14 d and 21 d.
