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01 September 2024, Volume 57 Issue 17

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Scientia Agricultura Sinica. 2024, 57(17):  0. 

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Construction of ms1 Basic Recurrent Populations Adapted to Different Ecological Regions Using Maturity Genes E1 and E2 in Soybean

HU XueJie, LIU LuPing, WANG FengMin, HAN YuHua, SUN BinCheng, MA QiBin, HUANG ZhiPing, FENG Yan, CHEN Qiang, YANG ChunYan, ZHANG MengChen, ZHANG Kai, QIN Jun

Scientia Agricultura Sinica. 2024, 57(17):  3305-3317.  doi:10.3864/j.issn.0578-1752.2024.17.001

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【Objective】Soybean is a short day crop that is sensitive to photoperiod, and it maybe lead to premature or late flowering when it is planted in different ecological areas. Therefore, in the application of ms1 (male sterility 1) basic population for recurrent selection in different ecological regions, there are problems such as the flowering time unsynchronization between local donor parents and acceptor sterile plants and low introduction rate. The purpose of this study is to construct ms1 basic recurrent population adapted to three ecological regions for improving the probability of flowering time synchronization between donor parents and acceptor sterile plants and reveal the changes of maturity genes E1 and E2 genotypes and phenotype of each population after two rounds of cross-fertilize for providing evidence for improvement of the flowering and maturity time of soybeans.【Method】We used 528 donor parents from different ecological regions and the ms1 basic population as materials. The donor parents were genotyping with the KASP markers of maturity genes E1 and E2 reported by previous research. The donor parents were classified according to E1 and E2 genotypes and mixed with seeds of ms1 basic population respectively, and these populations were planted in different ecological areas according to the suitable genotypes of each region for two rounds of cross-fertilize in two years. Northeast ecological region population was planted in Hulunbuir, Inner Mongolia and Chengde, Hebei, respectively. Huang-Huai-Hai ecological region population was planted in Shijiazhuang, Hebei and Xuchang, Henan. South ecological region population was planted in Guangzhou, Guangdong. Seeds harvested from different ms1 populations were planted in Sanya, Hainan every winter. The flowering and maturity time of donor parents and ms1 basic population were investigated, and the proportions of E1 and E2 genotypes in populations of different region were calculated.【Result】According to genotypes of maturity genes E1 and E2, the donor parents were divided into four groups E1E1/E2E2, E1E1/e2e2, e1e1/E2E2 and e1e1/e2e2 with ratios of 12.1%, 65.0%, 19.3%, and 3.6%, respectively. In the ms1 basic population, the late flowering genotype E1E1/E2E2 had the highest proportion (48.6%), and the flowering time of the population was late, mainly concentrated in 45-51 days. After two rounds of import by cross-fertilize, the percentage of target genotype e1e1/e2e2 increased from 33.0% to 51.6% in Hulunbuir of Northeast China, and the percentage of the e1e1/e2e2 genotype increased from 1.6% to 8% in Chengde. The percentage of target genotype e1e1/E2E2 increased from 18% to 23.1% in Shijiazhuang of Huang-Huai-Hai ecological area, and the percentage of E1E1/e2e2 increased from 12.5% to 30% in Xuchang, respectively. The percentage of E1E1/E2E2 remains above 80% in Guangzhou of South ecological region. The proportion of heterozygous genotypes of target imported genotypes was also increasing in the population. After two rounds of cross-fertilize, there were significant differences in flowering time among ms1 populations of different ecological regions, indicating that phenotypes of different populations also changed with the change of genotype of flowering genes.【Conclusion】Importing genotype of donor parents into the ms1 population based on their genotypes of flowering genes can increase the frequency of suitable genotypes in each ecological region, construct ms1 basic recurrent populations adapted to different ecological regions, increase the probability of flower time synchronization of local donor parents and acceptor ms1 sterile plants, achieve open pollination, gene aggregation and accumulation in soybean, and enrich the genetic diversity of the population, further improve breeding efficiency.

Progress on Detection Methods for Gene-Edited Organisms

WU YuHua, ZHAI ShanShan, PU HaoZhen, GAO HongFei, ZHANG Hua, LI Jun, LI YunJing, XIAO Fang, WU Gang, XU LiQun

Scientia Agricultura Sinica. 2024, 57(17):  3318-3334.  doi:10.3864/j.issn.0578-1752.2024.17.002

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Gene editing techniques have made gene edited (GE) organisms enter commercial applications from laboratories. In 2022, the Ministry of Agriculture and Rural Affairs specifically issued the “Guidelines for Safety Evaluation of Genetically Edited Plants for Agricultural Use (Trial)” for the safety evaluation of GE plants without introducing exogenous genes. In 2023, China granted the first biosafety certificate for GE soybean AE15-18-1, marking the official start of the commercialization process of GE crops in China. GE organisms are different from traditional genetically modified organisms (GMOs) containing exogenous DNA sequences, making common GM detection strategies inapplicable to the detection of GE organisms. As the industrialization of GE crops progresses positively, how to efficiently and accurately detect whether a product is gene-edited and its editing characteristics is an important basis for the commercial use and intellectual property protection of GE products. There is an urgent need to develop detection technologies suitable for GE products. With the goal of detecting whether the target sequence has been edited, many detection technologies have been developed based on PCR, sequencing, and other technologies, and are widely used in the screening of GE products in the research and development process. After industrialization, safety supervision and intellectual property protection require not only the detection of whether the sample has been edited but also the rapid identification of the nucleotide sequence characteristics of the sample to determine its origin and identity. Subsequently, precise quantification of the GE components is necessary to determine whether quantitative labeling is required. Currently, it is difficult to quickly identify the identity of GE products with only a few base insertions, deletions, and single nucleotide variations (SNV) using conventional PCR or sequencing technologies. It is even more challenging to accurately quantify the content of GE components. Aiming at the rapid identification of the DNA sequence characteristics after editing and precise quantification, based on the molecular characteristics of GE products, this paper reviews the application of the gel electrophoresis-based PCR method, the sequencing-based method, the real-time PCR-based method, the digital PCR-based method, the editing enzyme-based method, and the instrument-based method in detection of GE organisms, and expounds the advantages and disadvantages of each method during detection. This review initially explores the detection and quantification strategies suitable for GE organisms and provides a reference for subsequent development of detection methods for GE organisms.

Cloning and Biological Function Verification of Alfalfa MsSPL17

CHEN FeiEr, ZHANG ZhiPeng, JIANG QingXue, MA Lin, WANG XueMin

Scientia Agricultura Sinica. 2024, 57(17):  3335-3349.  doi:10.3864/j.issn.0578-1752.2024.17.003

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【Objective】Branching is a significant factor influencing alfalfa yield, and the SPL family of transcription factors represents a crucial class of regulatory genes involved in branching (tillering) development in a diverse range of plants. The objective of this reserch is to investigate the biological function of MsSPL17 in alfalfa and to elucidate the role of MsSPL17 in regulating the development of alfalfa meristems. This will provide a valuable reference for alfalfa high-yield biological breeding.【Method】Bioinformatics methods were used to anlyze MsSPL17 sequences and also constructing a phylogenetic tree. The tissue expression specificity of MsSPL17 in alfalfa was analyzed by real-time fluorescence quantitative PCR (qPCR). The subcellular localization of MsSPL17 protein was determined by tobacco transient expression system, and the transcriptional self-activation activity of MsSPL17 was verified. The transgenic alfalfa was obtained by Agrobacterium-mediated transformation and phenotypic analysis was carried out. Transcriptome analysis was utilized to screen for differentially expressed genes in transgenic lines and validate them for further research.【Result】MsSPL17 contained an open reading frame of 1 011 bp, encoding a protein composed of 366 amino acids, belonging to the SBP protein family. Phylogenetic analysis showed that the evolution of MsSPL17 and its homologous genes was highly similar to the differentiation of species, indicating that it is a functional conserved gene. MsSPL17 expressed in all tissues, including stems, nodes, leaves and tops during the critical period of alfalfa growth and development, implied the necessary regulating function of this gene in alfalfa branching. Subcellular localization assay showed that MsSPL17 protein was localized in the nucleus. Transcriptional self-activation assay showed that MsSPL17 did not have self-activation activity and could be used in interacting proteins screening. MsSPL17 transgenic silenced lines exhibited a notable phenotype, including an increase in branch number and stem node number, a reduction in internode length, and an enhancement in nutritional quality.【Conclusion】MsSPL17 was successfully cloned, it expressed in key tissues of alfalfa branching development. The protein encoded by MsSPL17 was localized in the nucleus and demonstrated no transcriptional self-activation activity. Transgenic lines exhibiting multi-branching traits were obtained, and the number of branches increased significantly in yield, while the crude protein content increased in quality.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY·AGRICULTURE INFORMATION TECHNOLOGY

Effects of Unmanned Dry Direct-Seeded Mode on Yield, Grain Quality of Rice and Its Economic Benefits

WENG WenAn, XING ZhiPeng, HU Qun, WEI HaiYan, SHI YangJie, XI XiaoBo, LI XiuLi, LIU GuiYun, CHEN Juan, YUAN FengPing, MENG Yi, LIAO Ping, GAO Hui, ZHANG HongCheng

Scientia Agricultura Sinica. 2024, 57(17):  3350-3365.  doi:10.3864/j.issn.0578-1752.2024.17.004

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【Objective】This study aimed to provide the theoretical and technical support for the innovation of green, high-yield, high-quality and high-efficiency unmanned dry direct-seeded (UDDS) cultivation technology of rice.【Method】Medium-maturing medium japonica rice (Nanjing 5718) was selected as the experimental material, with unmanned carpet seedling mechanical transplantated (UCSMT), and conventional carpet seedling mechanical transplantated (CSMT) serving as control methods. A three-year field experiment was conducted to assess the impact of UDDS on growth, yield formation, quality characteristics of rice, and its economic benefits.【Result】(1) Although UDDS was carried out with 2-3 days earlier than the control, it exhibited a full growth cycle that was 12-13 days shorter than those of UCSMT and CSMT, primarily due to the shortened period from sowing to jointing stage. (2) The average yield under UDDS from 2020 to 2022 was 10.5 t·hm^-2, representing a 3.0% increase than that of CSMT, although this difference was not statistically significant. In comparison with UCSMT, UDDS exhibited a significant yield reduction of 5.4%, and this decrease could be attributed to a reduction in the spikelet number per panicle, resulting in fewer total spikelet numbers and a decrease in dry matter accumulation and transport capacity from heading to maturity. (3) Compared with CSMT, UDDS exhibited slightly reduced processing quality, amylose, and protein contents, with no significant differences were observed. However, the significant reductions in chalkiness percentage and degree were noted, while the taste value increased, though not significantly. Compared with UCSMT, UDDS demonstrated a significant decrease in head milled rice rate, chalkiness percentage, degree, and amylose content, and protein content also decreased, though not significantly. Additionally, UDDS exhibited higher RVA peak viscosity and a significant improvement in taste value. (4) Under the UDDS mode, the cost of rice planting decreased, and the net income increased by 1.15 × 10³ yuan·hm^-2 and 0.93 × 10³ yuan·hm^-2, than that under UCSMT and CSMT, respectively.【Conclusion】In the rice-wheat rotation system, UDDS realized the synergy of high yield and income increase, and improved the appearance quality and cooking and eating quality of rice, the UDDS cultivation technology should be optimized in terms of improving the total spikelet number, accumulation and translocation of dry matter during filling stage, thereby getting the goals of high rice yield, great quality, and efficient synergy, simultaneously.

Effects of Straw Returning and Irrigation Methods on Seedling Emergence and Growth in Soybean and Maize Strip Intercropping

YANG LiDa, PENG XinYue, ZHU WenXue, ZHAO Jing, YUAN XiaoTing, LIN Ping, LUO Kai, LI YiLing, LUO ChunMing, LI YuZe, YANG WenYu, YONG TaiWen

Scientia Agricultura Sinica. 2024, 57(17):  3366-3383.  doi:10.3864/j.issn.0578-1752.2024.17.005

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【Objective】Soybean and maize strip intercropping is an important cultivation pattern for soybean productivity improvement project in China. In this experiment, the effects of straw returning and irrigation methods on the emergence and seedling growth quality in soybean and maize strip intercropping were investigated, in order to provide the theoretical support for the strip intercropping to solve the problem of seedling emergence.【Method】Two-factor split plot zone design was adopted, three straw returning methods (non-returning straw (S1), returning straw with no stubble (S2), and returning straw with stubble (S3)) and three irrigation methods (non-irrigation (W1), check irrigation before sowing (W2), and spray irrigation after sowing (W3)) were set up, and their effects on seedling emergence and growth of strip intercropping crops were researched.【Result】Irrigation could significantly increase soil water content and alleviate soil compactness, thus effectively improving the emergence rate of soybean and maize, and shortening the emergence time. The seedling emergence rates under W3, W2 and W1 with S2 were 71.00%, 45.70% and 38.50% in Yucheng, respectively. The seedling emergence rates under W3, W2 and W1 with S2 were 90.17%, 88.50% and 61.67% in Anju, respectively. The emergence time under W2 and W3 was 3.29 d and 2.92 d shorter than that under W1, respectively. Under different irrigation methods, there was no significant difference in the seedling emergence rate of maize, which could reach more than 90%, but the seedling emergence time was significantly different. The emergence time of maize under W2 and W3 was 1.9 d and 3.1 d shorter than that under W1 in Yucheng, respectively. The emergence time of maize under W2 and W3 was 0.96 d and 0.6 d shorter than that under W1 in Anju, respectively. Straw returning significantly increased soil water content and decreased soil compactness, and the effects in both places were S2>S3>S1. Straw returning to the field under W1 could significantly improve the soybean seedling emergence rate in Yucheng, in which S2 was 45.08% higher than S1. Straw returning had no significant effect on the emergence rate of maize in the two places. Straw returning and irrigation significantly increased the activity of soybean lipase (LPS) and maize α-amylase (α-AL). The LPS of W2 and W3 were 26.86% and 37.77% higher than that of W1, respectively. The LPS under S2 was 14.14% and 18.05% higher than that under S3 and S1, respectively. The α-AL under W2 was 189.47% higher than that under W1, and the α-AL under S2 was 61.52% and 127.33% higher than that under S3 and S1, respectively. The two irrigation treatments could promote the growth and development of soybean and maize, and improve the seedling growth rate and uniformity. The soybean plant height under W3 and W2 was 21.74% and 15.70% higher than that under W1, respectively, wihle the stem diameter was 12.52% and 28.15% higher, respectively, and the leaf area was 11.84% and 38.78% higher, respectively. The maize plant height under W3 and W2 was 21.80% and 20.62% higher than that under W1, respectively, while the stem diameter was 37.69% and 26.39% higher than that under W1, respectively, and the leaf area under W3 was 36.56% and 73.33% higher than that under W2 and W1, respectively. Straw returning significantly affected the growth of maize seedlings in Yucheng, showing S3>S1>S2. The plant height under S3 was 19.92% and 27.31% higher than that under S1 and S2, respectively, while the stem diameter was 27.59% and 59.80% higher, respectively, and the leaf area was 42.76% and 68.54% higher, respectively.【Conclusion】Successful emergence and construction of a good seedling population were the basis for achieving high yield. Spray irrigation after sowing improved the physical structure of the plough layer, thus promoted the emergence of seedlings and shortened the emergence time in strip intercropping, and provided favorable conditions for subsequent crop growth. Returning straw with stubble could improve the growth quality of strip intercropping seedlings in Yucheng. Returning straw with no stubble had the characteristics of water storage and alleviating soil compaction, it is beneficial to soybean emergence without irrigation, and has a promoting effect on the formation of strong seedlings of strip intercropping crops in Anju.

PLANT PROTECTION

Cloning and Expression Analysis of Genes of Small Heat Shock Protein in Setosphaeria turcica

ZHANG ShuHong, ZHANG YunFeng, GAO FengJu, WU QiuYing, XU Ke, LI YaZi, LI YanMei, GU ShouQin, FAN YongShan, GONG XiaoDong

Scientia Agricultura Sinica. 2024, 57(17):  3384-3397.  doi:10.3864/j.issn.0578-1752.2024.17.006

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【Objective】The objective of this study is to clone the small heat shock protein (sHSP) genes in Setosphaeria turcica, elucidate their structural characteristics, and explore their expression profiles during pathogen development and in response to HT-toxin induction.【Method】The hidden Markov model (HMM) was used to identify sHSP family members across the entire S. turcica genome. PCR technology was used to clone sHSP genes from S. turcica strain 01-23. Bioinformatics methods were then applied for the analysis of physicochemical properties, subcellular localization, structural prediction, and phylogenetic analysis of the sHSP genes obtained. Additionally, RNA-Seq and RT-qPCR were performed to determine the expression of sHSP genes across different developmental stages and during HT-toxin induction in S. turcica.【Result】Three sHSP family members (StHSP37.2, StHSP37.0 and StHSP22.6) were identified from the genome of S. turcica. The corresponding DNA sequences were successfully cloned from strain 01-23. The encoded sHSP proteins were weakly acidic and hydrophilic proteins, without transmembrane domain or signal peptide. Random coil in the secondary structure accounted for 58.97% to 60.35%, and β-turn ranged from 2.69% to 7.83% only. Subcellular localization prediction indicated that StHSP37.2 and StHSP37.0 were located in the nucleus, while StHSP22.6 was located in both nucleus and cytoplasm. Conserved ACD_sHSP-like domains were identified near C-terminus, with 2, 3, and 5 conserved motifs in StHSP37.2, StHSP37.0, and StHSP22.6, respectively. The monomer tertiary structure models of sHSP were constructed using SWISS-Model and AlphaFill. Phylogenetic analysis indicated close relationships between StHSP22.6 and sHSP in Alternaria alternata, and between StHSP37.2/StHSP37.0 and sHSP in Bipolaris maydis. The sHSP genes of S. turcica had the highest expression levels in hyphae, followed by germ tubes, appressoria, and penetration pegs, with the lowest expression levels in conidia. StHSP22.6 and StHSP37.2 showed significant negative correlations with HT-toxin induction, and the relative gene expression was upregulated by 6.45 and 18.12 folds on day 14, respectively. On day 21 and 28, StHSP37.2 showed modest upregulations of 2.56 and 1.78 folds, respectively, while StHSP22.6 did not differ from the wild-type (WT). StHSP37.0 exhibited significant positive correlations with HT-toxin induction, with a significant downregulation by 59.23%, 86.30%, and 88.11% on day 14, 21, and 28, respectively. Exploration of expressed genes significantly associated with sHSP of S. turcica suggested that StHSP37.2 and StHSP22.6 were mainly related to HSP90, HSP104, catabolism, and mitochondrial Mg²⁺ transport, while StHSP37.0 appeared to be associated with vacuolar alkaline amino acid transport, organic synthesis, and substance secretion.【Conclusion】The sHSP family members in S. turcica demonstrate a high degree of conservation yet exhibit structural and phylogenetic differences from other sHSPs. They are integral to the development of hyphae, germ tubes, appressoria, and penetration pegs, and also exert significant regulatory functions during HT-toxin induction.

Study on the Synergistic Control Effect of Metarhizium rileyi and Harmonia axyridis Toward Aphids

SHI Na, LU Yang, SUI Li, WANG JiaJiang, ZHAO Yu, LI QiYun, ZHANG ZhengKun

Scientia Agricultura Sinica. 2024, 57(17):  3398-3407.  doi:10.3864/j.issn.0578-1752.2024.17.007

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【Objective】The purpose of this study is to clarify whether the combination of Metarhizium rileyi and Harmonia axyridis can achieve synergistic effect, and to provide theoretical basis and application technology for efficient biological control of aphids.【Method】The direct and indirect pathogenicity of M. rileyi to adult H. axyridis was measured by spraying adult H. axyridis with M. rileyi conidia and feeding H. axyridis with aphids after spraying, the H. axyridis without spraying M. rileyi and the H. axyridis fed with aphids without spraying M. rileyi were used as controls, respectively. After spraying the aphids with conidia of M. rileyi, the feeding selectivity of the H. axyridis to aphids under different starvation times was measured. In order to clarify the impact on the aphid predation ability of H. axyridis after feeding on aphids treated with M. rileyi, the predation function, egg production, and egg hatching rate of the H. axyridis were determined after feeding on aphids treated with M. rileyi. Two treatments were set up to determine the jointly control effect of H. axyridis and M. rileyi on aphids using the reduction rate of insect population as an indicator, one of which was to apply M. rileyi before releasing H. axyridis, and the other was to release H. axyridis alone.【Result】The evaluation of direct and indirect pathogenicity showed that the survival rate of H. axyridis was not significantly different from that of the control group. At 0 h of starvation treatment, the feeding preference rate of H. axyridis to Acyrthosiphon pisum was significantly lower than that of the control group, but there was no significant difference between the two groups at 24 and 48 h of starvation treatment, which was consistent with the conclusion of predation functional response model. The instantaneous attack rate of H. axyridis against A. pisum in M. rileyi treatment group and control group was 0.6585 and 0.6479, respectively, with no significant difference (P>0.05). The total number of eggs laid by single female H. axyridis in M. rileyi treatment group and control group for 7 consecutive days was 161.67 and 167.33, and the egg hatching rate was 65.60% and 67.60%, respectively, with no significant difference (P>0.05). The treatment of releasing H. axyridis after applying M. rileyi showed better control effect on A. pisum on the 2nd to 3rd day and Rhopalosiphum maidis on the 2nd to 4th day after the release of H. axyridis.【Conclusion】M. rileyi had no significant effect on the predation ability, egg production and hatching rate of H. axyridis, and the control effect of H. axyridis on aphids was improved after the application of M. rileyi, and the two agents had a synergistic effect.

SOIL & FERTILIZER·WATER-SAVING IRRIGATION·AGROECOLOGY & ENVIRONMENT

Effects of Tillage Methods Under Straw Returning on the Labile Organic Carbon Fractions and Carbon Pool Management Index in Black Soil Farmland

LIU YaJie, ZHANG TianJiao, ZHANG XiangQian, LU ZhanYuan, LIU ZhanYong, CHENG YuChen, WU Di, LI JinLong

Scientia Agricultura Sinica. 2024, 57(17):  3408-3423.  doi:10.3864/j.issn.0578-1752.2024.17.008

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【Objective】Soil-related indicators were measured during the mature period of maize in 2020 and 2021. The purpose of this study was to investigate the effects of tillage methods with straw returning on soil labile organic carbon and carbon pool management index of black soil farmland at the southern foot of the Daxing’an mountains based on four consecutive years of tillage experiment.【Method】Seven treatments were set up in the tillage positioning experiment, including deep tillage with straw returning (DTS), deep loosening and shallow with straw returning (DSS), subsoiling tillage with straw returning (STS), heavy harrowing straw returning (SHS), rotary tillage with straw returning (RTS), and no-tillage straw returning (NTS), with shallow tillage without straw returning (CK). 0-60 cm surface soil was collected. The contents of labile organic carbon (R₃₃₃), medium labile organic carbon (R₁₆₇) and high labile organic carbon(R₃₃) were determined by potassium permanganate solution with different concentrations (0.333, 0.167 and 0.033 mol·L^-1), and the effects of different tillage methods on soil labile organic carbon content and carbon pool management index were studied.【Result】(1) Compared with CK, the R₃₃₃ content in 0-10 cm soil layer treated by DSS, DTS, NTS, RTS and STS significantly increased by 9.0% to 63.7% in two years, respectively. DSS was the highest, followed by DTS and NTS. R₃₃₃ in 10-60 cm soil layer, DTS, DSS and NTS significantly increased by 30.8%-134.5%, 14.1%-97.8% and 18.9%-63.0%, respectively (P<0.05). (2) Compared with CK, the medium labile organic carbon (R₁₆₇) of 0-10 cm soil layer under different tillage methods was significantly increased (P<0.05). The DSS treatment of R₁₆₇ content was the highest, with an increase of 37.3%- 101.0%, and the DTS treatment of 10-60 cm soil layer was the highest, with an increase of 44.8%-72.9%, showing DTS>DSS>NTS treatment. (3) Compared with CK, the R₃₃ content in 0-10 cm soil layer was significantly increased by 13.8%-55.6% under DSS treatment (P<0.05). In 10-20 cm soil layer, R₃₃ content of DTS, DSS, STS, RTS and NTS treatment was significantly increased by 3.6%-29.3% (P<0.05), with DTS being the highest, followed by DSS. In 20-60 cm soil layer, R₃₃ under DTS, DSS and STS treatment was significantly increased (P<0.05), and the proportion was 68.1%-20.0%. (4) The inert organic carbon (IOC) of 0-10 cm soil layer under straw returning was significantly increased by 4.7%-21.8% (P<0.05). In 20-60 cm soil layer, DTS and DSS significantly increased by 5.3%-156.6% and 4.2%-138.8% compared with other treatments (P<0.05). (5) Compared with CK, DTS treatment significantly increased carbon pool activity and carbon pool activity index in 0-20 cm soil layer (P<0.05), and increased by 7.7%-44.8% and 7.7%-45.0%, and significantly increased by DTS, DSS, STS and RTS soil layer carbon pool index (P<0.05). DTS, DSS and NTS treatment significantly increased the carbon pool management index of 0-60 cm soil layer by 21.9%-140.9%, 4.9%-103.7%, 13.3%-62.0% (P<0.05). (6) In 0-60 cm soil layer, R₃₃₃, R₁₆₇, R₃₃ and IOC were positively correlated with organic carbon content, carbon pool activity index, bulk density and geometric mean diameter, but negatively correlated with total soil porosity (P<0.01). Increasing the content of active organic carbon could improve soil physical structure and enhanced aggregate stability. The IOC was positively correlated with maize yield and dry matter mass (P<0.01).【Conclusion】Comprehensive analysis shows that both deep tillage with straw returning (DTS) and deep loosening and shallow with straw returning (DDS) can increase soil labile organic carbon and inert organic carbon to a certain extent, and effectively improve the organic carbon pool of farmland.

Effects of Water Saving and Nitrogen Reduction on Lodging Resistance and Grain Yield of Spring Wheat in the Yellow River Irrigation Area of Ningxia

LI Hong, WANG XiNa, WEI GuangYuan, MA YongXin, TIAN HaiMei, WANG YueMei, QIAN ZhiJin, TAN JunLi

Scientia Agricultura Sinica. 2024, 57(17):  3424-3439.  doi:10.3864/j.issn.0578-1752.2024.17.009

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【Objective】The study on the effect of nitrogen reduction and water saving on the stem strength and grain quality of spring wheat aims to provide theoretical basis for the sustained and stable yield increase of spring wheat, efficient utilization of irrigate and nitrogen, and improvement of spring wheat’s lodging resistance in Yellow River Irrigation Area of Ningxia.【Method】Using Ningchun No.4 as test material, in 2021 and 2022, split-zone field experiment was conducted to investigate the effects of irrigation treatments (conventional irrigation (400 mm, WC), 20% water saving (320 mm, W1), and 40% water saving (240 mm, W2) and nitrogen application treatments (conventional nitrogen application (270 kg·hm^-2, NC), 25% nitrogen reduction (202.5 kg·hm^-2, NJ), and no nitrogen application, N0) on stem strength, yield and grain quality of spring wheat.【Result】The 25% N reduction and 20% water savings did not significantly reduce spring wheat plant height, stem diameter, or accumulation of aboveground biomass compared to conventional N application. There was no significant difference in stem strength and stem potassium content of spring wheat treated with reduced and conventional nitrogen application levels, but on the basis of reduced nitrogen, stem strength and stem potassium content of spring wheat treated with 20% water saving was significantly higher than that of conventional irrigation treatment. At the filling stage, stem strength increased by 14.9% and 16.3%, and stem potassium content increased by 13.4% and 11.9% in the water-saving 20% treatment compared to the conventional flooding treatment in both years at the reduced nitrogen level, while at the maturity stage, stem strength increased by 19.0% and 8.3%, and stem potassium content increased by 10.5% and 9.0%, respectively. Stem strength of spring wheat showed a decreasing trend as the reproductive process progressed. Correlation analysis showed that stem strength was highly significantly positively correlated with plant height and above-ground biomass, significantly positively correlated with stem potassium content, and not significantly correlated with stem diameter. Among the water-nitrogen treatments, the spring wheat yield was highest in the 20% nitrogen reduction and water conservation treatment, amounting to 8 092 and 5 516 kg•hm^-2 in 2021 and 2022, respectively. At the same nitrogen application, the soluble sugar and protein contents of spring wheat grain showed an increasing and then decreasing trend with the decrease of irrigation quota, and the 25% nitrogen reduction and 20% water saving treatment reached the maximum value, which increased by 14.4%, 16.7%, and 25.5%, 23.5%, respectively, compared with the conventional water and nitrogen treatments, while there was no significant difference in starch content among the irrigation and nitrogen treatments. It was further found that stem strength was highly significantly and positively correlated with yield and protein content in grain and not significantly correlated with starch and soluble sugar content in grain.【Conclusion】Water saving of 20% under nitrogen reduction promoted the growth of spring wheat plant height and stem diameter, increased the accumulation of aboveground biomass, and increased the potassium content of stems, which in turn improved the stem strength of spring wheat, reduced the risk of lodging, increased the yield of spring wheat and improved the grain quality. Therefore, it was concluded that 20% water saving under nitrogen reduction conditions is a suitable irrigate and nitrogen management model for spring wheat in the Yellow River Irrigation Area of Ningxia.

HORTICULTURE

Genetic Diversity Analysis of Wax Gourd and Chieh-Qua Germplasm Resources Based on Phenotypic Traits and SSR Markers

ZHAI CaiJiao, GE LiJiao, CHENG YuJing, QIU Liang, WANG XiaoQiu, LIU ShuiDong

Scientia Agricultura Sinica. 2024, 57(17):  3440-3457.  doi:10.3864/j.issn.0578-1752.2024.17.010

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【Objective】To analyze the genetic diversity of wax gourd and chieh-qua germplasm resources, this study constructed a comprehensive evaluation system of wax gourd and chieh-qua germplasm and screened out excellent wax gourd and chieh-qua germplasms, so as to provide the valuable theoretical support for the innovation and variety selection of wax gourd and chieh-qua germplasm.【Method】148 wax gourd and chieh-qua germplasms from different sources were used as the test materials, and then the genetic diversity analysis was conducted using 28 phenotypic traits and 19 pairs of SSR markers. A variety of multiple statistical methods, including variation coefficient, Shannon-Wiener genetic diversity index, correlation analysis, principal component analysis, subordinate function value analysis, stepwise regression analysis, and cluster analysis, were used to analyze the genetic diversity and comprehensively evaluate on wax gourd and chieh-qua germplasm resources.【Result】Wax gourd and chieh-qua germplasm resources exhibited high genetic diversity, with the genetic diversity index of the 11 qualitative traits ranging from 0.39 (Generotype) to 1.45 (Fruit shape), the genetic diversity index of the 17 quantitative traits ranging from 1.89 (First male flower node) to 2.09 (Petiole length), and the variation coefficients of the 17 quantitative traits ranging from 9.76% (Seed shape index) to 63.95% (Weight per fruit). The variation coefficients of the first female flower node (42.32%), fruit length (42.95%), fruit shape index (47.05%), first male flower node (47.48%) and weight per fruit (63.95%) were all greater than 40%, which showed great potential for genetic improvement. Principal component analysis showed that the 18 main phenotypic traits were integrated into 6 principal components, with contribution rates ranging from 6.427% to 29.605%, and the additive contributing rate came up to 81.236%. The phenotypic comprehensive evaluation F value calculated by subordinate function values analysis showed that the BR12 (1.47) and BR25 (1.14) had the best characteristics. 15 phenotypic traits were extremely significantly correlated with the F value. The mathematical model of phenotypic evaluation was established by stepwise regression analysis, and 9 phenotypic comprehensive evaluation indicators were screened out. The number of alleles amplified by 19 SSR primers in the population material ranged from 2 to 6, the variation range of polymorphic information was 0.02-0.70, the Shannon’s diversity index distribution range was 0.06-1.48, which showed that 148 wax gourd and chieh-qua germplasm resources had rich genetic diversity. The genetic diversity of chieh-qua population was slightly higher than that of wax gourd population, and the genetic variation within individuals was the main reason for the overall genetic diversity of wax gourd and chieh-qua. Based on the classification of phenotypic traits and molecular markers, 148 wax gourd and chieh-qua germplasm resources were divided into 6 categories and 3 categories, respectively.The clustering results of the two methods did not cluster wax gourd and chieh-qua resources into two categories, and there was no obvious correlation with geographical location.【Conclusion】148 wax gourd and chieh-qua germplasms resources had rich phenotypic genetic variation and high genetic diversity. The leaf length, first female flower node, fruit length, fruit thick, pedicle length, seed width, wax powder, fruit shape and seed type could be used as the key indicators for identifying wax gourd and chieh-qua germplasm resources. The clustering results based on the classification of main agronomic traits and molecular markers were consistent to some extent. There was no obvious correlation between the cluster and the geographical origin.

Occurrence Rules of Citrus Fruit Shape and Peel Cracks

WANG XianDa, ZHANG LiJie, WU XingMing, CHENG DeMing, LI Jian

Scientia Agricultura Sinica. 2024, 57(17):  3458-3468.  doi:10.3864/j.issn.0578-1752.2024.17.011

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【Objective】The occurrence rules of cracks in citrus fruits with different fruit shapes were fully investigated to provide a new perspective for understanding the swelling and cracking of citrus fruits caused by field water imbalance before harvest.【Method】Based on the hierarchical characteristics of citrus peel structure, the fruit shell was considered a closed pressure vessel. By using the stress analysis method for the pressure vessel wall, the distribution of shell swelling pressure and the occurrence rules of peel cracks in different types of fruit shapes were evaluated.【Result】The shape of fruit shells affected the distribution of swelling pressure and the occurrence rules of cracks. (1) While the fruit shape index FSI in oval fruit was <1, the stress at the top of the fruit shell (i.e., σ_Top) was>equatorial meridional stress (i.e., σ_Φ-Mid) and>equatorial circumferential stress (i.e., σ_θ-Mid), which explained why the cracks in the oval-shaped fruit were often observed at the top of the fruit, e.g., the case for the early maturing cultivar Citrus reticulata Satsuma. If the fruit shape index FSI was >1, the stress at the top of the fruit shell (i.e., σ_Top) was<equatorial meridional stress (i.e., σ_Φ-Mid) and<equatorial circumferential stress (i.e., σ_θ-Mid), which could be frequently found in the elongated oval-shaped fruit with many longitudinal cracks like in the cultivar C. sinensis Navelina Navel. As for the fruit shape index FSI was =1, the cracks in the nearly spherical fruit shell were often located at the thinnest part of the fruit shell, and the ratio of stress at the top of the fruit to equatorial stress was inversely proportional to the thickness of the corresponding part of the fruit shell (i.e., σ_Top/σ_Mid=d_Mid/d_Top). For example, the cultivar Spring-sweet Tangelo often had circular transverse cracks at the thinnest part of the fruit waist, while the cultivar C. sinensis Newhall Navel cracks started at the thinnest part of the navel top. (2) The concave part of the nearly heart-shaped pomelo fruit was prone to forming a stress concentration condition for swelling, showing a great overlap with the point of maximum swelling pressure at the top of the sand sac, which led to a regular cracking at the top of the fruit as observed in C. grandis Duweiwendan. (3) Over the period with a dramatic increase of water potential in the field, the volume swelling ratio and fruit cracking rate in high-sugar fruits were higher than those in low-sugar fruits.【Conclusion】The cracks in citrus peel started at the point where the shell had the highest swelling pressure, while the direction of crack extension was perpendicular to the direction of maximum stress. Moreover, the more severe the non-sphericity and the more significant the difference in fruit shell thickness, the less the swelling pressure distribution and the higher the cracking rate of the fruit. A higher cracking rate of fruits with high sugar content than that of fruits with low sugar content was probably attributed to the unexpected increase in water potential.

FOOD SCIENCE AND ENGINEERING

Research Progress on Adsorption Properties of Solid Particles with Different Morphologies at the Interface of Pickering Emulsions

LU LiRong, YAO XiaoLin, LI Dan, WEI XiangYing, YUE Juan, YI GaoYang

Scientia Agricultura Sinica. 2024, 57(17):  3469-3481.  doi:10.3864/j.issn.0578-1752.2024.17.012

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Pickering emulsions represent a novel type of emulsion that employs solid particles as stabilizers. Solid particles can be tightly arranged at the oil-water interface by irreversible adsorption to form a monolayer or multilayer film, providing a spatial physical barrier for droplets. Compared with traditional emulsions, Pickering emulsions have attracted wide attention due to their advantages of high stability, low toxicity and low cost. The stability of Pickering emulsion is affected by many factors, such as solid particle properties, concentration, pH and preparation method, etc. Among them, the morphology of solid particles is one of the important factors that determines the interface adsorption behavior and the stabilization ability of emulsion. The different morphology of the solid particles leads to different ways of stabilizing the emulsion at the oil-water interface, mainly includes electrostatic interaction, capillary force, and mutual entanglement to form three-dimensional network structure. However, there is currently no systematic summary on the effects of solid particles with different morphologies on the interfacial adsorption characteristics of Pickering emulsions. Based on this, this review summarized the types of solid particles with different morphologies used to stabilize Pickering emulsions at home and abroad in recent years, including spherical, rod-like, thread-like, flaky, cubic, nanotube, dumbbell, ellipsoid and disc-like, etc. It focused on their interfacial adsorption properties for stabilizing Pickering emulsions, such as adsorption activity, arrangement and assembly behavior, inter-particle interactions and emulsion viscosity, etc. Based on the special interfacial adsorption properties of Pickering emulsions, the applications of Pickering emulsions in food fields such as active component encapsulation and delivery, lipid substitution, interfacial catalysis, antimicrobial and so on were reviewed. Furthermore, the study discussed the problems in the study of Pickering emulsions stabilized by non-spherical solid particles, and analyzed the development potential for active component encapsulation and delivery. The review provided the reference for the in-depth research and application of Pickering emulsions stabilized by solid particles with different morphologies.

ANIMAL SCIENCE·VETERINARY SCIENCE

Effects of Sodium Selenite on the in vitro Maturation of Porcine Oocytes and Their Embryonic Development Potentials

ZHANG Bing, YANG YanYan, FENG QianHui, SHI Wen, FANG YiZhen, HUANG JiaBao, SHI DeShun

Scientia Agricultura Sinica. 2024, 57(17):  3482-3493.  doi:10.3864/j.issn.0578-1752.2024.17.013

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【Objective】The aim of this study was to investigate the effects of sodium selenite (SS) on the in vitro maturation of porcine oocytes and their embryonic developmental potential, and to conduct a preliminary analysis of its mechanism, so as to provide the theoretical references for the improvement of the in vitro maturation system of porcine oocytes.【Method】After culturing porcine cumulus-oocyte complexes (COCs) in maturation medium containing different concentrations of SS (0, 20, 40, 60, and 80 nmol·L^-1) for 44 hours, observations were made, and cumulus cell expansion and oocyte maturation status were collected. Cumulus cell RNA was extracted, and oocytes were subjected to parthenogenetic activation (PA) treatment. The cleavage rate and blastocyst rate of parthenogenetic embryos were statistically analyzed at 48 and 168 hours of in vitro culture. Real-time fluorescence quantitative PCR and observation were used to detect cumulus cell expansion index (CEI), expression of cumulus expansion-related genes (Has2, Ptgs2), first polar body (PB1) extrusion rate, and cleavage rate and blastocyst rate of parthenogenetic embryos, to investigate the effects of different concentrations of SS on oocyte maturation, early embryo development, and cumulus cell expansion, and to determine the optimal concentration of SS. Total antioxidant capacity of COCs, glutathione (GSH) content, malondialdehyde (MDA) levels, and expression of antioxidant-related genes (CAT, PRDX2) in oocytes were detected by spectrophotometry and RT-qPCR to explore the effect of adding SS to the maturation medium on oocyte antioxidant capacity. Immunofluorescence technology was combined to detect the total number of cells in blastocysts and the expression of pluripotency genes (Nanog, Sox2) in blastocysts, to investigate the effect of SS on the developmental potential of parthenogenetic embryos.【Result】The RT-qPCR results showed that the addition of different concentrations of SS significantly promoted the expression of the PTGS2 gene (P<0.05), and at a concentration of 40 nmol·L^-1, the expression of the HAS2 gene, CEI, PB1 extrusion rate of oocytes, and blastocyst rate of early embryos were all significantly promoted (P<0.05). SS at concentrations of 40, 60, and 80 nmol·L^-1 promoted oocyte cleavage, with significant promotion observed at a concentration of 40 nmol·L^-1 (P<0.05). Based on those results, the optimal concentration of SS adding to the in vitro maturation medium for porcine oocytes was determined to be 40 nmol·L^-1. The results of antioxidant capacity testing showed that SS significantly increased the total antioxidant capacity of COCs, the level of GSH in oocytes, and the expression of antioxidant genes CAT and PRDX2, while significantly reducing MDA content (P<0.05). Immunofluorescence and PCR results showed that the number of inner cell mass in blastocysts and the expression of Nanog were increased in the SS group (P<0.05).【Conclusion】The addition of SS to the in vitro maturation medium of oocytes promoted cumulus cell expansion, enhanced oocyte maturation rates, and improved the developmental potential of matured oocytes. The beneficial effects of SS on the in vitro maturation of oocytes might be associated with its antioxidant properties.

Prokaryotic Expression, Antibody Preparation and Application of Major Non-Structural Proteins of Porcine Rotavirus

BIAN XianYu, LI SuFen, WANG JianXin, HAN Nan, LU HongTing, CHENG Xi, ZHOU JinZhu, TAO Ran, ZHU XueJiao, DONG HaiLong, ZHANG XueHan, LI Bin

Scientia Agricultura Sinica. 2024, 57(17):  3494-3506.  doi:10.3864/j.issn.0578-1752.2024.17.014

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【Background】Rotavirus (RV) is one of the main causes of acute viral gastroenteritis in young children and young animals worldwide, and it is of great significance in public health. Porcine rotavirus disease, caused by Porcine Rotavirus (PoRV), is an acute intestinal infectious disease that often results in gastrointestinal dysfunction in piglets, leading to severe symptoms, such as vomiting, diarrhea, and dehydration. Outbreaks of PoRV can result in significant economic losses in the pig industry. At present, there is no specific drug treatment for PoRV infection, so vaccination is the most economical way to control the infection. However, PoRV genotypes are various and easily mutable, and cross-protection between different genotypes is poor. Therefore, it is urgent to strengthen the epidemiological surveillance and pathogenic mechanism research of PoRV to explore new prevention and control strategies.【Objective】The prokaryotic system of Escherichia coli was employed to express the non-structural proteins (NSP), such as NSP2, NSP4, and NSP5 of PoRV. Subsequently, rabbits were immunized to produce polyclonal antibodies (pAbs) specific to these proteins, which could offer novel insights to the detection and prevention of PoRV.【Method】The NSP2, NSP4, and NSP5 genes of PoRV were codon-optimized and cloned into the pCold-sumo vector. The positive recombinant plasmids, with correct sequencing, were transformed into E. coli BL21 (DE3), and the recombinant proteins were obtained with IPTG induction. Protein expression was identified using SDS-PAGE and Western blot assay. The recombinant proteins were then purified and quantified using affinity chromatography. New Zealand white rabbits were immunized with NSP2, NSP4, and NSP5 recombinant proteins by a subcutaneous multi-point injection method to prepare pAbs. The titers of pAbs were determined using indirect ELISA technology. The reactivity of pAbs with PoRV was verified by indirect immunofluorescence (IFA) and Western blot assay, and their applications in PoRV infection were also explored.【Result】SDS-PAGE analysis indicated that the recombinant proteins of NSP2, NSP4, and NSP5 were expressed well in a soluble form. Indirect ELISA analysis showed that the titers of pAbs against the three proteins reached 1﹕81 000, indicating good immunogenicity of the expressed proteins. The results from IFA and Western blot assay demonstrated that the prepared pAbs could specifically react with the dominant prevalent genotypes of PoRV, but had no reaction with other common diarrhea pathogens. Western blot assay results also showed that the pAbs could be used for dynamic expression analysis of NSPs during PoRV infection and validating transfection of the three recombinant eukaryotic plasmids.【Conclusion】Here, the NSP2, NSP4 and NSP5 of PoRV were successfully expressed in E. coli, and their pAbs with high titer and good specificity were obtained, which laid the foundation for the study of PoRV pathogenesis and the development of prevention and control strategies.