Scientia Agricultura Sinica

Genetic Composition Analysis of a New High Quality and High Yield Wheat Cultivar Taikemai33

QI XiaoLei, WANG Jun, LÜ GuangDe, MU QiuHuan, MI Yong, SUN YingYing, YIN XunDong, QIAN ZhaoGuo, WANG RuiXia, WU Ke

Scientia Agricultura Sinica. 2024, 57(22): 4391-4401. doi:10.3864/j.issn.0578-1752.2024.22.001

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【Objective】Taikemai33, derived from a cross between Zhengmai366 and Huaiyin9908, is a new released wheat cultivar with high quality, high yield, and excellent disease resistance, which has a broad genetic base, and a high potential for application in wheat production. The objective of this study is to dissect the genetic composition of Taikemai33 to provide information for parental selection to use this cultivar to develop more new wheat cultivars. 【Method】Taikemai33 and its pedigree parents including Zhengmai366, Huaiyin9908, Yumai47, PH82-2-2, Yumai13, Yumai 2 hao, Bainong3217, Yanda24, Xiannong39, Fengchan 3 hao and Funo were screened using the 55K wheat SNP chip to dissect the genomic composition of Taikemai33 to evaluate the genetic contributions of each parental line to Taikemai33. 【Result】The similarity coefficient between Taikemai33 and its pedigree parents ranged from 0.72 to 0.93, and the genetic composition of Taikemai33 was highly similar to Zhengmai366, the pedigree mother parent, with a genetic similarity coefficient of 0.93. SNP marker analysis showed that the pedigree parents contributed different proportion to the genome of Taikemai33, with the pedigree mother contributed 66.57%, whereas the pedigree father contributed 33.43%, indicating that Taikemai 33 inherits more genetic materials from the maternal lineage. Furthermore, the pedigree mother contributed 71.0%, 85.0% and 49.4% to subgenome A, B and D of Taikeimai33, whereas those were 29.0%, 15.0% and 50.6% contributed by the pedigree father. For each chromosome, the pedigree mother contributed more on chromosome 1A, 2A, 3A, 4A, 7A, 1B to 7B, 1D and 2D, whereas the pedigree father contributed more on chromosome 5A, 4D, 6D and 7D. The contributions of the pedigree parents on 6A, 3D and 5D were equal. Taikemai33 genotype map showed that the contribution loci of the pedigree mother were distributed in clusters on chromosome 1A, 5A, 7A, 2B, 7B, 2D, with those from the pedigree father were on chromosome 4A, 5A, 6D, 7D. Interestingly, among the polymorphic SNP loci, between Zhenmai366 and Huaiyin9908, Taikemai33 showed 109 loci that were absent in both parents, distributing on 19 chromosomes except 1A and 6A. Chromosome 4A, 2B, 6B and 7D of Taikemai33 confer most of the polymorphic SNPs in clusters with cluster number of 10, 9, 11, and 9. 【Conclusion】We constructed the genotype map and dissected the genetic composition of Taikemai33, determined the loci contributed by the pedigree parents and identified that Taikemai33 inherited more genetic materials from the pedigree mother and conferring some specific loci different with the pedigree parents.

Development and Identification of Molecular Markers for Oil-Related Functional Genes and Polymerization Analysis of Excellent Alleles in Soybean

WU ChuanLei, HU XiaoYu, WANG Wei, MIAO Long, BAI PengYu, WANG GuoJi, LI Na, SHU Kuo, QIU LiJuan, WANG XiaoBo

Scientia Agricultura Sinica. 2024, 57(22): 4402-4415. doi:10.3864/j.issn.0578-1752.2024.22.002

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【Objective】Polymerizing soybean high oil genotypes aims at breeding varieties with higher oil content to improve economic efficiency and nutritional value. It is of great significance to increase agricultural output, reduce processing costs and meet global demand for vegetable oil growth.【Method】Glyma.18G027100 C2 gene family was identified by bioinformatic analysis method at the whole genome level. A total of 66 soybean C2 gene family members were identified, named GmC2-01.1-GmC2-20.2 according to chromosome position. Tissue pattern analysis revealed that 7 genes were highly expressed in grains among 66 C2 family genes (GmC2-03.6, GmC2-02.7, GmC2-07.2, GmC2-18.1, GmC2-18.4, GmC2-19.1 and GmC2-20.2). In order to analyze the effect sites of these genes on soybean oil content, SNP sites in the coding regions of these genes were obtained from SFGB database. Correlation analysis of oil content in two years showed that GmC2-18.1 has SNP loci that significantly affect oil content. The genetic diversity of GmC2-18.1 coding region was analyzed by 12 extreme materials. There was a G/A mutation at 2 038 273 bp in coding region of Wm82.a2.v1 version, which regulated seed oil content. It was preliminarily speculated that this gene played a role in seed development or nutrient accumulation. Then, SNP/InDel molecular markers were developed for GmC2-18.1^-G/A gene combined with InDel natural allelic variation site 225 bp upstream of the start codon of GmSWEET39, T/C natural allelic variation site at 8 381 058 bp in coding region of GmST1, A/C natural allelic variation site at the third exon of 41 854 422 bp in coding region of GmMFT. 1 200 soybean germplasm resources from three ecological regions in China were identified by markers in 2 years.【Result】Analysis of variance showed that GmC2-18.1^-G, GmSWEET39^-Deletion, GmST1^-T and GmMFT^-A significantly increased oil content by 1.72, 1.95, 1.58 and 2.06 percentage points (P<0.01). The results showed that the average oil content of soybean seeds carrying GmC2-18.1^-G, GmSWEET39^-Deletion, GmST1^-T and GmMFT^-A high-oil allele type (PFAT-1) was 22.89%, which increased by about 4.5% compared with that carrying GmC2-18.1^-A, GmSWEET39^-Insertion, GmST1^-C and GmMFT^-C low-oil allele type (PFAT-14). 5 percentage points, the contribution rate to oil content is about 21.69%. 【Conclusion】Based on the markers developed above, 115 PFAT-1 high oil alleles were screened.

Cloning and Functional Verification of SiCIPK21 Gene in Foxtail Millet

DU YanWei, YAN XiaoGuang, ZHAO JinFeng, JIA SuQing, WANG GaoHong, YU AiLi, ZHANG Peng

Scientia Agricultura Sinica. 2024, 57(22): 4416-4430. doi:10.3864/j.issn.0578-1752.2024.22.003

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【Objective】The Ca²⁺-CBL-CIPK signaling pathway has important functions in plant response to abiotic stresses. By cloning the SiCIPK21 gene and studying its function under stress conditions, we provide a key candidate gene and theoretical basis for molecular breeding of foxtail millet with stress tolerance.【Method】Bioinformatics was used to analyze the cis-acting elements in the promoter region of this gene and predict the interactions between this protein and AtCBLs in Arabidopsis thaliana. SiCIPK21 was cloned by PCR, and a fusion expression vector was constructed for transient expression in tobacco to determine the subcellular localization. foxtail millet cv. Yugu 1 was used as material, and specifically amplified part of the SiCIPK21 gene fragment from Yugu 1 leaves, and recombinant vector VIGS-pTRV2-SiCIPK21 was constructed, using the phytoene desaturase gene (SiPDS) as the indicator gene, and seedlings of foxtail millet at the two-leaf stage were selected and infiltrated by cotyledon injection to investigate the role of SiCIPK21 under salt stress (250 mmol·L^-1 NaCl) by using virus-induced gene silencing (VIGS) technology. T₃ generation transgenic lines were obtained by overexpressing SiCIPK21 in Arabidopsis thaliana. Phenotypes at germination were analyzed under different concentrations of NaCl (150/175 mmol·L^-1), mannitol (300/400 mmol·L^-1) and ABA (0.25/0.5 μmol·L^-1) treatments, and salt and drought tolerant phenotypes at seedling stage were also analyzed.【Result】Subcellular localization revealed that SiCIPK21 was located in the nucleus. The protein SiCIPK21 might interact with AtCBL2, AtCBL3, AtCBL4, AtCBL9, and AtCBL10 in Arabidopsis thaliana. The promoter region of SiCIPK21 contained adverse response elements, suggesting that SiCIPK21 may participate in the adverse responses. The VIGS gene silencing demonstrated that SiCIPK21-silenced foxtail millet plants had increased sensitivity to salt stress than the control plants. Three independent T₃ generation Arabidopsis thaliana overexpression lines (2#, 3# and 6#) were obtained by genetic transformation. Overexpression lines showed significantly higher germination rate, germination speed, green cotyledon unfolding rate, root length and fresh weight than the wild-type plants (WT) at different concentrations of NaCl (150/175 mmol·L^-1), mannitol (300/400 mmol·L^-1) and ABA (0.25/0.5 μmol·L^-1). Moreover, phenotypic analysis of salt and drought tolerance in Arabidopsis seedlings showed that overexpression lines had significantly higher survival rates and chlorophyll contents than WT.【Conclusion】SiCIPK21 is a positive regulator of plant response to salt and drought stresses, which makes it a candidate gene for improving stress tolerance by molecular breeding in foxtail millet.

The Difference of Grain Starch Accumulation Dynamics and Yield Formation of Spring Maize Under Different Nitrogen Application Rates in Black Soil

CAO WenZhuo, YU ZhenWen, ZHANG YongLi, ZHANG Zhen, SHI Yu, WANG YongJun

Scientia Agricultura Sinica. 2024, 57(22): 4431-4443. doi:10.3864/j.issn.0578-1752.2024.22.004

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【Objective】The physiological mechanism of starch accumulation and yield formation of spring maize in black soil under suitable nitrogen application was studied, in order to provide the theoretical basis for high yield and high efficiency cultivation technology of spring maize.【Method】Field experiments were conducted in the spring maize growing seasons of 2022 and 2023 in Gongzhuling City, Jilin Province, Jilin Academy of Agricultural Sciences. Five nitrogen application treatments were set up: no nitrogen (N0), 90 kg·hm^-2 (N90), 135 kg·hm^-2 (N135),180 kg·hm^-2 (N180), and 225 kg·hm^-2 (N225). The synthesis capacity of sucrose in the ear leaf and the activity of key enzymes in sucrose metabolism were measured to investigate the sucrose synthesis capacity of the ear leaf and grain starch synthesis capacity under different nitrogen application rates. The accumulation characteristics of total starch and its components in maize grain were fitted by Logistic equation to clarify the impact of nitrogen application rate on the dynamic of starch accumulation in maize grain and grain yield formation.【Result】(1) With the escalation of nitrogen application rates, the yield of spring maize exhibited an initial increase followed by a subsequent decrease. The average yields under N0, N90, N135, N180, and N225 treatments over two years were 8 992.90, 11 199.47, 12 126.78, 14 049.42, and 13 213.21 kg·hm^-2, respectively. Notably, the N180 treatment resulted in the highest yield. (2) The sucrose content, sucrose synthetase (SS) and sucrose phosphate synthetase (SPS) activities in ear leaves at 0, 12, 24, 36 and 48 days after flowering under N180 treatment were significantly higher than those under N0, N90 and N135 treatment, and there was no significant difference between N225 and N180 treatment. At 24, 36 and 48 days after flowering, the activity of soluble amylase (SSS) in grains treated under N180 was the highest, and the average SSS activity of grains under N0, N90, N135 and N225 was increased by 62.43%, 31.33%, 14.85% and 7.80%, respectively. (3) Logistic equation analysis showed that the accumulation rate and active accumulation period of total starch, branch chain and amylose in grains of each treatment first increased and then decreased with the increase of nitrogen application amount, and N180 treatment was the best. Compared with N0, N90, N135 and N225 treatments, the two-year average total starch accumulation rate and total starch accumulation active period under N180 treatment were 43.35%, 23.16%, 13.22%, 5.92% and 7.30%, 3.84%, 4.11%, 3.83%, respectively. When the average grain starch accumulation rate reached the maximum in two years, the grain starch accumulation amount was 12.90 g, and the total starch accumulation amount at each treatment maturity stage was 6 725.60, 8 510.17, 9 150.62, 10 387.35 and 9 604.04 kg·hm^-2, respectively. (4) Correlation analysis results showed that spring maize yield was significantly positively correlated with sucrose content, sucrose synthase activity, sucrose phosphate synthase activity, soluble starch synthase activity in grains, total starch accumulation, amylopectin accumulation and amylose accumulation in grains at ear position at filling stage. Sucrose content, sucrose synthetase activity, sucrose phosphate synthetase activity and soluble starch synthetase activity in grain were also significantly positively correlated with starch and its component accumulation in grain.【Conclusion】Under the treatment of 180 kg·hm^-2 nitrogen application, the spring maize during grain filling exhibited the highest activities of key sucrose metabolism enzymes in the ear sheath leaves, as well as the highest activity of starch synthesis enzymes in the soluble grains. Additionally, it showed the maximum rate of starch accumulation and longest period of active starch accumulation. Furthermore, this treatment resulted in the highest grain yield and starch accumulation, making it the optimal treatment under the experimental conditions.

Effects of Different Strip Intercropping Patterns on the Growth and Productivity in Cotton

ZHANG YongLi, ZHANG Ning, XU Jiao, XU DouDou, CHENG Fang, ZHANG ChengLong, WU BiBo, GONG YangCang, HE YunXin, WEI ShangZhi, TU XiaoJu, LIU AiYu, ZHOU ZhongHua

Scientia Agricultura Sinica. 2024, 57(22): 4444-4458. doi:10.3864/j.issn.0578-1752.2024.22.005

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【Objective】By analyzing the effects of different strip intercropping patterns on cotton biomass accumulation and distribution, photosynthetic performance and yield, the potential mechanism of cotton yield increase and efficiency under different strip intercropping patterns was explored, so the optimum cotton strip intercropping planting pattern suitable for the Yangtze River basin was proposed. 【Method】A two-point field experiment was conducted with monocropping cotton (MC) as the control, and three intercropping patterns of cotton-sweet potato (CS), cotton-bean (CB) and cotton-melon (CM) were set up, while two strip configurations were as follows: 3:3 and 4:2. The effects of different strip intercropping patterns on biomass accumulation, organ distribution, light and performance and yield of cotton were analyzed, and the ratio of cotton to soil equivalent and economic benefit under different strip intercropping patterns were calculated and compared. 【Result】Compared with MC, The average seed cotton yield and lint cotton yield under strip intercropping patterns in two field trials were significantly increased. Among them, compared with cotton intercropping with sweet potato and cotton intercropping with melon, the cotton intercropping with bean had the most significant advantage in cotton yield. and the yield of CB 3:3 pattern seed cotton was 23.20% and 32.46% higher than MC, respectively; compared with MC, the yield of lint was increased by 26.43% and 32.53%, respectively; the main reason was that the number of bolls per plant was 26.58 and 24.43, respectively, which were significantly increased by 22.21% and 28.85% compared with that of single cropping. The boll weight of cotton intercropping with sweet potato CS 4:2 in Hengyang was 3.01% lower than MC. At full boll period, the biomass accumulation of cotton plant was higher than MC, and the proportion of reproductive organs allocation was significantly higher than that of stem and leaf, the proportion of reproductive organs in each intercropping pattern in Hengyang was more than 50%. From full squaring period to boll opening period, the leaf area index of all treatments showed a trend of first increasing and then decreasing. Compared with MC, the relative chlorophyll content and net photosynthetic rate of cotton plants were significantly increased under each intercropping pattern at full boll period. Among them, the cotton intercropping with beans at two field trials was the most advantageous. The net photosynthetic rate was 6.25%-6.29% and 2.85%-2.90% higher than MC, respectively, so it could effectively improve the photosynthetic performance of cotton plant and finally achieve yield increase. Under different strip intercropping patterns, the total economic benefit of cotton field in the two field trials increased by 1.24-2.70 times and 1.42-3.09 times, respectively, compared with MC. From the point of view of partial land equivalent ratio of cotton, except CS 4:2 pattern in Changsha, the other strip intercropping pattern in two field trials showed the advantage of intercropping yield. 【Conclusion】The increase of yield in different strip intercropping patterns was mainly achieved through the improvement of biomass accumulation, assimilate allocation and photosynthetic performance. The best performance was cotton intercropping with sweet potato CS 3:3 pattern, which ensured higher yield and intercropping advantages, and was suitable for spreading planting in the Yangtze River basin.

Effects of Planting Density on the Pod Characteristics and Exploring Strategie Analysis to Increase Yield in High-Yield Rapeseed

LI YiYang, WANG Long, QIAN Chen, LI Jing, LIN GuoBing, QU WenTing, WANG Yan, LIN YaoWei, HUANG YiHang, ZHENG JingDong, YOU JingJing, ZUO QingSong

Scientia Agricultura Sinica. 2024, 57(22): 4459-4472. doi:10.3864/j.issn.0578-1752.2024.22.006

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【Objective】Planting density is an important factor affecting pod quantity and quality in rapeseed. Based on a certain number of rapeseed pod quantity, the quality of rapeseed kernels was improved to further tap the potential of rapeseed production, so as to explore the effect of kernels quality on the formation of rapeseed population yield.【Method】The experiment was conducted to investigate the effects of planting density on rapeseed yield, canopy, and pod characteristics during the 2021 to 2022 and 2022 to 2023 growing seasons in Shiye Experimental site of Yangzhou University in Zhenjiang. Qinyou10 and Ningza1838 were used as the rape test materials. Five planting density levels were set as 2.4×10⁵ plant/hm² (D1), 3.6×10⁵plant/hm² (D2), 4.8×10⁵plant/hm² (D3), 6.0×10⁵plant/hm² (D4), and 7.2×10⁵·plant/hm² (D5). 【Result】As planting density increased from D1 to D5, the number of pods in population and plot seed yield initially increased and decreased thereafter. The number of pods in population in D3 and D4 was higher than that in other densities, and plot seed yield reached the maximum value in D2 and D3. The canopy thickness, ranging from 41.50 cm to 80.98 cm across different treatments, increased with an increase in planting density from D2 to D5. The pod density, ranging from 0.98×10⁴ to 2.16×10⁴ per cubic meter, significantly increased as planting density increased. According to the number of seeds per pod across different treatments, the pods were categorized into low efficient pod (≤14), middle efficient pod (15 to 17), and high efficient pod (≥18), respectively. The average yield per pod of low, middle, and high efficient pod was 19.40×10^-3, 53.41×10^-3 and 80.62×10^-3 g, respectively. The allocation ratio of pod number ranged from 27.60% to 40.96% for low efficient pod, 8.39% to19.73% for middle efficient pod and 39.31% to 63.28% for highly efficient pod, respectively. Among the three types of pods, the ratio of yield for highly efficient pod was the highest and the range of variation for low, middle and high efficient type was from 8.41% to 15.62%, 7.24% to 22.01% and 62.60% to 83.92%, respectively. As planting density increased from D3 to D5, the quantity and allocation ratio of highly efficient pod significantly decreased, resulting in decreasing seed yield. 【Conclusion】When the target seed yield was 4 500 kg·hm^-2, the appropriate planting density and population quality indicators with suitable sowing date were as follows: planting density ranged from 3.6 to 4.8×10⁵plant·hm^-2, the number of pods in population ranged from 83.0 to 94.0×10⁶·hm^-2, and the allocation ratio of high efficient pod (≥18 seeds per pod) is more than 50%. Increasing the number of seeds per pod to improve the quantity and allocation ratio of highly efficient pod was an effective way to further enhance the seed yield in rapeseed.

Research on Prevention and Control Technology of Citrus Yellow Vein Clearing Virus Based on VIGS

LI ChuXin, SONG ChenHu, ZHOU JinHuan, LI JiaXin, WANG XinLiang, TIAN XuBin, SONG Zhen

Scientia Agricultura Sinica. 2024, 57(22): 4473-4482. doi:10.3864/j.issn.0578-1752.2024.22.007

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【Objective】Citrus yellow vein clearing virus (CYVCV) is a novel virus that poses a significant threat to the citrus industry. Currently, there is no effective therapeutic agent. The primary strategies for prevention and management involve utilizing virus-free seedlings and implementing stringent control measures against insect vectors. The objective of this study is to investigate the technology of virus-induced gene silencing (VIGS) as a means of developing antiviral “vaccines” for CYVCV, and to offer innovative approaches for the prevention and management of citrus viral diseases.【Method】Based on the previously constructed VIGS vector pCLBV201 in the laboratory, a series of recombinant vectors were designed and developed to target the conserved regions of the CYVCV genome, specifically open reading frame 1 (ORF1), open reading frame 6 (ORF6), coat protein (CP), and triple gene block (TGB). Agrobacterium-mediated vacuum infiltration was inoculated on Eureka lemon, followed by RT-PCR detection. After acquiring several positive plants including pCLBV201-ORF1, pCLBV201-ORF6, pCLBV201-CP, and pCLBV201-TGB, CYVCV infectious clones were inoculated via Agrobacterium-mediated injection, with plants infiltrated with the pCLBV201 empty vector serving as controls. Subsequent RT-qPCR, Western blot analysis, symptom observation, and disease index statistics were conducted to elucidate the preventive and control effects of the various VIGS recombinant vectors on CYVCV. 【Result】A series of recombinant vectors of pCLBV201 were constructed, and the results of RT-PCR following inoculation indicated that multiple positive plants for pCLBV201-ORF1, pCLBV201-ORF6, pCLBV201-CP, and pCLBV201-TGB were obtained, respectively. CYVCV infectious clones were inoculated by injection. The results of RT-qPCR at 7, 14, 28, 70, and 150 dpi (days post infection) showed that the relative expression of CYVCV in the pCLBV201-CP and pCLBV201-TGB treatment groups was significantly lower than that in the control group. Western blot analyses conducted at 70 and 150 dpi showed a significant decrease in the expression of CP protein in the pCLBV201-CP and pCLBV201-TGB treatment groups. Observational symptoms indicated that the control group exhibited typical manifestations of CYVCV infection, such as severe vein clearing and leaf distortion, whereas the pCLBV201-CP treatment group displayed mild symptoms, and the pCLBV201-TGB treatment group showed no apparent symptoms. The disease index statistics at 70 and 150 dpi demonstrated that the disease indices of pCLBV201-CP and pCLBV201-TGB were the lowest, recorded at 17.6, 41.2 and 15.6, 29.1, respectively, while the control group had indices of 52.1 and 80.0, showing obvious differences.【Conclusion】The VIGS-based technology for the prevention and control of CYVCV was developed, which clarified that pCLBV201-CP and pCLBV201-TGB could significantly reduce the virus titers and alleviate the symptoms caused by the virus. They have the potential to be used as “vaccines” for CYVCV prevention and control.

The Mechanisms of Mitochondrial Protein-Coding Genes ND6 and ATP6 in Regulating Cold Tolerance of Cryptolestes ferrugineus

YUAN GuoQing, CHEN ErHu, TANG PeiAn

Scientia Agricultura Sinica. 2024, 57(22): 4483-4494. doi:10.3864/j.issn.0578-1752.2024.22.008

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【Background】Low temperatures can induce adaptive responses in ectothermic animals, the grain pest Cryptolestes ferrugineus has exhibited a remarkable adaptability to cold environment. Mitochondrial protein-coding genes are crucial for maintaining respiration metabolism and ATP synthesis in organisms, and they play various functions in insects. However, the role of these genes in cold adaptation is poorly understood.【Objective】The purpose of this study is to elucidate the roles of mitochondrial protein-coding genes in the formation of cold tolerance of C. ferrugineus.【Method】The cold tolerance of C. ferrugineus ST and CK populations was determined at a lethal low temperature (-20 ℃). The respiration rate and ATP content of C. ferrugineus ST and CK populations were measured using a CO₂ detector and an ATP content assay kit. The relative expression levels of 13 mitochondrial protein-coding genes between the ST and CK populations were assessed by using RT-qPCR. RNA interference (RNAi) technology was employed to knock down the key mitochondrial protein-coding genes ND6 and ATP6 in C. ferrugineus, and then the expression levels of the remaining 12 mitochondrial protein-coding genes, respiration rate, ATP content, and changes in cold tolerance were explored after effective silencing of ND6 and ATP6.【Result】The cold tolerance of C. ferrugineus CK population was higher than that of the ST population, while the respiration rate and ATP content of the CK population were only 58.68% and 62.54% of those in the ST population, respectively. Additionally, the expression levels of 12 mitochondrial protein-coding genes (except ND3) in the CK population were significantly lower than those in the ST population. These results suggested a negative correlation between cold tolerance and physiological indicators (respiration rate, ATP content, and the expression levels of mitochondrial protein-coding genes). When the key mitochondrial protein-coding genes ND6 and ATP6 were effectively silenced via dsRNA feeding, the respiration rate and ATP content were significantly reduced, while cold tolerance in C. ferrugineus was significantly enhanced.【Conclusion】The mitochondrial protein-coding genes ND6 and ATP6 are involved in the formation of cold tolerance by regulating energy metabolism in C. ferrugineus.

Effects of Nitrogen Reduction Application of Summer Maize- Soybean Intercropping on Agronomic Traits and Economic Benefits as well as Its Yield of Subsequent Wheat

DONG KuiJun, ZHANG YiTao, LIU HanWen, ZHANG JiZong, WANG WeiJun, WEN YanChen, LEI QiuLiang, WEN HongDa

Scientia Agricultura Sinica. 2024, 57(22): 4495-4506. doi:10.3864/j.issn.0578-1752.2024.22.009

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【Objective】The purpose of this study was to determine the effects of nitrogen application amount on the yield composition, economic benefit of summer sowing intercropping crops and the yield of winter wheat. 【Method】From 2022 to 2023, the representative farmlands were selected in Yucheng City, Shandong Province, which was the main extension area of maize-soybean strip intercropping. Maize monoculture (Nitrogen application rate: 225 kg·hm^-2), soybean monoculture (Nitrogen application rate: 45 kg·hm^-2), maize-soybean intercropping with full nitrogen application (Nitrogen application rate: 270 kg·hm^-2), maize-soybean intercropping with reduced nitrogen application (Nitrogen application rate: 135 kg·hm^-2) were set up in summer sowing season, and the subsequent crops were planted with wheat without fertilizer treatment. The effects of different summer sowing treatments on photosynthetic characteristics, agronomic traits, economic benefits and yield of subsequent wheat were analyzed. 【Result】Both planting pattern and nitrogen application amount had significant effects on crop growth and development. Compared with maize monoculture, the chlorophyll content, P_n, G_s, C_i and T_r of maize leaves were significantly decreased by intercropping reduced nitrogen application (135 kg·hm^-2). However, the P_n, G_s and T_r of leaves of intercropping full nitrogen maize (270 kg·hm^-2) were significantly increased by 8.8%, 10% and 11.6%, respectively. Intercropping system resulted in decreased chlorophyll content of soybean, inhibited leaf P_n, G_s, and T_r. In terms of agronomic characteristics, stem length increased, pod number per plant decreased, and yield decreased by 65.1%-68.4%. There was no significant difference in the agronomic characteristics and yield of maize under the intercropping system with full nitrogen application, and the economic benefit was the highest under this system, reaching 22 607 yuan/hm², while the agronomic characteristics such as ear length, grain number per ear and hundred-grain weight of maize under reduced nitrogen application significantly decreased, and the yield decreased by 14.8%. However, in general, the land equivalent ratio of both maize and soybean treatments was also greater than 1. Economic benefit and nitrogen uptake were increased by 4.8%-11.5% and 19.7%-38% compared with monocrop. When winter wheat was not fertilized, the grain yield and crop nitrogen uptake of aftercrop winter wheat with full nitrogen application in summer sowing were higher than that under other treatments, and there was no significant difference between the yield of winter wheat with reduced nitrogen application between summer sowing seasons and that of winter wheat with summer sowing maize. 【Conclusion】Therefore, from the comprehensive analysis of agronomic characteristics, yield and economic benefits as well as the effects on aftercrop, the effect of total nitrogen application in intercropping was better than that of reduced nitrogen application in intercropping. However, considering the yield, economic and environmental benefits, the amount of nitrogen application in intercropping should be further optimized.

Re-Evaluation of China’s Agricultural Net Carbon Sink: Current Situation, Spatial-Temporal Pattern and Influencing Factors

TIAN Yun, WANG XiaoRui, YIN MinHao, ZHANG HuiJie

Scientia Agricultura Sinica. 2024, 57(22): 4507-4521. doi:10.3864/j.issn.0578-1752.2024.22.010

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【Objective】Based on the current “dual carbon” strategic goal, this study aimed to clarify the current characteristics, spatio-temporal pattern and influencing factors of agricultural net carbon sink, so as to provide the important support for accelerating agricultural sink increase and emission reduction.【Method】Based on the scientific reconstruction of the index system, the carbon sink/carbon emission factor method was used to measure and analyze the current situation of China’s agricultural net carbon sink. Then the spatial autocorrelation model was used to discuss the spatial dependence and spatial heterogeneity. Finally, the least-squares method was used to analyze the main factors affecting the change of its intensity. 【Result】From 2005 to 2022, the total amount of agricultural net carbon sink in China was in an obvious upward trend, although there were some interannual fluctuations, and its evolutionary characteristics could be roughly divided into four stages, namely, “continuous rise”, “fluctuating decline”, “rapid rise”, and “slow rise”; the intensity of agricultural net carbon sink was also in an obvious upward trend, with only a slight difference in the trajectory of the evolution, and the difference in its growth rate could be roughly categorized into four stages: “continuous rapid growth”, “slow growth”, “fluctuating ups and downs”, and “slow growth”. 2022, the amount of agricultural net carbon sink had a large interprovincial difference, with Inner Mongolia being the first and Shanghai being the last, and compared with the year of 2005, all the provinces had a significant increase. In 2022, the net carbon sink intensity of agriculture would be the highest in Henan and the lowest in Qinghai, with all provinces showing different degrees of increase compared with 2005. China’s provincial agricultural net carbon sink intensity as a whole showed obvious spatial dependence, but there was also a local spatial clustering phenomenon, more than 70% of the provinces showed obvious spatial clustering characteristics, and the number of provinces located in the high-high clustering and the low-low clustering was approaching. The structure of arable land use, urbanization level, rural residents' income level and the internal industrial structure of agriculture all had a significant impact on the intensity of agricultural net carbon sink; specifically, the higher the ratio of sown area of grain crops, or the higher the urbanization rate, or the higher the income level of rural residents, or the larger the ratio of plantation industry to animal husbandry, the higher the intensity of net carbon sink in agriculture.【Conclusion】The total amount and intensity of China’s agricultural net carbon sink were in a fluctuating upward trend and there were obvious inter-provincial differences. The intensity of China’s agricultural net carbon sink showed obvious spatial dependence and spatial heterogeneity. The intensity of the agricultural net carbon sink was affected by the structure of arable land use, the level of urbanization, the level of rural residents' income, and the structure of the internal industries of agriculture. The measures should be taken to promote the enhancement of sink and emission reductions and to promote the enhancement of agricultural net carbon sink in agriculture, such as establishing a sound policy support system for the development of low-carbon agriculture, strengthening inter-provincial exchanges and cooperation, and increasing financial support for agriculture.

Effects of Streptomyces sp. TOR3209 on Chlorophyll Fluorescence Characteristics and Xanthophyll Cycle in Tomato Plants Under Cold Stress

MA Jia, PENG JieLi, JIA Nan, WANG Xu, WANG ZhanWu, HU Dong

Scientia Agricultura Sinica. 2024, 57(22): 4522-4540. doi:10.3864/j.issn.0578-1752.2024.22.011

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【Objective】In order to explore the biological mechanism of Streptomyces sp. TOR3209 in improving the low temperature tolerance of tomato, and to reveal the protective mechanism of TOR3209 on photosystem II (PSII) from two aspects (chlorophyll fluorescence characteristics and xanthophyll cycle).【Method】As the experimental material, tomato seedlings of quadrifoil stage were applied with TOR3209 when transplanted into the pots, cold stress (5 ℃) was imposed on the 30th day after transplanting. The experiment was divided into four parts, which were inoculated plants (TOR3209), non-inoculated plants (NI), inoculated plants exposed to cold stress (TOR3209+C) and non-inoculated plants exposed to cold stress (NI+C). The differences in PSII performance, chlorophyll fluorescence parameters related to NPQ, xanthophyll cycle component, violaxanthin de-epoxidase (VDE) activity, and ascorbate-glutathione (AsA-GSH) cycle in plants of different treatments were compared.【Result】Streptomyces sp. TOR3209 could alleviate the decrease of actual photochemical efficiency of PSII Y (II) by cold stress and avoid PSII photoinhibition. Defensing to the cold stress, the shape of chlorophyll a fluorescence transient (OJIP) curve was significantly changed with increased in J step and an emergence of K step; while the approximated initial slope of the fluorescence transient (M_o) increased, and the rate at which trapped excitons transfer electrons to other electron receptors downstream of primary quinone receptor (Q_A) in the electron transport chain (Ψ_o) decreased, and the performance index on absorption basis (PI_ABS) decreased in JIP-test of tomato leaves. The inoculation of TOR3209 under cold stress prevented a significant increase in variable fluorescence intensity at J step and an emergence of K step, while the M_o, Ψ_oand PI_ABSreturned to the levels in plants of NI, indicating that TOR3209 protected the electron transporters at PSII acceptor side and oxygen-evolving complex (OEC) at PSII donor side. The inoculation of TOR3209 also prevented a significant decrease in PI_ABS and the performance index on cross section basis (PI_CS) in tomato leaves as revealed by JIP-test, which in combination with the significantly increased NPQ and protective heat dissipation (Ф_NPQ), as well as the significantly decreased non-regulatory energy dissipation (Ф_NO), evidenced that the main mechanism of TOR3209 to protect PSII was the protective heat dissipation. Cold stress apparently decreased the de-epoxidation state (DEPS) of xanthophyll cycle, at the same time, reduced the levels of xanthophyll cycle components, the activities of VDE and antioxidases in AsA-GSH pathway (ascorbate peroxidase APX, glutathione reductase GR, monodehydroascorbate reductase MDHAR), and contents of antioxidants (ascorbate AsA, glutathione GSH), slowed down the xanthophyll cycle, and depressed the photosynthetic capacity of tomato leaves. However, TOR3209 inoculation could increase the DEPS of xanthophyll cycle, enhance the levels of xanthophyll cycle components and VDE activity under cold stress, which further raised the level of PSII non-photochemical fluorescence quenching coefficient, prevented excess excitation energy, and protected the photosynthetic apparatus. Meanwhile, TOR3209 inoculation improved the activities of the above-mentioned antioxidases and AsA content under cold stress, optimized the AsA-GSH cycle to confront the accumulation of reactive oxygen species (ROS) and facilitate xanthophyll cycle.【Conclusion】The improvement of cold tolerant capacity in tomato plants by TOR3209 inoculation was reflected in maintaining PSII stability by increasing the photosynthetic electron transfer activity, alleviating the damage of PSII photoinhibition via enhancing the xanthophyll cycle, and reducing oxidative stress on PSII by optimizing AsA-GSH cycle.

Effects of Wheat and Broad Bean Catch Crop and Their Decomposed Liquids on the Growth and Blight of Continuous Cropping Pepper Seedlings

LU Lu, LI YiNuo, ZHANG XiuGuo, GAO DanMei, WU FengZhi

Scientia Agricultura Sinica. 2024, 57(22): 4541-4552. doi:10.3864/j.issn.0578-1752.2024.22.012

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【Objective】To clarify the effects of catch crop decomposition liquid on the growth and blight of continuous pepper seedlings, and to provide the theoretical basis and technical support for wheat and broad bean catch crop to alleviate the continuous cropping obstacles of peppers. 【Method】 Pepper and pepper continuous cropping soil were used as the research object. Firstly, seven catch crop treatments were set up, including wheat (A), broad bean (B), large-leafed skunk cabbage (C), wheat and broad bean mixture (AB), wheat and large-leafed skunk cabbage mixture (AC), broad bean and large-leafed skunk cabbage mixture (BC), and wheat, broad bean and large-leafed skunk cabbage mixture (ABC), and the non-catch crops were used as the control (CK). Study the effects of different treatments on the pepper growth and blight. Secondly, in order to ascertain the role of its catch crop decomposition liquid in promoting growth and disease control, four treatments with different concentrations of wheat and broad bean mixture straw decomposition liquid (0.01, 0.03, 0.05, and 0.07 g·mL^-1) were set up to investigate different treatments the effects on the growth and blight of pepper seedlings, using distilled water as the control (CK). 【Result】 When transplanting for 20 and 30 d, the fresh weight of the whole plant, dry weight of the whole plant and plant height of pepper after mixed catch crop treatment of wheat and broad bean were significantly higher than those no-catch crops treatments, and the incidence and disease index were significantly lower than those no-catch crops treatments. The disease index of the wheat and broad bean mixed catch crop treatment was significantly lower than that of all other treatments. The whole plant fresh weight of pepper was significantly increased at 20 d and 30 d of treatment with wheat and broad bean mixed straw decomposed liquids. At 30 d, the dry weight of the whole pepper plant was significantly increased except for 0.01 g·mL^-1 treatment. Compared with distilled water treatment, 0.03 g·mL^-1 treatment significantly increased the root length, average diameter of roots, root surface area, root volume, root tip number and leaf peroxidase (POD) and polyphenol oxidase (PPO) activities of pepper (P<0.05). The mycelial diameter, zoospore germination rate and sporulation yield of Phytophthora capsici treated with different concentrations of wheat and broad bean mixture straw decomposed liquids were significantly lower than those of distilled water treatment (P<0.05). The mycelial diameter and zoospore germination rate of 0.03 g·mL^-1 treatment were significantly lower than those of other treatments, and the inhibition effect of 0.03 g·mL^-1 treatment on phytophthora blight and blight was the best. 【Conclusion】The mixed catch crop of wheat and broad bean had a growth-promoting and disease-inhibiting effect on continuous cropping pepper seedlings, and its straw decomposed liquids played an important role in which the decomposed liquids concentration of 0.03 g·mL^-1 when the best effect, and its role was closely related to the direct inhibition of the phytophthora blight and improved the activity of the plant defense enzymes.

Effects of Origin on the Volatile Flavor Components of Morels Based on GC-IMS and GC×GC-ToF-MS

ZHOU XiaoQian, LI XiaoBei, ZHANG YanMei, ZHOU ChangYan, REN JiaLi, ZHAO XiaoYan

Scientia Agricultura Sinica. 2024, 57(22): 4553-4567. doi:10.3864/j.issn.0578-1752.2024.22.013

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【Objective】This research aimed to screen the characteristic volatile compounds of morels from different origins and to reveal the flavor characteristics of morels from different origins. 【Method】 The same variety of Morchella sextelata were grown in six producing areas of Shanghai, Jiangsu, Yunnan, Qinghai, Hunan and Hubei according to the local production model. The freeze-dried morels were analyzed by gas chromatography-ion mobility spectrometry (GC-IMS) and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-ToF-MS) to identify the types and content of volatile components. Principal component, cluster and multi-factor analysis were performed for these compounds, and a basic database was established.【Result】A total of 183 volatile compounds were detected by GC-IMS. Compared with other regions, morels from Yunnan had a higher abundance and significant differences in alcohols and heterocyclic substances. The content of 1-octen-3-ol in morels from Hunan was higher than that from other regions. Meanwhile, morels from Jiangsu contain the highest aldehyde content. A total of 245 volatile compounds were detected by GC×GC-ToF-MS, and multivariate statistical analysis revealed differences in the volatile components of morels from Yunnan compared wtih five other regions, which was consistent with the results obtained from GC-IMS. In order to further reveal the characteristic flavors and environmental factors of different production areas, the odor activity value (OAV) of the differential compounds was analyzed and the correlation analysis with environmental factors was performed. The results showed that 3-methyl-1-butanol, n-hexanol and 1-octen-3-ol were common aroma substances in various production areas, providing fruity and mushroom aromas. Taking Yunnan as the reference object, 12 of the common differential volatile compounds with other provinces were identified as key aroma compounds (OAV>1). The characteristic volatile substances of morels in Yunnan were 2,5-dimethylpyrazine (OAV=387.97), 2,3-dimethylpyrazine (OAV=209.65), 2-methylpyrazine (OAV=13.02) and methyl acetate (OAV=3.13), and the characteristic aroma was roasted and fruity, which was related to the local sandy soil, high temperature and large temperature difference. The characteristic volatile substances of morels in Hunan were 1-octen-3-ol (OAV=17930.58) and 2-methyl-2-butenal (OAV=8.60), and the characteristic aroma was floral and mushroom aroma. The characteristic volatile substances of morels in Shanghai were benzeneacetaldehyde, ethylidene- (OAV=387.97), and ethane, (methylthio)- (OAV=7.78), and the characteristic aroma was floral and pungent. The characteristic volatile substance of morels in Jiangsu was 2-pentylfuran (OAV=97.23), and the characteristic aroma was licorice smell, which was related to the high organic matter content in the soil. The characteristic flavor of morels in Hubei and Qinghai was not obvious. In addition, the content of volatile substances in Qinghai was related to altitude.【Conclusion】 The characteristic volatile substances of morels from Yunnan, Hunan, Jiangsu, Shanghai, Hubei and Qinghai were screened by GC-IMS and GC×GC-ToF-MS techniques, and the environmental influencing factors of their flavor formation were preliminarily explored. The results indicated that it was feasible to distinguish morels from different origins by characteristic volatile flavor substances.

Random Regression Analysis on Residual Feed Intake in Laying Hens with and Identification of the Genetic Markers

GUO Jun, SHAO Dan, DOU TaoCun, MA Meng, LU Jian, HU YuPing, WANG XingGuo, WANG Qiang, LI YongFeng, GUO Wei, TONG HaiBing, QU Liang

Scientia Agricultura Sinica. 2024, 57(22): 4568-4577. doi:10.3864/j.issn.0578-1752.2024.22.014

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【Objective】In this study, the polynomial coefficients of the random regression model were analyzed with genome wide association study (GWAS) to dissect the genetic architecture of the residual feed intake (RFI) in the lay, so as to lay the foundation for the selection of the RFI in laying hens. 【Method】 Data were collected from an F₂ segregation population of Dongxiang blue-shelled chickens and White Leghorn. The phenotypic data set included body weight, egg size, egg production, and feed intake. The residual feed intake at 40 and 60 weeks of age were calculated with Koch’s method, respectively. Blood samples were collected in F₂ generation. Genomic DNA was extracted with the phenol chloroform method. 1 534 hens were genotyped using 600 K gene microarray. The SNPs data were quality controlled. Missing data was imputed by Beagle software. The principal components were determined by using Plink software. The random regression model was used to analyze the variance components and genetic parameters of the segregation population. Gemma software was used to analyze the polynomial coefficients with a mixed linear model to obtain the significant P-value associated with the RFI in the lay. Gene annotation was carried out on the significant SNP. Chromosome heritability and haplotype block were calculated for RFI polynomial coefficients. 【Result】The second-order Legendre polynomials should be embedded in fixed, additive genetic, and permanent environmental effects. The homogeneous residual variance was harbored in the random regression model. The RFI in the lay showed moderate levels of heritability. The heritability on the RFI ranged from 0.23 to 0.32, and increased with hen age. The repeatabilities were 0.63-0.68, so this indicated that the RFI phenotype value could be accurately estimated by 3-4 repeated measurements. The genetic correlation coefficients in the RFI gradually decreased as the week intervals increased, as did the phenotypic correlation coefficients. The first principal component of the additive genetic matrix accounts for 96.12%. The inflation factor of the GWAS analysis was 1.026, indicating that the principal components of the linear mixed model had eliminated the potential stratified structure. There was a locus close to NAV2 on chromosome 5 that was significantly associated with the RFI, which was supported by the additional 11 SNPs. This QTL explained 1.73% of the phenotypic variance, and the haplotype block size reached 286 kb. Furthermore, potential SNPs were also detected on chromosomes 12 and 27. The potential SNP markers on chromosome 27 were located the upstream of NGFR. The chromosome heritability was directly proportional to the chromosome size, indicating that the small-effect polygenes controlled the RFI. 【Conclusion】The random regression model was used to estimate the genetic parameters on the RFI in the lay. Using polynomial coefficients as GWAS pseudo-phenotypic data, it was found that the NAV2 gene was significantly associated with the RFI.

Establishment and Application of a Tube-Based Chemiluminescence Immunoassay Method for Detecting Antibodies Against Trichinella spiralis in Pigs

QIAN YanHong, SONG Shuai, WEN XiaoHui, NIU RuiHui, YANG YanQiu, ZHENG BoBin, YUAN ZiGuo, LUO ShengJun

Scientia Agricultura Sinica. 2024, 57(22): 4578-4588. doi:10.3864/j.issn.0578-1752.2024.22.015

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【Background】 Trichinella spiralis is a foodborne zoonotic parasitic nematode, listed as one of the seven major foodborne parasites in the world. In domestic animals, Trichinella spiralis mainly infects pigs and can be transmitted to humans through pork and by-products. It not only causes huge economic losses to China's pig farming industry, but also seriously endangers human health and public health safety.【Objective】This study aimed to establish a highly sensitive, specific, and rapid automated serological detection method for Trichinella spiralis in pigs.【Method】This study utilized gene cloning and prokaryotic expression techniques to construct a prokaryotic expression vector, obtained the recombinant protein of Trichinella spiralis 14-3-3 through induction of expression, and verified its reactivity. A chemiluminescence enzyme immunoassay method was established by encapsulating magnetic particles with prepared recombinant proteins as detection antigens, and the conditions for the established method were optimized. Finally, based on the optimized method, the critical values were defined and the specificity, sensitivity, and repeatability were determined; by testing 1 000 clinical serum samples of pigs from different pig farms in Guangdong and Guizhou provinces, the practicality and compliance rate of this testing method were evaluated.【Result】The recombinant protein Ts14-3-3 was successfully expressed and purified, which could specifically recognize antibodies in positive serum of Trichinella spiralis in pigs. The established detection method has been optimized, with the optimal pH value of the buffer solution being 5 and the optimal encapsulation amount of the Ts14-3-3 recombinant protein being 5 μg·mg^-1-beads, the optimal dosage of the activator was 50 μg·mg^-1-beads, and 1%BSA has the best sealing effect. The optimal dilution for enzyme-labeled antibodies was 1:40 000, the optimal reaction time was 10 minutes, the optimal incubation time for the sample to be tested was 5 minutes, and the optimal enzymatic reaction time was 2 minutes. Finally, after evaluation, the critical chemiluminescence value of this detection method was 374 185 RLU, and there was no cross-reaction with antibodies against Toxoplasma gondii, coccidia, Pseudorabies, and foot-and- mouth disease in pigs, as well as antibodies against porcine reproductive and respiratory syndrome, classical swine fever, pseudorabies, and foot-and-mouth disease. Compared with existing ELISA detection methods, this detection method had higher sensitivity, with intra - and inter-batch repeatability of less than 10%; the positive rate of trichinella antibodies in 1000 clinical pig serum samples detected was 0.6%, and a total compliance rate of 98.18% with commercially available ELISA kits. 【Conclusion】This study successfully established a tube-based chemiluminescence immunoassay method for detecting antibodies against Trichinella spiralis in pigs. The detection method had strong specificity, and good stability, and was more sensitive and rapid, and had a high clinical detection accuracy compared wtih ELISA methods.

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