Table of Content

    16 May 2024, Volume 57 Issue 10
    Genetic Diversity Analysis of Winter Wheat Germplasm Resources in Shanxi Province Based on 55K SNP Array
    LEI MengLin, LIU Xia, WANG YanZhen, CUI GuoQing, MU ZhiXin, LIU LongLong, LI Xin, LU LaHu, LI XiaoLi, ZHANG XiaoJun
    Scientia Agricultura Sinica. 2024, 57(10):  1845-1856.  doi:10.3864/j.issn.0578-1752.2024.10.001
    Abstract ( 178 )   HTML ( 27 )   PDF (2921KB) ( 132 )   Save
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    【Objective】 Analyzing the evolutionary patterns of genetic diversity of wheat germplasm resources, providing richer and more diverse original parental materials for parental selection and variety selection in wheat breeding in Shanxi Province.【Method】 Using 323 landraces and 105 cultivated varieties as natural populations, a 55K SNP chip was used to perform whole genome scanning on 428 natural populations, analyzing genetic diversity, genetic structure, principal components, genetic clustering, and phylogenetic relationships among varieties. 【Result】 The distribution of SNP loci on 21 chromosomes ranged from 329 to 1 639, with an average of 1 152. The distribution range of 7 partially homologous groups is 2 154-3 852, with an average of approximately 3 456. The distribution pattern of the genome is: B genome>A genome>D genome. Genomic annotation polymorphism markers have the highest distribution among gene regions, accounting for about 50%. Analysis shows that SNP loci cover 21 chromosomes, 7 homologous groups and 3 genomes, but their distribution varies, with a polymorphism rate of 45.60%. The average observed heterozygosity of the entire population (0.0185) was lower than the expected heterozygosity (0.4992). The changes in the average shannon wiener index and polymorphism information content of the entire natural population were not significant. Comparing the diversity parameters of natural populations, it was found that the genetic diversity of the population is not high, the genetic diversity of cultivated varieties is slightly higher than that landraces. The population structure analysis of natural populations divides the population into two major groups. Group I has 307 materials, mainly landraces. Group Ⅱ has 121 materials, mainly cultivated varieties. The natural groups were divided into five groups by both principal component and cluster analysis. The average genetic distance between the varieties in group I is 0.21831, with a range of 0.00127-0.72461. The average genetic distance between varieties in group Ⅱ is 0.14619, with a range of 0.00038-0.76489. The varieties in group Ⅲ the average genetic distance between the varieties of group Ⅳ is 0.16521, with a range of 0.00049-0.43033. The average genetic distance between varieties of group Ⅳ is 0.17643, with a range of 0.00118-0.60496. The average genetic distance between varieties of group V is 0.12039, with a range of 0.00042-0.37032. It can be seen that the variation of genetic distance between wheat varieties is large in Shanxi Province. However, the average genetic distance value is low, the clustering classification differentiation is obvious. The genetic relationship between varieties in the middle of the group is relatively close. Comparison shows that the average genetic distance of group I and group Ⅳ is higher than that of group Ⅱ, group Ⅲ and group V. The genetic distance variation of group I and group Ⅳ is higher than that of group Ⅲ and group V. It can be seen that the genetic distance of cultivated varieties is generally greater than that of landraces.【Conclusion】 The 55K SNP chip was used to analyze the genetic diversity of Shanxi winter wheat germplasm resources, clarifying the distribution characteristics of genetic diversity at the genomic level between Shanxi wheat cultivated varieties and landraces. The introduction of exogenous genes into cultivated varieties is beneficial for improving genetic diversity, while the genetic diversity of landraces is relatively low. At the same time, the genetic relationships of very few varieties are polarized, so it should be rationally used differently in subsequent utilization.

    Evaluation of Drought Resistance in Soybean Germplasm and Identification of Candidate Drought-Resistant Genes
    LI ShengYou, WANG ChangLing, YAN ChunJuan, ZHANG LiJun, SUN XuGang, CAO YongQiang, WANG WenBin, SONG ShuHong
    Scientia Agricultura Sinica. 2024, 57(10):  1857-1869.  doi:10.3864/j.issn.0578-1752.2024.10.002
    Abstract ( 200 )   HTML ( 23 )   PDF (4749KB) ( 180 )   Save
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    【Objective】 In order to provide theoretical basis for molecular breeding of soybean drought resistance, the different evaluation indexes of drought resistance were comprehensively used to screen soybean germplasm with drought-resistance, and the candidate drought-tolerant genes were identified. 【Method】 In 2018, 2019, 2020 and 2021, a total of 188 soybean germplasm were used to determine pod number per plant, biomass per plant and yield per plant under well-watered and drought stressed conditions. Drought resistance index (DI), improved drought resistance index (IDI), weighted drought resistance coefficient (WDC) and weighted drought resistance index (WDI) were used to identify drought resistance of soybean germplasm. The single nucleotide polymorphisms (SNP) loci significantly associated with these parameters were detected by genome-wide association study (GWAS), and the candidate genes for drought resistance were screened by RNA-seq and qRT-PCR analysis of soybean seedling leaves under drought stress. 【Result】 The DI, IDI, WDC and WDI of 188 soybean germplasm varied widely, and five classification criteria for each drought resistance parameter were determined by hierarchical classification method. Among them, Liaodou 15, Liaodou 69, Liaodou 14, Jinzhangzi Huangdou, Zhonghuang 606, Kexin 3 and Koreane 4 were identified as first-grade drought resistant by all evaluation methods. By using GWAS for DI, IDI, WDC and WDI, a total of 15 significantly SNP loci were detected under multiple environments, and the contribution rate of these loci to phenotypic variation ranged from 12.46% to 25.60%. There are 226 annotated genes within 200 kb intervals of upstream and downstream for the significant SNP loci. According to RNA-seq and qRT-PCR analysis of drought-resistant cultivar Liaodou 14 and drought-sensitive cultivar Liaodou 21 under drought stress, a total of 32 annotated genes were significantly differentially expressed by drought stress. Among them, eight genes including Glyma.02G182900, Glyma.04G012400, Glyma.06G258900, Glyma.15G100900, Glyma.01G172600, Glyma.04G012300, Glyma.01G172200 and Glyma.04G010300, encodes calcium-dependent protein kinase, universal stress protein A-like protein, G-type lectin S-receptor-like serine/threonine-protein kinase, protein phosphatase 2C, isoflavone reductase, isoflavone reductase homolog, auxin-like protein, and bZIP transcription factor, respectively. 【Conclusion】 Seven germplasm were identified from 188 soybean germplasm by comprehensive application of different drought tolerance parameters. A total of 15 SNP loci significantly associated with drought tolerance parameters were identified by GWAS, and eight candidate genes were identified.

    Development and Identification of an Interspecific Hexaploid Hybrid Between an A. hypogaea Cultivar and a Wild Species Arachis sp. 30119 in Peanut
    LIU Hua, ZENG FanPei, WANG Qian, CHEN GuoQuan, MIAO LiJuan, QIN Li, HAN SuoYi, DONG WenZhao, DU Pei, ZHANG XinYou
    Scientia Agricultura Sinica. 2024, 57(10):  1870-1881.  doi:10.3864/j.issn.0578-1752.2024.10.003
    Abstract ( 172 )   HTML ( 9 )   PDF (7914KB) ( 119 )   Save
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    【Objective】 Wild Arachis species containing many elite disease and insect resistant genes are an important gene pool for the improvement of cultivated peanut A. hypogaea L., so the introduction of chromatin from wild species into cultivated peanut remains an important task for distant hybridization of peanut. Unfortunately, only a few wild species have been successfully involved in the development of interspecific hybrids, despite the existence of a huge amount of wild germplasm resource. The wild species A. sp. 30119 contains multiple disease resistance. However, no interspecific hybrid between it and the cultivated peanut has been reported.【Method】 After crossing allotetraploid peanut cultivar Baitu 131 with diploid wild species A. sp. 30119 and followed by the embryo rescue, the interspecific hybrid F1 (W1212) was obtained. However, interspecific hybrid F1 did not produce seed when selfed. In order to reveal the reason for infertility and continue the generation, the chromosome number of root tip cells was counted and chromosome pairing in pollen mother cells during meiosis of W1212 observed. The chromosome of W1212 was doubled through colchicine treatment during the in vitro culture W1212 plantlet. Finally, we harvested four one-seeded pods from the established W1212 plants; one of the pods undergone in vitro cultured and a number of plants were established from the culture and named as Am1212. The chromosome composition of Am1212 was analyzed by sequential GISH/FISH and SSR marker. Additionally, phenotypic characteristics of Am1212 were investigated. The metaphase chromosome numbers of 8 randomly selected F3 plants were analyzed by rDNA FISH to evaluate the genetic stability of Am1212.【Result】 The average chromosome configuration during meiosis of pollen mother cells of W1212 was 1Ⅲ+6Ⅱ+15Ⅰ, and the abnormalities in chromosome pairings lead to the high sterility of F1 plants. The pollen viability of peg-setting branches of W1212 was significantly improved after chromosome doubling treatment. Sequential GISH / FISH of Baitu 131, A. sp. 30119 and Am1212 indicated that A. sp. 30119 may be a diploid with A genome. Am1212 has 60 chromosomes consisting of all chromosomes of both Baitu 131 and A. sp. 30119, which confirmed its nature of a hexaploid hybrid, but 37.5% F3 plants derived from Am1212 exhibited chromosome number variation. After conducting the screening of SSR molecular markers and phenotypic investigation, we obtained 17 dominant or co-dominant markers for specifically tracking wild species chromosomes and clarified the genetic characteristics of Am1212.【Conclusion】 In this study, we successfully created a new hexaploid peanut Am1212 which incorporated A. sp. 30119 chromatin. However, Am1212 exhibited instability in chromosome numbers and inherited unacceptable agronomic traits from wild species, such as small pods. Therefore, it is necessary to develop more accurate and efficient chromosome manipulation techniques to minimize the unfavorable gene linkage and generate alien chromosomal lines that possess compensatory effects and favorable traits for future breeding purposes.

    Quantification of Row Orientation Effects on Radiation Distribution in Maize-Soybean Intercropping Based on Functional-Structural Plant Model
    ZHOU YeYing, XIE ZiWen, ZHONG PeiGe, LI ShuangWei, MA YunTao
    Scientia Agricultura Sinica. 2024, 57(10):  1882-1899.  doi:10.3864/j.issn.0578-1752.2024.10.004
    Abstract ( 97 )   HTML ( 8 )   PDF (7428KB) ( 66 )   Save
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    【Objective】 The aim of this study was to develop functional-structural models of maize-soybean intercropping with different planting patterns and row orientations, so as to provide the support for analyzing the yield advantages, growth and developmental patterns, and the effects of planting patterns and row orientations on light interception, light distribution, and radiation use efficiency.【Method】 In this study, one year maize-soybean field experiment with two planting patterns (sole crop and 2:2 MS) and three row orientations (North-South orientation, East-West orientation and Control orientation (Lishu original planting orientation: south-west 40)) was conducted to analyze the effects of planting pattern and row orientation on the performance of biomass, yield and plant architecture. The three-dimensional functional-structural plant (FSP) model was used to simulate crop growth, development, structure and light interception in different planting patterns and row orientations, and to quantify the effects of planting patterns and row orientations on light interception and radiation use efficiency. Row orientation with high light interception was also explored using the FSP model.【Result】 The grain yield land equivalent ratio (LER) under 2:2 MS was the highest in NS orientation (1.20±0.07) and the lowest in EW orientation (1.16±0.09). The FSP model well simulated the growth and development of maize and soybean in different planting patterns and row orientations. Compared with the measured values in the maize field experiment and the simulated values, the root mean square error (RMSE) was 0.09-0.14 m for plant height, 0.04-0.08 m2·plant-1 for leaf area per plant and 0.07-0.12 for the fraction of light interception; for soybean, the RMSE was 0.07-0.09 m for plant height, 0.02-0.04 m2·plant-1 for leaf area per plant and 0.09-0.10 for the fraction of light interception. The accumulated light interception for 2:2 MS in Control orientation was the highest, which was (758.48±1.00) MJ·m-2. Compared with the Control orientation, the radiation use efficiency reduced 7.18% for NS orientation and 10.57% for EW orientation.【Conclusion】 Intercropping increased maize biomass and yield, but reduced soybean biomass and yield. Row orientation had a significant effect in maize-soybean intercropping system. Soybean adapted to the shading by changing morphological characteristics, such as leaf size, internode length, and petiole inclination, to increase the amount of light and optimize the photosynthetic efficiency, which was ultimately converted into an increase in yield. The planting row orientation had a great effect on the light interception, the radiation use efficiency and light interception of the intercropping system showed that the control orientation was better than NS orientation and EW orientation. The results of this study would help to optimize field management and provide the data and technical support for explaining the rational interception and distribution for maize-soybean intercropping in different row orientations.

    Response of Maize Growth and Yield with Different Nitrogen Application Rates to Intercropped Leguminous Green Manure
    DONG YongJie, ZHANG Diaoliang, LI Yue, PENG JianChen, HU FaLong, YIN Wen, CHAI Qiang, FAN ZhiLong
    Scientia Agricultura Sinica. 2024, 57(10):  1900-1914.  doi:10.3864/j.issn.0578-1752.2024.10.005
    Abstract ( 125 )   HTML ( 24 )   PDF (1744KB) ( 125 )   Save
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    【Objective】 This study aimed to clarify the response of maize growth and yield with different nitrogen application rates to intercropped green manure, so as to provide the basis for establishing maize production pattern with nitrogen fertilizer saving via green manure in arid irrigation area.【Method】 A split plot experiment design was adopted, and two planting patterns of maize intercropping with common vetch (MV) and sole maize (SM) were set up in the main plot. Five nitrogen application rates were set up in the split plot: the recommended nitrogen application rates were N360: 360 kg N·hm-2, application rates reduced with 25% (N270): 270 kg N·hm-2, and that reduced with 50% (N180): 180 kg N·hm-2, reduced with 75% (N90): 90 kg N·hm-2, and no nitrogen application (N0). Leaf area index (LAI), daily leaf volume (LAD), light energy utilization rate, dry matter accumulation and yield of maize were investigated.【Result】 In 75-150 days after maize emergence, the LAI, total LAD and light use efficiency of maize with reduced nitrogen application rate (N270, N180, N90, N0) were increased by intercropped green manure. The maize LAI, total LAD and light use efficiency under M||V with N270, N180, N90, and N0 were significantly increased by 9.8%, 8.2% and 4.6% than that under SM, respectively. The maize LAI, total LAD and light use efficiency under M||V with N270 was not different with that with N360, in 75-150 days after maize emergence, and which was greater than that of other treatments. Somehow, the maize LAI, total LAD and light use efficiency of SM was decreased with reduced nitrogen application rate. The dry matter accumulation of maize under N270, N180, N90, and N0 was significantly increased by intercropped with green manure than that of sole maize, in 90-150 d days after maize emergence, which was increased by 4.6%. In 75-130 days after maize emergence, the growth rate of maize under M||V was significantly increased by 5.9% compared that with SM. With the same reduced nitrogen application rate (N270, N180, N90, and N0), the maize grain yield under M||V was significantly increased by 8.5% than that under SM. The grain yield of intercropped maize under N270 was significantly higher than that of sole maize under N360. Compared with SM, the kernel number per ear and 1000-grain weight of maize under M||V were significantly increased by 6.0% and 6.3%, respectively. The results of the fitting curve showed that the greatest grain yield of maize intercropped with green manure was 14 876.4 kg·hm-2 with nitrogen application rate 261.4 kg·hm-2. While the greatest grain yield of sole maize was 14 012.5 kg·hm-2 with nitrogen application rate of 348.6 kg·hm-2. The effect of reducing nitrogen application on the fresh yield and nitrogen accumulation of green manure was significant. The fresh yield of green manure under M||VN270 was significantly higher than that under M||VN360, M||VN90 and M||VN0 by 3.8%, 4.6%, and 9.7%, respectively, while the nitrogen accumulation with M||VN 270 was significantly higher than that with M||VN90 and M||VN0 by 5.3% and 11.9 %, respectively. The total dry matter accumulation of maize with reduced nitrogen applied rate was increased by intercropped green manure, and then the number of grains per ear and thousand grains weight of maize was increased. Therefore, the intercropped maize could obtain a greater level of grain yield with the condition of reduced nitrogen application rate.【Conclusion】 The treatment of 25% reduced nitrogen rate with intercropped green manure could make maize obtain higher yield than sole maize with the recommended nitrogen application rate. This pattern could be used as a recommended production method for chemical nitrogen fertilizer reduced application of maize in the research region and even similar ecological region.

    Identification and Functional Analysis of the 5-Oxoprolinase Genes in Fusarium oxysporum
    LOU Hui, ZHU JinCheng, HAN ZeGang, ZHANG Wei
    Scientia Agricultura Sinica. 2024, 57(10):  1915-1929.  doi:10.3864/j.issn.0578-1752.2024.10.006
    Abstract ( 92 )   HTML ( 6 )   PDF (12175KB) ( 67 )   Save
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    【Objective】 5-Oxoprolinase (OXP) is one of the six core enzymes in the γ-glutamine cycle. The objective of this study is to characterize the OXP gene of Fusarium oxysporum, clarify its relationship with the pathogenicity of F. oxysporum, and to provide a theoretical basis for the analysis of the molecular mechanism of F. oxysporum pathogenicity and the prevention and control of cotton wilt.【Method】 Bioinformatics methods were used to identify the FoOXPs from the genome of F. oxysporum and analyze their gene structure, domains of the encoded proteins, chromosomal localization and evolutionary relationships. The phenotypes of F. oxysporum after FoOXP2 mutation were analyzed by using knockout mutant and complementary strain and the pathogenicity differences between the mutant and wild-type strains on cotton seedlings were detected. Furthermore, the disease grade rate and disease index on cotton were investigated by using host-induced gene silencing (HIGS) technology. The fungal biomass in cotton and expression of FoOXP2 in cotton stems transformed with interfering fragments of the FoOXP2 were examined by real-time quantitative PCR (qRT-PCR).【Result】 A total of two FoOXPs (FoOXP1 and FoOXP2) were identified in the F. oxysporum genome with coding sequence lengths of 4 080 and 3 921 bp, encoding 1 359 and 1 306 amino acids, respectively. Their protein molecular weights are 14.90 and 14.07 kDa, and theoretical isoelectric points are 5.73 and 5.30, respectively. The FoOXP1 protein is located in the mitochondria and the FoOXP2 protein is located in the cytoskeleton. FoOXP1 and FoOXP2 locate on chromosome JH657921 and chromosome JH657938, do not form gene clusters, with a sequence similarity of 52.00%. Phylogenetic analysis revealed that FoOXP1 and FoOXP2 belonged to two subgroups. Compared with the wild-type strain, the FoOXP2 knockout mutant strain showed significantly lower spore production and spore germination, loss of penetration ability, and increased tolerance to CR and sorbitol, but was more sensitive to cell wall stress (SDS and CFW), oxidative stress (H2O2), and osmotic stress (NaCl and KCl). Moreover, the pathogenicity on cotton was significantly reduced. The results of the HIGS assay illuminated that after 14 and 21 d of inoculation, the incidence of FoOXP2 silenced cotton plants was significantly reduced, whose disease indexes (17.3 and 40.2) were significantly lower than those of the control (28.2 and 77.1). The expression of FoOXP2 and fungal biomass were significantly lower than those of the control.【Conclusion】 The FoOXP2 positively regulates the pathogenicity of F. oxysporum and may play an important role in host-pathogen interactions.

    Function and Mechanism Analysis of Vm-milRN7 Regulating the Pathogenicity of Valsa mali
    ZHANG Jian, ZHAO BinSen, FENG Hao, HUANG LiLi
    Scientia Agricultura Sinica. 2024, 57(10):  1930-1942.  doi:10.3864/j.issn.0578-1752.2024.10.007
    Abstract ( 153 )   HTML ( 9 )   PDF (3916KB) ( 108 )   Save
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    【Background】MicroRNA-like RNAs (milRNAs) are a class of regulatory factors commonly found in fungi with similar generation and action mechanism as plant and animal microRNAs, which are widely involved in their growth and development, as well as in life activities such as infection and pathogenesis of plant pathogenic fungi. The apple Valsa canker caused by Valsa mali is the most destructive disease affecting apple production.【Objective】 The research aims to explore the function and mechanism of Vm-milRN7 in regulating the pathogenicity of V. mali, and to provide a theoretical basis for targeted disease resistance breeding of apple Valsa canker.【Method】 Vm-milRN7 precursor overexpression vector was constructed by amplifying Vm-milRN7 precursor sequence using genomic DNA of strain 03-8 as a template; upstream and downstream sequences of Vm-milRN7 precursor were amplified and Vm-milRN7 precursor knockout mutants were constructed by using Double-joint PCR technique. The Vm-milRN7 precursor overexpression strains and knockout mutants were constructed by PEG-mediated protoplast transformation. The vegetative growth rate of Vm-milRN7 precursor overexpression strains and knockout mutants was determined by cultivation on PDA medium, and the pathogenicity of these strains was verified by inoculation on apple twigs and leaves. The regulatory relationship between Vm-milRN7 and its potential target gene Vm-09496 was identified by qRT-PCR and co-infiltration experiment in Nicotiana benthamiana leaves; protein sequence characterization and phylogenetic analysis of Vm-09496 were performed using bioinformatics software. In order to analyze its function, Vm-09496 knockout mutants and complement strains were created and their phenotypes were characterized.【Result】 PEG-mediated genetic transformation was used to create Vm-milRN7 overexpression strains and knockout mutants. Vm-milRN7 overexpression strains showed no apparent alteration in vegetative growth rate compared with that of the wild-type strains, whereas the knockout mutants had a significantly lower vegetative growth rate. Compared with the wild-type strains, the overexpression strains showed a significant increase in the pathogenicity of V. mali on apple leaves, while the knockout mutants showed a significant decrease in the pathogenicity of V. mali on apple leaves and twigs. Further, qRT-PCR and co-infiltration in N. benthamiana leaves assay showed that Vm-milRN7 inhibited the expression of its potential target gene Vm-09496. Bioinformatics analysis revealed that the gene encodes an imaginary protein and is evolutionarily most closely related to VP1G_09956 in V. pyri. In order to analyze its function, the Vm-09496 knockout mutants and complement strains were created, and the pathogenicity of the knockout mutants on both twigs and leaves was significantly increased compared with that of the wild-type strain, while the vegetative growth rate and pathogenicity of the complement strains recovered to the wild-type level.【Conclusion】 Vm-milRN7 may be involved in the pathogenity of V. mali by regulating the expression of the target gene Vm-09496. The target gene Vm-09496 is an important endogenous gene affecting V. mali infection and negatively regulates V. mali pathogenicity.

    Model Simulation Research of Soil Organic Carbon Dynamics of Long-Term Conservation Tillage in Black Soil
    WANG WenJun, LIANG AiZhen, ZHANG Yan, CHEN XueWen, HUANG DanDan
    Scientia Agricultura Sinica. 2024, 57(10):  1943-1960.  doi:10.3864/j.issn.0578-1752.2024.10.008
    Abstract ( 119 )   HTML ( 7 )   PDF (1055KB) ( 83 )   Save
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    【Objective】 Conservation tillage is an important measure for restoring and enhancing soil fertility, and soil organic carbon (SOC) plays a crucial role in maintaining soil fertility, supporting crop growth, and protecting soil environment. However, there is currently a lack of long-term monitoring platforms for conservation tillage in China, so using modeling methods can help study SOC dynamics under long-term conservation tillage. 【Method】 A long-term tillage experiment was established in the black soil region in 2001 with three treatments: no-tillage (NT), moldboard plow (MP), and ridge-tillage (RT). The structures and parameters of process-based models (RothC, AMG model) and statistical models (MLPNN model) were optimized. The changes in SOC under long-term conservation tillage were simulated and compared. The effectiveness of different models in simulating and predicting the SOC dynamics under conservation tillage was evaluated, and the long-term response and influencing factors of SOC in black soil in Northeast China to conservation tillage were revealed. 【Result】 After optimizing parameters for carbon pool allocation, errors of the RothC and AMG models were significantly reduced. During the first 11 years (2001-2012) of conservation tillage, there was no significant difference in the simulation of SOC between RothC and AMG models, indicating that the structural complexity of process models does not have significant impacts on the simulation results for relatively short term. The simulation results of the statistical model MLPNN were similar to process models, proving the application of statistical models in small-scale regions. Over the next 100 years, RothC and AMG models predicted similar trends in SOC changes, but AMG model significantly overestimated the increase in SOC stocks, which may be attributed to SOC saturation and the influence of tillage practices. Both RothC and AMG models showed high sensitivity to carbon input, but they responded differently to climate and soil factor changes. 【Conclusion】 It is necessary to choose appropriate models based on local conditions while using models to simulate SOC in long-term conservation tillage. For short-term prediction of SOC under conservation tillage, a relatively simple AMG modelcan be used, while for long-term prediction, a more complex RothC model can be used. Under specific conditions, statistical models show similar effects to process models in simulating soil organic carbon at a small-scale regions, such as plots and fields.

    Response Difference and Its Cause Reasons for Simplified Panicle Fertilization in Different Rice Varieties After Wheat Straw Return
    SHU XiaoWei, WANG ShuShen, FU Tong, WANG ZiHan, DING ZhouYu, YANG Ying, ZHAO ShiRu, ZHOU Juan, HUANG JianYe, YAO YouLi, WANG YuLong, DONG GuiChun
    Scientia Agricultura Sinica. 2024, 57(10):  1961-1978.  doi:10.3864/j.issn.0578-1752.2024.10.009
    Abstract ( 166 )   HTML ( 24 )   PDF (650KB) ( 87 )   Save
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    【Objective】 The aim of this study was to explore and analyze the differences in yield, panicle differentiation and degeneration, soil microbial activity, and response of soil alkali-hydrolysable nitrogen to simplified panicle fertilization among different rice varieties under the condition of wheat straw return (SR). 【Method】 As test materials, two cultivars were selected, including late maturing medium japonica rice Nanjing 9108 (NJ 9108) and indica rice Yangdao 6 (YD6). Rice yield, spikelet differentiation, and degeneration were evaluated under the interactive conditions of SR and simplified panicle fertilization (0﹕0, no panicle fertilization; 2﹕0, full application of spikelet-promoting fertilizer; 1﹕1, equal application of spikelet-promoting and protecting fertilizers; 0﹕2, full application of spikelet-protection fertilizer). The nutritional basis of rice spikelet differentiation and degeneration was analyzed in terms of nutrient release from straw decomposition, alterations in soil microbial communities and enzyme activity, and soil alkaline nitrogen content. 【Result】 (1) After SR, the average yield of NJ 9108 and YD 6 increased by 4.2% and 3.2%, respectively. Under panicle fertilization treatments, the highest yield for NJ9108 and YD6 was achieved under the 2﹕0 and 1﹕1 treatment, respectively. After no wheat straw return treatment (NR), the yield of both varieties was highest under the 1﹕1 treatment. The yield trend of panicle fertilization treatments was consistent within the range of 180-360 kg N·hm-2. (2) After SR, the initial 0-30 days were a period of rapid decomposition, with the rapid release of carbon and nitrogen from the straw. At 30 days, the average number of bacteria, fungi, and actinomycetes in the soil increased by 179.2%, and the average activity of urease, acid phosphatase, and sucrase increased by 88.8%. During the period of 40 to 60 days, the straw's decomposition and carbon-nitrogen release rates diminished, and the number of microorganisms and enzyme activities decreased significantly. Decomposition and carbon-nitrogen release of straw essentially stalled between 60 and 90 days, while the number of microorganisms and enzyme activities decreased gradually. From 10 to 40 days after SR, the soil's alkali-hydrolysable nitrogen content decreased by an average of 4.8%, while it increased by an average of 5.2% between 50 and 90 days. (3) After SR, the increase in soil alkali-hydrolysable nitrogen caused an increase of 1.4% in the average number of spikelets differentiation, a decrease of 12.3% in the average number of spikelets degeneration, but an increase of 4.4% in the average number of surviving spikelets. Rice harvest increased primarily due to an increase in the number of spikelets per panicle (the number of surviving spikelets per panicle). After SR, the 2﹕0 treatment reduced the rate of spikelet degeneration in NJ9108 and YD6 relative to NR by 23.5% and 7.6%, respectively. The number of spikelet differentiation and degeneration of NJ9108 increased by 8.9 and 5.7 spikelets per panicle under the 2﹕0 treatment relative to the 1﹕1 treatment, whereas Yangdao 6 increased by 6.8 and 11.6 spikelets per panicle, respectively. As the increase in the number of spikelets differentiation was greater than the increase in the number of spikelets degeneration, NJ9108 had the highest number of surviving spikelets under the 2﹕0 treatment, while YD6 had the highest number under the 1﹕1 treatment. 【Conclusion】 Wheat straw return increased rice yield, with NJ 9108 achieving the highest yield under the full application of spikelet-promoting fertilizer and Yangdao 6 achieving the highest yield under the equal application of spikelet-promoting and protecting fertilizers. Those factors that contributed to the increase in yield were mainly due to a significant reduction in the rate and number of spikelets degeneration and an increase in the number of spikelets per panicle. The decrease in the rate of spikelets degeneration for NJ 9108 was greater than that for YD6, which was the main reason for the difference in their response to different panicle fertilization treatments in terms of the number of surviving spikelets.

    Response of Soil-Crop System to Different Nitrogen Fertilization Practices Under Maize and Rice Cropping System in the Paddy Soil of Dongting Lake Plain
    FANG KangRui, LONG ShiPing, PENG SiWen, CHEN Shan, LIAO YuLin, XU XinPeng, ZHAO ShiCheng, QIU ShaoJun, HE Ping, ZHOU Wei
    Scientia Agricultura Sinica. 2024, 57(10):  1979-1994.  doi:10.3864/j.issn.0578-1752.2024.10.010
    Abstract ( 90 )   HTML ( 5 )   PDF (1064KB) ( 68 )   Save
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    【Objective】 Crop yield increases and soil organic matter decreases when double rice cropping system shifted to wet and dry rotation cropping system, but little information is known that the effects of chemical fertilizer nitrogen combined with different organic materials on crop yield, nitrogen use efficiencies and organic matter content under the wet and dry cropping system.【Method】 The maize and rice rotation was regarded as object, five treatments were set up, including no nitrogen fertilizer applied (CK), only chemical fertilizer applied (NPK), NPK plus straw return (NPKS), NPK plus manure (NPKM) and NPK plus biochar (NPKB) in purple clayey soil and reddish clayey soil in Dongting lake plain from 2015 to 2021. The changes of yield, nutrient use efficiency, soil carbon and nitrogen content as well as carbon and nitrogen balance under different fertilization treatments were explored. 【Result】 The average maize yield, rice yield and total annual yield in the six-year in purple clayey soil and reddish clayey soil were 5.7, 7.3 and 12.9 t·hm-2, respectively. Moreover, the three yields above in purple clayey soil were slightly higher than that reddish clayey soil, though the differences in both soils were not significant. Compared with the NPK treatment, NPKM treatment significantly (P<0.05) increased the average yields in maize season or rice season in the two soils (P<0.05) by 10.6% and 4.20%, respectively. Among all the treatments, NPKM treatment had the maximum yield in the maize season, and the value was 6.0 t·hm-2; and NPKB treatment had the maximum yield in the rice season, and the value was 7.5 t·hm-2. The six-year average annual total yield under NPKM and NPKB treatments was significantly higher (P<0.05) than that under other treatments, respectively, but the difference between NPKM and NPKB treatments was not significant. Compared with the other treatments, NPKM treatment significantly (P<0.05) improved the chemical fertilizer nitrogen recovery efficiency, agronomic efficiency and partial productivity in maize, rice, the six-year average values of maize season were 66.3%, 39.5 kg·kg-1 and 56.0 kg·kg-1, respectively, and the six-year average of rice season was 53.8%, 21.9 kg·kg-1 and 68.6 kg·kg-1, respectively. NPKB treatment had significant higher chemical fertilizer N agronomy efficiency and partial productivity than the NPKS and NPK treatments in maize and rice seasons, and compared with NPK treatment, the nitrogen recovery rate of maize was also significantly improved. Soil organic carbon and total nitrogen content decreased significantly from the fourth years (the year of 2019). Compared with the soil organic carbon and nitrogen content between the beginning of the experiment (2015) and 2021, the annual average soil organic carbon in all the N applied treatments in purple clayey soil and reddish clayey soil decreased by 1.8 and 0.7 g·kg-1, and total nitrogen content decreased by 0.4 and 0.1 g·kg-1; the NPKM treatment in both the soils had the lowest decrease of soil organic carbon and total nitrogen, and the NPKB treatment was the second. The loss of soil organic carbon and total nitrogen in the NPKM treatments were the lowest, which were 0.48 t C·hm-2·a-1 and 94.7 kg N·hm-2·a-1, respectively.【Conclusion】 After the double rice cropping system shifted to wet and dry rotation cropping system, the chemical fertilizer nitrogen combined with manure and biochar could increase crop yield and hold back the decrease of soil organic matter, NPKM treatment had the maximum average maize yield and NPKB treatment had the maximum average rice yield during the experimental period.

    Transcriptome Analysis for Screening Key Genes Related to Regulating Branching Ability in Apple
    ZHANG HaiQing, ZHANG HengTao, GAO QiMing, YAO JiaLong, WANG YaRong, LIU ZhenZhen, MENG XiangPeng, ZHOU Zhe, YAN ZhenLi
    Scientia Agricultura Sinica. 2024, 57(10):  1995-2009.  doi:10.3864/j.issn.0578-1752.2024.10.011
    Abstract ( 184 )   HTML ( 31 )   PDF (5633KB) ( 179 )   Save
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    【Background】 The number of branches on an apple tree plays a pivotal role in its environmental adaptability, growth, survival, and resource competition. In production practice, the apple cultivars with more branches can better meet the needs of pruning and shaping, not only do they facilitate timely adjustments to the tree's structure based on local conditions, but also they ensure a uniform distribution of fruit-bearing branches, thereby guaranteeing both fruit quantity and quality. 【Objective】 In this study, by using the top buds and lateral buds of more-branched cultivar Huaxing and fewer-branched cultivar Huashuo at the same developmental stage, the transcriptome sequencing was carried out to identify key genes regulating the ability of branching, as well as to elucidate the potential mechanism underlying branching phenotype, and finally to provide the theoretical basis for improving the branching ability and yield of apple. 【Method】 The lateral and terminal buds of Huashuo and Huaxing were sampled for RNA-seq. By differential expressed gene (DEG) and analysis and weighted gene co-expression network (WGCNA) analysis, the core candidate genes that were responsible for branch number difference were identified and further demonstrated their function by Arabidopsis transformation.【Result】 A total of 2 920 DEGs were identified from the comparison between the terminal buds, while 5 127 DEGs were screened out from the comparison between the lateral buds. DEGs were mainly enriched in phytohormone signaling pathway. Notably, the auxin signaling pathway, and strigolactone signaling pathway seemed to have the closest connection with the branching ability of apple with the related genes encoding MdIAA3, MAX2, TCP, and JAZ, which showed significant differences between lateral buds. Furthermore, DEGs annotated to cell cycle and cell wall modification families, such as CYC (Cyclins), CDK (Cyclin-dependent kinase), and EXPA (Expansin), also demonstrated a positive correlation with apple branching ability. In addition, those candidate genes obtained from WGCNA analysis also showed high possibility of getting involved in branch number regulation. Heterologous transformation of Arabidopsis with MdIAA3 could significantly enhance the overall growth, increased pod number and branching number of Arabidopsis. 【Conclusion】 Through comprehensive research, 13 candidate regulatory genes were identified that potentially played a crucial role in transcriptional regulation for branch number. MdIAA3 was ectopically expressed in Arabidopsis, which significantly promoted plant growth and branching ability. It was plausible that these genes regulated branching through processes, such as cell differentiation and development, cell wall modification, auxin, and strigolactone signaling pathway.

    Basing Fuzzy Modeling to Evaluate Sensory Quality Differences of ‘Orah’ Mandarin Fruits from Various Production Regions
    WU YaNuo, LIU Yuan, KONG JiaTao, HU ZheHui, CHEN MingHua, WU JunChen, ZHANG HongYan, JIANG YouWu, XU Juan, CHEN JiaJing
    Scientia Agricultura Sinica. 2024, 57(10):  2010-2022.  doi:10.3864/j.issn.0578-1752.2024.10.012
    Abstract ( 85 )   HTML ( 5 )   PDF (1098KB) ( 67 )   Save
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    【Objective】 Fruit sensory quality is the most important factor in determining the competitive edge in the fruit market. The aim of this study was to establish a comprehensive sensory quality evaluation method for citrus fruits by analyzing Orah mandarin (Citrus reticulata Orah) fruits produced in nine different regions and showing quality differences. In addition, this study was aimed to identify sensory quality differences, consumer preference, and metabolites closely linked to citrus sensory attributes in Orah mandarin from different regions. This study could provide the theoretical support and digital method for citrus breeding, practical production and marketing. 【Method】 Firstly, evaluators assessed each sensory attribute and weight of fruit samples, and the fuzzy mathematics was used to derive the weight ranking of different sensory attributes. The samples were then ranked and grouped based on comprehensive sensory evaluation. Furthermore, the physical and chemical indexes were measured, and metabolites related to fruit flavor were analyzed by using GC-MS and HPLC, including soluble sugars, organic acids, amino acids, and flavonoids. OPLS-DA was used to analyze the main differential metabolites between samples from different groups. The relationship between sensory attributes and metabolites was determined by using Pearson correlation analysis. Finally, the important biomarkers reflecting the flavor quality of Orah mandarin were identifued. 【Result】 The sensory attribute weights of Orah mandarin were determined as pulp sweetness>pulp acidity>pulp mastication>fruit color>fruit aroma>fruit shape. Conventional solid-acid ratio was not suitable for accurate classification of the intrinsic quality of Orah mandarin samples. Therefore, based on comprehensive sensory quality, the nine Orah mandarin samples were divided into a high sensory quality group with a score larger than 60 and a low sensory quality group with a score smaller than 60. The OPLS-DA analysis revealed three key compounds (L-glutamic acid, hesperidin, and L-valine) distinguishing high and low sensory quality groups. Futhermore, the pearson correlation analysis indicated that the levels of α-ketoglutaric acid, L-glutamic acid and hesperidin were negatively correlated with sensory quality, sweetness and acidity. 【Conclusion】 Fuzzy mathematics was effectively used to evaluate the comprehensive quality of Orah mandarin. The results indicated that consumers were more concerned in pulp sweetness and acidity; L-glutamic acid and hesperidin might be trait components reflecting the flavor quality of Orah mandarin.

    Structural Composition and Stability of Oil Bodies from 5 Tree Nuts
    SUN XiaoYan, JIN Feng, YANG XuChang, WANG FengJun, ZHOU Ye
    Scientia Agricultura Sinica. 2024, 57(10):  2023-2034.  doi:10.3864/j.issn.0578-1752.2024.10.013
    Abstract ( 105 )   HTML ( 8 )   PDF (8120KB) ( 77 )   Save
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    【Objective】 In oilseeds, lipids are mainly stored in the organelles called oil bodies. Tree nuts, such as walnut and hazelnut, were important oilseed crops. Among the 5 selected tree nuts, the differences in morphology, structure and stability of their oil bodies were evaluated and discussed, which could provide the new ideas for the utilization of the nut oils.【Method】 5 tree nuts were used as materials, including walnut, almond, hazelnut, pecan, and pine nut. The morphology and size of the oil bodies inside the cells of different nut seeds were observed and compared by employing transmission electron microscope. The oil body membrane proteins were separated by SDS-PAGE, followed by the LC-MS/MS identification of the protein bands. The oil body membrane phospholipids, as well as the intrinsic triacylglycerols, were also analyzed through lipidomics. The stability of oil bodies was evaluated by analyzing their changes in morphology peroxide values and thiobarbituric acid values during storage under room temperature.【Result】 The cells of the nut seeds were occupied by the oil bodies and proteosomes. The asymmetric spheroid-shaped oil bodies were covered by intact membranes. The pecan oil body had the largest average diameter (2.34±0.48) μm, while the almond oil body had the minimum (1.21±0.19) μm. For all nut samples, oleosin was the most important oil body membrane protein, accounting for 72.76%-84.15% of the total amount of membrane proteins. Oleosin had a narrow molecular weight distribution of 14.7-18.8 kDa, yet the numbers of oleosin isomers were quite different. Caleosin accounted for 14.34%-4.96% of the total amount of membrane proteins, and its molecular weight in different nuts was approximately 26.5-27.1 kDa. No caleosin isomer was found in each nut sample. Steroleosin, accounted for 8.95%-12.89% of the total amount of membrane proteins, was identified only in walnut, pecan and pine nut oil bodies. The oil bodies of the 5 tree nuts had different triacylglycerol compositions but similar membrane phospholipid compositions. Phospholipidine (PS) and phosphatidylcholine (PC) were the most important oil body membrane phospholipids, accounting for 67.91%-75.06% of the total amount of membrane phospholipids. The proportion of unsaturated fatty acyl chains in membrane phospholipids was 69.64%-74.52%, while 38.64%-45.15% of the fatty acyl groups were oleoyls. The hazelnut oil body showed the highest stability at room temperature. During storage, the oil bodies aggregated and fused gradually, accompanied by an increasing degree of lipid oxidation. Eventually the phase separation phenomenon in oil body emulsions was observed.【Conclusion】 Among the oil bodies from 5 tree nuts, the pecan oil body was the largest in size, while the hazelnut oil body was the most stable. The different tree nut oil bodies had similar constituents of membrane proteins and membrane phospholipids, but there were significant differences in the number of oleosin isomers, triacylglycerol compositions and constituent proportions. The ratio of lipid content to oleosin, as well as the ratio of oil body membrane phospholipids to oil body membrane proteins, might have important influences on the size and stability of the oil bodies.

    Prediction Equations of Chicken Metabolizable Energy Values for Grain Ingredients Based on in Vitro Simulated Enzymatic Hydrolysate Gross Energy Values and Chemical Composition
    LI Kai, BAI GuoSong, TENG ChunRan, MA Teng, ZHONG RuQing, CHEN Liang, ZHANG HongFu
    Scientia Agricultura Sinica. 2024, 57(10):  2035-2045.  doi:10.3864/j.issn.0578-1752.2024.10.014
    Abstract ( 65 )   HTML ( 4 )   PDF (1133KB) ( 51 )   Save
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    【Objective】 This study aimed to measure the enzymatic hydrolysate gross energy (EHGE) of chicken for wheat, paddy, and brown rice ingredients using a monogastric simulated digestion system, and it also aimed to correlate these measurements with the chemical composition of these ingredients. Moreover, the study sought to establish predictive equations for chicken metabolizable energy values based on the EHGE values and the grain ingredients’ chemical compositions. The findings would provide a reference for the rapid prediction of the metabolizable energy value of grain ingredients for chickens. 【Method】 The EHGE values of nine samples from three sources of wheat, paddy, and brown rice ingredients were measured. Five replicates were set for each grain sample, with one digestion tube per replicate. The apparent metabolizable energy values (AME) and true metabolizable energy values (TME) of the same batch of ingredients were also measured by the free feeding method (FF) and the tube-feeding method (TF). A linear regression model was then used to establish predictive equations for AME and TME based on chemical composition and EHGE values. 【Result】 (1) Based on dry matter basis, the EHGE values of wheat, paddy, and brown rice from the three sources were 14.46, 14.63, and 14.80 MJ·kg-1; 12.52, 13.59, 13.40 MJ·kg-1, and 14.74, 15.10, 15.23 MJ·kg-1, respectively. (2) Ash and neutral detergent fiber exhibited a negative correlation with AME (AMEFF and TMEFF) and TME (AMETF and TMETF) measured by both FF and TF methods (P<0.01). EHGE exhibited a significant positive correlation with AMEFF, TMEFF, AMETF, and TMET measured by both methods (P<0.01), with correlation coefficients of 0.801, 0.864, 0.807, and 0.866, respectively. (3) Compared with the metabolizable energy prediction equations established by EHGE, the prediction equations based on chemical composition had higher coefficients of determination (R2) and lower residual standard deviations (RSD). For AMEFF and TMEFF, Ash was the best predictor, with prediction equations: AMEFF = 16.728-0.842 × Ash (R2= 0.809, RSD = 0.826, P = 0.001), and TMEFF = 16.812-0.842 × Ash (R2= 0.816, RSD = 0.806, P = 0.001). On the other hand, for the AMETF and TMETF variables, NDF was identified as the best predictor. The prediction equations for AMETF and TMETF were AMETF=16.106-0.157×NDF (R2=0.907, RSD=0.523, P<0.001), and TMETF=17.654-0.157×NDF (R2=0.903, RSD= 0.534, P<0.001), respectively. 【Conclusion】 The EHGE of wheat and brown rice was higher than that of paddy, and there was a good correlation between the EHGE values of the three grain ingredients and the metabolizable energy values measured by the in vivo method. The prediction model for the AME and TME of grains based on chemical composition was superior to the prediction model based on EHGE.

    Identification of Molecular Markers Associated with Body Size Traits Through Genome-Wide Association Analysis in Wenchang Chickens
    LUO Na, AN BingXing, WEI LiMin, WEN Jie, ZHAO GuiPing
    Scientia Agricultura Sinica. 2024, 57(10):  2046-2060.  doi:10.3864/j.issn.0578-1752.2024.10.01
    Abstract ( 169 )   HTML ( 9 )   PDF (4531KB) ( 115 )   Save
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    【Objective】 Body size traits are the primary indicators for evaluating avian growth characteristics. By selecting molecular markers and candidate genes related to body size traits in Wenchang chickens, this study could provide the theoretical support for deciphering the genetic mechanisms and molecular breeding of body size traits. 【Method】 Three generations of Wenchang chicken lines in Hainan Province (n=2 024) were used in this study. Five body size traits were measured on each chicken at market age, including shank length, shank girth, body slope length, keel length, and chest width. Blood samples were collected for DNA extraction, followed by sequencing and genotyping using the "Jingxin No.1" 55 K chip. Genome-wide association analysis was conducted using GEMMA and PLINK software to identify SNP loci and important candidate genes associated with body size traits. LD analysis was performed to identify haplotypes significantly associated with body size traits. 【Result】 Phenotypic data showed that, at 113 days of age, Wenchang cockerels had average shank length of 8.64 cm, shank girth of 0.46 cm, body slope length of 19.73 cm, keel length of 12.32 cm, and chest width of 6.81 cm. Wenchang hens had average shank length of 6.98 cm, shank girth of 0.40 cm, body slope length of 17.79 cm, keel length of 10.45 cm, and chest width of 6.24 cm. After quality control, 42 206 SNPs and 2 024 individuals were retained for further analysis. PCA analysis using PLINK software revealed some dispersion among the three generations, prompting the inclusion of the top three principal components as covariates in the GWAS analysis to correct for population structure effects. The GWAS results identified 19 SNPs significantly or suggestively associated with shank length (P value=2.17789E-06/4.35578E-05), 23 SNPs associated with shank girth, 7 SNPs associated with body slope length, and 2 SNPs associated with keel length. No SNPs significantly associated with chest width were identified. Annotation of significant loci identified 16 candidate genes related to body size traits, including LDB2, NCAPG, FAM184B, and KCNIP4. LD haplotype analysis revealed 3 significant haplotypes in GGA4, with candidate genes LDB2 and NCAPG annotated in significant block loci. Regarding the shank length trait, two loci, including rs316943436 and rs313978573, were situated within the haplotype block. For shank girth, five loci, namely rs313196946AA, rs316242963, rs315796839, rs313978573, and rs734365522, were located within the haplotype block. In the case of body slope length, only one locus (rs313978573) resides within the haplotype block. 【Conclusion】 Through the GWAS method, those potential candidate genes for shank length, including SEPSECS, LGI2, DHX15, KCNIP4, NCAPG, FAM184B, LDB2, and CC2D2A, were identified. For shank girth, potential candidate genes encompassed FH, TBC1D1, DTHD1, SEPSECS, LGI2, SOD3, PPARGC1A, KCNIP4, NCAPG, FAM184B, CLRN2, LDB2, TAPT1, and CC2D2A. KCNIP4, LDB2, TAPT1, and NRXN3 were identified as potential candidate genes for body slope length, while FAM184B emerged as a potential candidate gene for keel length. In summary, this study established LDB2, NCAPG, and FAM184B as potential functional genes associated with various body size traits, providing the theoretical support for molecular marker-assisted selection in enhancing body performance in Wenchang chickens.