Table of Content

16 January 2024, Volume 57 Issue 2

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

CRISPR/Cas9-Mediated Editing of MODD Enhances Rice Dormancy

GUO NaiHui, ZHANG WenZhong, SHENG ZhongHua, HU PeiSong

Scientia Agricultura Sinica. 2024, 57(2):  227-235.  doi:10.3864/j.issn.0578-1752.2024.02.001

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【Objective】 Dormancy is an important agronomic trait of rice. Proper dormancy can inhibit the preharvest sprouting of rice and is a key factor to ensure yield and quality. However, the genes and regulatory networks of rice dormancy regulation still need further study. The MODD encoded a protein with unknown function, and it negatively regulate rice abscisic acid signaling and drought resistance, but its function in regulating rice dormancy is unknown. Studying the function of MODD in regulating rice dormancy will help to improve the rice dormancy regulatory network, and at the same time provide a new theoretical basis and germplasm resources for genetic breeding of preharvest sprouting resistance.【Method】 Based on the gene sequences published in the RGAP database, a CRISPR-Cas9 knockout vector for MODD was constructed, and the calli of Zhonghua 11 was transformed through agrobacterium mediated genetic transformation to obtain transgenic rice plants. The MODD knockout homozygous lines were screened and identified using PCR amplification, sequencing technology, and qRT-PCR technology. The amino acid sequences of the two mutant lines (KO-1 and KO-2) were obtained according to the CDS of the two mutant lines, and then the protein sequences of ZH11 and the two mutant lines (KO-1 and KO-2) were compared by DNAMAN. The homologous genes of MODD in rice were screened using Linux system. Take the seeds 35 days after heading and investigated the germination rate of ZH11 and knockout lines. The yeast hybridization and LUC experiments were used to verify the upstream gene of MODD. 【Result】 Six MODD homologous genes were found in rice, which were LOC_Os07g41160, LOC_Os03g30570, LOC_Os03g53630, LOC_Os04g35430, LOC_Os03g17050, LOC_Os06g01170. The knockout vector was successfully constructed and transferred it into ZH11, two homozygous mutant lines (KO-1 and KO-2) were obtained. The qRT-PCR results showed that the expression level of MODD in the two mutant line (KO-1 and KO-2) was significantly reduced. Protein sequence analysis showed that the frameshift mutations of KO-1 and KO-2 caused the early termination of protein translation. The germination rate of the two mutant lines (KO-1 and KO-2) was significantly lower than that of ZH11 by 15% and 15% respectively on the third day after water absorption; After that, the difference gradually expanded and reached the maximum on the 6th day, which was significantly lower than that of ZH11 by 35% and 35% respectively. The preharvest sprouting of two mutant lines (KO-1 and KO-2) was significantly lower than that of ZH11. The results of Y1H experiment showed that ABI5 could bind to the promoter region of MODD in yeast, and the binding range was further reduced to less than 300bp. LUC results showed that the fluorescence value of ABI5 was 2.6 times that of none alone, indicating that ABI5 could activate the expression of MODD.【Conclusion】 Knocking out MODD could increase seed dormancy, and MODD may regulate seed dormancy through ABA signaling pathway.

The Construction and Application of SSR and SNP Molecular ID for Maize Germplasm Resources of Jilin Province

ZHANG MingQi, WANG Rui, ZHANG ChunXiao, SUN Bo, REN Jie, LI ShuFang, WANG Lu, ZHU ShaoXi, ZHANG JiangBin, SHI XinChen, WANG HaiJie, ZHANG YunLong, TIAN HongLi, ZHAO YiKun, KUANG Meng, WANG YuanDong, YI HongMei, LI XiaoHui, WANG FengGe

Scientia Agricultura Sinica. 2024, 57(2):  236-249.  doi:10.3864/j.issn.0578-1752.2024.02.002

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【Objective】 Crop germplasm resources hold a crucial strategic position. The Maize Germplasm Resources Bank in Jilin Province safeguards a collection of germplasm resources distinctively representative of the Northern Spring Maize Region. Traditional germplasm resource management faces challenges in ascertaining accurate identity information. To address this issue, molecular marker technology has been employed to establish a process for the construction and classification of molecular IDs for germplasm resources, thereby enabling precise identification and bolstering categorical management. Thorough exploration of the exceptional resources within Jilin Province's Maize Germplasm Resources Bank is intended to advance the shared utilization of these valuable germplasm resources. 【Method】 A total of 2 918 maize germplasm resources were utilized from the Jilin Provincial Maize Germplasm Resources Bank as subjects of the study, the molecular IDs were constructed by using 40 pairs of SSR markers and 61 214 SNP markers recommended in maize variety identification standards. Based on the molecular ID information, the germplasm resources were categorized into core, closely related, heterogeneous, and population groups for management purposes. Furthermore, the core germplasms were analyzed on genetic diversity. 【Result】 In this investigation, the SSR molecular IDs were constructed for 2 918 maize germplasm resources, while the SNP molecular IDs were constructed for 2 502 maize germplasm resources, excluding heterogeneous germplasm. The standards for the construction of SSR and SNP molecular IDs were established for maize germplasm resources. The SSR molecular ID is composed of a combination of three-digit numbers and one-letter code converted from 40 SSR loci fingerprints, stored in the form of a QR code. The SNP molecular ID converts the fingerprints of 61 214 SNP loci into visual barcodes. Based on the features of sample homozygosity and fingerprint specificity, the samples were categorized into 1 561 cores, 705 closely related, 416 heterogeneous, and 236 population types of germplasm resources. Genetic diversity analysis indicates that domestic germplasm resources, represented by Lüdahonggu and Huanggai groups, constituting the main germplasm resources in the Jilin Provincial Maize Germplasm Resources Bank, accounting for 64.38% of all core germplasm resources. 【Conclusion】 This research outlines a methodology for constructing molecular IDs for maize germplasm resources. The SSR molecular IDs were constructed for 2 918 accessions stored in the Jilin Provincial Maize Germplasm Resources Bank and the SNP molecular IDs were constructed for 2 502 among them. The germplasm resources were categorized into core, closely related, heterogeneous, and population types to achieve the classification management.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY·AGRICULTURE INFORMATION TECHNOLOGY

Exploring the Impacts of Temporal Composition Window for Integrating Multi-Source Decametric-Resolution Images on Crop Type Identification

TONG WanTing, WEI HaoDong, YANG JingYa, JIN WenJie, SONG Qian, HU Qiong, YIN GaoFei, XU BaoDong

Scientia Agricultura Sinica. 2024, 57(2):  250-263.  doi:10.3864/j.issn.0578-1752.2024.02.003

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【Background】 The decametric-resolution (≤30 m) image is an important data source to identify crop types in South China dominated by fragmented croplands and complex cropping patterns. Due to the relative long revisit frequency of decametric-resolution sensors and persistent rainy/cloud weather in South China, it is critical to integrate multi-source decametric-resolution images using the temporal composition method for the generation of spatiotemporal continuous crop type map. Due to the different temporal resolutions of different satellites, and the significant differences in phenological quaternal rhythms of various crop types, selecting the optimal temporal composition window for integrating multi-source images is vital to map crop type distribution accurately.【Objective】 This study aims to explore the impact of image temporal composition windows on crop type identification, and to provide significant references for large-scale crop type mapping in regions with complex terrain.【Method】 In this study, Landat-8 and Sentinel-2 data were integrated to extract the crop type distribution in the Jianghan Plain, Hubei Province, characterized by the various crop types and cloudy and rainy weather. Then, seven scenarios (15, 20, 25, 30, 40, 50, and 60 d) were established to analyze the effect of different temporal composition windows on crop type identification. Specifically, three aspects, including image coverage rate, spectral-temporal feature curves for different crops and classification accuracies, were combined to understand the performances of different scenarios comprehensively.【Result】 The crop type mapping using 20-day composition window performed the best, with the overall accuracy (OA) of 93.13%. In contrast, the scenarios that used narrower temporal composition window derived lower accuracy of crop type identification (e.g., OA=90.91% for the 15-day composition window), which can be primarily attributed to the low coverage rate of good observations in the study area. Meanwhile, since time series images composited in the wide window blurred the key phenological information for different crops, the classification accuracy of crop type mapping scenarios using wide temporal interval was also lower (e.g., OA=86.06% for the 60-day composition window). Additionally, the effect of temporal interval on different crops classification was ranked as following: other crops>rapeseed>rice>wheat>rice-crayfish. In detail, the reason why the classification performance of other crops was the most sensitive to the temporal composition window can be due to the high intra-class phenological variance of this type. Flowering period is the key phenology window to identify rapeseed, therefore, the classification accuracy of rapeseed decreased while the temporal composition window exceeds 30-day, and rapeseed was easily confused with wheat. Furthermore, because the key phenology window to distinguish rice-crayfish from single-cropping rice (i.e., the flooding stage of rice-crayfish fields) lasted a long period (e.g., from October 2020 to June 2021), the classification accuracy of rice-crayfish was less sensitive to the temporal composition window.【Conclusion】 In general, the 20-day impact of the temporal composition window can take into account the high-quality image coverage and capture of key phenological characteristics of crop identification, but the optimal temporal composition window of different crops identification is affected by the key phenological period of crops. This study provides theoretical reference and method support for selecting the optimal temporal composition window to generate multi-source image time series, which is promising to improve the efficiency and accuracy of large-scale crop type mapping.

Effects of Planting Density and Fertilization Level on Photosynthesis, Yield and Lodging Resistance of Common Buckwheat

LEI XinHui, WU YiXin, WANG JiaLe, TAO JinCai, WAN ChenXi, WANG Meng, GAO XiaoLi, FENG BaiLi, GAO JinFeng

Scientia Agricultura Sinica. 2024, 57(2):  264-277.  doi:10.3864/j.issn.0578-1752.2024.02.004

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【Objective】 Rational close planting and fertilization can effectively coordinate the competition among individuals, improve the light environment of the population and build a high-yield population, which is an important way to increase crop yield. The effects of different planting densities and fertilization levels on lodging resistance and yield of common buckwheat were discussed to provide technical reference for high yield and high yield cultivation of buckwheat. 【Method】 In this study, Xinong D4103, a new isostyle common buckwheat variety, was used as the experimental material, and Xinong 9976, the main cultivated variety in the Loess Plateau, was used as the control, and the two-factor split plot design was adopted. The main factors were two planting densities, namely D1: 9.0×10⁵ plants/hm² and D2: 1.35×10⁶ plants/hm². The secondary factors were low, medium and high fertilization levels, which were N: 120, P₂O₅: 76.8, K₂O: 56.4 kg·hm^-2 (F1), N: 180, P₂O₅: 115.2, K₂O: 84.6 kg·hm^-2 (F2), N: 240, P₂O₅: 153.6, K₂O: 112.8 kg·hm^-2 (F3) respectively, which were carried out in Yulin Experimental Station of Northwest A&F University in 2021-2022. The effects of canopy structure, photosynthetic characteristics, yield, yield components and lodging characteristics of common buckwheat population under different planting densities and fertilization levels were studied.【Result】 The two-year field experiment showed that with the increase of planting density, the leaf area index (LAI) of common buckwheat population increased significantly, the photosynthetic effective radiation (PAR) and relative chlorophyll content (SPAD) decreased significantly, and the photosynthetic capacity of leaves was weakened. Fertilization significantly increased LAI, SPAD and photosynthetic capacity of common buckwheat population, and decreased PAR. Compared with lower fertilizer level, the LAI, SPAD, net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of medium fertilizer level increased by 14.6%, 6.7%, 15.3%, 15.2% and 16.6% on average, while PAR and intercellular CO₂ concentration (Ci) decreased by 4.5% and 6.7% on average. Compared with D1, the plant height, height of gravity center, length of the second internode, lodging rate and lodging index of D2 increased by 9.6%, 12.5%, 24.7%, 19.8% and 26.2% on average, while the diameter, fullness, flexural strength of the second internode and fresh weight of whole plant decreased by 13.1%, 7.4%, 18.3% and 8.5%. Increased fertilizer application at the same density, the plant height, center of gravity height, length of the second internode, fresh weight of the whole plant, lodging rate and lodging index increased gradually, while the diameter, fullness, flexural strength of the second internode increased first and then decreased. The yield of common buckwheat was significantly increased by increasing the planting density and fertilization level. The yield of Xinong D4103 reached the maximum in D2F2 treatment, which was 15.1% higher than that of D1F1 and 17.0% higher than that of the control variety under the same fertilization amount. 【Conclusion】 Constructing a reasonable population structure is helpful to increase the light receiving area, improve photosynthetic characteristics, reduce the lodging rate in the field and increase yield. Therefore, Xinong D4103, an isostyle common buckwheat variety in the Loess Plateau, recommended the planting density of 1.35×10⁶ plants/hm², and the fertilizer application rate of medium fertilization level (N: 180, P₂O₅: 115.2, K₂O: 84.6 kg·hm^-2)

PLANT PROTECTION

Comparative Analysis of Pathogens of Rice Spikelet Rot Disease in Heilongjiang, Sichuan and Hainan Provinces

ZHANG YaLing, FU ZhongJu, LI Xue, SUN YuJia, ZHAO YuHan, GU XinYi, WANG YanXia, JIN XueHui, WU WeiHuai, HUA LiXia

Scientia Agricultura Sinica. 2024, 57(2):  278-294.  doi:10.3864/j.issn.0578-1752.2024.02.005

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【Objective】 The objective of this study is to identify the pathogenic species and dominant pathogens of rice spikelet rot disease (RSRD) in Heilongjiang, Sichuan and Hainan provinces of China, and to provide reference for accurate prevention and control of RSRD.【Method】 RSRD samples were collected from 13 major rice production areas in Heilongjiang, Sichuan and Hainan provinces. A total of 568 strains were isolated and purified by tissue separation and single spore separation methods. Morphological identification methods were performed for each strain, combined with rDNA-ITS sequence analysis and Koch’s rule verification and identification of RSRD pathogens in 13 major rice production areas. The dominant strains and pathogenic characteristics were analyzed.【Result】 There were three categories of pathogens of RSRD in Heilongjiang Province, they were Curvularia, Alternaria and Fusarium, and which accounted for 1.10%, 83.43% and 15.47% of the total pathogens, respectively. Alternaria was the dominant strains in Heilongjiang Province. In Hainan Province, there were Curvularia, Fusarium, Nigrospora, Lasiodiplodia and Exserohilum species of RSRD pathogens, which accounted for 1.62%, 89.47%, 0.81%, 1.62% and 6.48% of the total pathogens, respectively, and Fusarium was the dominant strains. There were Curvularia, Alternaria, Fusarium, Nigrospora and Exserohilum species of RSRD pathogens in Sichuan Province, which accounted for 23.57%, 13.47%, 22.86%, 16.43% and 23.57% of the total pathogens, respectively, and no dominant strain. According to the differences of conidia and colony morphology, 23 representative strains were selected, and then rDNA-ITS sequence analysis and Koch’s rule verification were combined. The pathogens of RSRD were identified as C. lunata of the genus Curvularia; A. tenuissima, A. alternata, A. brassicae of the genus Alternaria; F. verticillioides, F. andiyazi, F. equiseti, F. incarnatu, F. chlamydosporum of the genus Fusarium; N. oryzae, N. sphaerica of the genus Nigrospora; L. theobromae of the genus Lasiodiplodia and E. rostratum of the genus Exserohilum. The pathogens of RSRD were inoculated both at booting stage and heading and flowering stage, respectively. It was found that whether japonica or indica rice, the average disease index of pathogen of heading and flowering stage inoculation was higher than that of inoculation at booting stage in Hainan Province; while the pathogens’ average disease index of heading and flowering stage inoculation in Heilongjiang and Sichuan provinces was slightly lower than that at booting stage inoculation.【Conclusion】 The pathogens of spikelet rot disease in Heilongjiang, Sichuan and Hainan provinces of China were diverse. The dominant strain was Alternaria in Heilongjiang Province and Fusarium in Hainan Province. The dominant strain was not obvious in Sichuan Province.

Isolation, Genome Determination and Lysis Function Analysis of Phage Kuerle of Erwinia amylovora

CHEN Niu, YU ChengMin, CUI BaiMing, REN CaiXia, YANG LiYing, DONG Yu, LIU Lin, ZHENG YinYing

Scientia Agricultura Sinica. 2024, 57(2):  295-305.  doi:10.3864/j.issn.0578-1752.2024.02.006

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【Background】 Erwinia amylovora, the causal agent of fire blight in pome fruit trees, poses a serious threat to apple and pear production worldwide. With the emergence of antibiotic-resistant strains, control of E. amylovora causing fire blight is a huge challenge.【Objective】 The objective of this study is to isolate a new lytic E. amylovora bacteriophage and analyze the functions of the phage lytic-related genes, and to provide a new option for the control of fire blight.【Method】 Phage was isolated from fire-blight-endemic orchard soil using the double-layer plaque assay with E. amylovora strain Ea102 as the host. Morphology was observed by phage plagues and transmission electron microscopy. The phage genome was determined by PacBio sequencing, SPAdes assembly, and RAST annotation. The Escherichia coli prokaryotic expression system was used to analyze the lysis mechanism of bacteriophage.【Result】 A new E. amylovora bacteriophage, named Kuerle, was isolated and purified. Kuerle consists of an icosahedral capsid head and a short tail, with a latent phase of about 50 min and burst size of about 240 pfu/cell. The phage has a genome length of 75 599 bp with 48.0% GC content, and direct terminal repeat of 393 bp. No regulatory genes related to lysogency were identified. A total of 85 open reading frames (ORFs) were predicted, of which 33 known functional proteins contained a giant virion-associated RNA polymerase (vRNAP) (3 550 aa). The vRNAP is considered one of the main features of the family Schitoviridae. The morphology of viron and genome structure agree that phage Kuerle belongs to the family Schitoviridae. Three lysis-associated genes, holin, endolysin and spanin clustered in late expression DNA region compose “lysis cassettes”. The expression of Kuerle-holin in E. coli inhibited the growth of bacteria, while the expression of Kuerle-endolysin caused cell lysis. Kuerle-holin accelerated the process of cell lysis caused by Kuerle-endolysin. Inhibition of the general secretion system (Sec) of bacteria with sodium azide or deletion of the N-terminal signaling sequence of Kuerle-endolysin both resulted in the loss of endolysin lysis function. These results suggest that the phage Kuerle has a pinholin-SAR endolysin lysis system. Kuerle-holin (pinholin) depolarizes cytoplasmic membrane to activate the secreted Kuerle-endolysin (SAR endolysin) which degrades cell wall in periplasm.【Conclusion】 Kuerle is a virulent bacteriophage and Kuerle-endolysin has significant bacteriostatic effect, which provides theoretical basis and research materials for the preparation of subsequent fire blight control reagents.

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

Effects of Nitrogen Fertilization Levels on Grain Yield, Plant Nitrogen Utilization Characteristics and Grain Quality of Foxtail Millet

DONG ErWei, WANG Yuan, WANG JinSong, LIU QiuXia, HUANG XiaoLei, JIAO XiaoYan

Scientia Agricultura Sinica. 2024, 57(2):  306-318.  doi:10.3864/j.issn.0578-1752.2024.02.007

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【Objective】 To provide the theoretical basis for rational nitrogen (N) application and promoting high yield and high quality of foxtail millet (Setaria italica (L.) Beauv.), this study aimed to clarify the effects of different N application rates on plant N utilization characteristics, grain yield and grain quality of foxtail millet. 【Method】 To investigate the effects of different N application levels on plant N accumulation, transfer and utilization characteristics, grain yield and its components, grain micronutrients content and pasting properties, a 2-year field experiment (2020-2021) was performed with different N fertilization application at four levels (0, 75, 120, and 150 kg·hm^-2, represented as N0, N75, N120, and N150, respectively) in the Qinxian County of Shanxi Province, located in the spring sowing region of China.【Result】 Compared with N0, N application increased panicle number per unit area at harvest, grain number per panicle and plant productivity of foxtail millet. N application also significantly enhanced N translocation and promoted the distribution of both dry matter and N in grains. As a consequence, an enhanced grain yield was obtained when subjected to N application. Further, among all treatments, the highest values of panicle number per unit area at harvest, grain number per panicle, both grain yield and biomass, harvest index, total N accumulation and N translocation efficiency were obtained when 75 kg·hm^-2 was supplied; compared with the values produced by N0, the increased rate reached 7.5%, 23.3%, 31.0%, 21.2%, 8.6%, 40.3% and 9.2% by N75, respectively. Compared with N0 treatment, the content of Fe, Zn, Ca, Mg and Se in foxtail millet grains under N75 treatment were increased by 37.3%, 43.6%, 56.0%, 30.5% and 16.9% at most, respectively. Excessive N application (N 150) decreased grain number, harvest index and N translocation efficiency compared with N75 treatment. More than 75 kg·hm^-2 application resulted in diminished N translocation efficiency, by 23.1% and 28.1%, in 2020 and 2021, respectively. The content of amylopectin and starch yield were also limited by excessive N. Over-use N fertilizer also significantly decreased final viscosity, setback and trough viscosity. Pearson correlation coefficients demonstrated a strong positive relationship between plant N accumulation and the content of Fe, Zn, Ca, Mg and Se in foxtail millet grains, and a significant negative relationship between plant N accumulation and the content of amylopectin, final viscosity and trough viscosity in foxtail millet grains.【Conclusion】 The N application at 75-120 kg·hm^-2 could promoted the allocation of dry matter and N in grain, which was relative to the enhanced N transfer from vegetative organs to grains. Also the reasonable pasting properties and biofortification of beneficial trace elements of Fe, Zn, Ca, Mg and Se was produced by such N dose in this study area.

Effects of Irrigation Water Temperature and Nitrogen Application Rate on Soil Hydrothermal Environment and Cotton Growth and Yield Under Mulched Drip Irrigation

HE Jing, WANG ZhenHua, LIU Jian, MA ZhanLi, WEN Yue

Scientia Agricultura Sinica. 2024, 57(2):  319-335.  doi:10.3864/j.issn.0578-1752.2024.02.008

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【Objective】 The response mechanism of soil hydrothermal environment and cotton growth to irrigation water temperature and nitrogen application rate under mulched drip irrigation was explored to determine the reasonable irrigation water temperature and nitrogen application rate of drip irrigation cotton in northern Xinjiang.【Method】 A two-factor completely randomized experimental design was conducted with "Xinluzao 42" cotton as the experimental material with four irrigation water temperature levels (15 ℃ (T0), 20 ℃ (T1), 25 ℃ (T2), and 30 ℃ (T3)) and three nitrogen application levels (250 kg·hm^-2 (F1), 300 kg·hm^-2 (F2), and 350 kg·hm^-2 (F3)). The effects of nitrogen application on soil hydrothermal environment, cotton growth and yield, and water and nitrogen use efficiency under different irrigation water temperature were analyzed.【Result】 The conventional irrigation water temperature and low nitrogen treatment reduced soil temperature, inhibited cotton growth, decreased boll number per plant and seed cotton yield. Suitable irrigation water and nitrogen application could improve the soil's hydrothermal environment, promote cotton growth and development, and improve seed cotton yield and water and nitrogen utilization. Compared with 15 ℃ of conventional irrigation water temperature, the warming irrigation significantly increased the soil temperature by 0.58-3.30 ℃, and soil water storage was reduced by 1.2%-7.2%, while soil respiration rate was significantly increased by 5.7%-28.0%; cotton plant height, leaf area index, and above-ground dry matter accumulation increased and then decreased with the increase of irrigation water temperature, and reached the maximum at 25 ℃. With increasing nitrogen application rate, soil water storage decreased by 3.3%-6.7%, soil respiration rate increased significantly by 3.6%-9.5%, cotton plant height increased significantly by 3.2%-4.9%, leaf area index increased significantly by 5.8%-11.0%, and above-ground dry matter accumulation increased significantly by 1.2%-2.2%, these indicators all reached the maximum under 350 kg·hm^-2 nitrogen fertilizer application. Water use efficiency, nitrogen fertilizer bias productivity, and seed cotton yield all increased and then decreased with the increase of irrigation water temperature, and showed a trend of “increasing, decreasing, and increasing” with the increase of nitrogen application. The path analysis showed that soil temperature directly affected seed cotton yield, while nitrogen application indirectly affected seed cotton yield by promoting cotton growth. The seed cotton yield and water use efficiency reached the maximum under T2F2 treatment, which were 6 652.3 kg·hm^-2 and 1.17 kg·m^-3, respectively. But the nitrogen fertilizer bias productivity was significantly greater under T2F2 treatment (22.17 kg·kg^-1) than that under T2F3 treatment (18.80 kg·kg^-1).【Conclusion】 Considering the effects of irrigation water temperature and nitrogen application on soil temperature, soil respiration rate, cotton growth, yield, and water and nitrogen utilization rate, a suitable combination of irrigation water temperature of 25 ℃ and nitrogen application rate of 300 kg·hm^-2 were recommended in northern Xinjiang.

HORTICULTURE

Identification of Salt Resistance Functional of Grape Transcription Factor VvERF2

DAI YingZi, GUO HongYang, YANG ZhiFeng, WANG XianPu, XU LiLi

Scientia Agricultura Sinica. 2024, 57(2):  336-348.  doi:10.3864/j.issn.0578-1752.2024.02.009

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【Objective】 In order to give references for future study on the mechanism of the AP2/ERF superfamily on grapes, the protein bioinformatics analysis of grape transcription factor VvERF2 was performed. Additionally, the procedures of gene cloning and homologous genetic transformation were employed for exploring the function of VvERF2 under salt stress in grape callus. 【Method】 For the bioinformatics analysis of the VvERF2 protein, the NCBI Blast database (https://blast.ncbi.nlm.nih.gov/Blast.cgi) and additional online resources were utilized. The Thompson seedless (Vitis vinifera L.) callus was used as the material, and the grape homologous genetic transformation system of VvERF2 were constructed. The transgenic callus phenotype was determined by growth volume, total sugar, total acid, and other factors. Free proline, antioxidant enzyme activity, and other indices were used to assess the salt tolerance of transgenic callus. 【Result】 Based on the bioinformatical analysis of VvERF2 and the 7 most homologous orthologous protein sequences, the VvERF2 gene encoded 240 amino acids, which were quite similar to those of tomatoes and figs, with protein homology percentages of 78% and 67%, respectively. The amino acid residues in eight species varied from 240 to 348, their molecular weights from 26.43 to 38.60 kDa, their theoretical isoelectric points from 5.54 to 8.68, and their index of fatty amino acids were all belonged to unstable proteins, which was higher than 66%. The physicochemical properties of amino acid sequences in different species were quite different. In addition, the promoter of VvERF2 gene had a variety of cis-acting element related to abscisic acid and other transcription factors, such as MYB. Particularly, VvERF2 expressed specificity in different tissues, with callus exhibiting the lowest level of expression. Following salt stress, however, VvERF2 gene expression increased to three times that of the control group. Transgenic results showed that after overexpression of VvERF2 gene in grape callus, growth amount, total acid, total phenol content and antioxidant activity of DPPH (1, 1-diphenyl-2-trinitrophenylhydrazine) were significantly increased. The content of total protein and free proline in transgenic callus were almost higher than those in wild-type callus treated with different concentrations of NaCl. 【Conclusion】 The overexpression of VvERF2 promoted callus growth and accumulation of secondary metabolites, such as phenolic substances, and improved salt tolerance of grape.

Effects of Soil Texture on Rhizosphere Microbial Carbon Source Utilization, Nematode Community and Fruit Sugar of Jackfruit

SU LanXi, PU QiuJie, BAI TingYu, WU YueXian, WU Gang, TAN LeHe, HU YaLi

Scientia Agricultura Sinica. 2024, 57(2):  349-362.  doi:10.3864/j.issn.0578-1752.2024.02.010

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【Objective】 This study aimed to investigate the variations in soil microenvironments with different textures under identical fertilization pattern and their potential relationship with the key fruit quality (sugar content), so as to provide a theoretical foundation for regional orchard fertilization and enhancing yield and quality. 【Method】 Standardized jackfruit Malaysia No. 1 orchards, characterized by consistent fertilization practices and soil textures including loam, sandy loam and sand, was carefully selected for this study. Rhizosphere soil and mature fruit of jackfruit were collected during the tree growing, flower and fruit stages to investigate the variation of metabolic functions of soil microbial communities, nematode community structure, soil physicochemical properties and fruit sugars and potential relationships of them. 【Result】 The trend of carbon source utilization of soil microorganisms in sandy loam and sandy soil followed the pattern of tree growing stage > flower stage > fruit stage. The carbon source metabolic capacity of soil microorganisms in loamy soils was ranked as fruit stage > tree growing stage > flower stage. The main types of carbon sources utilized by soil microorganisms were carbohydrates, amino acids, carboxylic acids, and polymers. The diversity index of the soil microbial community and nematode abundance in each trophic group were exhibited consistently higher values in sandy soils compared with other soil types, with particularly elevated levels observed during the tree growing and fruit stages. The ecological index of nematode, soil pH and organic matter in loamy soils were generally higher than that in the other two soil types. The glucose content in fruit showed the following order: sandy loam soil> loam soil > sandy soil. The differences in other sugar components among different soil textures were not significant. The sampling stage had a significant direct effect on the diversity of soil nematode communities, and the soil texture had a significant indirect effect and total effect on the sugar content of jackfruit. 【Conclusion】 The combined application of organic and inorganic fertilizers had different effects on the microecological environment of soils with different textures. The soil texture exerted a direct or indirect influence on the composition and functioning of microbial and nematode communities in rhizosphere soil of jackfruit throughout the tree growing and fruit stages, thereby ultimately impacting both the soil nutrient transformation and fruit quality.

FOOD SCIENCE AND ENGINEERING

Metabolomic Analysis of Canarium album Fresh Food Quality Differences Based on Sensory Evaluation

XIE Qian, JIANG Lai, DING MingYue, LIU LingLing, CHEN QingXi

Scientia Agricultura Sinica. 2024, 57(2):  363-378.  doi:10.3864/j.issn.0578-1752.2024.02.011

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【Objective】 This study aimed to identify key metabolites that influence the quality of fresh Chinese olives and to investigate the metabolic mechanisms underlying quality differences. 【Method】 Four Chinese olive varieties were selected as test materials, with Huiyuan as the topgrafting rootstock. The quality of the fruits was evaluated through sensory evaluation. Metabolite identification and analysis of the KEGG pathway were conducted using ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), and the metabolic changes during the ripening process of the fruits were investigated too.【Result】 The results of sensory evaluation of four varieties (lines) of Chinese olive fruits showed significant differences in quality. Tianlan No.1 and Dongshan Changsui exhibited good quality, while Huiyuan and Ziyang No.1 had poor quality. A total of 651 metabolites belonging to 15 types were identified in the Chinese olive fruits of the four varieties (lines). Among these, 277 were primary metabolites of 6 types, and 365 were secondary metabolites of 9 types. Using variable projection and multiple differences, 26 characteristic differential metabolites that influence the quality of fresh Chinese olives were screened. These metabolites included amino acids and their derivatives (6), organic acids (2), lipids (2), and phenolic compounds (16). The phenolic compounds consisted of phenolic acids (3), flavonoids (3), flavonols (2), flavanols (3), and hydrolyzed tannins (5). A metabolic network were established based on the ripening process of Chinese olives to explain the differences in fresh food quality. Chinese olives with good fresh food quality showed a higher accumulation in the biosynthetic metabolic pathway of L-Asparagine and N, N-dimethylglycine, which influenced the taste of fresh food and its resilience. On the other hand, Chinese olives with poor fresh food quality exhibited relatively high levels of hydrolyzed tannins (digalloylchebuloylglucose, galloyl methyl gallate, heterophylliin A), flavonol [morin-3-O-xyloside, quercetin-3-O-(6′-galloyl], Flavan-3-ol [7-O-galloyltricetiflavan, catechin - (7,8-bc) -4α- (3,4-dihydroxyphenyl) - dihydro-2-(3H)-one, catechin-(7,8-bc)-4β-(3,4-dihydroxyphenyl)-dihydro-2-(3h)-one] in the synthesis pathway, which influenced the taste of fresh food and contributed to its bitter taste. 【Conclusion】 The differences in fresh quality of different olives were closely related to the accumulation differences in amino acid and its derivative synthesis pathways, as well as the synthesis pathways of hydrolyzed tannins, flavanols, and flavan-3-ol during their ripening process.

ANIMAL SCIENCE·VETERINARY SCIENCE

Review on Carbon Footprint Assessment of Pig Farming System

ZHOU YuanQing, DONG HongMin, ZHU ZhiPing, WANG Yue, LI NanXi

Scientia Agricultura Sinica. 2024, 57(2):  379-389.  doi:10.3864/j.issn.0578-1752.2024.02.012

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【Objective】 Livestock production is one of the important emission sources of greenhouse gases, while China is a major country in pig farming. Scientifically assessing the carbon footprint of pig farming system can provide a reference for further promoting carbon emission reduction of animal husbandry. 【Method】 This paper reviewed the research status of carbon footprint assessment of pig breeding system, including model, results and composition. The results of carbon footprint assessment were related to many factors, such as system boundary, emission sources, accounting methods and functional unit. In this study, we considered the main factors which affect the evaluation results, and analyzed the reasons for the difference of results. 【Result】 Through reviewing the domestic and foreign literature on carbon footprint assessment, it was realized that the assessment model of livestock had been constructed well in developed country. The carbon footprint of 1 kg functional unit product was 2.2-10.3 kg CO_2-eq. The assessment results varied due to the different evaluation methods in various studies. Different system boundaries and functional units were the important reasons for different results. The different emission sources, accounting parameters selected for the same emission source, or diverse allocation methods under the same system boundary also led to great differences. For the contribution to the carbon footprint of the pig production system, feed production was the largest link, accounting for 49%-83%; the second was manure management, accounting for 12%-41%. 【Conclusion】 In order to widely precise the carbon footprint of China’s pig production system, the suggestions were as follows: monitoring the key parameters of greenhouse gas emissions for various feeding modes in all regions of China should be carried out; the Chinese carbon footprint assessment database according to the development status of Chinese pig breeding systems should be established; the unified and standardized evaluation methods should be appeared publicly; an carbon footprint assessment model fit for different regions of Chinese production practice should be created to provide data reference support for the sustainable development of Chinese pig production system.

Cloning of PLZF Gene and Its Effects on the Proliferation of Undifferentiated Spermatogonia in Cattleyak

ZHANG Peng, WANG MingXiu, JING KeMin, LI YuQian, TIAN Yuan, ZHONG JinCheng, CAI Xin

Scientia Agricultura Sinica. 2024, 57(2):  390-402.  doi:10.3864/j.issn.0578-1752.2024.02.013

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【Objective】 As the product of interspecific hybridization between yak and cattle, cattleyak has excellent production performance, but the further application of its heterosis is limited by the male sterility of cattleyak. The aim of the study was to clone the PLZF of cattleyak, and to identify its differential expression in the testicular tissue and undifferentiated spermatogonia of cattleyak and yak, and to further reveal the effect of expressing this gene on the activity of undifferentiated spermatogonia of cattleyak. This study could provide a theoretical basis for clarifying the mechanism of spermatogenesis stagnation in cattleyaks. 【Method】 In this study, 24-month-old male Maiwa yak and F₁ generation male cattleyak were used as experimental animals, and the CDS sequences of PLZF in cattleyak were cloned by RT-PCR and analyzed by bioinformatics. The differential expression of PZLF in the testis tissues of cattleyak and yak was analyzed by RT-qPCR. The expression vector of PLZF was constructed by homologous recombination, and the overexpression efficiency and the expression of downstream target genes were detected by RT-qPCR. The effect of overexpression of PLZF on the undifferentiated spermatogonia of cattleyak was detected by PDT, CCK-8, EdU, and immunofluorescence. 【Result】 The CDS region of the PLZF was cloned, and it was found by bioinformatics analysis that the protein sequence encoded by the gene did not contain transmembrane domain and signal peptide sequence, and its tertiary structure was mainly α helix and random curl. Phylogenetic tree analysis showed that the PLZF of cattleyak was more closely related to the PLZF of cattle. The prediction of tertiary structure showed that although the tertiary structure of PLZF protein of cattleyak, yak and cattle was highly similar, the PLZF protein of yak was quite different from that of cattleyak and cattle at amino acids 531-540. RT-qPCR found that the expression levels of PLZF gene in the testis tissue and undifferentiated spermatogonia of cattleyak were significantly lower than that in yak (P<0.05). After overexpression of PLZF, the expression of PLZF in the undifferentiated spermatogonia of the cattleyak was up-regulated by 13.8 times (P<0.01), and the proliferation activity of the undifferentiated spermatogonia of the cattleyak was significantly increased (P<0.05), which showed that the down-regulation of PLZF expression affected the proliferation activity of undifferentiated spermatogonia of cattleyak. In addition, after overexpression of PLZF, the proliferation activity of undifferentiated spermatogonia was significantly increased All proliferation-related genes (Etv5, Bcl6b, Pcna and c-fos) were significantly up-regulated (P<0.05), and all differentiation-related genes (Stra8, Kit, Dmrt1 and Sohlh2) were significantly down-regulated (P<0.05), indicating that PLZF could promote the proliferation of undifferentiated spermatogonia by up-regulating the expression of proliferation-related genes and down-regulating the expression of differentiation-related genes.【Conclusion】 The abnormal expression of PLZF in cattleyak undifferentiated spermatogonia reduced the proliferative activity of cattleyak undifferentiated spermatogonia, resulting in its decrease in number and affecting the spermatogenesis of cattleyak. This study provided a theoretical basis for further elucidation of the mechanism of spermatogenesis and stagnation in cattleyak, and a new idea for solving the problem of male sterility in cattleyak.

RESEARCH NOTES

Comparison of Heat Tolerance of Maize Hybrids and Their Parental Inbreds with Different Genotypes

XU TianJun, LÜ TianFang, LI ZiHao, ZHANG Yong, LIU HongWei, LIU YueE, CAI WanTao, ZHANG RuYang, SONG Wei, XING JinFeng, ZHAO JiuRan, WANG RongHuan

Scientia Agricultura Sinica. 2024, 57(2):  403-415.  doi:10.3864/j.issn.0578-1752.2024.02.014

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【Objective】 In recent years, the adverse weather of high temperature and heat damage in the Huang-Huai-Hai maize region of China occurred frequently, which has become an important adverse factor threatening maize production. Study and clarify the effects of high temperature stress on male and female ear characteristics and yield of maize can provide useful guidance for the cultivation and selection of high temperature tolerant maize varieties. 【Method】 The variety of Zhengdan958 (Zheng58×Chang7-2), Xianyu335 (PH6WC×PH4CV), Jingnongke728 (JingMC01×Jing2416), MC812 (JingB547×Jing2416), and their parents were used as the test materials. High temperature stress before and after flowering (from V12 stage to 7 d after silking) were conducted. The effects of high temperature stress on the growth and development of male and female panicles, ASI, pollen activity, yield and yield components of different genotypes of maize hybrids and their parents were studied. 【Result】 High temperature stress before and after anthesis significantly reduced the ear length, rows per ear and grains per row of the tested maize varieties and their parents, and then resulted significant decrease in yield. Compared with the control, the grain number per spike of Zhengdan958, Xianyu335, Jingnongke728 and MC812 decreased by 22.28%, 47.69%, 6.13% and 8.11% respectively under high temperature stress, resulting yield decrease of 9.50%, 50.61%, 3.17% and 5.00% respectively. Among the parental materials, the decrease of rows per panicle, grains per row and yield of Jing2416 under high temperature treatment was the smallest and not significant, while the decrease of PH6WC was the largest. Under high temperature stress, the total number of tassel branches, the length of tassel, the total amount of loose pollen and pollen activity decreased significantly, the silking period of loose pollen was prolonged, and the duration of loose pollen was shortened. Among them, Jingnongke728 had the smallest decline, followed by MC812, showing good heat resistance, while Zhengdan958 had the largest decline in the length of tassel, but the amount of pollen was the largest due to the large number of tassel branches. Xianyu335 has fewer male panicle branches, a large decrease in male panicle length, the least amount of pollen and low activity. Among the parental materials, Jing2416 had a large amount of total loose pollen and strong pollen vitality under high temperature treatment, with the smallest decline, only 4.50 and 3.98 percentage points. Compared with the control, the interval of loose pollen silking (ASI) was prolonged by 1.6d under high temperature stress. The decrease in male spike length is manifested as Zhengdan958>Xianyu335>MC812>Jingnongke728. Zhengdan958 had the largest decrease in male spike length, but had more branches and the largest pollen yield; Xianyu335 has fewer branches of male spikes, a significant decrease in male spike length, the least pollen quantity, and the lowest activity; Jing 2416 has a large amount of loose pollen and strong pollen vitality, with the smallest decrease (only 4.50% and 3.98%). 【Conclusion】 High temperature stress before and after anthesis has a significant impact on the grain yield, male and female ear development process, pollen activity and filament microstructure of the tested maize varieties. Under high temperature stress at this stage, the decline of yield and pollen activity of Jingnongke728 and MC812 is significantly less than Xianyu335, showing higher single ear yield and heat tolerance. By comparing the heat resistance of the parental inbred lines of the tested maize hybrids, it was found that the heat resistance of the paternal inbred lines was better than that of the maternal inbred lines. The male panicle branch and length of the parent material Jing2416 decreased slightly, the amount of pollen was large, the pollen activity was high, the filaments were hairy, the ability to capture pollen was strong, the single panicle yield was high, and the heat resistance was the best. Therefore, in the planting area with frequent high temperature and heat damage, selecting maize varieties such as Jingnongke728 can achieve stable and high yield; and during the maize breeding process, we should pay more attention to the utilizing of the higher temperature resistant inbred such an Jing2416 and then combination higher temperature maize varieties.

Characteristics of Endophytic Microbial Community Structures in Stems Between Hylocereus undatus and H. polyrhizus

ZHOU XinYan, CHEN SiYu, WEI YuFei, ZHU Yu, FENG JunQian, DING DianCao, LU GuiFeng, YANG ShangDong

Scientia Agricultura Sinica. 2024, 57(2):  416-428.  doi:10.3864/j.issn.0578-1752.2024.02.015

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【Objective】 The differences of the endophytic microbial community structures between Hylocereus undatus and H. polyrhizus were analyzed, so as so to explore the correlation between the pulp color of H. polyrhizus and the endophytic microbial community composition and their functional microorganisms. 【Method】 Based on high-throughput sequencing technology, the diversity and richness of endophytic microorganisms (bacteria and fungi) in stems between H. undatus and H. polyrhizus were analyzed. Meanwhile, based on LEfSe analysis, the differences of endophytic microorganisms in stems between H. undatus and H. polyrhizus were also investigated.【Result】 The significant differences of the endophytic microbial community structures were found in stems between H. undatus and H. polyrhizus. Meanwhile, the numbers of specific bacterial and fungal OTUs in stems of H. polyrhizus were all higher than those of H. undatus. At the phylum level, the relative abundance ratio of Ascomycota in stems of H. polyrhizus was 1.15 times higher than that of H. undatus. At the genus level, Streptomyces and Penicillium were the highest abundant dominant bacterial and fungal genera in stems of H. polyrhizus, which were 1.24 and 4.27 times higher than those of H. undatus, respectively. In addition, some bacterial genera, such as Lechevalieria, Glycomyces, unclassified_f__Enterobacteriaceae, Actinomadura, and some fungal gerera, such as Talaromyces, unclassified_f__Serendipitaceae, unclassified_c__GS13, unclassified_o__Atractiellales, unclassified_o__Auriculariales were enriched in stems of H. polyrhizus. LEfSe analysis also showed that Promicromonospora and Xylomyces were significant enriched in stems of H. polyrhizus. 【Conclusion】 All above results suggested that the formation of pigment was closely related to the compositions of endophytic microbial community in stems of H. polyrhizus. The bacterial genera, such as Streptomyces, unclassified_f__Enterobacteriaceae, Promicromonospora, and the fungal phylum and genera, such as Ascomycota, Penicillium, Talaromyces and Xylomyces, were all the potential microorganisms in relating to pigment synthesis and metabolic accumulation in stems of H. polyrhizus.