Table of Content

01 July 2021, Volume 54 Issue 13

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

CRISPR/Cas9 Targeted Editing of OsIAA11 in Rice

LI ZhaoWei,LING DongLan,SUN CongYing,ZENG HuiLing,LIU KaiJi,LAN YingShan,FAN Kai,LIN WenXiong

Scientia Agricultura Sinica. 2021, 54(13):  2699-2709.  doi:10.3864/j.issn.0578-1752.2021.13.001

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【Objective】Auxin signaling pathway regulated by OsIAA11 plays an important role in the plant growth and response to various environment stresses, impacting on the final grain yield during the late stage. To explore the effect of OsIAA11 mutation on the yield, the OsIAA11 mutant plant was obtained using CRISPR/Cas9 system, and the agronomic characters of mutant plants were investigated in the field. 【Method】According to the principle of CRISPR/Cas9 technology, two 20 bp targeted sequences were designed in the first exon and second exon of the OsIAA11 genome sequence. The gene shuffling of non-specific target sites was eliminated using the blast analysis. The oligonucleotides of two target sites were inserted into the pYLgRNA-U6a and pYLgRNA-U6b plasmid vector, and then were amplified twice by PCR technology to construct U6a-IAA11-T1 and U6b-IAA11-T2 expression-boxes. The recombinant pYLCRISPR/Cas9-IAA11-T12 vector was obtained by linking two expression-boxes to pYLCRISPR/Cas9-MT vector. The pYLCRISPR/Cas9-IAA11-T12 vector was transformed into the callus ofjaponica rice ZH11 through Agrobacterium-mediated method. The T₀ generation of transgenic plants was obtained by tissue culture, and the positive transgenic plants were selected through PCR method. The target sites of each T₂ generation from T₀ positive plants were determined via PCR and sequencing method, and finally the mutated genotypes were identified. Meanwhile, agronomic traits of the T₂ generation were investigated in the field. 【Result】The pYLCRISPR/Cas9-IAA11-T12 expression vector was successfully transformed into the callus of ZH11. 25 transgenic lines were obtained, and 20 transgenic lines were identified as the positive plants. After analysis of T ₂ transgenic plants via PCR and sequencing the target locus, 17 different homozygous mutations were identified in the two target sites of the OsIAA11 genomic sequence. Except for the single base insertion mutation of osiaa11-20-1, osiaa11-21-2, osiaa11-23, and osiaa11-25 in target 1 and osiaa11-22-2 in target 2, other genotypes mainly deleted small fragment base in target 1 and mutated a single base in target 2. Agronomic traits results showed that 17 osiaa11 mutants did not present a significant difference in plant height, panicle length, grain number per panicle, seed setting rate, 1000-grain weight, harvest index, and grain-straw ratio in comparison with the wild type. However, the osiaa11 displayed a significant decrease in effective spike rate, suggesting a more ineffective tiller phenotype. 【Conclusion】CRISPR/Cas9 technology successfully editedOsIAA11 and 17 different homozygous mutations genotypes were obtained. The mutant showed the reduced effective spike rate and increased ineffective tillers, indicating that OsIAA11 was related to the tiller bud appearance dominated by auxin.

Cloning of TaBG and Analysis of Its Function in Anther Dehiscence in Wheat

TAN ZhaoGuo,LI YanMei,BAI JianFang,GUO HaoYu,LI TingTing,DUAN WenJing,LIU ZiHan,YUAN ShaoHua,ZHANG TianBao,ZHANG FengTing,CHEN ZhaoBo,ZHAO FuYong,ZHAO ChangPing,ZHANG LiPing

Scientia Agricultura Sinica. 2021, 54(13):  2710-2723.  doi:10.3864/j.issn.0578-1752.2021.13.002

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【Objective】 β-glucosidase (BG, 4-β-D-glueosidase) is a kind of hydrolase which hydrolyzes glycosidic bond from glycopolymer or oligosaccharide to release non reducing sugar group, which plays an important role in controlling anther dehiscence. The anthers of the photoperiod-temperature sensitive genic male sterile (PTGMS) wheat line BS366 did not dehiscence in sterile environment, but completely or partially cracked in fertile environment. In order to study the regulatory function of BG gene on anther dehiscence in wheat, the TaBG was cloned from BS366 and its potential function in anther dehiscence was analyzed, which provided theoretical basis for further analysis of molecular mechanism of abnormal anther dehiscence in photoperiod thermo sensitive male sterile line of wheat.【Method】TaBG was cloned from the anther of PTGMS line BS366, and the primary structure, secondary structure, tertiary structure of TaBG protein were predicted. In addition, the cis-acting elements in promoter region prediction, phylogenetic tree construction with other species, interaction between miRNA and TaBG were performed using bioinformatics software. The expression levels of TaBG and the interacted tae-miR395a in anthers and glumes under MeJA and SA treatment were determined. 【Result】 The total length of TaBG is 1 473 bp, which encoded 490 amino acids, and the theoretical pI is 8.12, belonging to the glycosylhydrolase superfamily. The results showed that TaBG may be regulated by stress resistance-related miRNAs, such as miR169and miR395a. Based on the prediction of protein interaction, it was found that TaBG might interact with glucose-methanol-choline oxidoreductase (GMC) and endoglucanase (EG). TaBG is located in the liquid bubble of the wheat proton. The qPCR results showed that the expression of TaBG in Bilocular stage (stage 13), Dehiscence (stage14) and Senescence (stage15) showed an upward and then downward trend. TaBG was the highest expression in Dehiscence, and the expression of TaBG in no dehiscence of anther was 2.8 times higher than that of complete dehiscence of anther. After treatment of MeJA, the expression ofTaBG in anther and glume showed downward. The tae-miR395a expression pattern was the opposite.【Conclusion】 TaBGmight be involved in anther dehiscence with stress tolerance related miRNA such as miR169andmiR395a. High expression of TaBG could increase the content of soluble sugar in the anther under the sterile environment, and then increase the osmotic potential in the anther, so as to slow down the dehydration of anther dehiscence. This study will lay a foundation for elucidating the biological function of BG in regulating anther dehiscence.

QTL Mapping of Resistance to Fusarium Ear Rot in Maize Based on Image Analysis

WEN Jing,SHEN YanQi,WANG ZiYu,LI ShiJie,MO LanYue,LEI YuHao,ZHANG Yan,HAN SiPing

Scientia Agricultura Sinica. 2021, 54(13):  2724-2736.  doi:10.3864/j.issn.0578-1752.2021.13.003

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【Objective】Ear rot in maize is a kind of fungal disease that is prevalent and giving serious threat to maize production worldwide, among which,Fusarium ear rot (FER) is the most commonly reported in China. The location of FER disease resistance QTL is very important for the genetic improvement of maize ear rot. Locating FER disease-resistant QTL by an image analysis method not only explores a new disease evaluation method for FER in maize, but also validated the FER resistance QTLs located in the early stage through the disease rating method. 【Method】In this study, three F₂ populations (namely F₂-C, F₂-D and F₂-J) and their corresponding F_2:3 families were used for QTL mapping of resistance to FER, which were constructed from a highly FER-susceptible inbred line ZW18 and three highly FER-resistant inbred lines (Cheng 351, Dan 598 and JiV203) respectively. The percentage of diseased spots was obtained by image analysis for the ears of F_2:3 families, then the FER resistance QTLs were mapped.【Result】18 FER resistance QTLs were mapped. Among them, qRf2,qRf3 and qRf4 located in 2.02-2.03 bins, 4.06-4.07 bins and 8.06 bin explained the phenotypic variation as high as 21.80%, 25.80% and 27.40%, respectively. The qRf11 of the F₂-J population and the qRf1 of the F₂-C population and the qRf6 of the F₂-D population all have an overlapping interval, and the explainable phenotypic variation rate reached 16.50%. The qRf9 from the F₂-D population and theqRf16 from the F₂-J population have an overlapping interval in 8.05 bin, and the qRf3 from the F2-C population and the qRf15 from the F₂-J population have an overlapping interval in the 4.06-4.07 bins of 4^th chromosome. In addition, compared with the results of the previous positioning by the disease rating method,qRf1, qRf6 andqRf11 overlap with the disease resistance site qRfer13 located by the rating method at 1.06-1.07 bins, and qRf3 and qRf15 at 4.06-4.07 bins and the resistance location located by the rating method. The disease site qRfer3 and qRfer17overlap, qRf7 and qRfer6 completely overlap in the 2.04 bin location interval, qRf17 and qRfer20 are located in the overlap interval of 9.03-9.05 bins in the S2 duplication, and are derived from the same source of resistance. 【Conclusion】 The 18 FER resistance sites located in 3 populations, among which the resistance sites located in 1.04-1.07 bins, 4.06-4.07 bins and 8.05 bin can be detected in different populations, located in 2.04 bin and 9.03-9.05 bins can be detected by different detection methods, indicating that FER resistance sites may exist in these intervals. The overlap of QTL positioning intervals in different populations verifies the authenticity of the positioning intervals to a certain extent. The overlapping intervals are located between different methods, indicating that the image analysis method is used to locate FER disease-resistant QTLs with certain accuracy.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY·AGRICULTURE INFORMATION TECHNOLOGY

Research Status and Trends of Automatic Detection of Crop Planting Rows

CHEN PengFei,MA Xiao

Scientia Agricultura Sinica. 2021, 54(13):  2737-2745.  doi:10.3864/j.issn.0578-1752.2021.13.004

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Field crops are generally planted in rows to improve planting efficiency and facilitate field management. Therefore, the automatic detection of crop planting rows is of great significance for intelligent agricultural machinery carrying sensors to capture images to achieve autonomous navigation and precision spray pesticide, and for drones equipped with sensors to capture high-resolution images to generating field precision management zones. It is an important part of smart agriculture. This research first systematically summarized the existing crop planting row automatic detection methods, and illustrated the basic principles, development status and advantages and disadvantages of the Hough transform method, least square method, green pixel accumulation method, Blob analysis method, filtering method, and vanishing point method for crop planting row detection. Secondly, considering the previous researches, this study proposed some scientific and technical issues that needed to be study in future, such as how different spatial and spectral resolution images affected the detection accuracy of crop planting rows; how to detection of crop planting rows with different spatial distribution features and then perform accurate mapping of crop growth status based on drone images; how to establish a standardized crop planting row detection process. Finally, based on the current status and existing problems of planting row detection technology, several research directions were suggested, including crop planting row detection technology that could adapt to complex environments, such as high weed pressure, to improve the accuracy of autonomous navigation of intelligent agricultural machinery; the method of accurately mapping crop growth status based on the results of planting row recognition and then delineating of field precision management zones; coupling crop growth monitoring technology from drone images and intelligent agricultural machinery to make field precision management. This article would provide valuable references for automatic detection of crop planting rows in images and its related application researches.

Effect of Field Microclimate on the Difference of Soybean Flower Morphology Under Maize-Soybean Relay Strip Intercropping System

DU Qing,CHEN Ping,LIU ShanShan,LUO Kai,ZHENG BenChuan,YANG Huan,HE Shun,YANG WenYu,YONG TaiWen

Scientia Agricultura Sinica. 2021, 54(13):  2746-2758.  doi:10.3864/j.issn.0578-1752.2021.13.005

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【Objective】The purpose of this study was to explore the effect of field microclimate change on the process of soybean flower bud differentiation under maize-soybean intercropping system, so as to provide a morphological basis for clarifying the response mechanism of soybean to the change of growth environment. 【Method】 The field experiment was carried out from 2018 to 2019. The two-factor split zone experiment was set. The primary factors were different soybean varieties: Nandou 25 (ND), Guixia 3 (GX), and Gongqiudou 8 (GQ), and the secondary factors were soybean monoculture (SS), maize-soybean relay intercropping system (RI), and maize-soybean strip intercropping system (SI). In 2018, the continuous morphological anatomy of the flower buds at the top of the main stem of soybean was observed at 40, 47, 54 and 61 days (d) after emergence, respectively. On this basis, the flower buds at the top, middle and bottom of the main stem of soybean were further observed at 54 d after emergence in 2019. At the same time, in 2019, the effects of microclimate changes such as light transmittance, field temperature, relative humidity and CO₂ concentration on flower bud differentiation in different parts of soybean under different planting patterns were statistically analyzed.【Result】In 2018, the flower bud differentiation of three soybean varieties showed that GQ was faster than ND and GX. At 47 and 61 d after emergence, soybean was in the late stage of vegetative growth and early stage of reproductive growth, and the biggest difference among different planting patterns was that the process of flower bud differentiation under intercropping system was slightly faster than that under monoculture. In 2019, the flower bud differentiation process of soybean in the critical period from vegetative growth to reproductive growth (54 d after emergence) was observed. It was found that the three soybean varieties all showed canopy > middle > bottom, but the performance was different in different planting systems. The flower bud differentiation process of SS in ND and GX was slower than that of RI and SI. The flower bud differentiation processes of GQ were no significant difference among the three planting systems. The light transmittance of ND, GX and GQ was an inflection point at 60 d after emergence, and the canopy light transmittance of RI and SI was not significantly different from that of SS. Although the light transmittance of the central and bottom showed a downward trend, it was significantly higher than that of SS. At 70 d after emergence, the canopy light transmittance of ND, GX and GQ of SI was the lowest, which was 82.1%, 88.2% and 86.8%, respectively, while the canopy transmittance of SS and RI was close to 100%. In the later stage of reproductive growth, the daily average temperature of ND, GX and GQ in RI and SI was higher than that of SS, and which of RI was higher than that of SI. The relative humidity of ND, GX and GQ under different planting systems all had a significant downward trend at 70 d after emergence, among which the relative humidity of RI was the lowest, which was 73.5%, 75.4% and 78.2%, respectively. The CO₂ concentration of ND, GX and GQ under RI and SI was lower than that of SS, and the CO₂ concentration of RI was the lowest, especially at 70 d after emergence, which was 10.3%, 10.2% and 10.9% lower than that of SS, respectively. 【Conclusion】 Maize-soybean relay strip intercropping system could promote the transformation of soybean flower buds from vegetative growth to reproductive growth. In the late growth stage of soybean, especially after relay intercropped maize harvested, the light transmittance of central and bottom of intercropped soybean was significantly higher than that of monoculture, while the interrow temperature, relative humidity and CO₂concentration of relay intercropping system were lower than those of monoculture. Therefore, the interrow microenvironment of this intercropping system was better than that of monoculture, which was beneficial to pod development in the later stage of soybean reproductive growth and provided a morphological basis for yield formation mechanism.

PLANT PROTECTION

The Actin Binding Protein FgAbp1 is Involved in Growth, Development and Toxisome Formation in Fusarium graminearum

ZHANG ChengQi,WANG XiaoYan,CHEN Li

Scientia Agricultura Sinica. 2021, 54(13):  2759-2768.  doi:10.3864/j.issn.0578-1752.2021.13.006

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【Objective】Abp1 is one of the actin binding proteins that plays a central role in actin cytoskeleton of diverse eukaryotic organisms. The objective of this study is to analyze functions of the actin binding protein FgAbp1 in growth and development, sensitivity to the novel fungicide phenamacril and toxisome formation inFusarium graminearum.【Method】Targeted gene deletion construct and fluorescent protein fusion vectors were generated by double-joint PCR and budding yeast gap repair system, respectively. Then, the mutant ΔFgAbp1 and fluorescently labeled strains were obtained using polyethylene glycol (PEG) mediated protoplast transformation. Mycelia growth, sexual/asexual reproduction and sensitivity to phenamacril of wild type PH-1, the mutant ΔFgAbp1 and complemented strain ΔFgAbp1-C were investigated. Localization of FgAbp1 in hyphae was examined through fusion green fluorescent protein. Transmission electron microscopy was carried out to assay the role of FgAbp1 in vacuole/vesicle morphology. Under noninducing medium and DON biosynthesis induction conditions, the role of FgAbp1 in the toxisome formation of F. graminearum was performed by dual fluorescence colocalization assay.【Result】FgAbp1 is primarily localized near the cell membrane in patches of F. graminearum. In MM medium, the growth rate of gene knockout mutant ΔFgAbp1 was reduced by 15% compared with the wild type. But in the nutrient-rich CM, the growth rate of ΔFgAbp1 was decreased by 38%. The mutant ΔFgAbp1 had no obvious defects in sexual and asexual reproduction in comparison with the wild type, while the mycelial growth of ΔFgAbp1 was completely inhibited and the conidia showed significant reduction of germination rate with 0.5 μg·mL ^-1 phenamacril treatment. Moreover,FgAbp1 deletion resulted in a high vesicle number and a block of normal vacuole formation. During growth in a toxin noninducing condition, FgAbp1 and the DON biosynthetic key enzyme Tri1 co-fluoresced in vesicles. Unexpectedly, FgAbp1 and Tri1 cellular co-localized in toxisomes under DON biosynthesis inducing conditions. Furthermore, disruption of FgAbp1resulted in abnormal toxisomes.【Conclusion】The actin binding protein FgAbp1 plays an important role in vegetative growth, development, phenamacril tolerance and toxisome formation inF. graminearum.

Control Effect of Orius similis on Frankliniella occidentalis Based on the Two-Sex Life Table and the Age-Stage-Specific Predation Rate

HU ChangXiong,FAN Wei,ZHANG Qian,CHEN GuoHua,YIN HongHui,XU TianYang,YANG JinBo,YANG Hang,WU DaoHui,ZHANG XiaoMing

Scientia Agricultura Sinica. 2021, 54(13):  2769-2780.  doi:10.3864/j.issn.0578-1752.2021.13.007

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【Objective】Frankliniella occidentalis is an important agricultural invasive pest, and Orius similis is the dominant predator species in China. The objective of this study is to systematically evaluate the control effect of O. similis on F. occidentalis and the biological differences between this two species in the same area.【Method】O. similis and F. occidentalis were collected from open field Capsicum annuum, then reared by fresh shoots with flowers of C. annuum for 2-3 generations under indoor condition, and the 2nd instar nymphs of F. occidentalis were feed to O. similis in the experiment. Growth, reproductive rate, predation rate were tested in Yunnan populations of O. similis and F. occidentalis using the two-sex life table and the age-stage-specific predation rate methods.【Result】The different insect periods of O. similis and F. occidentalis have different levels of overlap during their developmental stages, and the survival rate of female adults of both insect species was higher than that of male adults. O. similis nymph has 5 instars, while F. occidentalis has 4 instars. Compared with F. occidentalis, O. similis has a longer nymph duration and shorter adult lifespan, and the survival rate of each developmental period was lower than that ofF. occidentalis, especially the survival rate of female adults was obviously lower than that of F. occidentalis. The probability of O. similis successfully developing from egg to female adult and male adult was 32.67% and 20.67%, respectively, which was lower than that ofF. occidentalis’s 46.67% and 16.67%.F. occidentalis has a higher proportion of females within its population. The reproductive parameters (f_x) of O. similis and F. occidentalis peaked at 22 d and 16 d during the whole developmental stages, respectively. O. similis has an average egg production of 42.00 eggs per female, which was significantly lower than that of theF. occidentalis (59.86 eggs). The population net reproduction rate (R₀), gross reproduction rate (GRR), intrinsic rate of increase (r) and finite rate of increase (λ) in O. similis were lower than those ofF. occidentalis, while the mean generation time (T) and population doubling time (DT) in O. similis were longer than those of F. occidentalis. The population prediction results showed that the individuals of F. occidentalis reached 9.66 times than that of O. similis after 90 days of population growth and development, and the number of female adults reached 17.15 times. The predation rate of O. similis on the 2nd instar nymphs of F. occidentalis gradually increases with age, and the population characteristic net predation rate (C₀) of F. occidentalis was 140.81, and the transformation rate (Q_p) was 9.05. The average predation of female and male adult O. similis to F. occidentalis 2nd instar nymphs was 159.67 and 86.00 individuals, respectively.【Conclusion】O. similis population can finish its life history and has stable population growth when fed by F. occidentalis. F. occidentalis has a stronger population growth potential than that of O. similis under the same conditions. As an important natural enemy of F. occidentalis biological control, O. similisshould be released 10-20 d before F. occidentalis outbreak and continuous released during F. occidentalis outbreak, this can achieve better control effects to F. occidentalis.

Response of Liriomyza trifolii to Cold Acclimation and Differences of Cold Tolerance Among Different Populations

ZHANG QiKai,XING ZhenLong,WU ShengYong,XU RuiRui,LEI ZhongRen

Scientia Agricultura Sinica. 2021, 54(13):  2781-2788.  doi:10.3864/j.issn.0578-1752.2021.13.008

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【Objective】The response of the major invasive pest Liriomyza trifolii to cold acclimation and the cold tolerance of three geographical populations (Wuhan City, Hubei Province; Haikou City, Hainan Province; Anqing City, Anhui Province) were studied to provide references for the potential colonization of L. trifolii in high latitudes of China.【Method】The pupae and adults of L. trifolii population in Hainan were exposed to low temperatures of -12, -14, -16, -18, -20, -22 and -24℃ for 30 min, and the temperature with a survival rate of 15%-30% was selected as the recognition temperature. The L. trifolii pupae and adults were put at 5℃ for 1-6 h or 12℃ for 1-6 d, and then put at the recognition temperature for 30 min to detect the survival rate. The undomesticated pupae and adults were also placed at the recognition temperature for 30 min as a control, and the difference in low-temperature survival rate after cold acclimation was compared. Besides, five target temperatures were set at 0, -5, -10, -15, and -20℃, respectively, and the pupae of three geographical populations were exposed to the target temperatures for 2 h, the difference of survival rate was studied. Finally, the supercooling point (SCP) of pupae of three geographical populations was measured by supercooling point tester.【Result】When theL. trifolii pupae and adults were exposed to -20℃ for 30 min, the survival rates were 15.0%, 19.6%, and 21.0%, respectively. Therefore, -20℃ was determined as the cold acclimation recognition temperature of L. trifolii. The cold tolerance ofL. trifolii pupae and adults was improved after rapid cold acclimation at 5℃, and the adults responded more positively to rapid cold acclimation. The effect of cold acclimation for 1 h and 2 h was the best, and the effect of rapid cold acclimation decreased gradually until disappeared with the extension of exposure time. Within 6 days, the cold tolerance ofL. trifolii pupae and adults was improved by low-temperature exposure at 12℃ for different periods, and there was little difference in cold tolerance after cold acclimation for different periods. Besides, under the low-temperature exposure of 5, 0 and -5℃, there was no significant difference in the survival rate of pupae between the Hainan population and Anhui, Hubei populations, but under the low-temperature exposure of -10, -15 and -20℃, the pupa survival rate of Hainan population was significantly lower than that of Anhui and Hubei populations. The SCP of pupae in the Anhui and Hubei populations was significantly lower than that in the Hainan population.【Conclusion】The cold tolerance of L. trifolii can be enhanced by cold acclimation, which may be one of the reasons why L. trifolii gradually spread to high latitudes in China. The cold tolerance of the Hubei and Anhui populations is stronger than that of the Hainan population. The results are helpful to predict the overwintering distribution area of L. trifolii in China and guide its monitoring, early warning, and prevention and control.

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

Improving Farmland Soil Physical Properties by Rotary Tillage Combined with High Amount of Granulated Straw

DONG JianXin,SONG WenJing,CONG Ping,LI YuYi,PANG HuanCheng,ZHENG XueBo,WANG Yi,WANG Jing,KUANG Shuai,XU YanLi

Scientia Agricultura Sinica. 2021, 54(13):  2789-2803.  doi:10.3864/j.issn.0578-1752.2021.13.009

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Abstract: 【Objective】Aiming at the problems of soil physical properties deterioration because of the high input of chemical fertilizer and frequent cultivation, such as soil hardening, permeability reduction and water stable aggregate quantity decrease, the feasibility of improving the above soil physical properties by straw granular fertilizer and cultivation method was discussed. 【Method】Three years of field experiments were carried out with rotary tillage + no straw granular fertilizer (RG0) as the control. The three kinds of straw granular fertilizer (G1: 2 250 kg·hm^-2, G2: 4 500 kg·hm^-2, G3: 6 750 kg·hm^-2) and two tillage methods (rotary tillage: R, deep burying: T) were set, and the effects of straw granular fertilizer and tillage methods on soil bulk density, field water holding capacity, soil porosity and soil aggregate stability were studied. 【Result】The results showed that: (1) Compared with RG0, RG treatment significantly reduced soil bulk density in 0-20 cm soil layer by 6.7%-16.5%, while TG treatment significantly reduced soil bulk density in 20-40 cm soil layer by 3.0%-9.8%. The decrease rate of the high amount of straw granular returning was the highest. (2) RG was more conducive to increase the field water capacity of 0-20 cm soil layer, with RG3 increasing the most significant, up to 14.9%; the amount of straw granule fertilizer significantly affected the field water capacity of 20-40 cm soil layer, and the effect of twice and three times treatment was the most significant. (3) The total porosity of 0-20 cm soil layer was significantly affected by tillage, which was increased up to 17.9% under RG3, while TG3 significantly increased it in 20-40 cm soil layer. RG2 and RG3 could significantly increase the capillary porosity of 20-40 cm soil layer during three years. (4) The stability of soil aggregates in 0-20 cm soil layer was significantly improved under RG treatment in the later stage of returning to the field. What’s more, aggregate size of >2 mm, 小鱼0.106 mm, 0.5-1 mm, 0.106-0.25 mm and 1-2 mm were the important components (Exp>66%) that affected the physical properties of 0-20 cm soil layer, while 0.5-1 mm and 0.106-0.25 mm particle size aggregates were the important components (Exp>48%) that affected the physical properties of 20-40 cm soil layer. 【Conclusion】Treatment of RG3 reduced the soil bulk density, improved the water holding capacity, and promoted the soil aggregates stability of the two soil layers at the same time. Cluster analysis further indicated that the soil physical properties were at the first level treated by RG3. Thus, 6 750 kg·hm^-2 of straw granular fertilizer combined with rotary tillage was a feasible measure to improve the physical structure of local tobacco field soil effectively, and also provided technical guidance for the utilization of crop straw.

Evaluation on Fertilizer Application and Its Economic-Environmental Benefits Associated with Fertilizer Reduction Potential for Dryland Wheat in Loess Plateau of Southern Shanxi Province

MA HongMei,CAO HanBing,XIE YingHe,LI TingLiang,LIU Kai,ZHANG QiRu,JIANG LiWei,CAO Jing,SHAO JingLin,WU WenYue,LI WenQi

Scientia Agricultura Sinica. 2021, 54(13):  2804-2817.  doi:10.3864/j.issn.0578-1752.2021.13.010

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【Objective】 The aim of this study was to clarify situation of the farmers’ nutrient application, so as to provide a theory base for the realization of stable and high yield, high nutrient use efficiency, and lower environmental pollution in dryland wheat production. 【Method】 A 9-yr survey of 984 farmers was carried out, and a yield based fertilizer recommendation method were used to analyze and evaluate their nutrient applications and the fertilizer reduction potential and economic-environmental benefits in Loess Plateau. 【Result】 The farmers’ wheat yield was lower, with the average of 3 711 kg·hm^-2, and they were allocated into three groups as: low (≤3 200 kg·hm^-2) and moderate (3 200-4 220 kg·hm^-2), respectively, accounting for 56.0% and 18.1% of the total farmers. Farmers’ nitrogen (N), phosphorus (P₂O₅) and potassium (K₂O) applic^-2, 159.8 kg P₂O₅·hm^-2 and 92.0 kg K₂O·hm^-2. And the proportion of the high-application farmers were N 68.7% and P₂O₅ 65.1% and K₂O 57.9%, respectively, which was large in low-yield level. Generally, these high-application farmers were recommended to reduce 24.1 kg N·hm^-2, 12.8 kg P₂O₅·hm^-2, and 6.2 kg K₂O·hm^-2, and the reduction range was N 15.9%, P 16.7% and K 16.7%, respectively, but these very high-application farmers were recommended to reduce 250.9 kg N·hm^-2, 205.7 kg P₂O₅·hm^-2, and 124.6 kg K₂O·hm^-2, and the reduction range was 66.5%, 76.7%, and 80.0%, respectively. Then, their economic effects increased by 251 yuan/hm² and 3 425 yuan/hm², 4.0% and 55.0%, NPK agronomic efficiency increased by N 18.8%, P 23.2%, and K 22.1% for the high farmers, and N 192.5%, P 321.3%, and K 388.1% for the very high farmers. NPK partial productivity increased by N 20.2%, P 23.7%, and K 19.2%, and N 210.4%, P 317.9%, K 388.1%, respectively. According to the estimation, the environmental impact of reducing nitrogen application was that emission of the N-pollutant reduced, such as N ₂O emission decreased by 0.3 kg N₂O·hm^-2 and 6.3 kg N₂O·hm^-2, 11.2% and 72.5%, NH₃ volatilization decreased by 14.1 kg NH₃·hm^-2 and 90.7 kg NH₃·hm^-2, 20.8% and 62.8%, and NO₃ leaching decreased by 3.1 kg NO₃·hm^-2 and 231.1 kg NO₃·hm^-2, 4.9% and 79.6%, respectively. Total nitrogen pollutants (including N₂O emission, NH₃volatilization and NO₃ leaching) reduced 17.4 kg·hm^-2 and 328.1 kg·hm^-2, with 13.1% and 74.0%, respectively. In total, 12.5 kg N·hm^-2 and 130.9 kg N·hm^-2 with 65.0 yuan/hm² and 683.3 yuan/hm²were saved, respectively. 【Conclusion】 In this paper, based on the wheat yield, the farmer's fertilization was evaluated, and the potential of reducing excessive fertilization was estimated, and the economic benefits and the effect of the reducing nitrogen-pollutants emission were analyzed through reducing fertilizer application. It was known that the farmers with high and very-high fertilizer application not only had different potential for reducing fertilizer application,such as 24.1-250.9 kg N·hm^-2, 12.8-205.7 kg P₂O₅·hm^-2, 6.2-124.6 kg K₂O·hm^-2, but also farmers' economic benefits was improved by 251-3 425 yuan/hm², and fertilizer agronomic efficiency was improved by N 18.8%-192.5%, P 23.2%-321.3%, K 22.1%-388.1%,and partial productivity was improved by N 20.2%-210.4%, P 23.7%-317.9%, K 19.2%-388.1%, and the emission of total nitrogen pollutants (including N₂O, NH₃and NO₃) was reduced by 17.4-328.1 kg·hm^-2. This study comprehensively and systematically revealed the resource and environmental problems, challenges and opportunities in the current dry wheat production, which provided a certain theoretical basis for an environment-friendly fertilization with saving cost and increasing efficiency.

Research on Phosphorus Application Rate Based on Sugarcane Yield and Phosphorus Balance in Soil

OU HuiPing,ZHOU LiuQiang,HUANG JinSheng,ZHU XiaoHui,ZENG Yan,PENG JiaYu,XIE RuLin,TAN HongWei,LI ZhongNing,SHEN XiaoWei,LIU XiHui

Scientia Agricultura Sinica. 2021, 54(13):  2818-2829.  doi:10.3864/j.issn.0578-1752.2021.13.011

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【Objective】 This study was conducted to explore the phosphate fertilizer rate based on sugarcane yield and phosphorus (P) balance in soil, with an aim to provide a reference for the efficient utilization and scientific management of P in farmland. 【Method】A 3-year continuous field trail was conducted in Wuming district of Nanning city of Guangxi province from 2014 to 2016, which was designed with five phosphate fertilization treatments, including non-phosphate fertilization (P0), 75 kg P₂O₅·hm^-2 (P1), 150 kg P₂O₅·hm^-2 (P2), 300 kg P₂O₅·hm^-2 (P3) and 600 kg P₂O₅·hm^-2 (P4). The yield of cane and leaves and Olsen-P content in soil were measured, and the relation between cane yield and Olsen-P was evaluated by Mitscherlich model. The agronomic threshold of soil Olsen-P was also calculated. Plant P content, P uptake, P utilization efficiency and P balance in soil were further analyzed. 【Result】Compared with P0 treatment, the cane yield was significantly increased by 8.3% (2014), 18.0% (2015) and 15.5% (2016) under P2 treatment. P2 or P3 treatments had the highest yields for leaves and above-ground part, but there was no significant difference in cane, leaves and above-ground part among different P application rates. P accumulations in cane, leaves and above were also similar among P2 to P4 treatments. Olsen-P content, P balance and P surplus rate increased significantly with the increase of P application rate, while the PRE and PPFP decreased gradually with the increase of P application rate; where P1 treatment was the highest, which was significantly higher than that under P3 and P4 treatments. The agronomic threshold of Olsne-P was 13.4 mg kg^-1 based on Mitscherlich model. Correlation analysis showed that P surplus rate was significantly positively correlated with P application rate and soil Olsen-P (P<0.01), and which was significantly quadratic correlated with sugarcane stem yield (P<0.01), and significantly exponential correlated with PRE and PPFP (P<0.01). When P application rate was 40.9 kg·hm^-2, P surplus rate, soil Olsen-P content and cane yield were 0,15.87 mg kg^-1and 94.2 t·hm^-2, respectively. While the maximum cane yield was obtained by linear and platform fitting, soil P surplus rate, Olsen-P content and cane yield were 216.2%-232.7%, 24.7-25.4 mg·kg^-1 and 99.7-100 t·hm^-2, respectively. 【Conclusion】 In lateritic red soil with relatively high Olsen-P content, the P application rate of 40.9 kg·hm^-2would maintain the soil Olsen P content, meet the demand for high yield and high phosphorus utilization efficiency. Thus, it could be used as the recommended P application amount.

HORTICULTURE

Identification of Grape Cultivars Based on KASP Markers

WANG FuQiang,ZHANG Jian,WEN ChangLong,FAN XiuCai,ZHANG Ying,SUN Lei,LIU ChongHuai,JIANG JianFu

Scientia Agricultura Sinica. 2021, 54(13):  2830-2842.  doi:10.3864/j.issn.0578-1752.2021.13.012

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【Objective】This study was aimed to develop a set of kompetitive allele specific PCR (KASP) markers that can be used to distinguish the main cultivated grape cultivars in China, so as to provide the technical support for domestic grape cultivar protection, cultivar registration and market right protection. 【Method】60 highly polymorphic SNP loci from previous studies in grapes were selected to design KASP markers. 23 representative grape cultivars and 76 main cultivated grape cultivars in China were used for preliminary screening, re-screening, and verification of the successfully transformed KASP markers. A set of high-quality KASP markers was further selected to establish the DNA fingerprint database for the 76 grape cultivars. 【Result】Among the 60 SNP loci, 3 were not genome-specific, 6 could not be used to design KASP-PCR markers, and 51 could be successfully transformed to KASP markers with a conversion rate of 89.47%. Next, 23 representative grape cultivars were successfully genotyped by using the 51 KASP markers on LGC-SNP line platform. Then, 27 KASP markers of high quality were selected successfully based on the minor allele frequency (MAF) greater than 0.25, polymorphism information content (PIC) greater than 0.35, deletion rate less than 0.2, and heterozygosity rate less than 0.6. Finally, 22 KASP markers were successfully re-screened in the 76 main cultivated grape cultivars. The missing rate of the 22 markers was less than 0.12, the PIC value of them was greater than 0.30, the heterozygosity rate of 0.40-0.60 was 77.27%, and the MAF of greater than 0.30 was 95.45%. In addition, the consistent genotype data were acquired with different trees from each of the 23 representative cultivars by using the 22KASP markers, indicating that these 22 KASP markers had good reproducibility and stability for grape cultivar identification. The SNP genotyping results of 76 grape cultivars based on 22 markers were converted to binary coding data, and the fingerprints of 76 grape cultivars were obtained. Based on neighbor-joining cluster analysis, the 76 grape cultivars could be divided into 3 populations. Diploid and polyploidy cultivars were also correctly identified. The 10 markers (VIT_15_18567587, VIT_6_4258638, VIT_8_3320936, VIT_12_22228357, VIT_11_19390306, VIT_16_17950801, VIT_18_11138668, VIT_12_739916, VIT_16_ 13454358, VIT_16_21202286) were enough to be able to distinguish 70 of the 76 cultivars, of which 54 cultivars met the criteria for variety identification (the number of different loci ≥2). 【Conclusion】From 60 grape SNPs, 51 KASP markers were successfully transformed, and 22 high-quality KASP markers were selected successfully for developing the fingerprints of the 76 main grape cultivars in China. It was the first time to verify the feasibility of KASP genotyping in the identification of grape cultivars in China.

Isolation of PmARF17 and Its Regulation Pattern of Endogenous Hormones During Flower Development in Prunus mume

LI YanLin,SHAHID Iqbal,SHI Ting,SONG Juan,NI ZhaoJun,GAO ZhiHong

Scientia Agricultura Sinica. 2021, 54(13):  2843-2857.  doi:10.3864/j.issn.0578-1752.2021.13.013

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【Objective】The purposes of this study were to analyze the biological functions of PmARF17gene and to explore the regulation pattern between the expression of PmARF17 and plant endogenous hormones, which could provide the basis for studying the regulatory mechanism of pistil abortion inPrunus mume. 【Method】 PmARF17 gene was isolated from the cultivar Daqiandi of Prunus mume, and the gene structure, phylogeny and homology with other species were analyzed by bioinformatics software. Subcellular localization determined the position of PmARF17 protein in the cell. qRT-PCR was used to detect the spatiotemporal expression pattern of PmARF17in different stages of flower buds, leaf buds, flower buds with different pistil morphology, and different mature floral organs of the varieties Daqiandi and Longyan. The contents of IAA, GA₃, ABA and ZT in flower buds, leaf buds, pistil morphology flower buds and different mature flower organs of Daqiandi and Longyan were determined by UPLC method, and the correlation analysis was conducted with the qRT-PCR expression ofPmARF17.Cloning, element analysis and transient expression of PmARF17 promoter were performed to study the regulation pattern between PmARF17 and GA₃. 【Result】Phylogenetic tree analysis showed PmARF17 protein sequence was highly conserved with ARF protein of other plants. Subcellular localization experiment showed PmARF17 protein was located on the nucleus and cell membrane. The correlation analysis between qRT-PCR expression and endogenous hormone content showed the expression of PmARF17 had no obvious similarity with the change trend of IAA content in different flower samples. The expression of PmARF17 in complete pistil was significantly up-regulated compared to incomplete pistil, and GA₃ content was consistent with the expression trend ofPmARF17. The content of ABA and ZT in different flower samples and the expression of PmARF17 showed an overall opposite trend, indicating that they might inhibit the expression of PmARF17. The PmARF17promoter contained GAcis-element and had promoter activity and tissue expression specificity, specifically expressed in petals, stamens and roots. 【Conclusion】PmARF17 might be a positive regulation gene of flower development, and it might promote pistil development of Prunus mume. The expression of PmARF17 might be positively regulated by GA₃, which affected the pistil development of Prunus mume by acting on stamens and petals.

Anthocyanins and Flavonoids Accumulation Forms of Five Different Color Tree Peony Cultivars at Blooming Stages

CUI HuLiang,HE Xia,ZHANG Qian

Scientia Agricultura Sinica. 2021, 54(13):  2858-2869.  doi:10.3864/j.issn.0578-1752.2021.13.014

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【Objective】Tree peony (Paeonia suffruticosa), one of the famous traditional flowers in China, is rich in flower colors and varieties. The composition content and structure of anthocyanins and flavonoids in different color cultivars and these dynamic changes at different blooming stages were studied, in order to lay a foundation for further investigation of the floral pigment mechanism and molecular breeding of tree peony.【Method】 Five different color cultivars of tree peony were chosen as materials. Anthocyanins and flavonoids in those petals of flowers at four different blooming stages, such as bud stage (S1), initial blooming stage (S2), blooming stage (S3) and wither stage (S4), were determined by high-performance liquid chromatography (HPLC) and mass spectrometric (LC-MS) detectors. Then, the difference of anthocyanins and flavonoids among these five cultivars was analyzed, and the regulation of changing density was summarized.【Result】In total, 6 anthocyanins and 12 flavonoids were described. However, the compounds were distributed different among different cultivars. The purple cultivar, Luoyanghong, had four anthocyanins, and the white cultivar of Baixuetai had no anthocyanin. Among the 12 flavonoids, the relative contents of apigenin-5-glucoside (7.18%-58.46%), apigenin hexo-glucoside (1.44%-43.72%) and kaempferol-3,7-glucoside (2.83%-43.44%) were higher than other compounds. In addition, the significant changes were observed among the five cultivars. During the blooming periods, the total anthocyanin content were constantly accumulated and dramatically increased at S3, then reached the highest at S4. However, the total content of flavonoids was increased firstly and then decreased. It should be noted that the variation trend of different varieties was obviously different. The flavonoids contents of Luoyanghong showed the highest value at S4 ((752.93±48.10) μg∙g^-1 FW), and Zhaofen showed the highest value at S3 ((603.81±6.30) μg∙g^-1 FW). Baixueta reached the highest value ((673.45±9.96) μg∙g^-1 FW) at S2. But the other two cultivars, Yingrihong and Fenhe, reached the highest flavonoids content value at S1, with (525.88±22.38) μg∙g^-1 FW and (740.56±16.08) μg∙g^-1 FW, respectively.【Conclusion】The anthocyanins and flavonoids content were significantly different among different color cultivars. The purple cultivar always showed higher anthocyanins contents than other varieties. And the white cultivar almost did not detect any anthocyanin, relatively. What’s more, the anthocyanins were constantly accumulated during flower blooming stage, meanwhile, the flavonoids were increased first and then gradually degraded after flower opening.

FOOD SCIENCE AND ENGINEERING

Natural Occurrence and Characteristic Analysis of 40 Mycotoxins in Agro-Products from Yangtze Delta Region

FAN Kai,JI Fang,XU JianHong,QIAN MingRong,DUAN JinSheng,NIE DongXia,TANG ZhanMin,ZHAO ZhiHui,SHI JianRong,HAN Zheng

Scientia Agricultura Sinica. 2021, 54(13):  2870-2884.  doi:10.3864/j.issn.0578-1752.2021.13.015

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【Objective】 The purpose of this survey was to investigate the natural occurrence and contamination characteristics of 40 mycotoxins in agro-products (wheat, maize, rice, tomato and peach) from Yangtze Delta Region, so as to provide a scientific basis for the supervision of agro-products. 【Method】 A total of 720 ago-product samples, including 120 wheat samples, 150 maize samples, 150 rice samples, 150 tomato samples and 150 peach samples, were collected from supermarkets, farmers and farmers' markets in Shanghai, Anhui, Jiangsu and Zhejiang in 2019. The grain samples were extracted with water and acetonitrile containing 1% (V/V) formic acid, and fruit and vegetable samples were extracted with acetonitrile containing 1% (V/V) formic acid. The extractions were salted out with sodium chloride and anhydrous magnesium sulfate, and the concentrations of 40 kinds of important mycotoxins were determined by ultra-performance liquid chromatography-tandem mass spectrometry. Chi-square test and one-way analysis of variance (ANOVA) were utilized to investigate the mycotoxin contamination levels among different types of agro-products in different regions, while Spearman’s rank correlation coefficient was used for the analysis of the relationship between mycotoxin concentrations and temperature and humidity.【Result】In 720 samples, a total of 36 kinds of mycotoxins were detected, mainly including aflatoxins, ochratoxins, alternaria toxins, fumonisins, deoxynivalenol (DON) and its modified forms and zearalenone (ZEN). The detection rate of mycotoxins in total agro-products was 75.3%. Among the positive toxins, fumonisin B ₁ (FB₁) was the most frequently detected (49.0%), followed by tenuazonic acid (TeA) (37.5%), fumonisin B₂ (FB₂) (35.7%), tentoxin (Ten) (29.6%), fumonisin B₃ (FB₃) (29.3%), ZEN (22.6%), DON (21.4%), 3-acetyl-deoxynivalenol (3-ADON) (10.7%), ochratoxin A (OTA) (10.4%), ochratoxin B (OTB) (8.1%), deoxynivalenol-3-glucoside (D3G) (7.2%), ochratoxin C (OTC) (6.4%), aflatoxin B₂(AFB₂) (5.8%) and 15-acetyl-deoxynivalenol (15-ADON) (5.4%). Additionally, 59.5% of the agricultural products were contaminated with two or more mycotoxins, and the maximum number in one sample was 23. According to GB 2761-2017, the concentrations of AFB₁ in one maize sample, OTA in one rice sample, ZEN in 6 wheat samples and 2 maize samples exceeded the relative limit standards. The contamination levels of mycotoxins in agro-products from the Yangtze River Delta region were relatively lower, compared with other studies, which showed significant types and regional differences. The most prevalent mycotoxins were Ten, TeA, DON in wheat, fumonisins in maize, Ten, TeA, fumonisins in rice, and ochratoxins, alternaria toxins, fumonisins in fruits and vegetables, respectively. Regionally, maize samples from Zhejiang were seriously contaminated with DON and ZEN, while the highest concentrations of fumonisins were detected in Anhui maize samples. The detection rates and concentration levels of DON and ZEN in rice samples from Jiangsu were significantly higher than those from other regions. The contamination levels of Ten, TeA, FB₁, DON and ZEN in grain samples were in significant correlation with temperature and/or humidity, while no statistical relationship was found in tomato and peach samples. 【Conclusion】 Agro-products from the Yangtze River Delta region were contaminated by various mycotoxins. Although the overall contamination level was relatively low, the multi-mycotoxin co-occurrence in single sample was frequently found, which should be given enough considerations.

Preparation of Soybean Protein-Derived Pro-osteogenic Peptides via Enzymatic Hydrolysis

LI Yu,WANG Fang,WENG ZeBin,SONG HaiZhao,SHEN XinChun

Scientia Agricultura Sinica. 2021, 54(13):  2885-2894.  doi:10.3864/j.issn.0578-1752.2021.13.016

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【Objective】 The aim of this study was to develop an effective method and to identify the active peptides and to provide reference for the development of soybean products, so as to promote the proliferation of osteoblasts from soybean protein isolated with the two-step enzymatic hydrolysis. 【Method】The proliferative activity of osteoblast was served as an indicator. Soybean protein isolate (SPI) was hydrolyzed by papain, and the effect of papain hydrolysates on osteoblast proliferation was detected by a MTT assay. The degree of hydrolysis of the papain hydrolysates was determined by the pH-Stat method after 1, 2, 3, 4, 5 and 6 h treatment, respectively. The effects of papain hydrolysates on pro-liferation of osteoblast were determined. Two kinds of ultrafiltration membrane with 30 kDa and 10 kDa cut-off were used to separate the fractions of papain hydrolysates, and their proliferation activities on osteoblast were determined. The enzymatic hydrolysates with the highest pro-proliferative activity of osteoblast were further hydrolyzed with alkaline. The effect of alkaline enzymatic hydrolysate on the proliferation of osteoblast was examined after 0.5, 1, 1.5, 2 and 2.5 h treatment, respectively. The Sephadex G-15 was used to isolate the enzymatic hydrolysates with high pro-proliferative activity of osteoblasts, and the proliferation activity of each component on osteoblasts was determined. Furthermore, the amino acids of the separated fractions were analyzed. The structure of the most active fraction was identified by ESI-TOF MS/MS, and the soybean protein derived from peptides with strong activity to promote osteoblast proliferation was identified. 【Result】 The proliferative rate of osteoblasts was (118.24±2.73)% by the treatment with enzymatic hydrolysis products of papain for 5 h at the concentration of 200 μg/ml. After the enzymatic hydrolysates were separated by ultrafiltration membrane, the active fraction was further hydrolyzed with alkaline protease. The final hydrolysates were separated with gel filtration chromatography (Sephadex G-15). A fraction of component with the strongest pro-proliferative activity on osteoblasts, F3, was identified, and the proliferative rate of osteoblasts treated with this faction was (125.80±2.94)%. Amino acid analysis showed that the contents of hydrophobic amino acids, such as alanine, valine, isoleucine, leucine, and phenylalanine, aromatic amino acids and essential amino acids in F3, were significantly higher than other fractions. In addition, mass spectrometry (ESI-TOF MS/MS) revolved that F3 was mainly composed of 10 small peptides, among which, DAMDGWFRL, GQTPLFPR, ADFYNPK and KDWYDIK had high contents of hydrophobic amino acids, aromatic amino acids and essential amino acids. Moreover, 100 μmol∙L ^-1 of GQTPLFPR had the strongest pro-proliferative activity on osteoblasts, with a proliferative rate of (129.11±3.12)%.【Conclusion】 Two-step enzymatic hydrolysis combined with ultrafiltration membrane and gel filtration chromatography could identify the most active pro-proliferative peptides from SPI, which provided a technical reference for the preparation of peptides with the bio-activity to stimulate the proliferation of osteoblasts.

ANIMAL SCIENCE·VETERINARY SCIENCE·RESOURCE INSECT

Functions of Antibacterial and Inducing Defense Peptide Expression of Medium-Chain Fatty Acid and Its Application in Piglet Feeds

YU ZhengWang,ZHOU ZhongXin

Scientia Agricultura Sinica. 2021, 54(13):  2895-2905.  doi:10.3864/j.issn.0578-1752.2021.13.017

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In recent years, more and more studies have shown that medium-chain fatty acid (MCFAs) resistance to pathogenic bacteria is an important component of innate defense system of mammals, and MCFAs can also induce expressions of endogenous host defense peptides (HDPs) in human, pig and chicken. However, these new functions of MCFAs have not attracted much attention. MCFAs also have a synergistic antibacterial synergistic effect with feeding organic acids or feeding plant essential oils, which can reduce the use of these active substances. In addition, compared with long-chain fatty acids, the addition of MCFAs in the diet can significantly increase the oxygen consumption and mitochondrial respiration rate in the body of animals, but it produces less reactive oxygen species, which is in line with the characteristics of rapid energy supply required by intestinal metabolism and liver metabolism in young animals. Adding low concentration of MCFAs (0.1%-0.5%, mass ratio) to the diet can significantly increase the survival rate of newborn or weaned piglets, the digestibility of crude protein and crude fat as well as the feed conversion rate, regulate the intestinal flora, and improve the intestinal epithelial structure, thus promoting the growth of animals. Based on the above advantages of MCFAs, mixing MCFAs with forage organic acid or plant essential oil to prepare coated particles may be a good way to use it as a substitute for antibiotics in piglets.

The Ability of Acidic Calcium Sulfate to Kill Common Clinical Pathogenic Microorganisms

FU XiaLi,ZHENG ZiFang,MA ZhiQian,XU LeLe,LI ZhiWei,LI Yang,XIAO ShuQi,LI Shuang

Scientia Agricultura Sinica. 2021, 54(13):  2906-2915.  doi:10.3864/j.issn.0578-1752.2021.13.018

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【Objective】The purpose was to study the effect of disinfectant acid calcium sulfate (ACS) on the killing of microorganisms, and to provide basic data and theoretical basis for disinfectant prevention and control of human and animal diseases.【Method】After incubating ACS with 3% lecithin and 5% Tween-80 as phosphate buffer neutralizer for a period of time, Escherichia coli, Staphylococcus aureus, Salmonellaand porcine reproductive and respiratory syndrome virus (PRRSV) were added respectively for a period of time, We spread the culture mixture with bacteria on nutrient agar plates and cultured at 37℃ biochemical incubator for 18-24 h, the mixture with virus was inoculated on the cell plates and incubate in 37℃ cell incubator for a certain period of time to evaluate the neutralizing effect of the neutralizer. The comparison settings and evaluation criteria were as follows: disinfectant mixed with bacterial suspension or virus suspension (group 1), the mixture of disinfectant and bacterial suspension or virus suspension was mixed with neutralizer (group 2), the mixture of neutralizer and disinfectant was mixed with bacterial suspension or virus suspension (group 3), the mixture of sterile hard water and bacterial suspension or virus suspension was mixed with neutralizer (group 4), the mixture of sterile hard water and bacterial suspension or virus suspension was mixed with PBS (group 5), sterile hard water mixed with PBS (group 6). The evaluation criteria of the neutralizer effect in the bacteria killing test were as follows: group 1 had a very small amount of bacterial growth or aseptic growth; group 2 had bacterial growth, which was significantly less than that of groups 3, 4, and 5, but more than the group 1; the number of bacteria in group 3, 4,5 was close to that of the positive control group, no bacterial growth in group 6. All three repeated tests met the above conditions, and the results were consistent, it was determined that the selected neutralizer and concentration were appropriate. The evaluation criteria of the neutralizer effect in the virus inactivation test were as follows: group 1 had very little virus growth or no virus growth; group 2 had virus growth and was significantly less than that of groups 3, 4, and 5, but more than group 1. The growth of viruses in groups 3, 4, and 5 was similar to the original inoculation; the cells in group 6 grew normally. The results of the three repeated tests were consistent, and it was determined that the selected neutralizer and concentration were appropriate. We used the suspension quantitative sterilization method and the method of determining the virus titer to evaluate the elimination effect of ACS on the above-mentioned bacteria and viruses. We diluted the ACS 200, 300, 400, 500, 600, and 700 times to interact with the above-mentioned bacteria or virus for different time and added neutralizer for neutralization, then spread the bacterial mixture on nutrient agar plates to evaluate the killing effect of ACS by calculating the number of colonies, and determined the virus titer in the virus mixture to evaluate the killing effect of ACS on the virus.【Result】 The selected neutralizer can effectively neutralize the residual effects of ACS 200-fold dilution on bacteria and viruses, and the neutralizer was non-toxic to bacteria, viruses and cells. When ACS interacted with the bacteria for 0 h, it was neutralized immediately. The sterilization rate ofEscherichia coli at the maximum dilution of 300 times was 100%, the sterilization rate of Staphylococcus aureusat the maximum dilution of 600 times was 100%, and when the maximum dilution was 700 times, the sterilization rate of Salmonella was 100%. When ACS was diluted to 700 times, it was neutralized one day or six days after treatment with the above bacteria, and the sterilization rate was 100%. In addition, when ACS was diluted to 200 times, it was neutralized 60 minutes after treatment with PRRSV, and no virus titer was detected.【Conclusion】 When ACS diluted 700 times withEscherichia coli,Staphylococcus aureus and Salmonella for one day or more, it can produce better killing effect; when ACS diluted 200 times with PRRSV for 60 minutes, it can completely kill the virus, which will provide strong data support for the selection of disinfectants in the farms and provide reference for the prevention and control of epidemic diseases.

RESEARCH NOTES

Genetic Analysis of Peanut Kernel Traits in a Nested-crossing Population by Major Gene Plus Polygenes Mixed Model

ZHANG MaoNing,HUANG BingYan,MIAO LiJuan,XU Jing,SHI Lei,ZHANG ZhongXin,SUN ZiQi,LIU Hua,QI FeiYan,DONG WenZhao,ZHENG Zheng,ZHANG XinYou

Scientia Agricultura Sinica. 2021, 54(13):  2916-2930.  doi:10.3864/j.issn.0578-1752.2021.13.019

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【Objective】Peanut kernel traits are important components of peanut yield. The genetic models of peanut kernel traits were analyzed in a peanut nested-crossing population to provide material and theoretical basis for further QTL mapping in the derived nested association mapping (NAM) population and for marker developing to assist breeding for high yield peanut varieties.【Method】The nested-crossing population containing five combinations of Yuanza 9102×Yuhua 15, Zhonghua 6×Yuhua 15, Yuhua 15×Yueyou 20, Yuhua 15×Fuhuasheng and Yuhua 15×NC94022 was constructed using Yuhua 15 as common parent and other five varieties as founder parents. A total of 1812 F_2:3 families were obtained by single plant harvesting in F₂, and the six kernel traits including kernel length, width, ratio of length to width, surface area, surface perimeter and average-kernel weight were measured for each family. The fitness and correlation between each pair of the traits were analyzed. The major gene plus polygene mixed genetic model of quantitative traits was tested and the genetic parameters, the number of control genes, the genetic effects and the heritability were estimated.【Result】 In the segregated populations of nested- crossing, the variation of kernel traits were extensive, and all the six traits showed normal distribution exceeding both parents in each of the combinations. There were significant correlations between each pair of the three traits including the kernel length surface area and surface perimeter. However, the correlation between kernel width and the ratio of length to width was low. The greater the correlations between each pair of the six traits, the higher the fitness. The genetic models of the kernel traits differed among the combinations. The genetic pattern of kernel surface area and kernel surface perimeter in all of the five combinations belonged to one major gene of additive-dominant model (1MG-AD), while that of the width, ratio of length to width and average kernel weight in four combinations also followed 1MG-AD pattern. The kernel length conformed to one major gene and negative completely dominant (1MG-NCD) model in three combinations, and the kernel length and ratio of length to width in one combination conformed to two major genes of equally dominant (2MG-EAD) model. The heritability of major genes was 3.80%-77.06% and the various implied the exist of multiple alleles or non-alleles in major genes as well as the minor genes in the backgrounds of different combinations.【Conclusion】Most of the kernel traits in the peanut nested-crossing population had polygenic genetic effects, and followed different genetic models. These results indicated that the genetic background of kernel traits differed in this nested-crossing population and the genetic materials will further benefit the comprehensive dissection of the genetic mechanism of complex kernel traits.