Table of Content

16 January 2022, Volume 55 Issue 2

Previous Issue    Next Issue

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Phenotypic Characteristics and Related Gene Analysis of Ningmai Series Wheat Varieties

JIANG Peng, ZHANG Peng, YAO JinBao, WU Lei, HE Yi, LI Chang, MA HongXiang, ZHANG Xu

Scientia Agricultura Sinica. 2022, 55(2):  233-247.  doi:10.3864/j.issn.0578-1752.2022.02.001

Abstract ( 594 )   HTML ( 50 )   PDF (2042KB) ( 253 )   Save

Figures and Tables | References | Supplementary Material | Related Articles | Metrics

【Objective】The phenotypic characteristics, genetic diversity and distribution of the loci controlling important traits in Ningmai series varieties (lines) were clarified by analyzing the main traits of Ningmai series varieties and the genotype of the varieties and lines in order to provide a basis for genetic improvement and utilization in breeding and production. 【Method】The main traits including yield, quality and disease resistance of the twenty-three approved varieties were analyzed, and all the approved varieties and lines were genotyped with Affymetrix 50K array, and some other functional genes were identified additionally. 【Result】Ningmai series wheat varieties had good performance in yield, medium and weak gluten quality, and resistance to Fusarium head blight (FHB), and poor performance in resistance to powdery mildew and rust. After quality control, 28 253 high-quality SNPs were obtained. The genetic similarity coefficients among the 23 approved varieties ranged from 0.407 to 0.964, with an average of 0.600, and ranged from 0.456 to 0.985 for those among 51 high-generation lines, with an average of 0.684. The spring habit of Ningmai series varieties (lines) was mainly caused by the variation of Vrn-D1, and Ppd-D1 made all materials photoperiod insensitive. Rht-B1b was mostly present in Ningmai series varieties (lines) to reduce the plant height, and there were lots of favorable alleles on thousand grain weight and pre-harvest sprouting. 48.6% of Ningmai series varieties (lines) had the major resistance gene Fhb1 to FHB, and nearly 30% carried the major resistance gene Pm21 to powdery mildew. 【Conclusion】The genetic diversity of Ningmai series varieties (lines) showed a decreasing trend, and it was necessary to strengthen germplasm innovation and broaden genetic background. Ningmai series varieties (lines) carried many favorable genes on thousand grain weight, pre-harvest sprouting and resistance to FHB, and could be used as excellent parents for genetic improvement of wheat varieties. Ningmai series varieties were mainly medium and weak gluten quality type, and the selection of medium-strong gluten and strong gluten varieties needed to be taken into account, as well as the resistance to powdery mildew and rust.

Restricted Two-Stage Multi-Locus Genome-Wide Association Analysis and Candidate Gene Prediction of Boll Opening Rate in Upland Cotton

XIE XiaoYu, WANG KaiHong, QIN XiaoXiao, WANG CaiXiang, SHI ChunHui, NING XinZhu, YANG YongLin, QIN JiangHong, LI ChaoZhou, MA Qi, SU JunJi

Scientia Agricultura Sinica. 2022, 55(2):  248-264.  doi:10.3864/j.issn.0578-1752.2022.02.002

Abstract ( 350 )   HTML ( 35 )   PDF (2911KB) ( 126 )   Save

Figures and Tables | References | Supplementary Material | Related Articles | Metrics

【Objective】Boll opening rate (BOR) is one of the most important indicators reflecting the early maturing trait of upland cotton (Gossypium hirsutum L.). The genome-wide association study (GWAS) was applied to dissect the QTL (quantitative trait locus) and its genetic effect for providing a theoretical basis for molecular breeding of early maturing traits in upland cotton. 【Method】The natural population composed of 315 different upland cotton varieties (lines) were used to identify the BOR under three environments. Simultaneously, a total of 9 244 SNP linkage disequilibrium block (SNPLDB) markers with multiple alleles were constructed. Then, the restricted two-stage multi-locus GWAS (RTM-GWAS) was utilized to detect SNPLDB loci significantly associated with BOR, estimate its phenotypic effect value, establish QTL-Allele matrix for significantly associated loci in the population, and further detected the stable major SNPLDB loci and elite haplotypes. Finally, according to the gene expression levels of the two transcriptome data, candidate genes that may be related to the target trait were mined within the 1 Mb genome range of the flanking sequence of the significant SNPLDB loci. 【Result】The variation of BOR was ranged from 37.78% to 100.00% and the broad-sense heritability was 67.03% in the natural population under three environments. The multi-environment variance analysis revealed that the BOR was significantly different among genotype, environment and genotype × environment interaction (P<0.001). A total of 52 SNPLDB loci significantly associated with BOR were detected through the RTM-GWAS procedure, containing 179 alleles or haplotypes, among them, the effect values of 90 increasing alleles or haplotypes ranged from 0.014 to 19.43, and the effect values of 89 decreasing alleles or haplotypes ranged from -21.49 to -0.039. Among the significant SNPLDB loci mentioned above, 6 SNPLDB loci were detected simultaneously in both multi-environment and single environment, which were considered as stable SNPLDB loci significantly associated with BOR. Through the significance analysis of phenotypic traits corresponding to different allelic variations of the above six stable SNPLDB loci, the four favorable alleles were identified as LDB_16_37952328(TT), LDB_5_96395565(AA), LDB_16_49503485(TT), and LDB_4_81118668(TT). Besides, further analysis showed that there were significant differences in the frequency distribution of favorable alleles among varieties (lines) in four different ecological regions. Additionally, a total of 178 genes were annotated and 23 potential candidate genes were predicted in the adjacent regions of 4 stable major SNPLDB loci by transcriptome data analysis. 【Conclusion】A total of 52 SNPLDB loci significantly associated with BOR were identified, of which 4 loci were stable major SNPLDB loci. Furthermore, it was predicted that 23 genes might be related to the BOR of upland cotton. These SNPLDBs loci and candidate genes will provide a theoretical basis for marker-assisted breeding of early maturity in upland cotton.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Precise Characterization of Maize Germplasm for Resistance to Pythium Stalk Rot and Gibberella Stalk Rot

DUAN CanXing,CAO YanYong,DONG HuaiYu,XIA YuSheng,LI Hong,HU QingYu,YANG ZhiHuan,WANG XiaoMing

Scientia Agricultura Sinica. 2022, 55(2):  265-279.  doi:10.3864/j.issn.0578-1752.2022.02.003

Abstract ( 490 )   HTML ( 32 )   PDF (2664KB) ( 215 )   Save

Figures and Tables | References | Related Articles | Metrics

【Objective】The objective of this study is to establish and perfect the method for precise characterization of maize germplasm resistance to Pythium stalk rot (PSR) and Gibberella stalk rot (GSR), and then precisely evaluate maize accessions with rich genetic background for resistance to stalk rot, and to screen out resistant germplasm and provide valuable resources to the maize community for enhancing disease resistance. 【Method】The total of 2 004 maize accessions with extensive genetic background were identified for resistance to stalk rot in multi-plot demonstration for three years under natural condition in order to preliminarily screen out germplasm with resistance or other excellent traits. Using drilling inoculation, precise evaluation of 690 maize germplasm for resistance to PSR and GSR was conducted at 6 different sites from 2018 to 2020. 【Result】During 2016-2018, 508 accessions with different resistance to stalk rot were identified at multiple sites in non-inoculated fields, including 79, 106, and 323 highly resistant, resistant, and moderately resistant germplasm, respectively. The method of drilling inoculation at the base of stem for precise characterization of maize resistance to stalk rot was established and perfected. Correlation coefficient (r) between soil inoculation and drilling inoculation for screening of maize resistance to PSR was 0.87, with 0.84 for GSR, indicating strong correlation between maize resistance to stalk rot identified by drilling inoculation and soil inoculation. Compared with soil inoculation, the severity of stalk rot on maize treated with drilling inoculation is higher. The precise resistance evaluation of 690 maize accessions to PSR was conducted with drilling inoculation at 6 different environments in Changping of Beijing, Changge of Henan, and Yuanyang of Henan from 2018 to 2020. The incidence of PSR was considerable and the majority of accessions were susceptible or highly susceptible, merely 3.5% of maize exhibited stable PSR resistance. Correlation coefficient of maize resistance to PSR between any two sites among six different environments varied from 0.46 to 0.72. The r values between two sites in 2018, 2019, and 2020 were 0.66, 0.60, and 0.65, respectively. The r values between pairwise annual comprehensive resistance to PSR among 3 years were 0.67, 0.84, and 0.87, indicating the resistance reaction of 690 maize accessions to PSR exhibited good consistency among different environments. A total of 24 maize germplasm expressed stable resistance to PSR, such as Jizi H676, Liao 2235, Jizi 14L88, Jizi 14L101, Dan 337, M02N-23, Y1747, HRB16232, and T628358, and so on. During 2018-2020, 690 maize resources were precisely identified for resistance to GSR with drilling inoculation at 6 different environments in Shenyang of Liaoning, Lishu of Jilin, and Gongzhuling of Jilin. The results indicated GSR on maize accessions in Shenyang was severe, with the majority of maize expressing susceptibility or high susceptibility, while it was significantly slight in Lishu and Gongzhuling. Correlation coefficient of GSR resistance in 690 maize germplasm between any two sites among six environments ranged from 0.00 to 0.76. The r values between two sites in 2018, 2019, and 2020 were 0.12, 0.04, and 0.05, respectively, indicating considerable differences in GSR resistance at two sites. The r values between pairwise annual comprehensive resistance to GSR among 3 years were 0.40, 0.74, and 0.72, showing annual comprehensive GSR resistance in 690 maize accessions were relatively consistent. The six-point experimental data showed that 5 accessions (Jizi C32, Liao 785, Liao 2235, Jizi 1034, and 16SD088) exhibited stable resistance to GSR. The r value of 0.44 between PSR and GSR resistance in 690 maize germplasm indicated moderate correlation between two stalk rot resistances. 【Conclusion】The resistance level of 2004 maize accessions to stalk rot was determined at multiple environments under natural conditions. The method of drilling inoculation at the base of stem for precise characterization of maize germplasm resistance to stalk rot was established and validated. The precise resistance characterization of 690 maize accessions to PSR and GSR was performed with drilling inoculation at 6 different environments among 3 years. Twenty-four and five maize germplasm expressed stable resistance to PSR and GSR at diverse sites among 3 years, respectively, which were important sources for breeding stalk rot resistant varieties or improvement of cultivar resistance.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY·AGRICULTURE INFORMATION TECHNOLOGY

Phosphorus Altered the Response of Ionomics and Metabolomics to Drought Stress in Wheat Seedlings

LI Gang, BAI Yang, JIA ZiYing, MA ZhengYang, ZHANG XiangChi, LI ChunYan, LI Cheng

Scientia Agricultura Sinica. 2022, 55(2):  280-294.  doi:10.3864/j.issn.0578-1752.2022.02.004

Abstract ( 416 )   HTML ( 48 )   PDF (1316KB) ( 200 )   Save

Figures and Tables | References | Related Articles | Metrics

【Objective】 This study was conducted to explore the adaptive mechanism of wheat plants to drought stress under two kinds of phosphorus supply conditions and its response after rehydration, so as to provide more information for revealing the interaction mechanism of water and phosphorus and breeding the wheat varieties with stress resistance and high phosphorus efficiency. 【Method】 The wheat cultivar Xindong23 were used. The response of wheat plants to drought stress (0, 3, 5, 7 d) and the reaction of rehydration 3 d under low phosphorus (LP: 0.05 mmol·L^-1) and conventional phosphorus (CP: 1.0 mmol·L^-1) were studied by means of ionomics and metabonomics. 【Result】The root system of wheat was dense under LP treatment. From 0 d to 7 d of drought stress and then to 3 d of re-watering, the dry weight of shoot and whole plant under CP treatment increased firstly and then decreased, but that under LP treatment increased firstly and then decreased and then increased. After re-watering for 3 days, the increase rate of total root volume under LP treatment was significantly higher than that under CP treatment. The decrease rate of root DNA content under LP treatment was 21.7%, which was significantly lower than that under CP treatment. Ion group analysis showed that compared with CP, the content of most elements in roots decreased and that in shoots increased under LP treatment. Metabonomics analysis showed that CP treatment was more sensitive to drought stress, and the effect of drought stress on shoot was greater than that of root. With the extension of drought stress time, the metabolism of amino acids, fatty acids and terpenoids was more affected. 【Conclusion】Wheat plants with low phosphorus supply were less sensitive and more adaptable to drought stress, and had stronger recovery ability after rewatering than those with normal phosphorus supply, the main reason is the change of root morphology, rearrangement of ion balance and the change of metabolism of amino acid and abscisic acid to regulate osmotic balance, maintain ion homeostasis and enhance tolerance to drought stress.

Uniform Distance Single Seed Linear Seeding Method for Control of Wheat Physiology and Ecology

LI Pei, HE RuiYin, WANG XiaoChan, DING QiShuo

Scientia Agricultura Sinica. 2022, 55(2):  295-306.  doi:10.3864/j.issn.0578-1752.2022.02.005

Abstract ( 267 )   HTML ( 23 )   PDF (551KB) ( 102 )   Save

Figures and Tables | References | Related Articles | Metrics

【Objective】The benefit of uniform distance single seed linear seeding method could be due to its tracing position and relative stable space assigned to each individual plant in the seeding stage. Thus, the precision seeding of wheat using an uniform distance single seed linear seeding (UDSSLS) was investigated and its density effect on wheat seedling and maturing stages were analyzed in this study. 【Method】Wheat species of Ningmai 13 was used for no-till post-paddy field experiment by using UDSSLS method in 2017 and 2018. Wheat seed was linear sowing in single seed and keeping seed-to-seed distance uniformly, in 1.5 (T1.5), 3.0 (T3) and 4.5 cm (T4.5), respectively. Row distance was 20 cm. Physiological and ecological monitoring and analyzing on the stand, individual plant and organic scales were made in both seedling and maturing stages. 【Result】 The stable density effect was created with the UDSSLS seeding method. And the density effect could be expressed in both the stand, the individual plant, and the organ level. A small seed distance significantly increased the 50% emergence days. Seed grain yield of the stand increased with reduced seed distance, while no significance was observed between T1.5 and T3, while which under T4.5 was significantly lower than that under other treatments. In the stand level, stem weight and ear weight under T1.5 and T3 were significantly lower than that under T4.5. In the individual plant level, however, plant ear number, ear-bearing grain number and grain yield increased significantly with increased seed distance. No difference was observed for 1000-grain weight. Above-ground biomass yield, ear biomass and stem weight were also increased with enlarged seed distance, which clearly explained a density compensation effect. In the individual level, the distribution of each indices were observed to shift from normal distribution to L shaped distribution. In the organic level, no significant difference was observed on ear grain yield and 1000-grain weight. Only ear grain number varied amid the 2 years. No significant difference was observed for above-ground biomass, leaf weight, stem weight and ear weight under different treatments. 【Conclusion】 The UDSSLS method created stable density effect on wheat, which could be observed in both seedling and maturing staged and quantified on the stand, individual plant and organic level. Complicated interactions existed among different phenomics and scales of observation. It thus might be concluded that UDSSLS could be potentially used for wheat physiology and ecology studies.

Regulation Mechanism of Planting Density and Spraying Ethephon on Lignin Metabolism and Lodging Resistance of Summer Maize

GENG WenJie, LI Bin, REN BaiZhao, ZHAO Bin, LIU Peng, ZHANG JiWang

Scientia Agricultura Sinica. 2022, 55(2):  307-319.  doi:10.3864/j.issn.0578-1752.2022.02.006

Abstract ( 459 )   HTML ( 40 )   PDF (979KB) ( 196 )   Save

Figures and Tables | References | Related Articles | Metrics

【Objective】 The purpose of this study was to investigate the regulation mechanism of planting density and spraying ethephon on lignin metabolism and lodging resistance characteristics and to explore the mechanism of planting density and ethephon application on lodging resistance characteristics of summer maize. 【Method】 In this study, the summer maize hybrid, Xundan20, was grown by spraying water or ethephon at the seven-expanded-leaf stage under three different plant densities (60 000 plants/hm², low density, L; 75 000 plants/hm², medium density, M; 90 000 plants/hm², high density, H) in order to explore the effects of density and ethephon on plant morphology, the third internode microstructure, lignin metabolism and yield, etc. 【Result】 Compared with LCK at milking stage, the internode length of the third stem under HCK increased by 19.75%. The stem diameter, stalk rind penetration strength, small vascular bundle number, small vascular bundle area and cortex thickness under HCK were 8.00%, 43.46%, 20.41%, 26.92% and 22.05% lower than those under LCK, respectively. The lignin accumulation and enzyme activity of PAL, 4-CL, CAD and POD under HCK were 24.04%, 33.81%、10.92%, 49.06% and 20.78% lower than those under LCK, respectively. Compared with HCK at milking stage, the internode length of the third stem under HE decreased by 34.84%. The stem diameter, stalk rind penetration strength, small vascular bundle number, small vascular bundle area and cortex thickness of HE were 14.22%,66.10%,22.71%,22.11% and 35.96% higher than those under HCK, respectively. The lignin accumulation and enzyme activity of PAL, 4-CL, CAD and POD of HE were 28.28%, 30.74%, 13.01%, 59.26% and 16.99% higher than those under HCK, respectively. 【Conclusion】 Lodging resistance of summer maize decreased with the increasing of planting density. After the application of ethephon, the stem strength and lignin metabolism of summer maize were enhanced, the lodging resistance was enhanced, and finally maize yield was increased. The effect of spraying ethephon on the lignin metabolism and lodging resistance of XD 20 was the most significant when the planting density was 90 000 plants/hm², and yield was the highest.

PLANT PROTECTION

Control Efficacy of Pseudomonas alcaliphila Strain Ej2 Against Rice Blast and Its Effect on Endogenous Hormones in Rice

SHA YueXia, HUANG ZeYang, MA Rui

Scientia Agricultura Sinica. 2022, 55(2):  320-328.  doi:10.3864/j.issn.0578-1752.2022.02.007

Abstract ( 640 )   HTML ( 102 )   PDF (596KB) ( 310 )   Save

Figures and Tables | References | Related Articles | Metrics

【Objective】The objective of this study is to clarify the antagonist activity of Pseudomonas alcaliphila strain Ej2 against various phytopathogens (Fusarium spp., etc.) in vitro, focusing on the control efficacy of P. alcaliphila strain Ej2 against rice blast and influences of endogenous hormones in rice plant. The result will provide new biological control resources for the research and development of fungicides against rice blast. 【Method】P. alcaliphila strain Ej2 was isolated from rice leaf tissue. Antagonistic action of strain Ej2 against Magnaporthe oryzae and other pathogenic fungi such as Fusarium spp., Colletotrichum gloeospoioides, Alternaria alternata which can cause apple spot fallen leaf disease and strawberry black spot, etc, was determined by dual culture assay. In addition, antagonistic activity of volatile substance produced by P. alcaliphila strain Ej2 against M. oryzae and promoting efficacy of fermentation broth increasing the germinating rate of rice seeds were tested in the experiment. The control efficacy of strain Ej2 was determined for the control of rice leaf blast under greenhouse condition by pot-culture method. The plot experiments were conducted to verify the growth promoting effect on rice and control efficacy against leaf blast and neck blast of strain Ej2. Targeted metabonomics based on MRM method was used to detect the effect of strain Ej2 on endogenous hormones in rice plant such as stress hormone and cytokinin after spraying fermentation broth for three times. 【Result】The strain and volatile substance significantly suppressed the hypha growth rate of M. oryzae P131. The control efficacy against rice blast under greenhouse condition was 78.26% and it had no significant difference with 75% tricyclazole wettable powder. The control efficacy against rice leaf blast and neck blast in fields was 75.07%-83.67% and 62.79%-75.09%, respectively. It had a significant difference between the control efficacy of strain Ej2 and 20% fenoxanil suspending agent against rice leaf blast, but it had no significant difference between the control efficacy of strain Ej2 and 20% fenoxanil suspending agent against rice neck blast. P. alcaliphila strain Ej2 showed strong antagonist activity against other five pathogenic fungi, such as F. oxysporum f. sp. niveum, F. solani, F. moniliforme, C. gloeospoioides, A. alternata. The fermentation broth of P. alcaliphila strain Ej2 significantly increased the germinating rate of rice seeds, plant height, and panicle weight compared with water control. After spraying three times, the levels of the stress hormone in plant such as ethylene (ETH) and abscisic acid (ABA) were significantly increased, but the levels of cytokinin such as zeatin riboside (czR), trans-zeatin riboside (tZR) and N6-isopentenyladenine riboside (iPR) were significantly decreased. In addition, the levels of several endogenous hormones in rice plant including IAA, jasmonic acid (JA), cis-OPDA, jasmonoyl-L-isoleucine (JA-LIE), cis-zeatin (cZ), trans-zeatin (tZ), N6-isopentenyladenine (iP) and salicylic acid (SA) had no significant change. 【Conclusion】P. alkalophilis strain Ej2 possesses the application value to control disease, promote crop growth and enhance stress resistance of rice plant, and it is considered to be a biological control microorganism against rice blast and other fungi diseases.

Antibody Preparation and Subcellular Localization of LmKnk3-5′ in Locusta migratoria

ZHANG Rui,ZHANG XueYao,ZHAO XiaoMing,MA EnBo,ZHANG JianZhen

Scientia Agricultura Sinica. 2022, 55(2):  329-338.  doi:10.3864/j.issn.0578-1752.2022.02.008

Abstract ( 260 )   HTML ( 22 )   PDF (2584KB) ( 69 )   Save

Figures and Tables | References | Related Articles | Metrics

【Objective】LmKnickkopf3-5′ (LmKnk3-5′) is an important cuticular protein involved in the development of Locusta migratoria. The purpose of this paper is to get the anti-LmKnk3-5′ polyclonal antibody and confirm the localization of LmKnk3-5′ in L. migratoria. The results will be beneficial to the biological function analysis of LmKnk3-5′ from protein level, meanwhile, it can lay the foundation for further study of the interaction of cuticular proteins in cuticle formation of L. migratoria. 【Method】Three specific antigen sequences (R1, R2 and R3) of LmKnk3-5′ were chosen after amino acid sequences alignment of Knickkopf (Knk) family genes in L. migratoria, including LmKnk, LmKnk2, LmKnk3-FL and LmKnk3-5′. The target antigen sequences were amplified by PCR using primers with BamH I, Hind III restriction sites and full-length cDNA sequences of LmKnk3-5′ as template. The antigen sequences and pET-32a vector were all digested by BamH I, Hind III and ligated to each other by T4 ligase enzyme to make recombinant plasmids, then the recombinant plasmids were transformed into BL21 (DE3) competent cells. The cells were incubated with 0.5 mmol·L^-1 IPTG at 16℃ for 20 h to produce the recombinant fusion protein, SDS-PAGE was used to analysis the expression of target proteins. After that, E. coli cells that can express target proteins in dissolved state were expanded cultured for protein extraction. Ni-NTA agarose was used for target proteins purification and BCA method was used to determine the protein concentration. The LmKnk3-5′ polyclonal antibodies were obtained after immunizing BALB/c mouse four times. ELISA and Western blot were used to analyze the antibody titer and specificity, respectively. Finally, the paraffin sections were prepared using the integument of 8-day-old 5th-instar nymphs after dsLmKnk3-5′ and dsGFP injection, immunofluorescence was conducted to confirm the subcellular localization of LmKnk3-5′ in L. migratoria. 【Result】 R1, R2 and R3 were selected as specific antigen regions through amino acid sequences alignment. R1, R2 and R3 contain 208, 147 and 131 aa, respectively, with the predicted molecular weights of 24.0, 17.0 and 14.8 kD, respectively. Three recombinant plasmids (pET-32a-R1, pET-32a-R2, pET-32a-R3) were obtained successfully after enzyme digestion and ligation. SDS-PAGE analysis showed that only the cells consist of pET-32a-R2 plasmids could express target proteins in dissolved state after induced by IPTG. R2 recombinant fusion protein was purified and used to obtain anti-LmKnk3-5′ polyclonal antibody successfully after immunizing mice. ELISA analysis indicated that the titer of LmKnk3-5′ antibody was up to 1﹕512 000. The results of Western blot demonstrated that after dsLmKnk3-5′ injection, the expression of LmKnk3-5′ was significantly decreased in comparison of the dsGFP injection group. The results of immunofluorescence showed that LmKnk3-5′ was located in the epidermal cells and new cuticle, especially the apical site of newly synthesized exocuticle in L. migratoria. 【Conclusion】Anti-LmKnk3-5′ polyclonal antibody was obtained successfully, it has high titer and specificity. LmKnk3-5′ is mainly located in the apical site of newly synthesized exocuticle in L. migratoria. The results will provide protein level evidence for the functional research of LmKnk3-5′ in the cuticle formation of L. migratoria.

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

Effects of Single-Sided Application of Humic Acid on Maize Root Growth

ZHOU LiPing,YUAN Liang,ZHAO BingQiang,LI YanTing

Scientia Agricultura Sinica. 2022, 55(2):  339-349.  doi:10.3864/j.issn.0578-1752.2022.02.009

Abstract ( 382 )   HTML ( 39 )   PDF (686KB) ( 135 )   Save

Figures and Tables | References | Related Articles | Metrics

【Objective】 Humic acid has complex structure and diverse functions. Studying the direct and indirect effects of humic acid on the growth of maize roots and revealing the regulation mechanism of humic acid on maize roots can provide the theoretical support for further research on the development and application of humic acid fertilizer synergists. 【Method】 A hydroponic experiment was carried out using Hoagland nutrition solution as the basic cultural liquid and maize cultivar of ‘Zheng Dan 958’ as material with a split-root design. The method of field plot split zone experiment was adopted and eight test treatments was set which was CK-control side (CK-C), CK-control side (CK-C) ), HA-non-applied side (HA-C), HA-applied side (HA-T), OHA3-non-applied side (OHA3-C), OHA3-applied side (OHA3-T), OHA6-non-applied side ( OHA6-C) and OHA6-applied side (OHA6-T) to study its effects on biomass, root vitality, root morphology and main chemical components of maize different organs. 【Result】 (1) Single-sided application of humic acid to separate roots significantly increased the fresh root weight of maize on the applied and unapplied sides. Compared with the control, the fresh root weight of maize with the applied side was increased by 21.9%-78.6%, which with the unapplied side was increased by 27.9%-49.3%. (2) The addition of humic acid significantly increased the maize root activity and the total TTC reduction of maize on the applied side and the non-applied side. Compared with the control, the maize root activity and total root TTC reduction of the OHA6-applied side increased the most, which increased by 76.9% and 216.9%, respectively. Compared with the control, HA-applied side and OHA3-applied side treatments increased the maize root activity by 59.8% and 35.1%, respectively. Compared with the control, OHA6-non-applied side, HA-non-applied side and OHA3-non-applied side treatments increased the maize root activity by 62.2%, 53.6% and 25.5%, respectively. (3) Adding humic acid treatment significantly increased the root volume, root surface area, average root diameter, root length and root number on the non-applied and applied sides of maize. (4) Single root application of humic acid could effectively increase the content of maize root ester compounds, protein, amino acids, nucleic acid cellulose and polysaccharides. The application side of humic acid treatment was more conducive to maize root carbohydrates than the non-application side. However, the untreated side under humic acid treatment was more conducive to the accumulation of maize root nucleic acid. The carbohydrate content of the aboveground parts of maize treated with humic acid was significantly higher than that under the blank treatment. 【Conclusion】 Regardless of whether it was HA or OHA3 and OHA6, when humic acid was applied to separate roots on one side, the growth and activity of maize roots on the side where humic acid was applied were significantly higher than those on the side without humic acid, indicating that humic acid had a direct effect on root regulation. The root growth of the whole plant treated with humic acid on one side was better than that under the control treatment without humic acid on both sides, indicating that humic acid also had an indirect effect in regulating root growth. The root growth of the whole plant treated with humic acid on one side was better than that under the control treatment without humic acid on both sides, indicating that humic acid also had an indirect effect in regulating root growth.

The Single Season Wheat Straw Returning to Promote the Synergistic Improvement of Carbon Efficiency and Economic Benefit in Wheat- Maize Double Cropping System

WANG Liang,LIU YuanYuan,QIAN Xin,ZHANG Hui,DAI HongCui,LIU KaiChang,GAO YingBo,FANG ZhiJun,LIU ShuTang,LI ZongXin

Scientia Agricultura Sinica. 2022, 55(2):  350-364.  doi:10.3864/j.issn.0578-1752.2022.02.010

Abstract ( 559 )   HTML ( 41 )   PDF (572KB) ( 199 )   Save

Figures and Tables | References | Related Articles | Metrics

【Objective】 The objective of this study was to optimize straw returning method in wheat-maize double cropping system and to realize the coordinated improvement of system carbon efficiency and economic benefits, so as to promote the sustainable production of wheat-maize double cropping system. 【Method】Based on the long-term field experiment with 8 years of straw returning, this study analyzed the effects of wheat-maize straw returning (D) and single season wheat straw returning (S) on crop straw production and farmland carbon input, and identified the effects of different carbon inputs on wheat, maize, and annual yields, as well as yield stability and sustainability. The response characteristics of carbon efficiency and economic benefits to different carbon inputs in wheat-maize planting system were systematically analyzed. 【Result】 (1)The average annual straw returning quantity of D and S was 13.54 and 5.43 t·hm^-2, respectively. The biomass of roots and stubble putting into farmland soil under D were about 3.04 and 2.14 t·hm^-2, respectively, with no significant difference compared with S (P>0.05). The carbon input of root, root stubble and root exudates under S was 1.34, 0.97 and 1.35 t·hm^-2, respectively, which showed no significant difference compared with D (P>0.05). (2) The input of agricultural resources and management carbon under S was 1.73 t C·hm^-2, which was 51.29 kg C·hm^-2 less than that under D. The total carbon input under S and D were 9.00 and 12.30 t C·hm^-2, respectively, with a significant decrease of 26.82% (P<0.05). The difference of straw input was the main factor that caused the significant difference of farmland carbon input. The annual average straw carbon input under S was 2.31t C·hm^-2, which was 60.85% less than that under D. (3) The annual average maize yield under S was 7.29 t·hm^-2, which was 5.48% lower than that under D. The wheat yield under D (7.76 t·hm^-2) was 5.67% and 0.26% lower than that under S, respectively. However, the sum of wheat and maize yields under S was not significantly different from that under D. The annual yield stability and sustainability indexes under S were 0.19 and 0.63, respectively, which showed no significant difference compared with D (P>0.05). (4) The annual grain carbon production of S and D were 6.27 and 6.25 t C·hm^-2, respectively, and the plant carbon production were 15.96 and 15.74 t C·hm^-2, respectively. The carbon production efficiency and carbon ecological efficiency under S were 0.69 kg·kg^-1 and 1.77 kg·kg^-1, respectively, significantly increased by 60.47% and 39.37% compared with D (P<0.05). (5) In wheat season, the inter-annual average output value and inter-annual average net income under S were ¥18 900 and ¥7 200 per hectare, respectively, which showed no significant difference compared with D (P>0.05). In the maize season, the annual average output value and the annual average net income of S were ¥19 100 and ¥8 010 per hectare, respectively, which were increased by ¥3 880 and ¥3 990 compared with D, respectively. The annual interannual average output value and interannual average net income under S were ¥38 600 and ¥15 600 per hectare, with 14.81% and 51.54% higher than those under D, respectively. 【Conclusion】Under the premise of not significantly affecting the annual wheat - maize grain yield, stability and sustainability of crop production, the only wheat straw returning reduced the maize straw returning, and synergistic improved the carbon efficiency and economic benefit of wheat-maize double cropping system.

HORTICULTURE

Inhibiting Eeffect of Root-Cutting and Top-Pinching on Graft Healing of Tomato

CUI QingQing, MENG XianMin, DUAN YunDan, ZHUANG TuanJie, DONG ChunJuan, GAO LiHong, SHANG QingMao

Scientia Agricultura Sinica. 2022, 55(2):  365-377.  doi:10.3864/j.issn.0578-1752.2022.02.011

Abstract ( 356 )   HTML ( 27 )   PDF (1524KB) ( 122 )   Save

Figures and Tables | References | Related Articles | Metrics

【Objective】The root-cutting grafting seedlings and top-pinching double-stem grafting seedlings or multi-stem grafting seedlings have been widely used in tomato cultivation, which have significant effects on high yield. Understanding the mechanism of root-cutting and top-pinching on tomato graft healing could provide the theoretical basis for tomato grafting production. 【Method】Using ‘YingFen No. 8’ as scion and ‘ZhenAi No. 1’ as rootstock, the grafting healing process, survival rate and xylem connectivity of tomato after root-cutting and top-cutting were observed, and the contents of auxin and cytokinin as well as the expressions of healing related genes in the grafted part were measured. 【Result】Root-cutting and top-pinching inhibited the expression of xylem differentiation gene VND7 above the graft union, and significantly delayed xylem remodeling. The root-cutting treatment significantly decreased the contents of trans-Zeatin riboside (tZR) and trans-Zeatin (tZ) at 12 and 72 hours after grafting, as well as the contents of indole-3-acetic acid (IAA), methyl indole-3-acetate (ME-IAA) and indole-3-carboxaldehyde (ICAld) at 12 hours after grafting. The contents of IAA and ME-IAA at 12 hours after top-pinching grafting were significantly lower than those of the control and root-cutting treatment, and the expression level of the phloem differentiation related gene NEN4 at 3 and 12 hours after grafting was down-regulated. Root-cutting or top-pinching down-regulated the expression levels of cell division related genes Histone H4 and SlcycB1-4 above the graft union at 3-48 hours after grafting. Under root-cutting and top-pinching treatment, the contents of IAA and ME-IAA in grafting union were significantly lower than those under root-cutting treatment, and the contents of tZR and tZ and xylem connectivity were significantly lower than those under top-pinching treatment. The application of 10 mmol∙L ^-1 IAA and 10 mmol∙L^-1 6-BA at the grafted union after top-pinching and root-cutting could significantly promote the xylem remodeling of grafted seedlings. 【Conclusion】In conclusion, root-cutting and top-pinching could reduce the accumulation of cytokinin and auxin, down-regulate the expression of genes related to healing, reduce xylem transduction capacity, and delay the process of tomato grafting healing.

Effects of Nitrogen Level and Form on Root Morphology of Mini Chinese Cabbage and Its Physiological Index

MA YuFeng,ZHOU ZhongXiong,LI YuTong,GAO XueQin,QIAO YaLi,ZHANG WenBin,XIE JianMing,HU LinLi,YU JiHua

Scientia Agricultura Sinica. 2022, 55(2):  378-389.  doi:10.3864/j.issn.0578-1752.2022.02.012

Abstract ( 369 )   HTML ( 43 )   PDF (2349KB) ( 162 )   Save

Figures and Tables | References | Related Articles | Metrics

【Objective】 All higher plants regulate their root morphology to obtain sufficient nutrients and moisture from the soil environment, of which nitrogen is a critical factor in regulating root morphology. The purpose of this study was to explore the effects of nitrogen levels and forms on root morphology of mini Chinese cabbage and its physiological mechanism and to identify the key factors involved in root morphology shaping, which laid a foundation for further research on the molecular mechanism of nitrogen regulation on plant root morphology. 【Method】 Mini Chinese cabbage (variety ‘Hui nong jin wawa’) were used as test material, four combinations including two nitrogen concentrations (0.1 mmol∙L ^-1 and 1 mmol∙L^-1) and two nitrogen forms (NO₃^- and NH₄⁺) were set up. The root morphological parameters, including total root length, root volume, root surface area and root tip number, and root physiological indicators, including NO₃^- content, NH₄⁺ content, sugar, nitric oxide (NO), hydrogen peroxide (H₂O₂), as well as the activities of rooting related enzymes such as peroxidase (POD), polyphenol oxidase (PPO) and indole acetic acid oxidase (IAAO), were evaluated by root scanner and physiological experiment methods. The contents of endogenous hormones, including cytokinins (CTK), jasmonic acids (JA), auxin (IAA), salicylic acid (SA), 1-aminocyclopropyl-1-carboxylic acid (ACC) and abscisic acid (ABA), were determined by LC-MS/SM absolute quantitative analysis using isotope internal standard method. The correlation between root morphology and physiological indexes were also analyzed. 【Result】Under the same nitrogen form, the different nitrogen levels had different effects on the root morphology and physiology of mini Chinese cabbage. Compared with higher concentration (1.0 mmol∙L^-1) NO₃^- (HN), low concentration (0.1 mmol∙L^-1) NO₃^- (LN) significantly increased the total root length, surface area and number of root tips by 43%, 24% and 50%, respectivley. Compared with HN treatment, the content of reducing sugar increased by 55.81%, the content of NO increased by 18.3%, while the content of H₂O₂ decreased by 20.44% in LN-treated plants. Compared with higher concentration (1.0 mmol∙L^-1) of NH₄⁺ (HA), the low concentration (0.1 mmol∙L^-1) of NH₄⁺ (LA) increased the total root length, total root volume, total root surface area and root tips by 96%, 73%, 85%, and 45%, respectively. Compared with HA treatment, LA treatment increased the reducing sugar content by 200%, and both NO and H₂O₂ decreased to 74.59% and 13.58%, respectively. Under the same nitrogen level, the different nitrogen forms affected the root morphology and physiological indexes of mini Chinese cabbage. Compared with LA treatment, LN treatment increased the total root length and total root surface area, decreased the total root volume and total root tip number, and increased the content of reducing sugars. The contents of NO and H₂O₂ under LA treatment were 73.68% and 40.98% lower than that under LN treatment, respectively. Compared with HA treatment, HN treatment increased total root length, total root volume and total root surface area, and decreased the total number of root tips. Compared with HN treatment, HA treatment reduced NO and H₂O₂ content by 82.16%, and 58.66%, respectively. The content of 12-oxo- phytodienoic acid (12-OPDA) in root hormones was the highest under LA treatment, which was 55.18% higher than that under HA treatment. Under each treatment, the content of 12-OPDA was LA>LN>HA>HN; the content of indole acetic acid (IAA) was the largest in HN, which was 44.10% higher than LN, and the IAA content of LA was 93.79% higher than that of HA. The content of IAA under each treatment was HN> LA>LN>HA. The results of correlation analysis between root morphology and physiological indexes showed that root length was significantly positively correlated with reducing sugar (P<0.01), and the number of root tips was positively correlated with 12-OPDA (P<0.05). 【Conclusion】The low concentration of nitrate nitrogen affected root reducing sugar and promotesd the elongation of the main root and lateral roots of mini Chinese cabbage. The low concentration of ammonium nitrogen regulated the 12-OPDA content, which could increase the number of lateral roots of mini Chinese cabbage root system.

FOOD SCIENCE AND ENGINEERING

Fissure Development of Three Japonica Rice Grain during Water Desorption

SHAO XiaoLong,XU Wen,WANG Xiao,YANG XiaoJing,SHEN Fei,LIU Qin

Scientia Agricultura Sinica. 2022, 55(2):  390-402.  doi:10.3864/j.issn.0578-1752.2022.02.013

Abstract ( 277 )   HTML ( 27 )   PDF (3874KB) ( 119 )   Save

Figures and Tables | References | Related Articles | Metrics

【Objective】 Based on the explanation of food moisture adsorption/desorption, were used to detect fissures and moisture in japonica rice. The aim of this study was to investigate the change of grain kernel fissures and to summarize the development law for the fissures in grain kernels. 【Method】Three japonica rice, Ruanyu, Huaidao 5 and Nanjing 5055 were investigated. The japonica rice kernels with fissures and the degree of fissures were detected by X-ray imaging technology. The microstructure of fissures in Nanjing 5055 was observed by scanning electron microscope. Water characteristics in three japonica rice grains were measured by LF-NMR technology. The relationship between kernel fissure and water characteristics was analyzed. 【Result】 A model based on the low-field nuclear magnetic data accurately predicted the moisture content of three japonica rice. The number of fissures increased with increasing the degree of water desorption of the grains. The percentage of fissure kernel for the rice varieties Ruanyu, Huaidao 5, and Nanjing 5055 increased significantly when the moisture content was lower than 14.96%, 15.21%, and 17.84%, respectively. The percentage of fissure kernel decreased with moisture content in paddy rice kernels. The microstructure of starch and cell on the internal fracture surface of cracked kernels were very different from that of the control sample. The water desorption led to the production of starch granules and cell fracture surfaces, and this fracture surface was the initial fissure. When the number of fissures continued to increase, the initial fissures developed into observable fissures. These fissures were developed from slight level to moderate and even severe level. The water desorption led to the shortening of the transverse relaxation time T₂₁ and T₂₂ of the grain kernel. The content of “bounded water” decreased, whereas the content of “free water” initially decreased and then increased. There was a migration and transformation of water molecules between the bounded and free water. Therefore, in addition to the decrease of moisture content, the molecular mobility of each water component decreased, and the decrease of “bound water” content was also an important feature of water change in the process of water desorption of paddy rice. Correlation analysis between fissures and moisture showed that fissures changes were related to changes in the transverse relaxation time of each water component and “bound water” content, but not related to the “free water” content. 【Conclusion】This study proposed a method to classify grain kernel into four types based on the number and types of cracks. The change of crack type in the process of water decomposition was closely related to water distribution. The migration and transformation of grain moisture, especially the decrease of bound water, were the important factors affecting the changes of grain fissures.

ANIMAL SCIENCE·VETERINARY SCIENCE·RESOURCE INSECT

Impacts of Somatic Cell Count in Early Lactation on Production Performance over the Whole Lactation and Its Genetic Parameters in Holsteins Cattle

ZHU Lei,ZHANG HaiLiang,CHEN ShaoKan,AN Tao,LUO HanPeng,LIU Lin,HUANG XiXia,WANG YaChun

Scientia Agricultura Sinica. 2022, 55(2):  403-414.  doi:10.3864/j.issn.0578-1752.2022.02.014

Abstract ( 295 )   HTML ( 27 )   PDF (563KB) ( 94 )   Save

Figures and Tables | References | Related Articles | Metrics

【Objective】 The objective of this study was to explore the relationship between somatic cell count in early lactation (6-35 d) (SCCel) and test-day somatic cell count (SCC), test-day milk yield in different lactation stages, and to estimate genetic parameters of SCSel in Holstein, so as to provide a new idea for the breeding of Holstein mastitis resistance. 【Method】Dairy herd improvement (DHI) records for 182 378 Holstein cows were collected from 141 dairy farms from 2008 to 2018. After quality control, a total of 1 869 976 date records were obtained for 150 864 cattle. The pedigree information of three generations were collected (father, mother, grandfather and grandmother from both father side and mother side) to form the pedigree file, comprising a total of 6 451 bulls and 103 452 cows. The GLM process of SAS software analyzed the factors affecting SCSel, such as measurement scale of pasture, measurement season, measurement year, number of lactation days and fetal secondary, etc, and the relationships between SCSel and test-day SCS and test-day milk yield in different lactation stages by REG procedure using SAS software. The genetic parameters for SCSel traits were estimated by single trait repetition model, single trait and two traits animal model using DMU software, and including heritability and genetic correlation. 【Result】The results showed that the SCC of Holstein changed significantly at 2 weeks postpartum. SCCel of Holstein showed a trend of gradual decline with the increase of lactation days. The farm scale, parity, test season and days in milk had significant impacts on SCCel (P<0.05), and the SCSel of cows with an average annual measurement size of more than 1 000 cows in early lactation was significant lower than the average annual measured size of less than 1 000 (P<0.05). SCSel was firstly decreased and then increased with the increase of parity. The SCSel was the highest in summer and the lowest in winter. There were highly significant regression relationships between SCSel and the test-day SCS in different lactation stages (P<0.01), with regression coefficients ranging from 0.06 to 0.19. There was a highly significant regression relationships between SCSel and the test-day milk yield in different lactation stages (P<0.01), and the regression coefficient ranged from -0.46 to -0.16, and early lactation SCSel could affect breast health and performance during lactation. The heritability of SCSel in 1st, 2nd, 3rd parity and over all parity was 0.05 ± 0.005, 0.07 ± 0.01, 0.04 ± 0.01, and 0.03 ± 0.01, respectively. There were moderate to high genetic correlations among SCSel traits under different parity in Holstein, ranging from 0.54 to 0.87. 【Conclusion】The SCC of Holstein cows in early lactation (6-35 days) was affected by the number of conception and season, and the SCC of early lactation had the population characteristics different from those of the SCC of the measurement date of lactation. A high level of SCCel would have impact on the health and production performance over the whole lactation in Holstein cow. This study provided a theoretical basis for differentiated management by SCCel in postpartum cow pasture, laid a foundation for exploring the genetic mechanism of somatic cell number difference in early lactation of Holstein, and the development of new SCS traits in early lactation was helpful to improve mastitis resistance selection of Holstein in China.

Isolation and Identification of Brucella melitensis from Ticks on Cattle Surface in Hulunbuir Area

HUANG TianPeng,GUO Xu,SUN ChangYun,CHEN JingDiao,CHAOMULIGE ,WU Jie,GERILETU

Scientia Agricultura Sinica. 2022, 55(2):  415-424.  doi:10.3864/j.issn.0578-1752.2022.02.015

Abstract ( 313 )   HTML ( 26 )   PDF (1509KB) ( 89 )   Save

Figures and Tables | References | Related Articles | Metrics

【Objective】 The aim of this study was to elucidate the relationship between Dermacentor nuttalli and brucellosis in cattle and sheep. 【Method】 The species of ticks collected in Hulunbuir were identified by traditional morphological and molecular biology methods; the ticks collected from the cattle surface were used as materials, and the suspicious bacteria were isolated from their bodies. The isolated bacterial species were determined by methods, such as bacterial isolation and identification, morphological observation, serological detection and molecular biology. 【Result】 The dominant tick species were identified as D. nuttalli in this area, and four strains of suspicious bacteria were successfully isolated in their bodies. The isolated bacteria were gram-negative Brevibacterium by Gram staining, and the bcsp31 and omp22 gene sequences of Brucella were successfully cloned by PCR method. After gene sequencing and BLAST analysis, it was found that the similarity with the Brucella reference sequence was above 99.0%. The phylogenetic tree was successfully constructed by using Mega 7.0 software. The isolated strains were clustered in the same branch with the known sequences of Brucella. Using AMOS-PCR and Brucella typing test, four isolated strains were identified as Brucella melitensis. 【Conclusion】 In this experiment, four strains of B. melitensis were isolated from D. nuttalli collected from cattle in Hulunbuir area, which indicated that as a blood sucking arthropod, D. nuttalli might play an important role in the transmission of brucellosis among different hosts. This paper provided basic data for the investigation and control of Brucella in Inner Mongolia.