Table of Content

12 November 2017, Volume 43 Issue 11

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Development and Application of High Resolution Karyotypes of Chinese Spring Aneuploids

WANG Dan-Rui,DU Pei,PEI Zi-You,ZHUANG Li-Fang,QI Zeng-Jun

Acta Agron Sin. 2017, 43(11):  1575-1587.  doi:10.3724/SP.J.1006.2017.01575

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Oligonucleotide (oligo hereafter) multiplex-based chromosome painting facilitates chromosome identification of both wheat cultivars and its relatives in a simple, easy and high efficient way. In this study, an oligo multiplex containing oligos pAs1-1, pAs1-3, AFA-4, (GAA)₁₀, and pSc119.2-1 developed earlierwas used for chromosome painting of 18 accessions from 17 Chinese Spring (CS) aneuploids. The high resolution karyotypes allowed to clearly distinguish individualwheat chromosomes. Fourteen aneuploidshad theexpected chromosome constitutions whereasthe other four had chromosome variations including one witha possible small segmental reciprocal translocation T6AS·6AL-6DL and T6DS·6DL-6AL occurred in N5BT5D. The following analysis on eightlandraces,ninecultivars (lines), and one synthetic hexaploid wheat, observed karyotypediversities from 15 chromosomes including six B- (except for 4B), five A- (except for 1A and 3A), and four D-genome (1D, 2D, 4D, and 7D) chromosomes. The three widely-used translocations in China, i.e. T1BL·1RS, T6AL·6VS and the reciprocal translocation T1RS·7DL and T7DS·1BL, were clearly detected after only oncefluorescence in situ hybridization(FISH) using the oligo multiplex and without genomic in situ hybridization (GISH). This oligo multiplex also produced rich signals in all chromosomes of Triticum monococum, rye cultivar ‘Jingzhouheimai’, durum wheat ‘Langdon’, and Thinopyrum elongatum, and 30 chromosomes of Thinopyrum intermedium. The karyotypes of these five species were thus developed. These results indicate that oligo multiplex-based chromosome painting will play active roles on chromosome identifying, and provide a reference for the standard karyotypes of CS aneuploids.

Antisense RNA-Mediated GmFAD2-1B Gene Silencing Enhances Accumulation of Oleic Acid in Transgenic Soybean Seeds

YANG Jing,XING Guo-Jie,NIU Lu,HE Hong-Li,DU Qian,GUO Dong-Quan,YUAN Ying*,YANG Xiang-Dong*

Acta Agron Sin. 2017, 43(11):  1588-1595.  doi:10.3724/SP.J.1006.2017.01588

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The content of oleic acid is usually taken as a crucial indicator of cooking quality and stability for soybean oil. Breeding soybean cultivars with high oleic acid has always been considered as one of the principal aims for soybean improvement. In this study, the anti-sense GmFAD2-1B gene from soybean was transformed into the cultivated soybean by Agrobacterium-mediated method and several soybean transgenic lines with dramatically increased oleic acid content were obtained. Southern blot analysis confirmed integration of the anti-sense GmFAD2-1B fragment into the soybean genome with one to five copies of T-DNA insertions in the selected independent transgenic plants. The results of qRT-PCR showed that the foreign anti-sense GmFAD2-1B was mainly expressed in the transgenic seeds and simultaneously resulted in a significant decrease of the endogenous GmFAD2-1 mRNA, however, there were no significant differences observed for GmFAD2-1 mRNA contents in the root, leaf, stem and flower tissues of the transgenic plants compared to the non-transgenic ones. Analysis of the fatty acid compositions indicated that the content of oleic acid increased to 27.38%–80.42% in twelve transgenic lines. Specifically, in transgenic lines L40 and L72, oleic acid content was raised to 68.91%–80.42% and 65.98%–80.22% respectively, with over 2.65-fold increase compared with the wild type Williams 82 (containing 17.8%–22.0% of oleic oil). Concomitantly, linoleic acid and saturated fatty acid were reduced to 4.84%–14.55% and 10.34%–11.16% respectively in the seeds of transgenic lines L40 and L72. However, there was no significant difference in total oil and protein contents, as well as agronomic traits such as maturity period, plant height, leaf shape, flower color, pod height and weight per 100 seeds between the transgenic lines and non-transformed controls.

Identification of QTLs Conferring Small Brown Planthopper Resistance in Rice (Oryza sativa L.) Using MR1523/Suyunuo F_2:3 Population

ZHONG Jie,WEN Pei-Zheng,SUN Zhi-Guang,XIAO Shi-Zhuo,HU Jin-Long,ZHANG Le,JIANG Ling,CHENG Xia-Nian,LIU Yu-Qiang,WAN Jian-Min

Acta Agron Sin. 2017, 43(11):  1596-1602.  doi:10.3724/SP.J.1006.2017.01596

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The small brown planthopper (SBPH), Laodelphax striatellus Fallén (Homoptera: Delphacide), is one of the most destructive insect pests in rice (Oryza sativa L.) production. SBPH not only causes direct damage by sucking plant sap but also transmits the main viral diseases, which seriously threatens the safety of rice production. An indica cultivar MR1523 displayed strong antixenosis against SBPH. In order to identify SBPH resistance genes, a F2:3 population derived from a cross between MR1523 and susceptible japonica cultivar Suyunuo was constructed, and then evaluated for SBPH resistance. Moreover, 120 polymorphic SSR markers between the parents uniformly distributed on 12 chromosomes of rice were used to construct the molecular linkage map, and then conducted the QTL assay for SBPH resistance. A total of four QTLs on chromosome 2, 5, and 6, Qsbph2, Qsbph5a, Qsbph5b, and Qsbph6 were detected in the interval of RM526–RM3763, RM17804–RM13, RM574–RM169, and RM190–RM510, with LOD score of 2.14, 3.13, 3.23, and 2.35, and explained the phenotypic variance of 12.0%, 14.7%, 17.4%, and 14.1% , respectively. All of the QTLs came from the resistance parent MR1523. The results in this study lay a foundation for furtherly fine mapping SBPH resistance and developing new cultivars by molecular marker assisted selection in the future.

Growth Regulation and the Mechanism of Propiconazole in Maize Seedlings

HAO Ling,XING Jia-Peng,DUAN Liu-Sheng,ZHANG Ming-Cai*,LI Zhao-Hu

Acta Agron Sin. 2017, 43(11):  1603-1610.  doi:10.3724/SP.J.1006.2017.01603

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Propiconazole (Pcz) has been widely used as fungistat in crop production. Meanwhile, Pcz can be used as plant growth regulator to influence plant growth. There is less study on the application of Pcz in maize. The present experiment using maize variety Zhengdan 958 was conducted to study the effect of Pcz on maize seedling growth, cell morphology and hormone signal. Pcz treatment inhibited the growth of mesocotyl and coleoptile, reduced plant height, shortened the length of sheath and leaf, and decreased leaf angle significantly. At the same time, longitudinal growth of sheath and leaf was inhibited and the shape of pulvinus cells changed from loosened rectangle type or oval type to closely spaced spindle cell. Furthermore, the GA content was reduced significantly and the expression of GA biosynthesis gene GA3ox1 was down-regulated, the expression of GA2ox5 and GA2ox8, genes involved in GA inactivation, was up-regulated, and the expression of GA biosynthesis gene GA20ox1 was up-regulated at the beginning and down-regulated later; the BR content was reduced significantly and the expression of BR biosynthesis genes CPD and DWF4 was up-regulated, which might be feedback regulated by endogenous BR levels. In addition, the expression of expansin genes EXPA4, EXPA5 and xyloglucan endotransglucosylase/hydrolase genes XTH1 and XET1 was down-regulated. In conclusion, Pcz treatment can adjust the signal transduction of GA and BR, inhibit the accumulation of GA and BR, regulate the expression of EXPs and XTHs, control the cell growth, and adjust plant type of maize effectively.

Mapping of QTL for Heading Date and Plant Height Using MAGIC Populations of Rice

SHEN Cong-Cong,ZHU Ya-Jun,CHEN Kai,CHEN Hui-Zhen,WU Zhi-Chao,MENG Li-Jun,XU Jian-Long

Acta Agron Sin. 2017, 43(11):  1611-1621.  doi:10.3724/SP.J.1006.2017.01603

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Association analysis was performed to map QTL for heading date (HD) and plant height (PH) using three multi-parent advanced generation inter-cross (MAGIC) populations including two four-parent- and one eight-parent- derived populations (DC1, DC2 and 8way), and their composite populations (DC12=DC1+DC2, RMPRIL=DC12+8way) derived from eight elite indica lines. Using the phenotypic data of HD collected in the two sites (Jiangxi and Shenzhen) across two years (2015 and 2016), PH collected in the two sites (Jiangxi and Shenzhen) in 2016, and SNP genotypic data of Rice 55K SNP chip, three HD QTLs, qHD3, qHD6 and qHD8 were identified in the same regions of DTH3, Hd3a and Ghd8, respectively. And five PH QTLs (qPH1.1, qPH1.2, qPH1.3, qPH4 and qPH6) were also identified, of which qPH1.1 and qPH1.2 were located in the adjacent regions of Psd1 and sd1. The other three PH QTLs were new loci which were detected only in one population under one environment showing larger effects of genetic background and environment. Different MAGIC populations had different mapping effects for HD and PH. Using eight-parent-derived populations such as 8way, DC12 and RMPRIL not only detected more HD and PH QTL (5, 5, and 6) but also had higher mapping resolution than four parents-derived populations such as DC1 and DC2 (2 and 4), showing an obvious advantage in two aspects of QTL mapping: highly significant level and closed to known genes. Especially, joint analyses of different populations such as DC12 and RMPRIL had significant advantage in QTL mapping. The results laid the foundation for mining the favorable allele of heading date and plant height, and provided materials and information of molecular breeding.

Pyramiding Pi-ta, Pi-b and Wx-mq Genes by Marker-assisted Selection in Rice (Oryza sativa L.)

YAO Shu, CHEN Tao,ZHANG Ya-Dong,ZHU Zhen,ZHAO Qing-Yong,ZHOU Li-Hui,ZHAO Ling,ZHAO Chun-Fang,WANG Cai-Lin*

Acta Agron Sin. 2017, 43(11):  1622-1631.  doi:10.3724/SP.J.1006.2017.01622

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In recent years, japonica rice variety Nanjing 46, Nanjing 5055 and Nanjing 9108 were planted in a large area in Jiangsu province because of their good eating quality. However, these varieties are not resistant to rice blast, and there is no japonica rice variety with good eating quality and suitable for planting in Huaibei area, Jiangsu province. The goal of modern rice breeding is to develop new varieties with good quality, high yield and multi-resistance. Marker-assisted selection combined with traditional breeding methods can greatly improve breeding efficiency. In this study, the high yield rice variety “Wujing 15” contained two blast resistance genes of Pi-ta and Pi-b was used as gene recipient to be crossed with the rice variety “Nanjing 5055”, which carries the low-amylose content gene Wx-mq. Self-designed multiple PCR system to detect rice blast resistance genes of Pi-ta and Pi-b and Tetra-primer Amplification Refractory Mutation PCR System for Wx-mq were used to detect the target loci in separation generation. Combining with many generations of breeding in the field, resistance identification, and classification of the grain endosperm appearance, a new japonica rice line “Nanjing 0051” with excellent agronomic traits and suitable for planting in Huaibei area, Jiangsu province was bred by multi-generational selection on resistance and endosperm appearance. This study successfully used the three sets of PCR detection system in the marker-assisted selection, providing a rapid selection method in rice breeding also important intermediate materials for quality and disease-resistance.

Differential Expression of Three Plant Hormone Related Genes in Wheat Infected by Fusarium pseudograminearum

LI Yong-Hui,CHEN Lin-Lin,SUN Bing-Jian,WANG Li-Min,XING Xiao-Ping,YUAN Hong-Xia,DING Sheng-Li*,LI Hong-Lian*

Acta Agron Sin. 2017, 43(11):  1632-1642.  doi:10.3724/SP.J.1006.2017.01632

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Fusarium pseudograminearum is a pathogenic fungus in wheat newly found in China. The purpose of this study was to disclose the responses of genes involved in the hormone signals pathway to F.pseudograminearum infection. Wheat cultivar Zhoumai 24 wasinfected by the wild-type strain WZ2-8A, and the seedling samples at fiveand fifteendays after inoculation (DAI)were subject to transcriptome analysis by RNA-seqmethod. Theselected differentially expressed genes were subsequently validated by qRT-PCR assay. The infection ofF. pseudograminearum had a negative impact on wheat growth with significantly decreased root length, seedling height, and fresh weights of root and shoot. Atotal of 29 genes expressed differentially in the signal transduction pathways of auxin, cytokinin (CTK) and abscisic acid (ABA). At 5 DAI, 11 genes were expressed differentially compared with the control group (without WZ2-8A inoculation), in whichtwo and nine genes were up- and down-regulated, respectively. At 15 DAI, 25 genes were expressed differentially,including eightup-regulated and seventeendown-regulated genes. In the auxin signaling pathway, auxin input transporter AUX1 was differentially expressed, influencing polar transport of auxin and disturbing cell elongation of wheat roots.In the CTK signaling pathway, the up-regulating role of B-ARR suggests that it couldfacilitate CTK signal transduction to inhibit cellular division,resulting in weaker wheat growth along with the interaction of the auxin signaling pathway. In the ABA signaling pathway, ABA receptor PYR/PYL was down-regulated, while the negative regulator PP2C was up-regulated. ABA plays a negative role in regulating host resistance to fungi and bacteria and its transduction has the antagonistic action against the jasmine acid (JA) / ethylene (ET) pathway, i.e., the repression of ABA signaling pathway might result in the opening ofJA/ET pathway. These results of transcriptome analysis were generally validated bythe qRT-PCR evidence, indicating that inhibition of ABA signal transduction after F. pseudograminearum infection might be the physiological basis of moderate resistance to the fungus in Zhoumai 24.

Mapping Stripe Rust Resistance Gene YrZM103 in Wheat Cultivar Zhengmai 103 by BSR-Seq

ZHANG Huai-Zhi,XIE Jing-Zhong,CHEN Yong-Xing,LIU Xu,WANG Yong,WU Qiu-Hong,Lu Ping,ZHANG De-Yun,LI Miao-Miao,GUO Guang-Hao,YAN Su-Hong,YANG Zhao-Sheng,ZHAO Hong,WANG Xi-Cheng,JIA Lianhe

Acta Agron Sin. 2017, 43(11):  1643-1649.  doi:10.3724/SP.J.1006.2017.01643

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Zhengmai 103 is a new wheat cultivar highly resistant to stripe rust. In order to detect the stripe rust resistance gene in Zhengmai 103, a segregating population was developed by making cross between Zhengmai 103 and a highly stripe rust susceptible wheat cultivar Nongda 399. The 214 F₂ derived F_2:3 progenies were inoculated with mixed prevailing Pst races CYR32, CYR33 and CYR34 (V26) in field condition for disease resistance evaluation at adult plant stage. Genetic analysis revealed that the stripe rust resistance of Zhengmai 103 is controlled by a single gene, temporarily designated YrZM103. By applying RNA-seq with bulked segregant analysis (BSA), six polymorphic markers were developed to map YrZM103 on chromosome 7BL flanked by markers ZM215 and ZM221 with genetic distances of 6.9 and 11.8 cM, respectively. Comparative genetic mapping indicated YrZM103 was located on different genetic interval from that of known stripe rust resistance genes on 7BL.

QTL Mapping for Leaf Morphological Traits of Rice Using Chromosome Segment Substitution Lines

ZHOU Yong,TAO Ya-Jun,YAO Rui,LI Chang,TAN Wen-Chen,YI Chuan-Deng,GONG Zhi-Yun, LIANG Guo-Hua*

Acta Agron Sin. 2017, 43(11):  1650-1657.  doi:10.3724/SP.J.1006.2017.01650

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Leaf morphology is an important component of ideal plant architecture in rice. Therefore, identification of genes associated with leaf morphologic traits is helpful to shape rice ideal architecture and reach the aim of super high-yield. A set of chromosome segment substitution lines (CSSLs) derived from Guanglu’ai 4 (recipient) and Nipponbare (donor) were employed to detect quantitative trait loci (QTL) for the length and width of top three leaves (flag leaf, the second and third leaf from top). We also examined the correlation between the leaf traits and grain yield per plant, indicating that except for flag leaf width, other leaf traits were significantly and positively correlated with grain yield per plant. One-way ANOVA and Dunnett’s test were used to detect QTL related to size of rice top three leaves. Thirteen and seven QTL, for leaf length and width, respectively, were identified. Among them, eight and four QTL had positive effects, respectively. Identification of these QTL provides useful information for improving rice leaf morphologic traits.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effects of Waterlogging on Bt Protein Content and Nitrogen Metabolism in Square of Bt Cotton

LI Yuan, LI Ya-Bing, HU Da-Peng, WANG Jun, HENG Li, ZHANG Xiang, CHEN Yuan, CHEN De-Hua

Acta Agron Sin. 2017, 43(11):  1658-1666. 

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Using Bt cotton conventional cultivar Sikang 1 and hybrid Sikang 3 as test materials, the experiments of water stress at different levels (relative soil water capacity at 90%, 100%, and 2 cm waterlogging above the soil surface respectively) and 90% soil water capacity remained 24–120 hours were conducted to investigate the square Bt insecticidal protein expression and nitrogen metabolism in bud developmental stage. The soil waterlogging treatments with three levels reduced the square Bt insecticidal protein content by 36.5%, 42.1%, and 51.4% for conventional cultivar Sikang 1 and by 19.2%, 57.2%, and 64.5% for hybrid Sikang 3, respectively. The continuous stress of 96 h in the 90% soil water capacity treatment decreased the square Bt insecticidal protein content significantly, which was 20.8% for Sikang 1 and 17.6% for Sikang 3, the longer the stress sustained, the more the Bt toxin content declined. The soluble protein content, NR, GOT, GPT, GS, and GOGAT activities decreased, and the free amino acids content, peptidase and protease activities increased under different levels of soil waterlogging and continuous stress of 90% soil water capacity stress. Therefore, the reduced protein synthesis ability, and enhanced protein degradation ability may decrease the square soluble protein content including Bt insecticidal protein content, resulting in reduction of the square insect resistance.

Effect of Controlled-Release Compound Fertilized on Photosystem II Performance, Yield and Quality of Intercropped Peanut with Wheat

LIU Zhao-Xin,LIU Yan,LIU Ting-Ru,HE Mei-Juan,YAO Yuan,YANG Jian-Qun,ZHEN Xiao-Yu,LI Xin-Xin,YANG Dong-Qing,LI Xing-Dong*

Acta Agron Sin. 2017, 43(11):  1667-1676.  doi:10.3724/SP.J.1006.2017.01667

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Peanut variety 606 was used to investigate photosynthetic characteristics, yield and quality of intercropped peanut with wheat, and to explore the mechanism of physiological responses of photosystemII to controlled-released compound fertilizer, which was 35% for base fertilizer, 35% applied at jointing stage and 30% applied at initial flower stage. The leaf area index (LAR), chlorophyll content(Chl) and net photosynthetic rate (P_n) were gradually reduced at the late growth stage of peanut. Application of the controlled-released compound fertilizerincreased Chl, decreased LAR and P_n, compared with that of common compound fertilizer. In JIP-test analyzing, the OJIP fluorescence induction curve was affected significantly by fertilization, and the fluorescence intensity of K, J, and I steps was significantly decreased. The probability of a trapped exciton moving an electron into the electron transport chain beyond Q_A(Ψ_o) and the performance index on absorption basis(PI_abs) were significantly increased under applying controlled-released compound fertilization, while the relative variable fluorescence intensity at the K-step(W_k) and at the J-step(V_j) was reduced. The comprehensive performance of electron transport chain in PSII reaction center and the electron transport capacity both in the donor side and the receptor side were increased obviously, and the performance of the receptor side was greater than that of the donor side. Applying controlled-release compound fertilizers increased the pod yield and kernel yield by 11.3% and 15.2% respectively as compared with those of applying common compound fertilizers. While the controlled-released compound fertilizer treatment also increased the contents of protein, fat and soluble sugar in kernel, and increased the O/L ratio significantly. Therefore, Under the same application rates of N-P₂O₅-K₂O, applying the controlled-released compound fertilizer can significantly improve the photosynthetic performance for improving yield and quality of peanut compared with applying the common compound fertilizer.

Effect of Exogenous Salicylic Acid, Proline and γ-Aminobutyric Acid on Yield of Rice under Salt Stress

SHA Han-Jing, HU Wen-Cheng, JIA Yan, WANG Xin-Peng, TIAN Xue-Fei, YU Mei-Fang, and ZHAO Hong-Wei*

Acta Agron Sin. 2017, 43(11):  1677-1688.  doi:10.3724/SP.J.1006.2017.01677

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Salicylic acid (SA), proline (Pro) and γ-aminobutyric acid (GABA) play important roles in plant growth and development and tolerating stress. In order to investigate whether the combination of SA, Pro, and GABA had synergistic effect on the yield of rice under salt stress, the mathematical models were established by means of quadratic general rotary unitized design. The optimal combination of SA, Pro, and GABA was obtained by frequency analysis. The results demonstrated that the quadratic models fit better. The effects on the yield of rice under salt stress were SA>GABA>Pro. The interactions between SA and GABA, and between Pro and GABA showed significant effects on rice yield under salt stress.The recommended optimal combination is 0.44-0.51mmol L^-1 for SA, 27.63-31.20mmol L^-1 for Pro and 3.55-4.28mmol L^-1for GABA, which can improve the rice yield more than 10% under salt stress. The effect of a single or a combinationof SA, Pro and GABA on the yield of salt-sensitive variety MDJ30 was larger than that of salt-tolerant variety LD5. The combination of SA and GABA, or Pro and GABA showed synergistic effect on the yield of rice under salt stress, while the combination effect of SA and Pro was related to the genotype difference in salt tolerance. The joint application of SA, Pro and GABA showed better effect on the yield of rice under salt stress than that of any two of them. The combination between any single agent and theother two agentsshowed synergistic effect.

Lignification Response and the Difference between Stem and Root of Brassica napus under Heat and Drought Compound Stress

YIN Neng-Wen**,LI Jia-Na**,LIU Xue,LIAN Jian-Ping,FU Chun,LI Wei,JIANG Jia-Yi,XUE Yu-Fei,WANG Jun,CHAI You-Rong*

Acta Agron Sin. 2017, 43(11):  1689-1695.  doi:10.3724/SP.J.1006.2017.01639

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Using histochemical, biochemical, and gas chromatography-mass spectrometry (GC-MS) technologies, the responsive trends of xylem structure and lignin components in the stem and the root of rapeseed (Brassica napus) cultivar Zhongshuang 10 under heat and drought stresses were investigated as compared with normal-growth plants. Histochemical staining of the frozen sections showed that, compared with the cage-grown plants (normal plants), the plants grown in greenhouse (stressed plants) had a thicker xylem part in both stem and root, with deeper staining color. Correspondingly, the total lignin content in the stem of stressed plants tested by acetyl bromide method increased by 31.64% compared with that of the normal plants. Besides, heat and drought compound stress reduced vessel inner diameter in the stem, while increased both vessel number and vessel inner diameter in the root. Stem total lignin monomer yield prepared by thioacidolysis of stressed plants was 40.08% lower than that of the normal plants, indicating higher condensed bonds in stressed plants. Meanwhile, the S/G ratio (1.82) was significantly higher than that of the normal plants (1.29), indicating increased proportion of S units and decreased proportion of G units. Furthermore, this study also revealed the difference of lignification traits between the stem and the root. The stem had lower condensed bonds and major proportion of S units (S/G=1.29), while the root had more condensed bonds and major proportion of G units (S/G=0.49). Moreover, the H unit percentage in the root (7.43%) was almost 10 folds as that in the stem (0.83%). Since H and G units have lower methylation levels and are easier to form condensed bonds, the high proportions of H and G units might be the main reason for the high proportion of condensed bonds in root lignin structure.

Activity and Physico Chemical Properties of Trypsin Inhibitor in Bruchid-Resistant Mung Bean

FAN Yan-Ping,ZHANG Yao-Wen,ZHAO Xue-Ying,ZHANG Xian-Hong

Acta Agron Sin. 2017, 43(11):  1696-1704.  doi:10.3724/SP.J.1006.2017.01696

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Taking bruchid-resistant mung bean lines including B18, B20, B24, and A22 as experimental materials, a susceptible variety mung bean Jinlyu 1 as control, the activity of trypsin inhibitor and the stability of mung bean trypsin inhibitor under high temperature, pH and ultrasonic were measured. The trypsin inhibitor activities of four bruchid-resistant mung bean lines were significantly higher than those of control (Jinlyu 1). There were significant differences of trypsin inhibitor activity between four bruchid-resistant mung bean lines and the control at the 1% probability level. Among them, B18 had the highest activity (70.2 TI U g^–1), following by B20 and A22, and B24 had the lowest one (55.2 TI U g^–1). When treated with temperature, pH and amplitude of ultrasonic, the residual activities of trypsin inhibitor from the four bruchid-resistant mung bean lines were higher than those of control. The residual activities decreased with the increase of temperature and time of warm bath, which enhanced initially and then weakened when pH value was elevating between 2–12, with the highest when pH ranged from six to eight. The residual activities also reduced with the increasing ultrasonic intensity and treatment time. Among the four tested lines, B18 had the highest tolerance to high temperature, high acid and alkali stress, and ultrasonic intensity; B20 had the moderate tolerance, B24 had the lowest tolerance to high temperature, acid and alkali stress, while A22 had the lowest tolerance to ultrasonic treatment. We concluded that among four lines, B18 and B20 have the highest residual activity of bruchid-resistant mung bean trypsin inhibitor under temperature, pH and ultrasonic treatments, being of higher value of its application.

Effects of Water and Nitrogen Coupling on Root Length Density and Yield of Spring Wheat in Permanent Raised-bed Cropping System

MA Zhong-Ming,CHEN Juan,LYUXiao-Dong,LIU Ting-Ting

Acta Agron Sin. 2017, 43(11):  1705-1714. 

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Permanent raised-bed (PRB) with fixed traffic lane and furrow irrigation is a new cropping pattern of spring wheat in Hexi Corridor of China, which may substitute the traditional flat-planting and flood irrigation technique in this area. To guild water and N application in spring wheat cultivation under PRB condition, we carried out a two-year (2014–2015) field experiment in a split-plot design, with irrigation as the main plot and nitrogen (N) application as the sub-plot. The irrigation amounts were 1200 (W1200), 2400 (W2400), and 3600 m³ ha^-1 (W3600), and the N application rates were 0 (N), 90 (N90), 180 (N180), and 270 kg ha^-1 (N270). The effects on wheat root length density (RLD) at different growth stages and final yield were assessed. With increasing the level of irrigation or N application, wheat RLD showed a up–down changing trend, and the irrigation effect was larger than the nitrogen effect. Grain yield was positively correlated with RLD at anthesis, filling and maturity stages. Regression analysis revealed that the highest RLD could be obtained under the combination of 2850 m³ ha^-1 irrigation and 196–207 kg ha^-1 N. In the moderate irrigation treatment (2400 m³ ha^-1), the RLD significantly increased at major wheat growth stages. Meanwhile, the RLD proportion in 40–80 cm soil depth raised, leading to increased water use efficient (WUE) and N agronomic efficiency (NUE_a) of wheat. The comprehensive consideration of wheat yield, NUE_a and WUE indicates that moderate irrigation (2400 m³ ha^-1) and N application rate (180 kg ha^-1) is the best management in PRB cropping wheat in Hexi Corridor. More irrigation to 3600 m³ ha^-1 had no significant effect to increase yield but resulted in significant decreases of WUE and NUE_a because wheat RLD at major growth stages was decreased under luxurious irrigation condition and the RLD proportion in 40–80 cm soil depth was low resulting from the increased RLD proportion in 0–40 cm soil depth.

RESEARCH NOTES

Development of PCR Functional Markers for Multiple Alleles of Wx and Their Application in Rice

MAO Ting,LI Xu,LI Zhen-Yu,XU Zheng-Jin

Acta Agron Sin. 2017, 43(11):  1715-1723.  doi:10.3724/SP.J.1006.2017.01715

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Amylose content (AC) is one of the most important factors impacting rice eating quality, which was mainly determined by Wx locus. Multiple alleles, such as Wx^a, Wx^b, Wxⁱⁿ, and Wx^mw contribute to the variation of AC in rice varieties. Selecting rice varieties with low-medium AC through Marker-assisted selection (MAS) is an important way to improve rice eating quality. However, distinguishing the Single Nucleotide Polymorphisms (SNP) of Wx alleles requires the DNA sequencing or restriction enzyme digestion, which is time consuming and labor-intensive. In this study, we developed effective MAS markers by tetra-primer ARMS-PCR technology utilizing functional SNPs corresponding to the different alleles, moreover we put forward corresponding solving schemes on low amplification efficiency and inaccuracy extension through adjusting the location of deliberate mismatch bases introduced. We easily differentiated the multiple alleles of Wx utilizing the markers Waxy^gt-ARMS² and Waxy^ac-ARMS², showing that these markers have significant application value with the features of rapid operation and low cost. We further analyzed the genotype distribution of Wx allele in Liaoning Province rice varieties, and found all of the forty tested varieties carried the Wx^b allele with a narrow genetic diversity. The results of this study could provide theoretical basis and technical support on both new rice varieties breeding and rice eating quality improvement utilizing Wx alleles corresponding to low-medium AC by MAS in Liaoning Province.

Physiological Indices of High-Yielding Sugar Beet Under Drip Irrigation and Plastic Mulching

LI Zhi,LI Guo-Long,ZHANG Yong-Feng,YU Chao,SU Wen-Bin,FAN Fu-Yi,ZHANG Shao-Ying

Acta Agron Sin. 2017, 43(11):  1724-1730.  doi:10.3724/SP.J.1006.2017.01724

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Sugar beet is one of the important sugar crops in China, having high biological yield and high water consumption. The reasonable irrigation is one of the effective measures to save water and improve yield. In this experiment, the relationship among sugar beet yield, leaf area index, net photosynthetic rate, transpiration rate, leaf water potential, soil moisture and water consumption, and different irrigation water effects on sugar beet yield and water use efficiency were studied under plastic mulching with drip irrigation for two consecutive years in Inner Mongolia semi-arid regions. In high yielding sugar beet leaf area index was more than 7.37 in fast growth stage of leaf, 6.08–6.51, and 4.19–5.57 in root growth and sugar accumulation periods, in fast growth stage of leaf, root growth and sugar accumulation periods leaf water potential was 0.09–0.22 MPa, 0.18–0.39 MPa, 0.26–0.48 MPa, net photosynthetic rate was 21.28–28.23 μmol m^–2 s^–1, 21.90–28.75 μmol·m^–2 s^–1, 22.06–26.58 μmol m^–2 s^–1, respectively, transpiration rate in fast growth stage of leaf and root growth period was 9.36–10.21 mmol·m^–2 s^–1 and 6.37–7.73 mmol·m^–2 s^–1, respectively, and more than 4.69 mmol m^–2 s^–1 in sugar accumulation period, water consumption was 140.15–312.78 mm, 44.93–200.45 mm and 44.93–113.06 mm in the three growth stages, respectively. For high yield, high sugar yield and high water use efficiency, the reasonable irrigation water should be 1350 m³ hm^–2 in the year of abundant rain (growth periods rainfall > 500 mm)and 1800 m³ hm^–2 in the year of little rain (growth periods rainfall < 300 mm), which provides a theoretical basis and physiological indicators for sugar beet water-saving irrigation.