Table of Content

12 May 2016, Volume 42 Issue 05

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Effect of ω-Secalin Gene Silencing on Processing Quality of Wheat 1B/1R Translocation Line

CHAI Jian-Fang*,WANG Hai-Bo*,MA Xiu-Ying,ZHANG Cui-Mian,DONG Fu-Shuang

Acta Agron Sin. 2016, 42(05):  627-632.  doi:10.3724/SP.J.1006.2016.00627

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Omega-secalin is an important factor for the poor processing quality of wheat 1B/1R translocation lines. In this study, an expression vector of silencing ω-secalin gene was constructed and transferred into wheat variety Jinhe 9123 via Agrobacterium tumefaciens strain EH105. The three T₀ transgenic plants obtained were consecutively multiplied after PCR validation until the T₄ lines. Acid-PAGE assay indicated that total amount of ω-secalins in the transgenic lines decreased 53% on average compared with that in their respective control. In the three homozygous transgenic lines, gluten index, precipitation value, and stabilization time increased significantly, whereas the agronomic traits, such as plant height, grain number per spike, 1000-grain weight and plot yield, had no significant changes compared with those in the wild type. These results suggest that silencing ω-secalin genes can improve the processing quality of wheat 1B/1R translocation lines on the premise of not affecting grain yield.

Effect of HMW-GS Deletion on Processing Quality of Soft Wheat Ningmai 9

ZHANG Ping-Ping,MA Hong-Xiang*,YAO Jin-Bao,ZHOU Miao-Ping,ZHANG Peng

Acta Agron Sin. 2016, 42(05):  633-640.  doi:10.3724/SP.J.1006.2016.00633

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Gene knockout is an effective approach to investigate gene function of high-molecular-weight glutenin subunit (HMW-GS). In this study, we developed a set of single HMW-GS deletion lines of Ningmai 9 (soft wheat) to understand the effects of HMW-GS deletion on kernel quality, quantity of gluten protein fractions and processing quality. Among the 29 lines tested, three lines were wild type and the remaining were knockout mutants including Glu-A1x, Glu-B1x,Glu-B1y, Glu-D1x, and Glu-D1y deletion types of five, seven, five, five, and four lines, respectively. Compared with the wild type, the HMW-GS deletion lines had no significant difference in flour protein content, wet gluten content, kernel hardness, and solvent retention capacity. All the single HMW-GS deletion types decreased the ratios of glutenin-to-gliadin and HMW-GS-to-LMW-GS in quantity, and the decreases in Glu-B1x and Glu-D1x deletion types were significant at P < 0.05. In the wild type, mixograph peak time was 2.00 min and TIMEX width was 4.57%; whereas, those in the HMW-GS deletion lines were significantly lower (P < 0.05), varying from 1.38 min to 1.64 min and from 3.38% to 3.98%, respectively. Particularly, the Glu-B1x and Glu-D1x deletion lines showed the lowest mixograph peak time and TIMEX width. Although similar sugar snap cookie diameter was observed among the five deletion types, Glu-B1x, Glu-B1y, and Glu-D1y deletion types showed significantly higher cookie diameter than the wild type (P < 0.05). In this study, single deletion of HMW-GS weakened gluten strength and improved sugar snap cookie processing quality, indicating that HMW-GS knockout can be used to improve soft wheat quality.

Analysis of Interspecific SNPs in Sweetpotato Using a Reduced-Representation Genotyping Technology

SHI Xuan,WANG Ru-Yuan,TANG Jun,LI Zong-Yun,LUO Yong-Hai

Acta Agron Sin. 2016, 42(05):  641-647.  doi:10.3724/SP.J.1006.2016.00641

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Xushu18 (2x), Nancy Hall (6x), I. trifida (2x) 4597-10, I. trifida (2x) 4597-21, I. trifida (4x), I. trifida (6x), I. temussima (2x), and I. littorallis (2x) were used as experimental materials for sequencing by specific-locus amplified fragment sequencing (SLAF-seq), a high-throughput reduced-representation genotyping technology. In total, 724 589 SLAF tags were obtained and 40 765 SNPs were identified out of 35 310 polymorphic SLAF tags. A total of 40 765 single nucleotide polymorphisms (SNPs) were obtained by sequence analysis. Population structure and phylogenetic relationship of eight germplasm were analyzed using the SNP dataset, which suggests that SLAF-seq can be used to develop large-scale SNPs for population genetic analysis, effectively and economically. Our analysis revealed that the relationship between sweet potato cultivars and the wild species I. trifida is closer. These results provide empirical data for further study of the origin of sweet potato.

Relationship between Indica-Japonica Index of Parents and Heterosis of Hybrid and Its Genetic Basis in Japonica Two Line Hybrid Rice

YU Ya-Hui,LIU Yu,LI Zhen-Yu,CHEN Guang-Hong,XU Zheng-Jin,TANG Liang,MAO Ting,XU Hai

Acta Agron Sin. 2016, 42(05):  648-657.  doi:10.3724/SP.J.1006.2016.00648

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In order to further reveal the relationship between composition of subspecies lineage and heterosis in Oryza sativa L., we built a bridgefor morphological index, Cheng’s index (Chi) andmolecular index, japonica discrimination values (D_j) based on two populations, a recombinant inbred lines (RILs), derived from the cross betweenindicacultivar Qishanzhan and japonica cultivar Akihikari, and japonica photo-thermo sensitive genic male sterile(PTGMS) lineGB028S and their F₁ hybrids. Two indexs achieved relatively consistent results in two populationsindependently. Significant curvilinear relationship appeared among D_jvalues, F₁ yield and yield heterosis. The peaks of F₁ yield and yield heterosis were detected in D_jinterval from 0.55 to 0.70 and from 0.50 to 0.65 respectively, indicating that 0.55−0.65 is the preferential D_j interval for producing high yield and heterosis of F₁ hybrids. Compositions of subspecies lineage on Chr.8, Chr.11, and Chr.12 were closely related with yield and heterosis of F_1, however, the relationship among parent’s genetic distance, F₁ yield and heterosis was not significant.

Cloning and Characterization of Phospholipids:Diacylglycerol Acyltransferase (BnPDAT1) cDNA from Brassica napus L.

TAN Tai-Long,FENG Tao,LUO Hai-Yan,PENG Ye,LIU Rui-Yang,GUAN Chun-Yun

Acta Agron Sin. 2016, 42(05):  658-666.  doi:10.3724/SP.J.1006.2016.00658

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Phospholipids:diacylglycerol acyltransferase (PDAT1) is a key enzyme in triacylglycerol (TAG) biosynthesis of plants. In this study, three novel PDAT1 coding sequences (CDSs) were isolated from cDNA of Brassica napus L. cv. Xiangyou 15 seeds, which were mapped to the chromosomes A02, A10, and C09, and designated as BnPDAT1-A02, BnPDAT1-A10, and BnPDAT1-C09, respectively. Three BnPDAT1 CDSs were 1998, 2002, and 2005 bp in length and encoded predicted proteins with 665, 666, and 667 amino acid residues, respectively. BnPDAT1 proteins were predicted to be located on the cell membrane and have a typical PDAT1 conserved domain. Multiple sequence alignments and phylogenetic analysis showed that the deduced amino acid sequences of BnPDAT1 were highly homologous to previously reported PDAT1 in Brassica oleracea, Arabidopsis thalian, and Eruca sativa. Furthermore, the catalytic enzyme activity of the cloned BnPDAT1 genes was confirmed by the yeast complementary experiment. The expression level of BnPDAT1s increased gradually in seed development and reached the maximum from 25 to 30 days after flowering. However, three BnPDAT1 copies were also found to be different in expression pattern.

Physiological Characteristics and Gene Mapping of a Precocious Leaf Senescence Mutant ospls3 in Rice

GONG Pan,LI Kun-Yu,HUANG Fu-Deng,WEI Li-Quan,YANG Xi,CHENG Fang-Min,PAN Gang

Acta Agron Sin. 2016, 42(05):  667-674.  doi:10.3724/SP.J.1006.2016.00667

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Leaf senescence is the final stage of leaf development. However, premature aging of functional leaves leads to yield reduction and quality decline. Thus, it is very important for developing novel crop germplasms with delayed leaf-senescence characteristics through investigating the molecular mechanism of leaf senescence. In this study, an ospls3 (Oryza sativa precocious leaf senescence 3) mutant, produced by ⁶⁰Co γ-radiation treatment of indica cultivar N142, was identified. The symptoms of the premature senescence mutant presented firstly at tillering stage showing brown leaf tip and brown spots in top part of leaf blade, then spread rapidly to basal part of leaf blade and led leaf to die. The physiological analysis indicated that, in the ospls3 mutant, the content of chlorophyll was the highest in the flag leaf, the following was in second-top and third-top leaves, but all of them were significantly lower than those in the wild type. The contents of MDA, O₂^?, and H₂O₂ and the activities of SOD and POD among these top three leaves in the wild type maintained similar levels, which were significantly lower than those in the mutant type. The soluble protein contents and the activity of CAT had no significant difference among top three leaves in the wild type while significantly decreased in the mutant. Genetic analysis verified that the ospls3 is a recessive mutant and was mapped in a 294 kb interval between RM6953 and RM28753 on the long arm of chromosome 12, which establishes a solid foundation for further cloning and functional studies of this gene.

Cloning and Functional Analysis of Different TruncatedGbU6Promoters in Cotton

LEI Jian-Feng,LI Yue,XU Xin-Xia,AERZUGULI?Tashi,PU Yan,ZHANG Ju-Song,LIU Xiao-Dong

Acta Agron Sin. 2016, 42(05):  675-683.  doi:10.3724/SP.J.1006.2016.00675

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U6 promoter is an important element for the transcription of sgRNA in the CRISPR/Cas9 genome editing system. Using a short promoter is also one of the basic requirements for the construction of CRISPR/Cas9 genomeediting vector. According to the sequence of GbU6-5Ppromoter cloned, six different truncated U6promoterswere successfully cloned using Transfer PCR method and their length were 672, 468, 358, 280, 202 and 105 bp, respectively.Together with GbU6-5P::GUS-pCAMBIA1300, GUS fusion expression vectors driven bycorresponding truncated promoter were constructed and transformed into cotton pollen by the vacuum infiltrationtransformation method.Results of GUS histochemical staining showed that the cloned seven truncatedGbU6-5Ppromoters could drive GUS expression in cotton pollen and all corresponding cottonpollen could be stained blue, but there exist different shades among them. Results showed that the shorter promoter, the stronger transcription activity, and so did the two other GbU6 promoter. In this study three short GbU6 promoters withtranscription activity in cotton pollen were cloned. GUS staining results showed that the shorter U6 promoter had higher transcriptional activity, which was the common characteristics in different U6 promoter.The above results indicated that using shorter U6 promoter not onlyconform to the requirement of constructing CRISPR/Cas9 genome editing vector,but also improve the transcription of sgRNA, which mayenhance the efficiency of genome editing finally.

Genetic Analysis and Gene Mapping of a Yellow-green Leaf Mutant in Rice

CHU Zhi-Zhan,GUO Hai-Bin,LIU Xiao-Lin,CHEN Yuan-Ling,LIU Yao-Guang

Acta Agron Sin. 2016, 42(05):  684-689.  doi:10.3724/SP.J.1006.2016.00684

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A yellow-green leaf rice mutant, temporarily named as ygl8951 (yellow-green leaf 8951), was identified from ⁶⁰Co γ-ray radiation mutation in japonica rice varietyNipponbare. The mutant showed albino phenotype from germination to 3-leaf-stage, then turned yellow-green phenotype till apoptosis. The contents of chlorophyll and carotenoid were obviously decreased in ygl8951 compared with the wild type. Electron microscope observation showed that no grana thylakoids but some stroma thylakoids-like structures were found in chloroplast of ygl8951 mutant. The expression levels of some genes involved in photosystem Iand photosystem II were dramatically decreased, while the ribosomal and RNA polymerase genes in chloroplast were increased in ygl8951 mutant compared with the wild type. Mapping-based cloning was used to identify the ygl8951 locus using an F₂ population from a crossing between the mutant and Huanghuazhan. The result showed that the mutated locus was located in a 191 kb region on chromosome 6, which was assumed to be a new gene controlling leaf color.

Map-based Cloning and Functional Analysis of Low Chlorophyll Fluorescence Gene LCF3 in Arabidopsis thaliana

LIU Ling-Yun,LIU Hao,ZHAO Jing,WANG Yan-Xia,WANG Peng-Tao*

Acta Agron Sin. 2016, 42(05):  690-695.  doi:10.3724/SP.J.1006.2016.00690

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Chlorophyll fluorescence has exclusive role for determining the kinetics of light energy absorption, transmission, dissipation and distribution in leaf photosynthesis. In this study, a mutant was screened by chlorophyll fluorescence equipment from EMS mutagenesis of wild-type Arabidopsis Col-0, which showed lower F_v/F_m than wild-type and was named lcf3-1 (lower chlorophyll fluorescence 3-1). Genetic analysis of lcf3-1 mutant suggested that the mutation was controlled by single recessive gene. LCF3 gene, which encodes PsbW protein, wasisolated by map-based cloning. The T-DNA insertion mutant lcf3-2 showed low chlorophyll fluorescence phenotype as lcf3-1,and this phenotype could be complemented by LCF3 gene of wild-type. These experiments implied that the phenotype of low-chlorophyll-fluorescence resulted from LCF3 gene mutation. Furthermore, our results indicated that LCF3 protein is located in chloroplast and LCF3 gene is expressed in various tissues. PsbW protein is important for the contact and stability between several PSII-LHCII supercomplexes.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Analysis of Heterosis in Sorghum-Sudangrass Hybrids Seedlings Based on Proteomics

HAN Ping-An,LU Xiao-Ping,MI Fu-Gui,ZHANG Rui-Xia,LI Mei-Na,XUE Chun-Lei,DONG Jing,CONG Meng-Lu

Acta Agron Sin. 2016, 42(05):  696-705.  doi:10.3724/SP.J.1006.2016.00696

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Sorghum-sudangrass hybrids are typically used for studying heterosis in forage crops. In this study, we carried out proteomic research on sorghum-sudangrass hybrids and their parents at the three-leaf stage by two dimensional electrophoresis-based proteomics and bioinformatic methods. More than 400 protein spots were detected, in which 34 proteins showed significant differences between hybrid and parents in expression, including dominant expression (showing three single-parent silent, seventeen high-parent and five low-parent expression) and overdominant expression (showing one hybrid-specific, six above-high-parent, two below-low-parent expression). Thus, we speculated that dominant and overdominant effects play key roles, and dominant effect is a major factor in the formation of heterosis in sorghum-sudangrass hybrid. Moreover, the 27 out of 34 proteins were related to eight functional categories, i.e., photosynthesis, carbohydrate metabolism, stress response, ATP synthesis, protein synthesis, electron transfer, signal transduction and unknown. The up-regulated photosynthetic proteins were the biggest category, which indicates that photosynthesis in the leaves of sorghum-sudangrass hybrid is enhanced resultig in producing more organic matter, so that showing heterosis. The identified key node proteins in the interaction networks were the potential target proteins for future genetic manipulation of the specific proteins of heterosis. Our findings provide a theoretical basis on heterosis analysis of sorghum-sudangrass hybrids, which is potentially useful for other forage plants.

Establishment of Ultra Performance Liquid Chromatography (UPLC) Protocol for Analyzing Carotenoids in Common Wheat

LI Wen-Shuang,XIA Xian-Chun,HE Zhong-Hu

Acta Agron Sin. 2016, 42(05):  706-713.  doi:10.3724/SP.J.1006.2016.00706

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Carotenoids is an important criterion in the assessment of color and nutritional qualities of end-use products in common wheat. In this study, grain powders of Zhongmai 175 (soft wheat) and Zhongyou 206 (hard wheat) were used as samples to develop an optimal procedure for extraction and separation of carotenoids compositions extracted from flours using ultra performance liquid chromatography (UPLC). The most effective extraction of carotenoids extraction was obtained using the solvent system of N-hexane; acetone of 80:20 (v/v, 0.1% BHT w/v) under the oscillation condition of 300 rpm, 35ºC, and 1 h. The separation was conducted using YMC C30 Carotenoid column (100.0 mm × 4.6 mm, 3 µm) with photodiode array (PDA) detector, and the column was thermostated at 35°C. Under a gradient system consisting of acetonitrile: methanol: water: triethylamine (81:14:5:0.05, v/v/v/v) (A) and methanol: ethylacetate:triethylamine (68:32:0.05, v/v/v) (B) at a constant flow rate of 0.4 mL min^–1, the carotenoids of common wheat flour samples can be well separated in less than 25 min. Carotenoids were detected at 450 nm. All the present results provided useful information for carotenoids compositions and quality improvement.

Soluble Oligosaccharide and Small Heat Shock Protein Correlated with Seed Germination and Vigor during Hybrid Rice Seed Maturation

ZHU Li-Wei,CAO Dong-Dong,FU Yu-Ying,HU Qi-Juan,LI Zhan,GUAN Ya-Jing,HU Wei-Min,HU Jin

Acta Agron Sin. 2016, 42(05):  714-724.  doi:10.3724/SP.J.1006.2016.00714

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To study the relationship between seed soluble oligosaccharide, small heat shock protein (sHSPs) and seed vigor, we systematically studied their changes during hybrid rice seed maturity.The mean fuzzy subordinate function values of germination percentage, germination energy, germination index, vigor index and mean germination time, root number, root length, shoot length and seedling weight were analyzed. The resultsindicated thatseeds harvesting at 19 to 34 days after pollination (DAP) had a higher viability and vigor. The seed moisture content had a decline trend, with a decrease from 48.2% at 10 DAP to 23.9% at 22 DAP. The raffinose content increased significantly, the fructose content kept decreasing, the contents of stachyose and glucose significantly increased firstly and then decreased during seed development. The relative expression levels of 64SHsp18.0 and Os03g0267200 genes increased significantly from 10 to 19 DAP, and then decreased. The moisture content,the contents of raffinose,stachyose andsucrose, thousand seed weight of fresh seeds and dry seeds,relative transcriptions of 64SHsp18.0 and Os03g0267200 genes were all significantly correlated with seed germination during seed maturity.

Grain Yieldand Water Use Characteristics of Winter Wheat under Micro-sprinkler Irrigation

DONG Zhi-Qiang,ZHANG Li-Hua,LI Qian,Lü Li-Hua,SHEN Hai-Ping,CUI Yong-Zeng,LIANG Shuang-Bo*,JIA Xiu-Ling

Acta Agron Sin. 2016, 42(05):  725-733.  doi:10.3724/SP.J.1006.2016.00725

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The objective of this study was to establish the water-saving and high-yield irrigation system using micro-sprinkler in winter wheat in North China Plain. A two-yield experiment was carried out in the same field in 2012–2013 (normal precipitation) and 2013–2014 (dry year) wheat growing seasons to compare the effects of different irrigation amounts in micro-sprinkler and furrow irrigation modes on wheatpopulation, leaf area index,grain yield, water use efficiency, and water consumption.The water amount in micro-sprinkler mode ranged from 60 to 180 mm in 3–6 irrigations and the water amount in furrow irrigation mode ranged from 74 to 229 mm in 1–3 irrigations. In the 2012–2013 growing season, the average wheat yield of micro-sprinkler irrigation was 5.6% higher than that of furrow irrigation, andthe highest yield was obtained under micro-sprinkler irrigation of 120 mm. Yield increased significantly in the micro-sprinkler treatment than in the furrow irrigation treatment when water amount£90 mm, but decreasedsignificantlywhen the water amount waslarger than 150 mm. In the 2013–2014 growing season, the average yield of micro-sprinkler irrigation was 0.8% higher than that of furrow irrigation, and the highest yield was obtained under micro-sprinkler irrigation of 150 mm. Thousand-grain weight and water use efficiency under micro-sprinkler irrigationwere also higher than thoseunder furrow irrigation, and the increased rations were 5.1% and 8.7% in 2012–2013 growing season and 7.9% and 10.7% in 2013–2014 growing season, respectively. We recommend that winter wheat production with micro-sprinkler under the similar condition of this experiment should be irrigated with water amount of 90–120 mm and water consumption of 325–355 mm in normal precipitationyear andwith water amount of 105–150 mm (30–45 mmfor each irrigation) and water consumption of 335–380 mm in dry year. Compared withfurrow irrigation, micro-sprinkler irrigationhas thewater-saving potential of 20–50 mm in normal year and 70–110 mm in dry yearat the same yield level.

Physiological Mechanism Regulating Light-induced Mesocotyl Elongation by Polyamine Oxidase (PAO) in Maize

ZHANG Tong-Zhen,LI Yong-Sheng,LI Yue,YAO Hai-Mei,ZHAO Juan,WANG Chan,ZHAO Yang,WANG Han-Ning,FANG Yong-Feng,Hu Jin

Acta Agron Sin. 2016, 42(05):  734-742.  doi:10.3724/SP.J.1006.2016.00734

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In this study, maize inbred line PH4CV was culturedunder in MS mediumunder both dark and light conditionsto investigate the relationship of length of mesocotyl with activity of Polyamine Oxidase(PAO), activity of peroxidase (POD), contents of H₂O₂ ang lignin. In addition, after treated with5 mmolL^-1 2-hydroxyethylhydrazine (2-HEH) and 5 mmolL^-1 N, N’-Dimethylthiourea (DMTU), the origin and accumulation site of H₂O₂ in mesocotyl elongationwere assessed by using histochemical stainingmethod and the effect of lighton expression of ZmPAO gene was evaluated. The results indicated that the elongation of mesocotyl was significantly inhibited while the contents of H₂O₂ and lignin and the activities of POD and PAO were enhanced by light. Correlation analysis showed that the length of mesocotylwas negatively correlated with the PAO activity, H₂O₂ content, POD activity, and lignin content, and the PAO activity was positively correlated with the H₂O₂ content, the POD activity, and the lignin content. The assay with 2-HEH and DMTU, the microgram of epidermal cells, and histochemical localizationof H₂O₂ revealed that H₂O₂ participated in mesocotyl elongation, in which PAO catalyzedpolyamines (PAs)degradation to produce H₂O₂resulting in the inhibition of mesocotyl elongation.Results of qRT-PCR revealed that the expression level of ZmPAO was relatively stable in dark and rose rapidly of0.5 hour after exposing to light, with a maximum value after three hours of light treatment, then declined gradually, and finally showed a steady level after ten hours. This study suggests that the activity of PAO can be promoted by light treatment, and initiate the PAs-mediated induction of H₂O₂, resulting in the oxidation of lignin monomers on cell wall by POD. The produced free radicalsare then transformed into lignin in a polyforming process which marked the cell wall hardened and cell elongationinhibited . This study may provide a theoretical basis for understanding the physiological mechanism underlying the PAO-mediated mesocotyl elongation and gain insights into the response of maize mesocotyl to the light stress.

Aboveground Architecture ModelBased onBiomass of Winter Wheat before Overwintering

CHEN Yu-Li,YANG Ping,ZHANG Wen-Yu,ZHANG Wei-Xin,ZHU Ye-Ping,LI Shi-Juan,GONG Fa-Jiang,BI Hai-Bin,YUE Ting,CAO Hong-Xin

Acta Agron Sin. 2016, 42(05):  743-750.  doi:10.3724/SP.J.1006.2016.00743

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The aboveground morphogenesis is an important basis of plant morphological construction and visualization for winter wheat before overwintering. For quantitatively analyzing the relationship between the aboveground architectural parameters and organ biomass of winter wheat before overwintering, field experiments with different varieties (Jimai 22, Tainong 18, and Luyuan 502) and nitrogen levels were carried out in 2013–2014 and 2014–2015 wheat growth seasons. Simulation models for aboveground architectural of winter wheat before overwintering were built with the 2013–2014 dataset of aboveground architectural parameters before overwintering and organ biomass and validated by the2014–2015dataset, showing the models exhibited satisfactory predictions for leaf blade length, leaf maximum blade width, leaf blade tangent angle, and leaf blade bowstring angle, except for leaf sheath length and leaf bowstring length. The models built in this study are suitable to simulate the aboveground architecture of winter wheat varieties before overwinteringunder different nitrogen levels.

Effects of Wheat Straw Returning Patterns on Characteristics of Dry Matter Accumulation, Distribution and Yield of Rotation Maize

YIN Wen**,FENG Fu-Xue**,ZHAO Cai,YU Ai-Zhong,CHAI Qiang*,HU Fa-Long,GUO Yao

Acta Agron Sin. 2016, 42(05):  751-757.  doi:10.3724/SP.J.1006.2016.00751

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Research on the response of dry matter accumulation, distribution and yield of crops to previous straw returning usually plays an important role for optimizing cropping systems. In this investigation, a field experiment was carried out in typical oasis irrigation region, to determine the characteristics of dry matter distribution and yield of rotated maize with four previous wheat straw treatments, including 25 cm no tillage with straw standing (NTSS); 25 cm no tillage with straw covering (NTS); 25 cm tillage with straw incorporation (TIS); and conventional tillage (CT). The results showed that, compraed with CT,NTSS, NTS, TIS significantly increased dry matter accumulation by an average of 4.8% to 12.7% after maize heading stage in two years; and improved contribution rate to grain yield (i.e. GCR) of maize by an average of 12.8% to 25.0% from leaf, 6.3% to 11.3% from stem, and 18.3% to 78.4% from sheath, respectively. especially, NTS had more improvement than NTSS, TIS. The grain yield of maize was 11.3% to 17.5% higher in the three straw returning treatments than in CT check. NTS exhibited the most significant effect opf improving yield, reaching 13 470 and 13 274 kg ha^-1 in two study years, which was 5.6% to 9.0% higher than that of TIS due to the increase of kernel number per spike. Meanwhile, NTS had the best effect on increasing harvest index, which was increased by 6.4% to 8.4% during the two study years,and redulted in a high grain yield. Our results showed that NTS treatment is recommended as thebest feasible cultural method to optimize dry matter accumulation, distribution and obtain high yield for rotated maize in the oasis irrigation region.

RESEARCH NOTES

Meta-analysis and Validation of QTL for Resistance to Gray Leaf Spot in Maize

YAN Wei,LI Yuan,SONG Mao-Xing,ZHANG Kuang-Ye,SUN Ming-Ze,QU Hui,LI Feng-Hai,ZHONG Xue-Mei,ZHU Min,DU Wan-Li,Lü Xiang-Ling*

Acta Agron Sin. 2016, 42(05):  758-767.  doi:10.3724/SP.J.1006.2016.00758

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Gray leaf spot (GLS) is one of the most severe leaf diseases of maize worldwide. The breeding progress for resistance to GLS has been seriously hindered by less knowledge about QTL number, QTL intervals and mechanism of GLS. Based on meta-analysis, we conformed 13 consensus QTL regionsfrom 14 articles on resistance to gray leaf spot of maize. One backcross with inbred line 81162 as recurrent parent and inbred line CN165 as donor parent, was used to test the consensus of those 13 QTL regions on the basic of linkage disequilibrium gettingmore than 20 partial separated loci. High level of partial separationindicated that there were QTLs with high effects of resistance to GLS on chromosome 1 and chromosome 4. On chromosome 1, the donor genes closed to markers of umc2227, bnlg1832, umc1243, umc2025, umc1515, umc1297, umc1461 showed the frequency over 50%. Therefore, we inferred that there were a few of highly linked QTLs on chromosome 1. The resistant QTL on chromosome 4 was located between markers bnlg2291 and umc1194. Consequently, this study could lay a foundation for the QTL fine mapping on chromosome 1 and 4 in the donor parent CN165.

Contents of Protein and Amino Acids of Wheat Grain in Different Wheat Production Regions and Their Evaluation

LIUHui,WANG Zhao-Hui*,LI Fu-Cui,LI Ke-Yi,YANG Ning,YANG Yue-E

Acta Agron Sin. 2016, 42(05):  768-777.  doi:10.3724/SP.J.1006.2016.00768

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In order to understand thenutritional status ofamino acidsof China’s wheat varieties, we collected 655 grain samples of wheat growing in 22 provinces from2009 to 2011 and analyzedthe content of total protein and 18 amino acids. The average grain protein contents of spring and winter wheat were13.7% and 12.7%, respectively. In spring wheat, 45%, 22%, and 33% of samplesmet the protein standard for strong, medium, and weak gluten wheat,while the portion was 18%, 24% and 58% in winter wheat, respectively.Spring wheat had higher contents in all amino acidsexceptfor tyrosinethan winter wheat, but their ratios ofessential to total amino acids were both 28.8%.Protein content decreased in the trend of from the north to the south, and from the east to the west.In addition, the single and the total essential amino acid content decreased from the east to the west. Lysine and tryptophan were the limiting amino acids in 98% and 2% of the wheat samples, respectively. The amino acid scorevaried acrossyears, with an average of 53 in spring wheat and 56 in winter wheat.In conclusion,the overall protein content level of wheat grain was lowin the sampling area. Particularly, the lowcontentsand proportions of lysine and essential amino acids are limited factors in wheat protein nutrition.

Effects of Se Application on Se Accumulation and Transformation and Content of Gross Protein and Mineral Elements in Wheat Grain

LIU Qing,TIAN Xia,SHI Yan-Xi*

Acta Agron Sin. 2016, 42(05):  778-783.  doi:10.3724/SP.J.1006.2016.00778

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The objectives of this study were to understand the characteristics of selenium (Se) accumulation and transformation from inorganic to organic form in wheat grain and the effects of exogenous Se on grain yield, quality and Se utilization. In the 2012–2013 and 2013–2014 winter wheat growing seasons, we carried out a field experiment with foliage spray of Se fertilizer (sodium selenite solution) in four Se levels and three spray timing treatments. The results showed that grain yield and thousand-grain weight of wheat received no significantly effect from Se foliage spray. In contrast, the total and organic Se contents in grain increased with increasing the exogenous Se level, with the proportion of organic Se to the total Se from 78.5% to 82.1%. Under the same Se application rate, spraying at early-filling stage resulted in larger Se accumulation in grain than spraying at booting stage. The maximum Se content in grain was 3101 μg kg^-1 in the treatment of Se 150 g ha^–1 sprayed at early-filling stage. The Se utilization rate in wheat ranged from 3.3% to 19.0%, showing a decrease trend with more exogenous Se applied. Se utilization rate was influenced by Se application timing, with the maximum rate at early-filling stage and the minimum rate at booting stage under the same Se application rate. Besides, grain quality of wheat was improved by exogenous Se application. The contents of gross protein and accumulations of P, Fe, Mn, and Zn elements increased and the absorption of Na decreased in grain. Application of Se fertilizer had no significant effect on the accumulations of K, Mg, and Cu elements in wheat grain.