Table of Content

12 October 2013, Volume 39 Issue 10

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Development and Application of Allele-Specific PCR Markers for Imidazolinone-Resistant Gene BnALS1R in Brassica napus

HU Mao-Long,LONG Wei-Hua,GAO Jian-Qin,FU San-Xiong,CHEN Feng,ZHOU Xiao-Yin,PENG Qi,ZHANG Wei,PU Hui-Ming*,QI Cun-Kou,ZHANG Jie-Fu,CHEN Song

Acta Agron Sin. 2013, 39(10):  1711-1719.  doi:10.3724/SP.J.1006.2013.01711

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A BnALS1R gene conferring resistance to the imidazolinone herbicides was previously isolated from an ALS (acetolactate synthase) inhabiting herbicide-resistant mutant line M9 in Brassica napus. A single nucleotide polymorphism leading to an amino acid substitution from serine to asparagine at site 638 of ALS was found between the BnALS1R in the mutant and BnALS1 in the wild type. We reported here the development of polymorphic molecular marker for allele-specific PCR (AS-PCR) assays to distinguish herbicide-susceptible and resistant ALS alleles in either homozygous or heterozygous genotypes. Thirty primers were designed according to the SNP (site 638, Ser was replaced by Asn) and the difference in DNA sequence between the BnALS1 and BnALS3 cloned from M9 and other susceptible cultivars. Three primers of them with polymorphism were obtained, which can differentiate the homozygous resistant M9 from susceptible rapeseed. Meanwhile, these PCR markers can effectively discriminate among three genotypes using polymorphic primers and were evaluated in F₂, BC₁, and BC₂ populations. Observed segregation ratios fitted the expected 1:2:1, 1:1, and 1:1 ratios, respectively, which confirms the single-locus Mendel model. Furthermore, we used the markers for detecting the resistant gene and evaluating the size of DNA segments introgressed from the M9 donor in the resistant restoring lines containing BnALS1R. All the resistant restoring lines had the DNA banding pattern of BnALS1R. Therefore, PCR-based assays using the markers could be used for the detection and characterization of the herbicide-resistant gene BnALS1R in rapeseed. The validated AS-PCR markers will facilitate the breeding of herbicide-resistant rapeseed by using BnALS1R in marker-assisted selection.

Interaction between Wheat Resistance-related Kinase TiDPK1 and BYDV Coat Protein

WANG Xin-Dong,CHEN Liang,ZHANG Zeng-Yan

Acta Agron Sin. 2013, 39(10):  1720-1726.  doi:10.3724/SP.J.1006.2013.01720

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Yellow dwarf virus disease is one of the important diseases of wheat (Tritium aestivum L.) worldwide. It is caused by Barley yellow dwarf virus (BYDV) that is vectored by aphids. A kinase protein encoding gene TiDPK1, which is derived from Thinopyrum intermedium, is an important gene involved in BYDV resistance in wheat-T. intermedium translocation lines. In this study, we used yeast two-hybrid and bimolecular fluorescence complementation assays to explore the relationship between TiDPK1 and coat protein (CP) of BYDV (BYDV-CP). The results proved that the protein TiDPK1 interacted with BYDV-CP, which may offer an insight to the resistance mechanism of TiDPK1.

Sequence Diversity of ZmLEC1 and Association Analysis of Embryogenic calli Formation Ability in Maize

LI Zhao,ZHANG Deng-Feng,SUN Yong-Hua,WU Xun,LI Yong-Xiang,SHI Yun-Su,SONG Yan-Chun,YANG De-Guang,WANG Tian-Yu,LI Yu

Acta Agron Sin. 2013, 39(10):  1727-1738.  doi:10.3724/SP.J.1006.2013.01727

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A maize association mapping population consisted of a mini core collection of ninety-five maize inbred lines and three elite maize accessions (A188, HiII, and Zong 31)usually for genetic transformation was used to analyze the sequence diversity and linkage disequilibrium (LD) of ZmLEC1, a candidate gene of regeneration ability in maize. A candidate gene association strategy was used to reveal the relationship between this gene and embryogenic calli formation ability and discover favorable alleles and genotypes enhancing the embryogenic calli formation ability. The results showed that there existed significant differences in abilities of embryogenic calli formation and regeneration among these accessions. The calli induced from Yue267-1-1 were very similar to those of HiII, the popularly used genotype in maize transformation. Yue267-1-1 had the highest ability of embryogenic calli formation and regeneration and could be a new germplasm for immature embryo-based genetic transformation. The result of sequence polymorphism analysis of ZmLEC1 showed that there were thirty-three SNPs and nine InDels in the coding region of 852 bps. The LD between all of the informative polymorphisms decayed rapidly to about 300 bp at R²=0.1. Totally four polymorphic sites in the ZmLEC1 gene were significantly associated with embryogenetic calli formation ability.

Cloning and Expression Analysis of an Adenylate Kinase Gene GmADK in Soybean

GAI Jiang-Tao,ZHAO Tuan-Jie,LI Yan,GAI Jun-Yi

Acta Agron Sin. 2013, 39(10):  1739-1745.  doi:10.3724/SP.J.1006.2013.01739

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Adenylate kinase (ADK) is an important enzyme in cellular energy homeostasis, which catalyzes the interconversion of adenine nucleotides, ATP+AMP⇔2ADP, and is involved in many processes including plant growth, development and response to abiotic stresses. To date, there has no report on cloning and expression analysis of soybean ADK gene yet. In this study, a soybean ADK gene was cloned from the leaves of a salt tolerant cultivar NN1138-2 using RT-PCR, and was designated as GmADK. The coding sequence (CDS) of this cloned ADK gene is 804 bp in length, encoding a polypeptide of 267 amino acids. Its protein was predicted to be located in plastids, containing a typical ATP-AMP (Ap5A) binding site and an AMP binding site. Multiple sequence alignments and phytogenetic analysis of ADK proteins showed GmADK is most similar with ADK from Phaseolus vulgarisand Medicago truncatula. Tissue expression pattern of GmADK showed its mRNA was more abundant in soybean roots and leaves than in stems. Quantitative RT-PCR showed a differential expression pattern of GmADK in response to salt between salt tolerant (NN1138-2) and sensitive (Kefeng-1) soybean genotypes. Compared with untreated plants, the expression of GmADK in both leaves and roots was repressed after 6, 12, and 24 hours of 200 mmol L^–1 NaCl treatment in the salt sensitive cultivar, but induced in the salt tolerant cultivar, indicating that GmADK might be involved in soybean response to salt stress.

Genetic Dissection of Elite Line Zhongpin 03-5373 Pedigree and Identification of Candidate Markers Related to Resistance to Soybean Cyst Nematode

ZHANG Shan-Shan,LI Ying-Hui,LI Jin-Ying,QIU Li-Juan

Acta Agron Sin. 2013, 39(10):  1746-1753.  doi:10.3724/SP.J.1006.2013.01746

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Zhongpin 03-5373 with resistance to SCN3 is an elite soybean line, which is traced back to 10 parental lines. Three elite resistant sources (Huipizhiheidou, Peking and PI437654), diversely used in the soybean cyst nematode resistant breeding, were included in the pedigree of Zhongpin 03-5373. In this study, 152 molecular markers were selected to detect polymorphism among the 11 materials. A total of 437 alleles were identified with average of 2.9, ranging from two to five alleles on each locus. The average of Nei’s genetic identity among pairwise cultivars were 0.458, the haplotypes formed by four SSR markers (Satt152, Satt179, Barcsoyssr_18_107, and Satt196) could distinguish 11 cultivars in this study. Pedigree tracing elucidated genomic variation in breeding. IBD analysis showed that Huipizhiheidou contributed the most of specific alleles (39) to Zhongpin 03-5373 among three resistant genetic resources (Huipizhiheidou, Peking, and PI437654), followed by PI437654 (6). In addition, 20 markers identified were related to the resistance to SCN 3. These results supplied the information for further cloning resistant gene and resistant breeding by marker assistant selection.

Mapping of QTL for Ferrous and Zinc Toxicity Tolerance at Seedling Stage Using a Set of Reciprocal Introgression Lines in Rice

ZHANG Jian,Aijaz Ahmed SOOMRO,CHAI Lu,CUI Yan-Ru,WANG Xiao-Qian,ZHENG Tian-Qing,XU Jian-Long,LI Zhi-Kang

Acta Agron Sin. 2013, 39(10):  1754-1765.  doi:10.3724/SP.J.1006.2013.01754

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Ferrum and zinc are essential microelements for rice, and also the heavy metal pollution elements in soil. Rice grow in lowland or acid soil is easily subjected to ferrous and zinc toxicities which harm plant growth and decrease biomass and yield in production. The aim of this study was to identify quantitative trait locus (QTL) underlying ferrous toxicity tolerance (FTT) and zinc toxicity tolerance(ZTT) of rice using a reciprocal advanced backcross introgression lines derived from a cross between Lemont (japonica) and Teqing (indica), and 308 evenly distributed single nucleotide polymorphism (SNP) markers developed from the two parents. Total of 42 putative QTLs affecting shoot height (SH), shoot dry weight (SDW) and root dry weight (RDW) under control and stress conditions and for the relative value of the stress to the control were detected, the alleles at most loci improving the tolerance of ferrous and zinc toxicities were from Lemont. Among them only four QTLs (9.52%) were detected under the two backgrounds, indicating the expression of most QTLs is specific to genetic background.Nine QTLs were detected from the same genetic background affecting the tolerance of both ferrous and zinc toxicities in which QSdw5 was expressed under the two backgrounds with the same direction and similar quantity of gene additive effect,suggesting that there is a genetic overlap between FTT and ZTT at seedling stage in rice. It is likely, therefore, to develop varieties with both FTT and ZTT in rice by introgressing and pyramiding Lemont favorable alleles of the overlapping QTLs underlying FTT and ZTT and to improve Teqing’s FTT and ZTT via marker-assisted selection (MAS).

Gibberellin Responsiveness and Gene Mapping of the Rice Extreme Dwarf Mutant s2-47

LI Chen-Chen,HOU Lei,YIN Liang,ZHAO Jin-Feng,YUAN Shou-Jiang,ZHANG Wen-Hui,LI Xue-Yong

Acta Agron Sin. 2013, 39(10):  1766-1774.  doi:10.3724/SP.J.1006.2013.01766

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We have isolated a dwarf mutant s2-47 from Nipponbare mutagenized by EMS, which is an extreme dwarf with dark green leaves and without reproductive development. GA₃ treatment of seedlings and α-amylase activity analysis in endosperm showed that the mutated gene is involved in GA biosynthesis. Fine mapping showed that the mutant phenotype was tightly linked with the OsCPS1 locus, which encodes the ent-copalyl diphosphate synthase, the first key enzyme in GA biosynthesis. Sequence analysis showed that there is a single nucleotide deletion in the 6th exon of the OsCPS1 gene in the s2-47 mutant. OsCPS1 was expressed in all the above-ground parts of plants with the highest expression in nodes. The OsCPS1 expression was down-regulated by GA₃ treatment but up-regulated in the s2-47 mutant.

Cloning of NPR1-like Genes and their Response to Fusarium graminearum Infection in Wheat

YANG Zai-Dong,MA Xin,WU Shi-Wen,WANG Hong-Wei,SU Xin,JI Xian-Ling,LI An-Fei,KONG Ling-Rang

Acta Agron Sin. 2013, 39(10):  1775-1782.  doi:10.3724/SP.J.1006.2013.01775

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NPR1 gene plays a key role for systemic acquired resistance (SAR) and provides broad-spectrum resistance in Arabidopsis. Fusarium head blight (FHB), which is caused by Fusarium graminearum Schwabe, is a devastating disease of wheat worldwide. Based on the analysis of the gene expression profiling, we clonedthree NPR1-likegenes from wheat FHB near-isogenic lines induced by F. graminearum using RT-PCR protocol, and they were designated as TaNPR1, TaNPR2,and TaNPR3. The open reading frames of the three genes encoded 580, 607, and 601 amino acid residues, respectively. The three wheat NPR1-like proteins had conversed BTB/POZ, ANK, and NPR1_like_C domain as well as conversed amino acid residues with important functions. However, only TaNPR1 had two conversed cysteine residues that are essential for the NPR1 oligomer formation. Phylogenetic analysis showed that TaNPR1 was involved in the NPR1 protein group, while TaNPR2 and TaNPR3 were close to NPR1 homologues. Quantitative RT-PCR assay revealed that the three NPR1-like genes could be induced by defense related signal molecules, such as salicylic acid and methyl jasmonate. TaNPR1 and TaNPR3 were induced earlier and up-regulated more significantly in response to F. graminearum infection in the resistant line Apogee73S2 than in the susceptible line Apogee. However, the transcription of TaNPR2 was not obviously changed in either the resistant or susceptible near-isogenic lines after inoculation with F. graminearum. These results suggest that TaNPR1 and TaNPR3 may be involved in the defense response to F. graminearum.

Identification and Evaluation for Resistance to Sclerotinia Stem Rot in 44 Soybean Mini Core Collections

HAN Fen-Xia,HAN Guang-Zhen,SUN Jun-Ming,ZHANG Jin-Wei,YU Shao-Xuan,YAN Shu-Rong,YANG Hua

Acta Agron Sin. 2013, 39(10):  1783-1790.  doi:10.3724/SP.J.1006.2013.01783

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Sclerotinia stem rot, also called white mould, is a fungal pathogen disease worldwide in soybean caused by Sclerotinia sclerotiorum (Lib.) de Bary. A total of 44 soybean cultivars were inoculated with four isolates of S. Sclerotiorum from different geographical regions and host plants in the two consecutive years experiment in the field to screen excellent germplasm for its resistance breeding. The results were as follows: (1) Different soybean cultivars had different resistance level to S. sclerotiorum. Among them, six cultivar (13.64%) were moderate resistant; twenty-seven (61.36%) were moderate susceptible; nine (20.45%) were susceptible; two (4.55%) were highly susceptible, showing that soybean cultivars with resistance to S. sclerotiorum are rare. Six soybean cultivars with moderate resistance, i.e. Hefeng 24, Big Swan egg, Nidinghuamei soybean, Niumaohuang, Big soybean and May soybean, could be used for soybean breeding for S. sclerotiorum resistance. (2) The pathogenicity of S. sclerotiorum isolates from different geographical regions and host plants is different. Isolate Heixi 5 from the soybean field of Heilongjiang had the strongest pathogenicity with 49.32 in DSI and 5.93 mm in lesion length. Isolate Heirao 24 from the soybean field of Heilongjiang and isolate Qin 24 from the oilseed rape field of Qinghai province had the moderate pathogenicity. Isolate Hef 50 from the oilseed rape field of Anhui province was the weakest in infection, with 39.02 in DSI and 3.65 mm in the lesion length. In conclusion, isolate Heixi 5 is the best one for effectively screening for the resistance to S. sclerotiorum in soybean breeding.

Genetic and Correlation Analysis on Pod Shattering Traits in Brassica napus L.

CUI Jia-Cheng,LIU Jia,MEI De-Sheng,LI Yun-Chang,FU Li,PENG Peng-Fei,WANG Jun,HU Qiong

Acta Agron Sin. 2013, 39(10):  1791-1798.  doi:10.3724/SP.J.1006.2013.01791

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Pod shattering resistance is a very important trait of oilseed rape, and the genetic research has been extremely weak. In this study, pod shattering resistance index (SRI) and other seven pod traits were analyzed based on data collected from a 6×5 incomplete diallel design at two environments. The results demonstrated that obvious genetic variation existed among elite breeding lines and their crosses for pod SRI. Pod shattering resistance was likely controlled by few genes with mainly additive effects, and dominant effects were much less important, whereas the environments played only minor role for pod SRI. There was no significant heterosis in most of the crosses. Pod SRI was detected to be significantly positively correlated with pod length, pod wall weight, 1000-seed weight and seed diameter, but negatively correlated with pod density and number of seeds per pod. The genetic variations of pod length, 1000-seed weight, pod density and seed diameter were mainly explained by additive effects, whereas those of pod wall weight and number of seeds per pod were mainly affected by dominant effects. Among the 11 elite breeding lines, ZS11B and R11 were recommended for using as direct parental lines for making pod shattering resistant cross varieties as maintainer and restorer of lines for Polima cytoplasmic male sterility system, respectively, due to their higher general combining ability on pod SRI and other yield component traits.

Genetic and Expression Analyses of Ef7-l, a Novel Ef7 Allele, in Rice

ZHAO Dong-Sheng,ZHANG Chang-Quan,GU Ming-Hong,LIU Qiao-Quan

Acta Agron Sin. 2013, 39(10):  1799-1805.  doi:10.3724/SP.J.1006.2013.01799

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Ef7 controls rice heading date. In present study, the allele of Ef7, Ef7-l, was cloned from an indica rice cultivar Longtefu. Sequence analysis indicated that Ef7-l is a novel Ef7 allele and there are five amino acid substitutions in Ef7-l compared with its wild type from Nipponbare. Based on the sequence variation between Ef7-l and Ef7,we developed a near-isogenic line (NIL) CL63 with the background of japonica Nipponbare via marker-assisted selection. The heading date of the NIL CL63 was postponed forapproximate six days under long day (LD) condition compared with Nipponbare. In short day (SD) condition, there was no obvious difference in heading date between Nipponbare and CL63. Under the natural field at Yangzhou, the novel allele Ef7-l could result in significant increase of plant height and grain weight in CL63 compared with Nipponbare. The qRT-PCR analysis revealed that there was not significant difference in Ef7 gene expression level between Nipponbare and CL63 under both LD and SD conditions. But the Ef7-l allele could affect rice heading date by up-regulating the expression level of OsPHYB gene under LD condition.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effect of Indica-Japonica Hybridization on Grain Quality of Rice Cultivars in Northeast China

GAO Hong,LI Fei-Fei,Lü Guo-Yi,XIA Ying-Jun,WANG Jia-Yu,SUN Jian,TANG Liang,XU Zheng-Jin

Acta Agron Sin. 2013, 39(10):  1806-1813.  doi:10.3724/SP.J.1006.2013.01806

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Most cultivated varieties were bred from indica–japonica hybridization in Northeast China. In this study, we collected major japonica rice varieties widely cultivated in Northeast China and Japanese varietiesas research materials, using subspecies-specific InDel and SSILP markers determined the proportion of indica pedigree in japonica cultivars, compared the morphological differentiation with the Cheng’s index, and measured 10 rice quality traits to study the relationship of indica pedigree, morphological differentiation and grain quality with correlation analysis. The results indicated that the indica-type allele frequency of Northeast japonica cultivars was 4.71% and extremely higher than that of Japanese varieties (0.30%); Indica-type loci frequency of Northeast japonica cultivars among 12 rice chromosomes was greatly different, that of chromosomes 5, 6, 10, and 11 was more than 5%, indica-type loci frequency of chromosome 5 was the most (9.83%), while chromosomes 7 was the least (0.59%). Indica-type allele frequency of rice cultivars in Northeast China showed an order of Liaoning (6.17%) > Jilin (3.92%) > Heilongjiang (3.44%), with significant different between Liaoning and Jilin, Heilongjiang, and no great difference between Jilin and Heilongjiang. The subspecies type of the Northeast cultivated varieties and Japanese varieties was japonicalinous and typical japonica respectively identilgied by Cheng’s index, and vascular bundle characters also greatly differred too. Rice milling quality of Japan preceded than that of Northeast China. Cheng’s index had very significantly positive correlations with rice milling quality. Indica-genotype frequencies had very significantly or significantly negative correlations with milling quality and taste score. The chalky grain rate was very significantly and positively correlated with indica-genotype frequencies. The main reason of lower chalkiness traits of japonica in Northeast China than in Japan was that the chalky grain rate and chalkiness were very low in Heilongjang.

Effects of Planting Methods on Culm Lodging Resistance of Indica Hybrid Rice (Oryza sativa L.)

LEI Xiao-Long,LIU Li,GOU Wen,MA Rong-Chao,REN Wan-Jun

Acta Agron Sin. 2013, 39(10):  1814-1825.  doi:10.3724/SP.J.1006.2013.01814

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In order to investigate the effects of mechanized seeding and transplanting on lodging resistance of indica hybrid rice, a split plot field experiment was conducted by using Fyou 498 as material. The effects of planting methods with mechanized seeding, mechanized transplanting and artificial transplanting and different number of seedling per hill on the physical and mechanical characteristics and lodging resistance of indica hybrid rice were studied in the thirty days after full heading. Furthermore, the correlation between lodging resistance and main physical and mechanical characteristics was calculated. The main results were as follows: (1) The lodging index of rice plants was different significantly among three planting methods, with the lowest in artificial transplanting and the highest in mechanized transplanting, which was mainly attributed to the difference in breaking moment of basal internodes. The breaking moment of the first to the fourth internodes was positively and significantly correlated with culm type index, internode diameter and thickness, ratio of weight to length of culm, dry weight of internode, section modulus, bending stress, respectively, while negatively and significantly correlated with internode length. The bending moment was larger in lower internodes than in higher internodes, with relatively small changes in basal internodes. That’s why the first and second internodes were lodging-susceptible. (2) In artificial transplanting basal internodes was short, internode diameter, thickness and culm type index were large, plumpness status of culm and sheath was good, and bending stress and breaking moment of internode were high, so the artificial transplanting had good lodging resistance. The population structure of mechanized transplanting was so large that individual plant growth was limited, and its lodging index was the largest in three planting methods. We suggest that in order to get a coordination of high-yielding and high lodging resistance a suitable population should be conducted with 3–4 seedlings per hill for mechanized seeding and transplanting and two seedlings per hill for artificial transplanting.

Effects of Low-light Stress on Kernel Setting, and Carbon and Nitrogen Metabolism of Different Maize (Zea mays L.) Genotypes

ZHOU Wei-Xia,DONG Peng-Fei,WANG Xiu-Ping,LI CHAO-Hai

Acta Agron Sin. 2013, 39(10):  1826-1834.  doi:10.3724/SP.J.1006.2013.01826

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Light is one of the important factors influencing kernel growth and development of maize (Zea mays L.). A split plot experiment was conducted under field conditions to study the effects of low-light stress and light recovery on kernel setting, and carbon and nitrogen metabolism of different maize genotypes in 2011 and 2012. Light treatments (natural light and 50% shading from three days before tasselling to ten days after silking) were the main plots and cultivars [low light sensitive hybrid (Yuyu 22) and low light tolerance hybrid (Zhengdan 958)] were sub-plots. The results showed that low-light stress delayed the growth and development of kernels, raised the number of abortive kernel, reduced kernel volume and dry weight. Contents of soluble sugar, sucrose and starch of apical kernel were increased while the content of nitrogen and C/N ratio decreased. Starch grain density in kernel endosperm cells of YY22 reduced while that of ZD958 almost remained the same. Differences between treatments of YY22 were greater than those of ZD958, the reduction of kernel growth and development was greater in the apical than in the middle of ear. ZD958 showed stronger compensatory effect after light recovery, differences between light treatments and the control in kernel volume, dry weight, kernel carbon and nitrogen contents and C/N ratio of ZD958 were lower than that of YY22. The declines of the starch synthesis and C/N ratio are the primary causes leading to kernel abortion.

Mechanisms of Tiller Occurrence Affected by Exogenous IAA, GA₃, and ABA in Wheat with Different Spike-types

CAI Tie,XU Hai-Cheng,YIN Yan-Ping,YANG Wei-Bing,PENG Dian-Liang,NI Ying-Li,XU Cai-Long,YANG Dong-Qing,WANG Zhen-Lin

Acta Agron Sin. 2013, 39(10):  1835-1842.  doi:10.3724/SP.J.1006.2013.01835

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Two winter wheat cultivars, Shannong 15 and Shannong 8355, were used to study the effects of exogenous indole-3-acetic acid (IAA), gibberellic acid 3 (GA₃), and abscisic acid (ABA) on tiller occurrence in wheat and the underlying mechanism. Exogenous IAA and GA₃ inhibited occurrence of wheat tiller, while exogenous ABA reduced the rate of tiller occurrence. Furthermore, exogenous IAA and GA₃ completely inhibited growth of tiller bud, while exogenous ABA significantly slowed the growth rate of tiller bud. The growth of tiller bud was positively correlated with content ofzeatin (ZT), but negatively correlated with IAA content and ratios of IAA/ZT and ABA/ZT. In contrast, the growth of tiller bud had slightly negative correlations with GA₃ and ABA contents. These results suggest that IAA and ZT play a key role in regulating tiller occurrence in wheat, and exogenous hormones regulate the growth of tiller bud through changing contents of IAA and ZT and the ratios of IAA/ZT and ABA/ZT in tiller node.

Systemic Feedback Regulation of K⁺ Uptake in Cotton at Seedling Stage

WANG Ye,TIAN Xiao-Li

Acta Agron Sin. 2013, 39(10):  1843-1848.  doi:10.3724/SP.J.1006.2013.01843

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This hydroponic split-root experiment was conducted to elucidate the long-distance systemic regulation of K⁺ uptake in cotton (Gossypium hirsutum L.) seedlings with two cotton cultivars CCRI41 and Liaomian17 as materials. Inverted Y grafting (one scion/two rootstocks, hypocotyl-to-hypocotyl) was used to establish split-root plants. The K⁺-uptake characteristics of cotton seedlings were measured by depletion method and described by kinetic parameters, I_max (the maximum rate of uptake), K_m (the external concentration at which the uptake rate is 0.5 I_max) and C_min (the external concentration at which no net flux occurs). In relative to the sufficient K⁺ control (both root halves supplied with 2.50 mmol L^–1 K⁺), the root half supplied with 2.50 mmol L^–1 K⁺ for six days showed 79% to 92% more I_max owing to the induction of K⁺-demand signal derived from the root half starved with K⁺. Compared with the K⁺ starvation control (both root halves supplied with 0.01 mmol L^–1 K⁺), I_max of root half supplied with 0.01 mmol L^–1 K⁺ for six days decreased by 27% to 40% due to the suppression of K⁺-supply signal initiated by the root half grown in sufficient K⁺. When the root half starved with K⁺ in CCRI41 was removed after three days of split-root treatment, the remained root half incessantly supplied with 2.50 mmol L^–1 K⁺ for six days had less I_maxrelative to the whole split-root plants, which is likely attributed to the loss of K⁺-demand signal from the other root half during last three days. This systemic feedback regulation of K⁺ uptake in cotton seedlings was independent of K⁺ content of either root or shoot.

Interaction of Genotypes with Environments for Three Quality Traits of Rice in Cold Region by AMMI Model

LIU Li-Hua,HU Yuan-Fu,CHEN Qiao,LI Hong-Yu,QIAN Yong-De,Lü Yan-Dong,ZHENG Gui-Ping,ZUO Yu-Hu

Acta Agron Sin. 2013, 39(10):  1849-1855.  doi:10.3724/SP.J.1006.2013.01849

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In order to provide a scientific basis for varietal approval and application of rice in cold region, the genetic stability and adaptability of six rice cultivars from Heilongjiang Reclamation region planted in six different ecological sites in Heilongjiang Province were evaluated for nutritional and eating quality traits (protein, free fatty acid and amylose contents) based on AMMI (additive main effects and multiplicative interactions) model. The results showed that differences in nutritional and eating quality traits among genotypes, environments and among genotype × environment interactions were all significant at 1% probability level. The protein content, free fatty acids content and amylose content were also significantly different in IPCA value. Environmental factors affecting stability of nutritional and eating quality traits were daily mean air temperature and daily mean air pressure from heading to maturity stages. The environment with high temperature, enough illumination and little rain at rice heading stage was advantageous to produce good quality of rice in cold region. The order of stability of nutritional and eating quality traits for the six cultivars was: Jian 07-1023>Kongyu 131>Longjing 20>Raoxuan 06-06>Beijing 9005=Kendao 08-924. The order for identifying rice quality of six test farms was: Chahayang Form >Wutonghe Form >853 Form =Junchuan Form >850 Form >290 Form.

Effects of Antisense Thioredoxin s on Starch Accumulation and Expressions of Enzymes Related to Starch Synthesis in Weak-gluten Wheat Cultivar Yumai 18

REN Jiang-Ping,WANG Ya-Ying,WANG Xin-Guo,WANG Na,CHEN Xin,MENG Xiao-Dan,LI Yong-Chun,YIN Jun

Acta Agron Sin. 2013, 39(10):  1856-1863.  doi:10.3724/SP.J.1006.2013.01856

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To clarify the functional mechanisms of starch accumulation by the antisense-thioredoxin s (anti-Trxs) gene into wheat, we conducted a pot experiment using two transgenic wheat lines, TY18-99 and TY18-100, and their wild type “Yumai 18” from October 2007 to June 2009. The effects of the anti-Trxs on starch accumulation and key enzymes involved in starch synthesis were compared between the transgenic lines and the wild type. Results indicated that the rates of starch and amylopectin accumulations in grain were significantly higher in the transgenic lines than in the wild type. During the whole grain-filling period, activity of starch-branching enzyme (SBE) in the transgenic lines increased significantly by 49.2% compared with that in the wild type. At late grain-filling stage, activities of ADP-glucose pyrophosphorylase (AGPase) and soluble starch synthase (SSS) in the transgenic lines increased by 45.8% and 16.0%, respectively. However, activity of granule-bound starch synthase (GBSS) in the transgenic lines had no significant variation. The real time RT-PCR assay indicated that the introduction of anti-Trxs resulted in increased expressions of SSS (SSS I, SSS II, and SSS III), SBE I, and AGPase genes and reduction of GBSS I transcription. Therefore, the enhanced expressions of AGPase, SBE I, and SSS may be the main reason for the increase in starch synthesis in anti-Trxs transgenic lines.

Effects of Different Drip Irrigation Systems on Yield and Water Use Efficiency of Potato in Intercropping System of Cotton and Potato

WANG Li-Xia,CHEN Yuan-Quan,LI Chao,SHI Jiang-Tao,TAO Zhi-Qiang,NIE Zi-Jin,ZHANG Jian-Sheng,SUI Peng

Acta Agron Sin. 2013, 39(10):  1864-1870.  doi:10.3724/SP.J.1006.2013.01864

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In order to explore the efficient water-saving irrigation system for the intercropping mode of cotton and potato, the research on potato with drip irrigation in intercropping system was conducted in 2011 and 2012, and the influences of different drip irrigation norms (75 mm /90 mm / 105 mm / 120 mm) on the potato yield and water use efficiency were analyzed.The results showed that the potato yield was proportional to the drip irrigation norm and significantly correlated with the precipitation and irrigation quota at tuber initiation stage and tuber growth stage, with the correlation coefficient of 0.960 and 0.998 respectively in 2011 and 2012. The potato yield didn't show significant differences between different treatments in 2011. The treatment with 120 mm irrigation exhibited the highest yield of 24 921.2 kg ha^–1 in 2012. It was 15.2% higher than that of the treatment irrigated 75 mm, with significant difference between them. The water consumption increased with the irrigation quota increasing, showing significant differences among different treatments. But the water use efficiency showed no significant differences. The research preliminarily indicated that increasing drip irrigation norm in potato and adjusting the irrigation structure rationally are beneficial to improving yield and water use efficiency.

Effects of Shading at Different Growth Stages on Different Traits and Yield of Soybean

WANG Yi,YANG Wen-Yu,ZHANG Xia,YONG Tai-Wen,LIU Wei-Guo,SHU Ben-Ying

Acta Agron Sin. 2013, 39(10):  1871-1879.  doi:10.3724/SP.J.1006.2013.01871

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Intercropping and relay-intercropping are important technologies to improve land utilization rate and crop yield, but their yields are limited by shading, which is different for intercropped soybean and relay-intercropped soybean at different growth stages. To clear the effect of shading at different growth stages on morphology and yield of soybean, we treated Guixia 2, Nandou 12, Nandongkang 22, E61, and C103 with the 50% transmittance shading net using the natural light as control. The results showed that effects of shading on different morphological characters were different at different growth stages, showing a significant influence on length of main stem and main stem length/stem diameter during the early growth period (VER1 and VER2). Compared with control, the main stem length and main stem length/stem diameter were increased by 45.75% and 93.64% respectively. Shading had significant influence on the number of branches and the height of lowest pod at the late growth stage (R1R8 and R2R8). Compared with control, the number of branches was decreased by 29.97% and the height of lowest pod was increased by 28.59%. The effects of shading on yield of cultivars with different growth periods were different, the cultivars with R/V below 1.4 was affected significantly by the early growth period shading, the cultivars with R/V equal to or greater than 1.5 was easily affected by the late growth stage shading. Results of correlation analysis and path analysis showed main stem length, first internode length, branch height, stem length/stem diameter and stem length/branch number were negatively correlated with yield per plant significantly, branch number was positively and significantly correlated with yield per plant, main stem length/stem diameter and main stem length/branch numbercould be key indexes for yield per plant.

Influences of Conservation Tillage Practices on Farmland Soil Ecological Factors and Productive Benefits in Dryland Region with Triple Cropping System in Southwest China

WANG Long-Chang,ZOU Cong-Ming,ZHANG Yun-Lan,ZHANG Sai,ZHANG Xiao-Yu,ZHOU Hang-Fei,LUO Hai-Xiu

Acta Agron Sin. 2013, 39(10):  1880-1890.  doi:10.3724/SP.J.1006.2013.01880

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Aimed at the problems such as shallow soil profile, severe soil and water erosion, and frequent seasonal droughts that were faced by the dryland agriculture in southwest China, a field experiment was conducted for 2 years to evaluate the influence of different conservation tillage measures on the soil ecological factors, yield and water use efficiency of crops in triple cropping system in dryland. There were 6 treatment including traditional farming (T), ridge planting (R), straw mulching (TS), ridge planting + straw mulching (RS), straw mulching + decomposing agent (TSD) and ridge planting + straw mulching + decomposing agent (RSD). The results showed that the condition of soil organic matter and nutrients was improved effectively under the conservation tillage measures, in which the contents of soil organic matter, total N, total K and alkali-hydrolyzable N were significantly increased under the 4 treatments with straw mulching, and the pH of acidic soil was raised to some extent. The soil moisture condition was improved, and the drought-resistant and water-saving ability of crops was strengthened under the conservation tillage measures. As for the 2-year mean water storage in 0-80 cm soil layer, the treatments could be ordered as: RSD (258.82 mm) > TSD (252.40 mm) > RS (250.19 mm) > TS (246.66 mm) > R (239.19 mm) > T (235.87 mm). The surface soil temperature in July was lowered under the conservation tillage measures, in which the temperature in 5 cm and 10 cm depth was significantly reduced under the 4 treatments with straw mulching, thus easing the injury of high temperature on maize during late growth stage. The growth of weeds was inhibited effectively under the conservation tillage measures, and the average height, density and biomass of weeds under TS, RS, TSD and RSD was extremely significantly lower than those under T and R. The reproduction and growth of earthworms were also accelerated under the conservation tillage measures, thus the farmland eco-environment was obviously improved. In general, straw mulching was effective in improving the soil fertility, increasing soil water storage, adjusting soil temperature, controlling weeds and stimulating earthworm growth, while ridge planting and decomposing agent were effective in increasing soil water storage. Consequently, the conservation tillage measures significantly raised the yield and water use efficiency of crops, and increased the economic benefits. From the viewpoint of 2-year mean yield and water use efficiency, the treatments were ordered as: RSD>RS>TSD>TS>R>T(CK); while from the viewpoint of output value and net income, the treatments were ordered as: RS>RSD>TSD>R>TS>T(CK). Among all the treatments, RSD and RS were the two optimal patterns with high comprehensive effects and deserved to be widely promoted in the dryland region with triple cropping in southwest China.

RESEARCH NOTES

Phosphorus Uptake and Utilization of Maize and Interspecies Interactions in Maize/Soybean and Maize/Sweet Potato Relay Intercropping Systems

DENG Xiao-Yan,WANG Xiao-Chun,YANG Wen-Yu,SONG Chun,WEN Xi-Chen,ZHANG Qun,MAO Shu-Ming

Acta Agron Sin. 2013, 39(10):  1891-1898.  doi:10.3724/SP.J.1006.2013.01891

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A field experiment with different phosphorus (P) application amount including 0, 35, 70, 105, 140 kg P₂O₅ ha^-1 and a root barrier pot experiment with no barrier and plastic barrier were conducted to study the effects of P nutrition on P accumulation and use efficiency of maize in maize/soybean and maize/sweet potato relay intercropping systems along with their inter-specific promotion and mechanism. A pot experiment with and without barrier was conducted to find the inter-specific interactions, when root was separated by plastic barrier, there were not any inter-specific interactions but only P fertilizer effects, when root was not separated, there existed inter-specific interactions and P fertilizer effects at the same time. Results showed that, whether applicating P fertilizer or not, P accumulation of soybean and sweet potato was restrained in no-barrier treatment, but alleviating P application increasing (Acs>0, NCRcs>1). Inter-specific interactions promoted P accumulation by 17.05% and 5.62%, and yield by 16.84% and 7.17% respectively, when P application amount was 70 kg ha^-1; the promoting effects were more obvious with P application. Inter-specific interactions promoted P use efficiency by 7.81%, and P utilization efficiency was higher in maize/soybean than in maize/sweet potato. P accumulation of stems, leaves and grains and maize yield increased with increasing P fertilizer when P application was less than 105 kg P₂O₅ ha^-1, it was opposite while P application was more than 105 kg P₂O₅ ha^-1. P accumulation and yield were significantly higher in maize/soybean intercropping system than in maize/sweet potato intercropping. Intercropping systems-phosphorus application interaction was extremely significant. The results were similar in both field experiment and pot experiment. Therefore increasing the application of P fertilizer and using intercropping are both helpful to improve P accumulation and yield. Compared with maize/sweet potato, maize/soybean is better for promoting P use efficiency.

Relationship between Root Morphological Characteristics and Yield Components of Major Commercial Indica Rice in South China

CHEN Da-Gang,ZHOU Xin-Qiao,LI Li-Jun,LIU Chuan-Guang,ZHANG Xu,CHEN You-Ding

Acta Agron Sin. 2013, 39(10):  1899-1908.  doi:10.3724/SP.J.1006.2013.01899

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Seven inbred and hybrid indica rice cultivars widely planted in recent years in South China were used in pot experiment in 2010–2011, and the root traits including root number, root length, root volume and root dry weight per plant, stem and single adventitious root were investigated at active tillering, heading and maturity stages, meanwhile, characteristics of root branching at heading stage was investigated by WinRhizo system. Furthermore, the correlation between root traits and yield was analyzed. Results were as follows: (1) The number of adventitious roots per plant (NARP), total length of adventitious roots per plant (TLRP), total length of adventitious roots per stem (TLRS) and length per adventitious root (LPAR) of the hybrid rice were significantly larger than those of the inbred rice at each stage. Volume of roots per plant (VRPP), volume of roots per stem (VRPS), dry weight of roots per plant (DWRP) and dry weight of roots per stem (DWRS) showed no significant difference between hybrid rice and inbred rice. However, the root quality such as volume per adventitious root (VPAR), dry weight per adventitious root (DWAR) and dry weight per unit length of root (DWPL) of inbred rice was better than that of hybrid rice. (2) The total surface area and volume of branched roots at heading stage were adventitious root > coarse branched root > fine branched root with significant difference. Total root length of hybrid rice was coarse branched roots > adventitious roots > fine branched roots, and that of inbred rice was adventitious roots > coarse branched roots > fine branched roots. Moreover, the total length of branched roots, total length, surface area, volume of coarse branched roots and fine branched roots of hybrid rice were very significantly higher than those of inbred rice. But the average root diameter of inbred rice was very significantly higher than that of hybrid rice. (3) The difference of root characteristics between hybrid rice and inbred rice was mainly come from number of adventitious roots per plant and root length, which was caused by the difference of tiller number and single root length between hybrid rice and inbred rice. (4) Twelve root traits showed a significantly positive correlation with yield per plant. Number of adventitious roots per plant (NARP) and total surface area of branched roots (SABR) were major factor influencing the yield. The results above provide some informations for genetic improvement of rice roots and super rice breeding and cultivation.

Effect of Water Management and Phosphorus on Agricultural Characters and As Concentration in Polished Rice of Two Rice Cultivars Differing in P-Efficiency under As-stress Conditions

ZHANG Xiu,GUO Zai-Hua*,DU Shuang-Shuang,WANG Yang,SHI Le-Yi,ZHANG Li-Mei,HE Li-Yuan

Acta Agron Sin. 2013, 39(10):  1909-1915.  doi:10.3724/SP.J.1006.2013.01909

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To explore the agronomic measures for mitigating As toxicity to rice, we conducted soil culture experiments to investigate the effect of three potential practical methods, water management regime, phosphorus (P) fertilization and their interaction on plant growth, grain yield and As concentration in polished rice in P-efficient rice cultivar 99011 and P-inefficient rice cultivar 99012 in various As-stress acid soils. Results indicated that compared with flooded conditions and / or insufficient P application, water-saving irrigation (maintaining the soil moisture from 65% of the maximum field water capacity to flooded conditions) and / or sufficient P application significantly increased the number of tillers, total spike, productive spike, root dry weight, biomass and grain yield of two rice cultivars regardless of As levels. Both rice cultivars had the best agricultural characteristics under water-saving irrigationcondition with sufficient P fertilization. So water management, P fertilization and their interaction all showed positive effect. At 50 mg kg^-1 of As level, water-saving flooded treatment, but sufficient P application increased the As concentration in polished rice significantly compared with insufficient P supply. Thus the effect of interaction of water management and P fertilization was worse than the independent effect of water management, but better than the independent effect of P fertilization. At 100 mg kg^-1 of As level, water-saving flooded conditions and/or insufficient P application, and their interaction effect was better than the independent effect of two factors. At the same treatment with As supply, all the investigated agricultural characteristics of low-P tolerant rice cultivar 99011 were better than those of low-P sensitive rice cultivar 99012, but the As concentration in polished rice was on the contrary. The study demonstrated that water management regime, P fertilization, and selection of P-efficient rice cultivars are effective measures that can be used to relieve the As stress to rice growth and the As accumulation in polished rice.management and/or sufficient P supply reduced the As concentration in polished rice clearly compared with management decreased the As concentration in polished rice markedly compared with