Table of Content

12 April 2014, Volume 40 Issue 04

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Transcriptional and Translational Characterization of Rice Chitinase Genes

FAN Wei,LI Xue-Jiao,GUAN Ming-Li,MIAO Liu-Yang,SHI Jia-Nan,DOU Shi-Juan,LIU Li-Juan,LI Li-Yun,LIU Guo-Zhen

Acta Agron Sin. 2014, 40(04):  571-580.  doi:10.3724/SP.J.1006.2014.00571

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Plant chitinases play roles in plant development and stress responses. Nineteen chitinase genes, belonging to pathogenesis related (PR) 3 family, were found in rice genome. In this study, constitutive and tissue-specific transcripted chitinase genes were identified, and the domain architecture of chitinase protein was predicted. Clustering analysis and subfamily classification were also carried out. Furthermore, chitinase protein expression profiling was surveyed using western blot (WB), it was found that the expression of CHIT5 was down-regulated in normal growth rice leaves, while the expressions of CHIT6, CHIT14, CHITC1, and CHITC2 were up-regulated. In the incompatible interaction between rice and Xanthomonas oryzae pv. oryzae (Xoo), the expressions of CHIT1, CHIT2, CHIT5, CHIT6, CHIT10, CHIT15, and CHIT16 were enhanced after inoculation and three of CHIT14, CHITC1 and CHITC2 down-regulated. In addition, the comparison of chitinase protein expression in different rice-Xoo interactions showed that these were similar alternation patterns between compatible and incompatible reactions, with a higher extent of alterations in incompatible interactions for most of chitinases. It is interesting to note that the expression of CHIT6 was enhanced in mock-treated samples, suggesting that the expression of CHIT6 may be induced by a mechanic wound. The data revealed in this research will provide useful clues for the understanding of the function of PR3 family chitinase genes.

A Comparison of Cadmium-Accumulation-Associated Genes Expression and Molecular Regulation Mechanism between Two Rice Cultivars (Oryza sativa L. subspecies japonica)

HUANG Zhi-Xiong,WANG Fei-Juan,JIANG Han,LI Zhi-Lan,DING Yan-Fei,JIANG Qiong,TAO Yue-Liang,ZHU Cheng

Acta Agron Sin. 2014, 40(04):  581-590.  doi:10.3724/SP.J.1006.2014.00581

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In plants, as in other eukaryotes, endogenous small interfering RNAs (siRNAs), a class of small non-coding RNAs, andDNA methylation regulate gene expression in developmental processes and adaptating to environmental stresses, including Cd stress. Cadmium (Cd) is a non-essential heavy metal and highly toxic to plants. To investigate the regulatory role of siRNAs and DNA methylation on genes involved in heavy metals transport, we compared these genes’ expression profiles between a high Cd-accumulating rice (Oryza sativa L. subspecies japonica) cultivar (Xiushui 11) and a low Cd-accumulating rice cultivar (Xiushui110). At five rice development stages investigated, the difference of these genes expression level between the two rice cultivars was not significant except OsPCR1, indicating OsPCR1 may be important in Cd transport in rice. Furthermore, quantitative real time PCR (qRT-PCR) was performed to examine the expression level of a siRNA matched OsPCR1 second exon. Results indicated that the expression level of the siRNA negatively correlated with OsPCR1 expression level at the five stages. In addition, McrBC-qRT-PCR technology was used to determine DNA methylation level, showing that OsPCR1 expression level also negatively correlated with OsPCR1 second exon methylation level. These results of regulatory roles of siRNA and DNA methylation on OsPCR1 expression will contribute to the studies on OsPCR1 function and rice breeding for low Cd accumulation.

Genetic Analysis and Gene Mapping of a Marginal Albino Leaf Mutant mal in Rice

MA Jiao,REN De-Yong,WU Guo-Chao,ZHU Xiao-Yan,MA Ling,SANG Xian-Chun,LING Ying-Hua,HE Guang-Hua

Acta Agron Sin. 2014, 40(04):  591-599.  doi:10.3724/SP.J.1006.2014.00591

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The research on the color change of plant leaf is very important to clarify the structure and mechanism of photosynthetic system, such as chloroplast development and chlorophyll biosynthesis. A novel rice mutant mal (marginal albino leaf) with marginal albino leaf, was derived from the EMS-treated restorer line Jinhui 10. The mutant trait inherited steadily after several generations’ self-crossing. The mal leaf displayed albino margin and narrow blade in the whole life. Compared with the wild type, mal decreased contents of photosynthetic pigments very significantly in the whole third leaf blade, margin parts of the second and third leaves at heading stage. The observation by that transmission electronic microscopy showed cells and chloroplasts in the green part of mal leaf developed normally, while in the albino part, the mesophyll cells were nearly hollow without obvious intact organelles and the chloroplast were fully degraded. Genetic analysis showed that the mutant trait was controlled by single recessive nuclear gene. MAL was finally mapped between SSR marker M22 and InDel marker ID27 with an interval of 171 kb on chromosome 8. These results provide a foundation for cloning and function analysis of MAL.

Isolation, Characterization and Farinograph Analysis of Novel HMW-GSs from Dasypyrum villosum

YANG Hua,GAO Xiang,CHEN Qi-Jiao,ZHAO Wan-Chun,DONG Jian,LI Xiao-Yan

Acta Agron Sin. 2014, 40(04):  600-610.  doi:10.3724/SP.J.1006.2014.00600

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Dasypyrum villosum carrying many novel HMW-GS alleles is an important genetic resource for wheat protein improvement. In this study, we isolated six HMW-GS genes from D. villosum TA10220 (1.0~1.7 kb, GenBank accession numbers: KF887414~KF887419), which were substantially smaller than those from common wheat, using a pair of specific primers. An in-frame stop codon was found in the coding sequences of KF887418 and KF887419 and thus these genes might be pseudogenes. The comprehensive analysis of deduced amino acid sequence, and phylogenetic and evolutionary analyses of full sequence, N- and C-terminal domains revealed that KF887414 was closely related to y-type HMW-GS, but KF887415~KF887416 had structural characteristics of both x- and y-types. DNA fragments of KF887414~KF887417 were subcloned into thepEASY-E2 expression vector and expressed in Escherichia coli Rosetta-gami B(DE3)cell under IPTG induction. The four genes were successfully expressed in E. coli system according to SDS-PAGE analysis (both the expressed protein and HMW-GS isolated from seed) and western-blotting assay. The fusion protein was purified and recovered by His-Trap affinity chromatography and low temperature cryodesiccation, and then integrated into the control flour by using a 4 g Micro-dough LAB Farinograph. Results showed that the four HMW-GSs originated from D. villosum had positive effects on dough quality property.

Resistance Genes of Wheat Variety Shannong 20 Identified by Diagnostic Molecular Markers

LI Ji-Fa,DENG Zhi-Ying,SUN Fu-Lai,GUAN Xi-Zhen,WANG Yan-Xun,TIAN Ji-Chun

Acta Agron Sin. 2014, 40(04):  611-621.  doi:10.3724/SP.J.1006.2014.00611

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Shannong 20 is a newly released winter wheat variety in the National Regional Trials for North and South Yellow-Huai River Valleys, which exhibits excellent resistance to major diseases of wheat. In this study, the possible resistance genes in Shannong 20 were identified by using SSR, SCAR, and STS markers tightly linked to resistance genes/loci against powdery mildew, stripe rust, leaf rust, sheath blight, and scab. A total of 15 resistance genes were detected, including six (Pm12, Pm24, Pm30, Pm31, Pm35, and Pm36) for powdery mildew resistance, six (Yr5, Yr9, Yr15, Yr24, Yr26, and YrTp1) for stripe rust resistance, two (Lr21 and Lr26) for leaf rust resistance, and one (Ses1) for sheath blight resistance. However, no resistance locus to scab was found. The result may partially explain the multi- resistance in Shannong 20, and provide some references for cultivating new varieties with disease resistance and stable yield by using molecular marker-assisted selection.

Signal Transduction Pathway of ZmHSF-Like Gene Responding to Different Abiotic Stresses

LI Hui-Cong,LI Guo-Liang,GUO Xiu-Lin

Acta Agron Sin. 2014, 40(04):  622-628.  doi:10.3724/SP.J.1006.2014.00622

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Based on our previous findings of cloning, expression characteristics and subcellular-location of gene ZmHSF-Like, We analyzed the signal transduction pathway responding to different abiotic stresses. The results showed that the relative expression of gene ZmHSF-Like was up-regulated by H₂O₂. Up-regulating gene expression by heat shock of 42 ºC was dependent on existence of H₂O₂, while that PEG-6000 treatment was not. Up-regulating gene expression with ABA was partially dependent on H₂O₂. The relative expression of gene ZmHSF-Like was up-regulated by Ca²⁺ too, and chelating Ca²⁺ with methyleneglycol-bis- (2-aminoethylether)-N,N,N´,N´-tetraacetic acid (EGTA) and blocking Ca²⁺ intracellular transport with verapamil (Vp) did not decrease gene expression up-regulated by heat shock, PEG and ABA treatments. Those results illustrated that ZmHSF-Like realizes the response to heat shock and ABA through H₂O₂ signal transduction pathway. While treated with H₂O₂, the HSP704 gene expression was synchronous with that of ZmHSF-Like gene, HSP704might be the downstream binding protein of ZmHSF-Like in this signal transduction pathway. HSP701, HSP702, and HSPeu701 had the synchronous gene expression with that of ZmHSF-Like gene after Ca²⁺ treatment, suggesting that they are the downstream binding proteins of ZmHSF-Likeresponding to Ca²⁺. Those results further indicated that ZmHSF-Like makes response to different stresses through binding different HSPs.

Mappingof QTLs for OilseedGermination RateunderStresses of Salinity and Drought in Brassica napus L. Based on SNP Genetic Map

JIAN Hong-Ju,XIAO Yang,LI Jia-Na,MA Zhen-Zhen,WEI Li-Juan,LIU Lie-Zhao

Acta Agron Sin. 2014, 40(04):  629-635.  doi:10.3724/SP.J.1006.2014.00629

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The objective of this study was to identify QTLs for seed germination percentage of Brassica napus under the salinity stress and drought stress using the composite interval mapping (CIM) method. The recombinant inbred lines (RIL) population derived from a cross between yellow-seeded female parent GH06 and black-seeded male parent P174 was established by selfing for nine successive generations with single seed propagating from F₂. The oilseeds were dealt with NaCl (16 g L^–1 solution) for salinity stress, 20% (W/W) PEG-6000 solution for drought stress. The QTLs of germination ratein two different stress conditions were detected using the SNP genetic map constructed in 2013, which contains 2795 SNP markers with the total map length of 1832.9 cM and an average distance of 0.66 cM. A total of 19 QTLs for seed germinationrate under two stresses were located onchromosomes of A01, A03, A06, A07, A09, and C06. Twelve QTLs related to salinity stress were detected, with explained phenotypic variation from 4.9% to 10.9% of, while eight QTLs related to drought stress were detected, with explained phenotypic variation from 3.8% to 6.9% of. Some QTLs located on A03 and A09 under two stresses were detected in a near region. In conclusion, (1) the seed germination percentage is a quantitative trait controlled by many minor-effect genes, and the expression of the QTL is affected by environmental factors greatly; (2) different genes are involved in the oilseed responses to the stresses of different stages.

Cloning and Expression Analysis of Copper and Zinc Superoxide Dismutase (Cu/Zn-SOD) Gene from Brassica campestris L.

ZENG Xiu-Cun,LIU Zi-Gang,SHI Peng-Hui,XU Yao-Zhao,SUN Jia,FANG Yan,YANG Gang,WU Jun-Yan,KONG De-Jing,SUN Wan-Cang

Acta Agron Sin. 2014, 40(04):  636-643.  doi:10.3724/SP.J.1006.2014.00636

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Superoxide Dismutase (SOD) is a key enzyme eliminating reactive oxygen species (ROS), and the copper and zinc superoxide dismutase (Cu/Zn-SOD) is the most important active oxygen scavenger in SOD family, which can improve plant tolerance to environmental stresses. The cDNA of Brassica campestris L. cultivar Longyou 7 was cloned by RT-PCR, using the primers designed according to the published crucifer Cu/Zn-SOD cDNA sequences. The sequence of Cu/Zn-SOD from B. campestris L. was 459 bp, encoding a predicted protein of 152 amino acid residues. Bioinformatics analysis showed that amino sequence similarity with Brassica napus was 99%, and the predicted Cu/Zn-SOD protein was a hydrophilic protein without signal-peptide as well as transmembrane region. It contained specific sequence characteristics and conserved domain of copper and zinc superoxide dismutase (Cu/Zn-SOD) superfamily. The expression analysis of Cu/Zn-SOD gene using semi-quantitative RT-PCR and results of SOD activity in response to lower temperature showed that the Cu/Zn-SOD was a differential expressed gene induced by lower temperature. Results of separating low-temperature-induced proteins from Brassica campestris L. cultivar Longyou 6 by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry further showed that Cu/Zn-SOD was a stress-responsed gene, whose expression was induced by lower temperature.

Genetic Analysis and Gene Fine Mapping of Yellow-Green Leaf Mutant ygl80 in Rice

LI Yan-Qun,GAO Jia-Xu,XIAO Yun-Hua,LI Xiu-Lan,PU Xiang,SUN Chang-Hui,WANG Ping-Rong,DENG Xiao-Jian

Acta Agron Sin. 2014, 40(04):  644-649.  doi:10.3724/SP.J.1006.2014.00644

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A yellow-green leaf mutant ygl80 was isolated by chemical mutagenesis. Compared with the wild-type parent 10079, chlorophyll content of the ygl80 mutantdecreased by 76.64% and 54.59%, and the carotenoid content decreased by 53.85% and 41.18% at the seedling and booting stages, respectively. In addition, plant height, number of productive panicles per plant, number of spikelets per panicle, panicle length and 1000-grain weight reduced by 14.8%, 16.5%, 21.3%, 9.1%, and 7.4%, respectively, at the maturity. Genetic analysis showed that the yellow-green leaf trait of the ygl80 mutant was controlled by one pair of recessive nuclear genes. Genetic mapping of the mutant gene was conducted by using 627 yellow-green leaf individuals from the F₂ mapping population of ygl80/Zhefu802. Finally, the mutant gene was mapped between InDel markers C2 and C3 on the long arm of chromosome 5, with genetic distances of 0.24 cM and 0.39 cM, respectively, and with physical distance of 90 kb, in this region eleven predicted genes had been annotated. Sequencing analysis of these candidate genes between the mutant and its wild-type parent revealed a single base change (C5027T) of YGL1 (LOC_Os05g28200) gene for chlorophyll synthase resulted in a missense mutation (P348L) in the encoded product, suggesting that the ygl80 mutant gene is allelic to the ygl1 gene. The ygl80 mutant exhibited yellow-green trait throughout the growing period. But the ygl1 mutant showed yellow-green trait at seedling stage, then turned into green slowly, and its leaf color and chlorophyll and carotenoid contents almost closed to those of the wild-type parent during the later stage of growth. Different phenotypes of the two mutants may be caused by different mutational sites of genomic sequenceof YGL1 gene encoding chlorophyll synthase.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effects of Harvesting Date on Yield Loss Percentage of Mechanical Harvesting and Seed Quality in Rapeseed

ZUO Qing-Song,HUANG Hai-Dong,CAO Shi,YANG Shi-Fen,LIAO Qing-Xi,LENG Suo-Hu,WU Jiang-Sheng,ZHOU Guang-Sheng

Acta Agron Sin. 2014, 40(04):  650-656.  doi:10.3724/SP.J.1006.2014.00650

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A field experiment was conducted at different harvesting periods ranging from 70% pod yellow to pod shattering significantly using a variety Huayouza 62 in 2012—2013. The yield loss, moisture content and seed quality were measured. The results showed that the total yield loss percentage ranged from 7.00% to 15.80% at different harvesting periods, and in the process of harvesting the total yield loss percentage decreased firstly and then increased. The total yield loss in mechanical harvesting was composed of the yield loss caused by shattering (SL), yield loss caused by combine header (CHL) and yield loss caused by cleaning and threshing (CTL). The percentage of CHL increased with lasting the harvesting date, and the ratio of CHL to the total yield loss ranged from 7.80% to 31.01%. Among them the percentage of CTL was the largest, which decreased with lasting the harvesting date, and the ratio of CTL to the total yield loss accounting for 56.87% to 92.90%. The total yield loss percentage had very significant and positive correlation with moisture contents of seed, shell, main inflorescence and branches. When the seed moisture content was 16.23%, the 1000-seed weight and oil content were the highest. With decreasing the seed moisture content further, 1000-seed weight, oil content, carbon content and C/N ratio decreased slightly. The period of mechanical harvesting with the seed or pod shell moisture content from 11% to 13% was suitable for getting relatively high 1000-seed weight, oil content, mechanical harvesting yield and oil yield.

Prediction for Soybean Grain Yield Using Active Sensor GreenSeeker

ZHANG Ning,QI Bo,ZHAO Jin-Ming,ZHANG Xiao-Yan,WANG Su-Ge,ZHAO Tuan-Jie,GAI Jun-Yi

Acta Agron Sin. 2014, 40(04):  657-666.  doi:10.3724/SP.J.1006.2014.00657

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Active remote sensing can be used to monitor soybean growth with a convenient, fast and nondestructive technology. At Shofine Academician Workstation, a total of 1272 soybean lines, including  breeding lines and recombinant inbred lines (NJRIKY), were grouped and tested in random complete block, block in replication or lattice design with three replicates in 2011 and 2012, respectively. Using active remote sensor GreenSeeker, the canopy NDVI (normalized difference vegetation index) was measured at seedling, flowering, podding and seed-filling stages, from which the yield prediction models depending on NDVI measurements were established and analyzed. The results showed that the soybean canopy NDVI presented a low-high-low changing trend from the early to the late stages. Among the single stage prediction models for yield, that for seed-filling stage was the best with higher coefficient of determination and lower standard errors. However, for a precise prediction, the regression of yield on NDVI at multiple stages was better than the others. Among which, the yield prediction model constructed from NDVI at flowering, podding and seed-filling stages of all breeding lines was the best one (y = e^6.9–4.1x₁^+4.3x₂^+1.4x₃) with R² = 0.66. Using this model to predict the NJRIKY lines, the coincidence between the measured and predicted values was 0.59. This model can be used at the middle stage of breeding programs for yield prediction of the breeding lines without replicated yield test.

Effect of Ridge & Terraced Cultivation on Rice Yield and Root Trait

ZHENG Hua-Bin,YAO Lin,LIU Jian-Xia,HE Hui,CHEN Yang,HUANG Huang

Acta Agron Sin. 2014, 40(04):  667-677.  doi:10.3724/SP.J.1006.2014.00667

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A field experiment was conducted in Changsha city of Hunan Province in 2011 and 2012 to find out a cultivation technique of ridge & terraced cultivation (RTC) for improving rice yield and root trait. Super hybrid rice Yliangyou 1, hybrid rice Shanyou 63 and conventional rice Huanghuazhan were used in the mid-rice season. The cultivation patterns were designed as ridge & terranced cultivation (T1, ridge width 60 cm; T2, ridge width 120 cm), bed cultivation (T3, bed width 70 cm; T4, bed width 140 cm; T5, bed width 230 cm), and traditional cultivation (T0). The characteristics of grain yield formation and root character under different cultivation patterns were analyzed. Results showed that ridge & terraced cultivation (T1) and bed cultivation (T3) could increase grain yield compared with traditional cultivation (T0), T1 had the highest yield, which was 22.2% (17.1%–27.2%) higher than that of T0, the next was T3, with the yield 10.4% (5.8%–15.0%) higher than that of T0. However, increasing range of yield declined gradually with the increase of ridge width or bed width. The important reason for increasing yield by using the two cultivation techniques was higher effective panicles and spikelets per panicles, better root trait (root oxidation ability, root surface absorption area and soil porosity) and higher dry matter accumulation after full heading stage. Meanwhile, root anatomical structureshowed that the thickness of root cortex was decreased and the size of root vascular cylinder and vessel areas was increased in RTC, so that the capacity of water absorption was enhanced.

Yield Components and Population Characteristics of Super-High-Yielding Late Japonica Hybrid Rice in Double-Cropping Rice Area

XU Ke,ZHANG Jun,HUA Jin,ZHANG Hong-Cheng,ZHOU Pei-Jian,CHENG Fei-Hu,HUANG Da-Shan, CHEN Zhong-Ping,CHEN Guo-Liang,DAI Qi-Gen,HUO Zhong-Yang,WEI Hai-Yan,GAO Hui

Acta Agron Sin. 2014, 40(04):  678-690.  doi:10.3724/SP.J.1006.2014.00678

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This study investigated the formation rule of super-high-yielding late japonica hybrid rice in the double-cropping rice area. Using Yongyou 8 as material in Shanggao of Jiangxi Province, we analyzed grain yield and its components and the population characteristics in three types of populations (medium yield: 8.25–9.75 t ha^-1, high yield: 9.75–10.50 t ha^-1; super high yield: >10.50 t ha^-1). Results showed that supper-high-yielding population had more panicle and spikelets per panicle than medium and high yielding population. There was no significant difference in filled-grain percentage and 1000-grain weight among the three populations. Supper-high-yielding population exhibited more tillers at the transplanting stage and achieved expected number of stems and tillers on time, maximum number of stems and tillers at jointing stage. Then, the number of population stems and tillers began to decrease stably, achieving an expected number again. At last, ratio of productive tillers to total tillers of supper-high-yielding population was about 78.0%, which was higher than that of medium and high yielding population. The leaf area index of supper-high-yielding population was lower than that of medium and high yielding population at the early growth stage, with the maximum leaf area index of about 8.0 at booting, and stably decreasing to above 3.5 at maturity. The photosynthetic potential of supper-high-yielding population was smaller at early stage and larger at middle and late stages, as compared with the medium and high yielding populations, which was above 300 × 10⁴ m² d ha^–1 from heading to maturity, and above 675 × 10⁴ m² d ha^–1 in total. The dry matter accumulation of super-high-yielding population was smaller before jointing, increased faster after jointing, and reached about 10.5 t ha^–1 at heading and 19.0 t ha^–1 at maturity, which was significantly higher than that of medium and high yielding populations. Its translocation ratio of output was above 14.0%. In the super-high-yielding population the weight of dry matter of root, root-shoot ratio at each growth stage, root bleedings, N content, N uptaking, and utilization were greater than those of the medium and high yielding populations. Based on the results of this study, we discussed the regulation approaches and key cultivation techniques for raising the super-high-yielding population.

Simultaneous Determination of Twelve Mycotoxins in Cereals by Ultra-high Performance Liquid Chromatography-Tandem Mass Spectrometry

UN Juan,LI Wei-Xi,ZHANG Yan,SUN Li-Juan,DONG Xiao-Li,HU Xue-Xu,WANG Bu-Jun

Acta Agron Sin. 2014, 40(04):  691-701.  doi:10.3724/SP.J.1006.2014.00691

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A determination method was developed using ultra-high performance liquid chromatography-tendem mass spectrometry (UPLC-MS/MS). Samples were sequentially extracted with 80% acetonitrile, and then the extracts were pooled and cleaned up with multifunction cleaning column before being separating by a chromatographic column of Waters ACQUITY UPLCTMBEH C18. The Mass spectrometry was conducted by using positive (ESI+) electrospray ionization and Multi-reactions monitoring (MRM) models, with external standard method. The results indicated that contants of the 12 mycotoxins had good linear relationship with than peak areas. The detection limits for them ranged from 0.016 to 1.000 μg kg^-1, and the average recovery rates at three levels of adding external standard were from 60.0% to 122.4%, with a relative standard deviation (RSD) varying from 0.9% to 20.3%. The method is simple, rapid, accurate and suitable for simultaneously by measuring 12 kinds of mycotoxins in cereals.

Physiological Characteristics of Drought Resistance in Common Bean (Phaseolus vulgaris L.)

LI Long,WANG Lan-Fen,WU Jing,JING Rui-Lian,WANG Shu-Min

Acta Agron Sin. 2014, 40(04):  702-710.  doi:10.3724/SP.J.1006.2014.00702

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hree common bean cultivars, Yuejindou (drought-resistant), 260205 (drought-resistant) and Naihuayundou (drought-susceptible) were evaluated with two treatments (drought stress and normal water supply) in pot experiments. We determined physiological and biochemical parameters during growth stage and yield and traits related to yield after harvest, analyzed the changes of all parameters and indicators under drought stress. The result showed that the root dry weight of Yuejindou and 260205 was 20.2% and 20.6% of the total biomass and the pod dry weight was 30.0% and 28.9% of the total biomass especially at 36 days of drought treatment, while, the root dry weight and pod dry weight only 10.6% and 17.1% of the total biomass in Naihuayundou, indicating that effective photosynthate distribution is significantly correlated with drought resistance in common bean.The water use efficiency in the drought-resistant cultivar (Yuejindou) increased by 230.5% compared with control, much higher than the 60% increase in drought-susceptible cultivar (Naihuayundou). The drought-resistant cultivars had an efficient CO₂ diffusion and fixation in leaf tissues, and an effective water-use. In drought-resistant cultivars, antioxidant enzyme and photorespiration played a significant role in reactive oxygen scavenging; proline and soluble sugar contributed to the maintenance of relative water content in leaves under low water potential. All together, our results indicated that the competence of drought-resistant cultivars to maintain seed production under drought stress relies on effective adjustments in morphology, stomatal conductance, osmosis and antioxidant capacity.

Effects of Different Cultivation Methods on Growth Stage, Dry Matter Accumulation and Yield of Early Rice in Double Cropping Rice Field

TANG Hai-Ming,PANG Huan-Cheng,XIAO Xiao-Ping,NIE Ze-Min,TANG Wen-Guang,YU Tian-Yi,WANG Ke,LI Qiang,YANG Guang-Li

Acta Agron Sin. 2014, 40(04):  711-718.  doi:10.3724/SP.J.1006.2014.00711

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To explore the characteristics of growth and development of early rice with different cultivation methods in the double cropping rice system in the Dongting Lake plain, we analyzed the growth stage, dry matter accumulation and distribution, grain yield of early rice with conventional and hybrid rice varieties by using seedling throwing (ST), hand transplanting (HT) and machine transplanting (MT). The results showed that the growth process of ST and HT was earlier and their whole growth period was 5−8 and 2−4 days shortened than that of MT, respectively. For dry matter weight of population, there was significant difference among the three cultivation methods at the main growth stages of early rice, showing on order ST>HT>MT. The dry matter weight ratio of root and panicle to total plant at mature stage and the dry matter weight of stem were both in a trend of HT>ST>MT. The dry matter weight ratio of leaf to total plant was MT>HT>ST at tillering and heading stages, and HT>ST>MT at grain filling and mature stages, respectively. In addition, the leaf SPAD of rice with ST and HT was significantly higher than that with MT at tillering, heading and grain filling stages. But there was no significant difference among ST, HT and MT at mature stage. Meanwhile, the leaf area index for different cultivation methods was ST>HT>MT at the main growth stages of early rice. Yield of early rice with different cultivation methods was significantly different, and that of ST was the highest, while that of MT was the lowest. Compared with MT, the yield of ST and HT increased by 1203.3−1346.7 and 776.7−1045.4 kg ha^-1, indicating that the dry matter accumulation and yield of early rice with different cultivation methods have their own characteristics. Compared with HT and MT, ST had significantly higher total dry matter accumulation and its reasonable distribution, and improved yield and yield components.

Effects of Mechanized Planting Methods on Yield Components and Plant Type Characteristics of Indica Hybrid Rice Fyou 498

LEI Xiao-Long,LIU Li,LIU Bo,HUANG Guang-Zhong,GUO Xiang,MA Rong-Chao,REN Wan-Jun

Acta Agron Sin. 2014, 40(04):  719-730.  doi:10.3724/SP.J.1006.2014.00719

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In order to identify plant type characteristics of high-yield population of indica hybrid rice using mechanized planting methods, a split plot field experiment was conducted using Fyou 498 as material. The plant type characteristics and their relationships with yield components in treatments of mechanized direct-seeding, mechanized transplanting and artificial transplanting with different seedlings per hill and different sowing dates were studied. The main results were as follows: (1) The traits of plant type differed markedly among the treatments of three planting methods. The length, width and leaf distance of top three leaves as well as blade tangent and drooping angle were larger under mechanized direct-seeding and transplanting. The top three leaves were erect with proper leaf area in the treatment of artificial transplanting. Plant height and leaf size of top three leaves were significantly larger in the treatments of mechanized direct-seeding and transplanting than in that of artificial transplanting. However, specific leaf weight, panicles per plant and total leaves were greater under artificial transplanting than under mechanized planting. For culm angle, spikelets and grain weight per panicle, the ranking orders of treatments were mechanized transplanting > artificial transplanting > mechanized direct-seeding. Leaf area increased with delaying sowing date or decreasing seedling number per hill and late sowing reduced the ratio of grain number to leaf area, panicles per plant, spikelets per panicle and seed-setting rate markedly. A significantly positive correlation was observed between grain weight per panicle and length, width, inserted height of leaf and plant height. Grain weight per plant was lower under mechanized direct-seeding than under mechanized transplanting and artificial transplanting. (2) The yield was significantly lower under mechanized direct-seeding than under mechanized transplanting and under artificial transplanting, which decreased by delaying sowing date or decreasing seedling number per hill. There were significant correlations between some traits of plant type and yield as well as its components. The notable characteristics of high-yield plant type in mechanized planting were proper plant height, length of top three leaves, LAI and culm angle. Meanwhile, the larger leaf width, specific leaf weight, leaf distance of top three leaves, erect leaves, adequate panicle number and large panicles were critical to high yield. Good plant type characteristics of individuality and optimal population structure are a prerequisite for increasing yield. Indica hybrid rice should be sowed earlier as the time allows with three seedlings per hill approximately in mechanized planting.

RESEARCH NOTES

Photosynthesis Characteristics of Flag Leaf and Dry Matter Accumulation and Allocation in Winter Wheat under Supplemental Irrigation after Measuring Moisture Content in Different Soil Layers

GUO Zeng-Jiang,YU Zhen-Wen,SHI Yu,ZHAO Jun-Ye,ZHANG Yong-Li,WANG Dong

Acta Agron Sin. 2014, 40(04):  731-738.  doi:10.3724/SP.J.1006.2014.00731

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This study aimed to propose a suitable soil layer depth used in determining the irrigation amount. A field experiment was conducted in the 2011–2012 and 2012–2013 wheat growing seasons to study the effects of supplemental irrigation based on the measurement of soil moisture contents on photosynthesis of flag leaves and dry matter accumulation and allocation. Four irrigation treatments were designed with target soil moisture of 65% at jointing and 70% at anthesis in 0–20 (D1), 0–40 (D2), 0–60 (D3), and 0–140 cm (D4) soil layers. Zero-irrigation (D0) was used as the control. D2 was superior to other treatments with higher values of leaf area index (LAI) and flag leaf area on one square meter land at anthesis, photosynthetic rate (P_n) and actual photochemical efficiency (Φ_PSII) at seven and fourteen days after anthesis; whereas, the stomatal limitation (L_s) of D2 was lower than that of other treatments. Compared with other treatments, D2 had larger dry matter accumulation at maturity, more dry matter allocated in grains, and higher contribution ratio of dry matter from vegetative organs to grain after anthesis. The grain yield in D2 was 9367.4 kg ha^-1 in 2011–2012 growing season and 9727.5 kg ha^-1 in 2012–2013 growing season, which were significantly higher than those in other treatments. The water use efficiency of D2 was significantly higher than that of D0, D3, and D4, but with out significant difference to that of D1. To obtain both high yield and high water use efficiency, we suggest the optimal soil layer for measuring moisture content is 0–40 cm, and supplementary water should be given at jointing and anthesis based on measured soil moisture.

Adaptability and Phenotypic Variation of Agronomic Traits in Mungbean Core Collection under Different Environments in China

WANG Li-Xia,CHENG Xu-Zhen,WANG Su-Hua,ZHU Xu,LIU Zhen-Xing

Acta Agron Sin. 2014, 40(04):  739-744.  doi:10.3724/SP.J.1006.2014.00739

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Mungbean (Vigna radiata L. Wilczek) is an important traditional pulse crop in China. However, its genetic breeding is much lagged. There are abundant mungbean germplasm resources conserved in the national gene bank. It is essential to evaluate diversity and adaptability of germplasm resources for their accelerating use in genetic breeding. In the present study, we assessed the genetic variations and environmental adaptability of mungbean core collection at Haidian of Beijing, Tangshan of Hebei, and Nanyang of Henan province, respectively. The results showed that growth habit and podding habit were affected by eco-environments, but they were not always agreeable with each other, some erect materials in growth were indeterminate in podding, and some erect in growth in south region performed climbing in north regions. All accessions in the core collection were mature at different eco-regions, but their growth period, plant height, number of branch per plant, number of pod per plant, number of seed per pod, pod length and 100-seed-weight, varied greatly in different regions. Based on these quantitative traits, we selected 26 germplasm as elite ones that may be useful for local production or breeding. According to the Mixed linear model, the effects of genetic composition for the seven quantitative traits were also analyzed. The results showed that there were differences among accessions and environment effects, and the genotypic effects were higher on pod length and 100-seed weight than on other traits, while environmental effects was the highest on growth period. The residued effects were the highest on the number of seeds per pod, while the interaction effect between genotypes or phenotypes not significant for any two of the seven traits. The environmental adaptability for all the traits was also analyzed by using Jackknife repeated sampling, and four useful in breeding for variety with wide adaptability were selected.

Overexpression of BnMAPK1 Enhances Resistance to Sclerotinia sclerotiorum in Brassica napus

WANG Shu-Wen,LU Jun-Xing,WAN Hua-Fang,WENG Chang-Mei,WANG Zhen,LI Jia-Na,LU KunLIANG Ying

Acta Agron Sin. 2014, 40(04):  745-750.  doi:10.3724/SP.J.1006.2014.00745

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Plant MAPKs (mitogen-activated protein kinases) play an important role in defense to biotic and abiotic stresses. In our previous studies, BnMAPK1 was cloned in Brassica napus and transgenic oilseed rape plants overexpressing BnMAPK1 were obtained. In this study, B. napus ZY821DH line was used as control and the corresponding transgenic plants overexpressing BnMAPK1 were used as experimental materials. The resistance to S. sclerotiorum and oxalic acid content were testedby using detached leaves inoculated with the pathogen. The dynamic changes of the relative expression of four pathogenesis-related genes, OXO, Cu/ZnSOD, PR2, and PR3were detected in the leaves inoculated with the pathogen. The results showed that the overexpression of BnMAPK1 significantly inhibited the invasion of the pathogen, controlled the accumulation of oxalic acid in the inoculated leaves, and maybe finally relieved the negative regulation of OXO expression caused by the pathogen and up-regulated the expression of the other three genes, Cu/Zn SOD, PR2, and PR3. The results indicated that overexpression of BnMAPK1 can effectively improve the resistance to S. sclerotiorum in oilseed rape.

Genetic Analysis of Traits Related to Plant Height in Ricinus communis L. Based on QTL Mapping

LIU Chen,LU Jian-Nong**,YIN Xue-Gui,BI Chuan,WEN Dan-You,ZHENG Jun,LIU Shuai,SHI Zhuo-Xing,and CHENG Yue-Xiang

Acta Agron Sin. 2014, 40(04):  751-759.  doi:10.3724/SP.J.1006.2014.00751

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The traits related to plant height were analyzed with correlation, regression and QTL mapping in two F₂ populations derived from crosses of YC2×YF1 and YC1×YF1 respectively. The results indicated that plant height (PH) was significantly and positively correlated with bearing height of primary raceme (PRH), length of main stem internode (MSIL) and main stem diameter (MSD) but not with node number of main stem (MSNN), PRH was significantly and positively correlated with MSNN, MSIL and MSD, MSNN and MSIL was significantly and negatively correlated with each other. In F₂ population from a cross of YC2×YF1, five, four, six, three, and two QTLs for PH, PRH, MSNN, MSIL, and MSD were detected by QTLnetwork 2.0, which explained for 45.9%, 45.3%, 66.1%, 55.4%, and 12.6% of the phenotypic variation respectively. In F₂ population from a cross of YC1×YF1, three, four, five, one and two QTLs for the five traits mentioned above were detected, which explained for 45.9%, 45.3%, 66.1%, 55.4%, and 12.6% of the phenotypic variation respectively. We concluded that the pleiotropy or linkage between QTLs results in the positive correlation between PH, PRH and MSIL, the additive effect was the main genetic component of PH, PRH, MSIL, and the epistatic effect is the main genetic component of MSNN and MSD. It suggested that PRH and MSIL should be used to select and predict PH indirectly in the early stage, more MSNN and shorter MSIL should be regarded as the target traits for high-yield breeding.