Table of Content

16 March 2015, Volume 48 Issue 6

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

The Genetic Effect of Wheat-H.villosa T5VS·5DL Translocated Chromosome on Agronomic Characteristics, Quality and Powdery Mildew Resistance of Common Wheat

ZHANG Rui-qi, FENG Yi-gao, HOU Fu, CHEN Shu-lin, BIE Tong-de, CHEN Pei-du

Scientia Agricultura Sinica. 2015, 48(6):  1041-1051.  doi:10.3864/j.issn.0578-1752.2015.06.01

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【Objective】The objective of this study is to understand the genetic effect of wheat-H.villosa T5VS·5DL translocated chromosome on yield traits, powdery mildew resistance，grain quality of common wheat and transmission of T5VS·5DL chromosome through male and female Gametes, and further learn more about its utilization value in wheat breeding improvement. 【Method】Based on the identification of T5VS·5DL translocated chromosome by GISH and five 5VS specific molecular markers, the advanced-generation backcrossing lines with T5VS·5DL translocated chromosome and their F₂, F_2:3 separation populations of which recurrent parents are Yangmai 15 and Yangmai 13, respectively, were used to investigate the yield traits, powdery mildew resistance and grain quality. The backcrossing lines were planted in greenhouse and field in 2013-2014, while the separation populations were only planted in greenhouse. Also, the mixed races of Blumeria graminis (DC.) E.O.Speer f. sp. tritici (Bgt) were used to infect the materials at seeding stage and adult plant stage. 【Result】The results showed that there were no significant differences between T5VS·5DL lines and their recurrent parents in agronomic traits，including plant height，spike length，spike/spikelets, grains/spike and 1000-kernal weight which might be due to the better compensation of 5VS instead of 5DS. Compared to Yangmai15 and Yangmai13, the advanced-generation backcrossing T5VS·5DL translocation lines appeared lower in SKCS values, water solvent retention capacities and Na₂CO₃ solvent retention capacities, and similar in sucrose solvent retention capacities, lactic acid solvent retention capacities and protein content, which might be due to the different genotypes of softness genes located on 5VS and 5DS. Therefore, T5VS·5DL might have a positive effect on soft wheat quality. In addition, the results of powdery mildew resistance investigated at seedling stage and adult plant stage indicated that T5VS·5DL lines were susceptible at seedling stage, while heighly resistant at adult plant stage, suggesting the adult-plant powdery mildew resistance gene was present in T5VS·5DL lines. Genetic analysis showed that powdery mildew resistance was controlled by a dominant single gene located on T5VS·5DL translocated chromosome. The results of specific molecular marker analysis in BC₅F₂ generation showed that the ratio of homozygous plants, heterozygous plants and non-translocated chromosome plants followed Mendelian rules, suggesting that translocation chromosome T5VS·5DL can transmit to offsprings stably. The co-dominant marker 5EST-237, Pinb-1 with simple amplification conditions and easily distinguishable specific bands should be preferred in molecular marker assisted selection in wheat breeding. 【Conclusion】From breeding point of view, the T5VS·5DL translocation lines with positive effect on soft wheat quality and powdery mildew resistance gene should be used widely in breeding and quality improvement of weak-strength wheat.

Development and Application of Specific Molecular Markers of Thinopyrum bessarabicum Löve Based on RNA-seq

LI Chen-xu, LIU Zhi-tao, ZHUANG Li-fang, QI Zeng-jun

Scientia Agricultura Sinica. 2015, 48(6):  1052-1062.  doi:10.3864/j.issn.0578-1752.2015.06.02

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【Objective】Development of adequate molecular markers covering the whole genome of an alien species is becoming more and more important in identifying the homoeology and structure of the alien chromosomes, developing small segmental translocations, tracing target genes and physical mapping. Thinopyrum bessarabicum Löve is an important alien species with multiple beneficial genes for wheat breeding, 8 wheat alien lines involving seven chromosomes (arm) of Th. bessarabicum have been developed in Cytogenetics Institute, Nanjing Agricultural University, China. Recently, many small segmental translocations involving different chromosomes of Th. bessarabicum have been induced via irradiation, gametocidal chromosomes and ph1b system. However, the current markers are not enough to identify these translocations. To develop more specific markers, a transcriptome of Th. bessarabicum leaves at tillering stage was sequenced and assembled.【Method】The sequences were then used to blast against the D genome sequences of Aegilops tauschii and 4957 “no hits found” sequences probably representing Th.bessarabicum specific were used for primers development.【Result】Of 507 pairs of primers, 204 produced specific amplicons in Th. bessarabicum with a polymorphism (40.2%) quite higher than 12% showed in 134 primers developed based on wheat ESTs and 14% showed in 100 primers developed based on the transcriptome sequences of Th. bessarabicum. Of them, 64 pairs of primers had no amplification in wheat indicating species specific. Using 8 wheat alien lines involving seven chromosomes or arms of Th. bessarabicum, total 198 including 189 markers developed based on the transcriptome sequences of Th.bessarabicum were chromosomally mapped, which distributed on 1J, 2JS, 2JL, 3JS, 4JS, 4JL, 5J, 6JS, 6JL and 7JS, respectively, with a number of 31, 15, 26, 20, 12, 12, 27, 13, 22 and 20. Using these markers, three wheat alien translocations involved chromosomes 1J and 6J preliminarily designated as T1JS·1JL-W, T6JS·W, T6JS-W·W and one intercalary translocation with two specific markers were identified. After analysis on these translocations, 7 markers were mapped on the distal part of 1JL and 23 on the left part of 1J. For 6JS, 8 markers were mapped on the distal region and 4 on the pericentric region of 6JS. 【Conclusion】Blast against wheat D genome sequences with the transcriptome sequences of Th. bessarabicum, a high efficient way to develop markers specific for alien species of both wheat and other crops was developed. These markers facilitate both the identification of wheat alien translocations and physical mapping.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Difference Analysis of Post-Anthesis Matter Production and Senescence Characteristics Among Different Nitrogen Efficiency Populations in Wheat Following Rice

DING Jin-feng, CHENG Ya-mei, HUANG Zheng-jin, LI Chun-yan, GUO Wen-shan, ZHU Xin-kai

Scientia Agricultura Sinica. 2015, 48(6):  1063-1073.  doi:10.3864/j.issn.0578-1752.2015.06.03

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【Objective】This study investigated the post-anthesis characteristics of wheat population in rice-wheat rotation system under high nitrogen utilization efficiency condition. 【Method】 From 2010 to 2012, using wheat variety Yangmai 20 as material, the field experiments were conducted as split-plot design which included 16 combinations of two applications of nitrogen amount (210.0 kg·hm^-2 and 262.5 kg·hm^-2), two nitrogen applied ratios of basis﹕tillering﹕elongation﹕booting (3﹕1﹕3﹕3 and 5﹕1﹕2﹕2), and four nitrogen topdressing stages (flag leaf stage, booting stage, heading stage and anthesis). In the rice-wheat rotation system, wheat populations at different nitrogen utilization rate (NUR) levels were established by agronomic management. The differences of grain yield, matter production, nitrogen absorption, and flag leaves senescence characteristics after anthesis among different NUR level populations were analyzed, respectively.【Result】The range of NUR in different populations was 31.18%-72.23%. Grain yield of NUR≥60% population (NUR-H) was more than 8 500 kg·hm^-2, which was 6.84% higher than NUR 40%-60% population (NUR-M) and was 21.6% higher than NUR≤40% population (NUR-L). There were significant differences among the three populations. NUR was significantly positively correlated with grain yield. And different NUR populations were not distinct in dry matter accumulation amount and nitrogen accumulation amount before the stage of anthesis. With NUR improvement, dry matter accumulation amount after anthesis and at maturity, plant nitrogen content at anthesis, and population nitrogen accumulation amount at maturity increased, which were more than 6 000 kg·hm^-2, 17 500 kg·hm^-2, 1.50% and 215 kg·hm^-2 in NUR≥60% population, respectively. Moreover, along with NUR increasement, decay of population photosynthetic area after anthesis gradually postponed, and net assimilation further increased, as well as flag leaves photosynthetic capacity and anti-oxidant ability after anthesis enhanced, which more obviously performed during the middle and late phase of grain filling. Therefore, photosynthetic material production capacity after anthesis was improved. Decay of leaf area, photosynthetic potential and net assimilation after anthesis in NUR≥60% population was about 0.14 LAI·d^-1, 105×10⁴ m²·d·hm^-2 and 9.50 g·m^-2·d^-1, respectively. In summary, grain yield and NUR were relatively high in the treatment of early topdressing panicle fertilizer (flag leaf stage or booting stage) under the condition of appropriate postponing nitrogen application (nitrogen applied ratios= 3﹕1﹕3﹕3). Rather, yield improvement of high nitrogen application (262.5 kg·hm^-2) was not obvious, and NUR even was quite low. The grain yield was more than 9 000 kg·hm^-2 in experiments carried in two years, and NUR was the highest under the treatment of applied nitrogen amount 210.0 kg·hm^-2, nitrogen applied ratios of basis﹕tillering﹕elongation﹕booting= 3﹕1﹕3﹕3 and topdressed nitrogen at flag leaf stage.【Conclusion】Under high nitrogen utilization efficiency condition, plant nitrogen nutrition level was high during the middle and late phases of plant growth and development, nitrogen absorption and accumulation amount increased in wheat following rice, which was better to improve transportation of nitrogen to grain. Additionally, the process of photosynthetic area decay and leaves senescence was postponed during the late phase, and photosynthetic material production capacity was improved, which could be the reason of simultaneous improvement in NUR and grain yield.

Effects of Tillage Before Sowing of Winter Wheat and Summer Maize on Yield Formation of Summer Maize

LI Xia, REN Bai-zhao, FAN Xia, ZHAO Bin, DONG Shu-ting, LIU Peng, ZHANG Ji-wang

Scientia Agricultura Sinica. 2015, 48(6):  1074-1083.  doi:10.3864/j.issn.0578-1752.2015.06.04

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【Objective】A typical double cropping of winter wheat and summer maize is practiced in Huang-Huai-Hai Plain. This study is to explore the effects of tillage methods before sowing both winter wheat and summer maize on yield formation of summer maize, to find which is helpful to improve the tillage system of double cropping for high yield and high efficiency in HuangHuaiHai Plain.【Method】Summer maize hybrid Zhengdan958 (ZD958) was used as experimental materials. Three tillage treatments were designed in this study, including rotary tillage before sowing winter wheat and no-till before sowing of summer maize (RN), conventional tillage (mobile tillage by plow) before sowing of winter wheat and no-till before sowing of summer maize (MN), and conventional tillage before sowing winter wheat and rotary tillage before sowing of summer maize (MR). Effects of tillage treatments on yield, leaf area index (LAI), accumulation and distribution of dry matter, and grain filling characteristics of summer maize were investigated.【Result】Results showed that tillage before sowing of both winter wheat and summer maize had significant effects on yield and yield components of summer maize. Compared with RN, LAI, dry matter (DM) accumulation after tasseling (VT), the ratio of DM after VT to total DM, and maximum grain filling rate (Gmax) in MR and MN increased by 15.01%, 21.14%, 3.21%, 15.00% and 16.44%, 24.92%, 4.49%, 12.60%, respectively. So DM accumulation, DM after tasseling (VT), distribution of DM to kernels, weight of maximum grain filling rate (Wmax) and Gmax increased significantly after conventional tillage before sowing of winter wheat. As a result, kernel number and weight per ear increased, thus grain yield increased. Compared with RN, grain yield in MR and MN increased by 30.61% and 24.03%, respectively. Rotary tillage before sowing of summer maize had no significant effects on DM accumulation after VT and growing rate of grains, however, the emergence rate of summer maize increased significantly, which increased ear number per planting area, thus grain yield increased. Compared with MN, the emergence rate of summer maize in MR increased by 6.29%, and grain yield increased by 5.23%.【Conclusion】Compared with RN, grain yield of MR and MN increased significantly. Though the yield in MR was higher than that in MN, taking grain yield and machinery costs into account, the tillage system of conventional tillage before sowing of winter wheat and no till before sowing of summer maize maybe helpful for high yield and high efficiency of summer maize production in Huang-Huai-Hai Plain.

Effect of Different Seeding Rates and Planting Patterns on Root Morphological Traits and Root Vigor of Super-High-Yield Soybean Cultivars

MA Zhao-hui, CHE Ren-jun, WANG Hai-ying, ZHANG Hui-jun, XIE Fu-ti

Scientia Agricultura Sinica. 2015, 48(6):  1084-1094.  doi:10.3864/j.issn.0578-1752.2015.06.05

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【Objective】Root absorbing ability of soybean is closely related to the yield, while the response of soybean cultivars to seeding rates is not the same. Two pot experiments were conducted to find out the root morphological traits and root vigor of super-high-yield soybean cultivars, and common cultivar under the treatments of different seeding rates and planting pattern. 【Method】Two super-high-yield soybean cultivars Liaodou 14, Zhonghuang 35,and one common cultivar Liaodou 11 were used in the pot experiments to investigate the effects of different seeding rates and planting patterns on soybean root morphological traits, root vigor and bleeding component in 2012 and 2013. The experiment was laid out in a randomized block experiment design with five replications. The treatments consisted of three levels of seeding rate (3, 6 and 9 plants/pot) and two planting patterns (single seeding and mixed seeding). At the stages of R2, R6 and R8, plant roots were selected for measurements. Root length, root surface and root volume were measured by root system scanner WinRhizo Program (Re．gent Instruments Inc．Canada).Root vigor was estimated by TTC method. Bleeding was collected by gravimetric method. The bleeding phosphorus, potassium and soluble sugar were, respectively, determined by molybdenum stibium anti (UV-2450) , flame photometer (PEAA800) and glucose oxidasedetection. Root competition ratio (RCR) of super-high-yield cultivar was calculated by the root character of super-high-yield cultivar at mixed seeding to those at single seeding ratio divided the root character of common cultivar at mixed seeding to those at single seeding ratio. RCR＞1 means that competitiveness of super-high-yield cultivar was stronger.【Result】The result showed that the root morphological traits, root vigor and bleeding components varied with different seeding rates and planting patterns. The whole growth stage, the root morphological traits, root vigor, and the bleeding sap reached maximum at seed filling stage and flowering stage, respectively. Super-high-yield cultivars had higher root length, root volume, root vigor, bleeding sap and bleeding components than those of common cultivar from seed-filling stage to maturity stage. The root length and root volume of super-high-yield cultivar were 8.2% and 10.4%, 53.9% and 34.6% higher than those of common cultivar, respectively, under single seeding and mixed seeding treatments. For another, the bleeding sap of super-high-yield cultivars was 16.9%, 42.0% and 49.1% higher than those of common cultivar at different densities. On the other hand, the root competition ratio of super-high-yield cultivar was higher as well. The root surface and root volume per plant of two cultivars were declined with seeding rates increased, especially the common cultivar which declined about 50.9% and 50.7%. With seeding rates increased the difference of root vigor between super-high-yield cultivar and common cultivar was added, and also the root competition ratio which increased from 1.00 to 1.63. The seed weight per plant of super-high-yield soybean cultivars was higher than that of common cultivar at 6 plants/pot and 9 plants/pot treatments, especially at mixed seeding. The biomass and seed weight per plant of two cultivars were declined with seeding rates increased, especially the common cultivar which declined by 62.5% and 60.0%. There existed significant positive correlation between root morphological characters, root vigor and biomass, seed weight per plant.【Conclusion】The research indicated that super-high-yield soybean had expanded root system under appropriate seeding rate, which maintained stronger absorption capacity and compatibility.

PLANT PROTECTION

Identification and Antimicrobial Ingredients of an Endophytic Actinomycete Strain H21 from Berberis thunbergii

WEI Shao-peng, GUO Zheng, JI Zhi-qin

Scientia Agricultura Sinica. 2015, 48(6):  1095-1102.  doi:10.3864/j.issn.0578-1752.2015.06.06

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【Objective】The objectives of this experiment are to screen bioactive endophytic actinomycete from Berberis thunbergii, a traditional Chinese medicinal plant, study the taxonomic status and antimicrobial activity of the active strain, investigate the chemical structures and antimicrobial activity of active ingredients in the fermentation, and to provide a basis for the development of agricultural fungicide.【Method】 The endophytic actinomycete was isolated from the leaf of B. thunbergii by using selective culture techniques, and the obtained strain was identified by using 16S rDNA sequencing. The antibacterial and antifungal activities of the fermentation broth against seven species of tested bacteria (such as Ralstonia solanacearum) and plant pathogenic fungi (such as Botrytis cinerea) were tested by cylinder-plate method and mycelial growth method, respectively. The active ingredients were obtained by the techniques of macroporous resin adsorption, silica gel column chromatography and preparative reverse phase high performance liquid chromatography. Structures of the obtained compounds were elucidated by NMR and ESI-MS techniques. Minimum inhibitory concentrations (MICs) of active ingredients against tested bacteria were determined by micro-broth dilution method. Antifungal activity of H2101 against B. cinerea was tested by the methods of mycelial growth and spore germination, respectively.【Result】Strain H21, an active species, was isolated from the plant, and it was identified as Streptomyces sp. by the method of 16S rDNA sequencing. Except Pseudomonas aeruginosa, the fermentation broth of H21 showed strong antibacterial against the tested bacteria, such as R. solanacearum, P. syringae pv. actinidiae, Bacillus subtilis, B. cereus, Staphylococcus aureus and Escherichia coli. However, the fermentation broth could only inhibit the mecelial growth of B. cinerea. No inhibitory effect was observed against other tested fungi. Holomycin, a member of the pyrrothine class of antibiotics, as well as N-acetyl-2-(4-hydroxyphenyl)-ethylamine and cyclo (L-Leu-L-Arg), was isolated from the broth of strain H21. Holomycin exhibited broad antimicrobial activity, and the MIC values against R. solanacearum, P. syringae pv. actinidiae, B. cereus, B. subtilis, E. coli and S. aureus were 0.156, 0.313, 0.078, 0.313, 0.156 and 0.313 µg·mL^-1, respectively. Meanwhile, holomycin had strong antifungal activity against B. cinerea, and its IC₅₀ values against mycelial growth and spore germination were 13.56 and 7.89 µg·mL^-1, respectively.【Conclusion】Streptomyces sp. is a newly discovered producer of holomycin, and it has the antibacterial holomycin against R. solanacearum and P. syringae pv. actinidiae, two species of plant pathogenic bacteria. In general, holomycin is a valuable lead compound for the development of agricultural fungicides with those acts on bacteria.

Susceptibility of Transgenetic Drosophila with Locusta migratoria CYP408B1 and CYP409A1 to Insecticides

GAO Cui-e, ZHANG Jian-qin, ZHANG Xu-bo, ZHANG Jian-zhen, FENG Yun-tao, WU Hai-hua, MA En-bo

Scientia Agricultura Sinica. 2015, 48(6):  1103-1111.  doi:10.3864/j.issn.0578-1752.2015.06.07

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【Objective】Cytochrome P450s are ubiquitous metabolic detoxification enzymes in insects. Locusta migratoria is a major agricultural pest. It is important to identify and validate the metabolic detoxification function of P450. The objectives of this study are to construct transgenic Drosophila melanogaster lines with locust CYP408B1 and CYP409A1 genes, determine the susceptibility of transgenic Drosophila expressed exogenous CYP408B1 or CYP409A1 to insecticides, and to reveal the characteristics of locust CYP408B1 and CYP409A1. 【Method】 Homozygous transgenetic Drosophila lines with locust CYP408B1 and CYP409A1 were successfully constructed by using transgenic technology. Male transgenic flies (UAS-CYP408B1 and UAS-CYP409A1), and parental flies attp40 were crossed with tub-gal4 virgin flies, respectively. Genomic DNA and total RNA were isolated from hybrid offsprings: transgenic flies expressed locust CYP408B1 and CYP409A1 (tub＞CYP408B1and tub＞CYP409A1) and the control tub＞attp40, respectively. At the same time, total RNA was used to synthesize cDNA using MLV reverse transcriptase. In order to validate transgenic flies UAS-CYP408B1 and UAS-CYP409A1, PCR amplification was conducted with DNA and cDNA as templates, respectively. The susceptibility of transgenicflies (tub＞CYP408B1 and tub＞CYP409A1) and control flies (tub＞attp40, UAS-CYP408B1, UAS-CYP409A1 and attp40) to three selected insecticides (deltamethrin, malathion and chlorpyrifos) were analyzed. Cytochrome P450 monooxygenase activity of transgenic flies (tub＞CYP408B1 and tub＞CYP409A1) and the control tub＞attp40 by fluorescence measurements were measured.【Result】PCR amplification showed a clear single target band in flies tub＞CYP408B1 (1 555 bp) and tub＞CYP409A1 (1 585 bp), respectively. RT-PCR and RT-qPCR showed the locust CYP408B1 and CYP409A1 were expressed in transgenic Drosophila flies, respectively. Insecticide bioassay results indicated that the sensitivity of transgenic flies tub＞CYP408B1 and tub＞CYP409A1 to deltamethrin was higher than the control groups and that the resistance ratios were 1.59 and 1.83 compared with tub＞attp40, respectively. However, the sensitivity of flies to malathion and chlorpyrifos did not increase. Measurements of cytochrome P450 monooxygenase activity showed that transgenic flies (tub＞CYP408B1 and tub＞CYP409A1) had no significant differences compared with the control tub＞attp40 by fluorescence quantitative determination. 【Conclusion】The transgenic Drosophila lines UAS-CYP408B1 and UAS-CYP409A1 were successfully constructed by using transgenic technology. CYP408B1 and CYP409A1 play a role in the deltamethrin detoxification.

Insecticidal Protein Genes of Bacillus thuringiensis Strain CPB012 and Its Effects in Controlling Different Insect Pests

LU Hui-hui, LIN Zhi-qiang, TAN Wan-zhong, LUO Hua-dong, XIAN Fei, BI Chao-wei, YU Yang, YANG Yu-heng

Scientia Agricultura Sinica. 2015, 48(6):  1112-1121.  doi:10.3864/j.issn.0578-1752.2015.06.08

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【Objective】The objective of this study is to identify the functional genes, with their expressed proteins, and insecticidal spectrum of Bacillus thuringiensis strain CPB012. This will be important for effective application of CPB012 in pest control in the future.【Method】CPB012 was cultured at 30℃ on LB plates for two to three days and the bacterial cells were stained with phenol magenta for microscopy observation of the protein crystals. cry1-cry10 were identified with the polymerase chain reaction-restriction frame length polymorphism (PCR-RFLP) technique, namely, a universal primer pair for a group of genes was designed and used to amplify the genes with PCR. The amplified genes were then catalyzed with restriction enzymes and thus the polymorphism of the insecticidal genes were decided. On the other hand, specific primers were designed for identifying sub-group or genes (such as cry1A, cry2Aa. etc.) in groups cry1-cry10 via PCR amplification and then these genes were sequenced and compared. cry1-cry40 and vip groups were identified with PCR through the design of primers. The crystal proteins were extracted, respectively, from the bacterial cells cultured on LB plates for 24, 47, 72 and 96 hours and SDS-PAGE chromatographic fingerprint analysis was applied to demonstrate different insecticidal proteins. The lethality of Bombyx mori (Lepidoptera), Leptinotarsa decemlineata (Cleoptera) and Bactrocera dorsalis (Diptera) by CPB012 was measured in the laboratory, the cooperative effects of CPB012 and MJ07 strains of Beauveria bassiana were tested under both laboratory and field conditions. 【Result】Continuous microscopic observations found that CPB012 produced spherical and cubic protein crystals in blastosporic cells. Gene type analysis showed that B. thuringiensis CPB012 contained cry1Aa, cry1Ia, cry2Aa, cry2Ab and vip3A genes. These genes were shown via SDS-PAGE chromatographic fingerprint to code crystal proteins of about 135, 80, 70, and 85-90 kD, respectively. Also, the bacterium was demonstrated to contain two new crystal proteins which were 30 and 50 kD. Laboratory tests showed that CPB012 infected B. mori, B. dorsalis and L. decemlineata caused more than 76% deaths of each pest. After a mixture of B. thuringiensis CPB012 and B. bassiana MJ07 (mixed at 0.5: 0.5) was applied in a laboratory test, the cumulative mortality rate of 2nd-instar L. decemlineata larvae was 96.5%, which was significantly higher than that of individual CPB012 (83.3%) and that of MJ07 (90.1%). The LC₅₀ calculated from the multiple regression equation was 1.10×10⁷ cfu/mL and the CTC was 254, which indicated the combined use of the two biocontrol agents increased pest control efficacy markedly. Under the local field condition, the mixture of CPB012+MJ07 treatment also improved the pest control effect markedly; the cumulative mortality of the 1st- and 2nd-instar larvae were 47.5% and 43.8%, respectively, which were significantly higher than those of separate CPB012, MJ07 and commercial Bt preparation.【Conclusion】The insecticidal function of B. thuringiensis CPB012 was decided by cry1Aa, cry1Ia, cry2Aa, cry2Ab and vip3A and these genes encoded insecticidal proteins of 135, 80, 70, and 85-90 kD. This bacterium had wide spectrum of insecticidal activity which was shown by high death rates of B. mori, B. dorsalis and L. decemlineata induced by CPB012 treatment. The insecticidal efficacy was significantly improved by combined application of CPB012 of B. thuringiensis and MJ07 of B. bassiana. Therefore, CPB012 is thought of as a wide-spectrum biocontrol agent and will be of potential significance and great value in developing effective bio-insecticide.

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

Recent Progresses in Research of Integrating Multi-Source Remote Sensing Data for Crop Mapping

SONG Qian, ZHOU Qing-bo, WU Wen-bin, HU Qiong, YU Qiang-yi,TANG Hua-jun

Scientia Agricultura Sinica. 2015, 48(6):  1122-1135.  doi:10.3864/j.issn.0578-1752.2015.06.09

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Crop mapping by using the remotely-sensed images provide basic information for further geographical and ecological researches. A systematic review on the recent literature regarding crop mapping was carried out in order to improve our understanding on the integration and application of multi-source remote sensing data. The literature search was performed in Google Scholar, the ISI Web of Knowledge and CNKI (e.g. Topic =”crop + mapping”; Topic =”classification + multi-source”; timespan = 2000-2014). According to the thorough analysis on the existing publications, it is suggested that (1) there are two main ways to identify crop types based on the integration of multi-source data in order to expand the spatial and temporal scales. The techniques of multi-source data fusion, which are aimed at improving the spatial resolution, include image fusion, normal fuzzy distributed neural networks, component substitution, semi-physical fusion approach, and multiresolution wavelet decomposition. With the integrated application of such approaches, the spatial resolution and clarity of remote sensing images are raised; the effect of mixed pixels is weaken to some extent. Nevertheless, crop spectral information is partly lost or distorted. The techniques of multi-source data fusion, which are aimed at improving the temporal resolution, can be categorized into two types: the integration of the same data source, and the integration of different data sources. By using such approaches, the crossover of growth period among different crops can be effectively eliminated. But such approaches are susceptible to transformation models of spectral reflectance or vegetation indices, and the differences in band coverage among different remote sensing data. (2) The modes of multi-source data fusion can be categorized into three types according to the data types applied: integration of optical data, integration of optical and microwave data, and integration of remote sensing and ancillary data sources. Taking complementary advantages of various satellite data resources, these techniques of data fusion fully mine the differences of spectral, temporal and spatial characteristics, among various crop species. However, there still remain challenges in previous researches about the crop identification based on the fusion of multi-source remotely sensed data.

Zoning of Arable Land Productivity Based on Self-organizing Map in China

HUANG Ya-jie, YE Hui-chun, ZHANG Shi-wen, YUN Wen-ju, HUANG Yuan-fang

Scientia Agricultura Sinica. 2015, 48(6):  1136-1150.  doi:10.3864/j.issn.0578-1752.2015.06.10

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【Objective】The productivity of arable land is critical to food security in China. Investigating the factors controlling the productivity in different regions and influence mechanism is of importance to decision-making about reasonable utilization of arable land resources, policy regulation for remediation of contaminated land, constructing high-quality farmland, and accordingly, the national food security. 【Method】Firstly, the index system of natural and socio-economic factors was developed. These factors include soil fertility, climatic conditions, topography, economic investment and effective feedback. Then, the arable land in China was divided into regions with different productivities based on previous studies and land productivity gradations. Because the relationships between arable land productivity and its influencing factors are very complex, which are non-linear and multiple dimensional, self-organizing map was employed, which is a powerful approach for pattern analysis. U-matrix and component planes were used in order to visually interpret diversity and similarity of arable land productivity, and intuitively reflect the sensitive factors of regional changes. In addition, pressure index of arable land was used for correction of the clustered results. Finally, sub-regions with different arable land productivities were determined based on the resulted clusters, arable land productivity gradation, and the principles (including comprehensive consideration, relative consistency, regional conjugation and administrative units). 【Result】 Results show that spatial visibilities of soil fertility, climatic conditions , topography, economic investment and effective feedback in provinces were significant and these factors were developed non-equilibrium. The natural elements and socio-economic factors were both clustered in six groups. By using the aforementioned method, the arable land was divided into 10 regions and 24 sub-regions in China with different productivities. The 10 regions are as follows: Northeast plains region, Northern China plain and hills regions, the Loess Plateau regions, Shichuan basins, the Middle and lower reaches of the Yangtze River plain regions, Southern China hills regions, Yunnan-Guizhou Plateau regions, Inner Mongolian Plateau regions, Northwestern lands regions, and Qinghai-Tibet Plateau regions. Sub-regions were briefly described for arable land productivity regions with advantages and constraints. Finally, China arable land productivity zoning system was established. 【Conclusion】Taking natural factors, socio-economic factors and pressure index of arable land into consideration, zoning results are in accordance with the objective reality, indicating that self-organizing map is an effective method to monitor and identify novel relationships between arable land productivity and factors with an intricate visualization process, as well as extract and determine zoning of arable land productivity. In addition, government officers can readily identify existing advantages and limiting factors of arable land productivities in different regions in China.

Characteristics of Nitrogen Transportation and Fractions in Different Organs of Barley Genotype with High Nitrogen Utilization Efficiency

HUANG Yi, LI Ting-xuan, ZHANG Xi-zhou, JI Lin, WU Yi-po

Scientia Agricultura Sinica. 2015, 48(6):  1151-1161.  doi:10.3864/j.issn.0578-1752.2015.06.11

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【Objective】Nitrogen plays important roles in promoting plant growth and development. The objective of this study is to clarify the characteristics of distribution and transportation for barley nitrogen efficiency genotype, and to provide a theoretical basis for efficient nitrogen management and high-yield cultivation of good varieties.【Method】In this study, a soil culture pot experiment was conducted with barley genotype of high nitrogen utilization efficiency (DH61, DH121+) and low nitrogen utilization efficiency (DH80). Four nitrogen treatments were designed, including no nitrogen, low nitrogen (125 mgN·kg^-1 soil), normal nitrogen (250 mgN·kg^-1 soil) and high nitrogen (375 mgN·kg^-1 soil), respectively. The purpose was analysis grain yield, aboveground biomass , the characteristics of nitrogen transportation and fractions in different organs of barley with high nitrogen utilization efficiency (NUE) at late growth stage.【Result】When applied nitrogen reduced, the amount of aboveground biomass and grain yield were decreased among all tested cultivars. Under the same nitrogen application level, the amounts of biomass and grain yield of high NUE genotype were higher than that of low NUE genotype. The grain yield of high NUE genotype was, respectively, 1.96 times and 2.03 times, 2.10 times and 2.37 times higher than that of low NUE genotype in no nitrogen and low nitrogen treatments. Nitrogen concentration of high and low NUE genotype had no significant difference in no nitrogen and low nitrogen treatments at flowering and grain filling stages. High NUE genotype had a strong ability in dry matter forming. The amount of nitrogen accumulation of high NUE genotype was higher than that of low NUE genotype. And the ratio of nitrogen accumulation during the whole growth period of high NUE genotype was higher than that of low NUE genotype before flowering stage. Nitrogen accumulation of high NUE genotype was 1.48 times, 1.36 times and 1.37 times higher than that of low NUE in low nitrogen (125 mgN·kg^-1 soil), normal nitrogen (250 mgN·kg^-1 soil), and high nitrogen (375 mgN·kg^-1 soil) treatments. Adequate nitrogen accumulation of high NUE before flowering had laid a foundation for early filling of seeds. When applied nitrogen reduced, nitrogen translocation showed a single peak curve, nitrogen transfer rate and the amount of nitrogen transported to grain contribution rate gradually declined, over fertilization of nitrogen fertilizer is not conducive to grain transport. For high NUE genotype(DH61,DH121+), nitrogen in grain mainly relied on nitrogen translocation from vegetative organs, which accounted for 35.06%, 40.06% and 76.37%, 81.72% in no nitrogen and low nitrogen treatments, respectively; but for low NUE genotype(DH80), nitrogen in grain mainly relied on nitrogen uptake by root at reproductive stage which accounted for 68.20% and 34.84%. Higher transfer efficiency associated with different forms of nitrogen in plant composition and change. In different nitrogen treatments, assimilable nitrogen content in stalk and leaf increased, functional nitrogen content changes smoothly and structural nitrogen content was reduced from flowering to filling, while assimilable nitrogen content increased, and structural nitrogen content slowly declined in grain. High NUE showed a strong decline and nitrogen transport capacity of the structural nitrogen content. The structural nitrogen content of high NUE in stem and leaf decreased by 49.65% and 62.54% in low nitrogen treatment from flowering to filling, and it decreased by 66.54% and 28.17% from heading to maturity.【Conclusion】Grain nitrogen content of high NUE in stems and leaves is decided by the structural nitrogen content decomposition and transformation after flowering, and structural nitrogen recycling in vegetative organs conducive to nitrogen use efficiency.

HORTICULTURE

A Review on Molecular Mechanism of the Modified Roots or Stems Development in Vegetables

SUN Yu-yan, LI Xi-xiang

Scientia Agricultura Sinica. 2015, 48(6):  1162-1176.  doi:10.3864/j.issn.0578-1752.2015.06.12

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Modified roots or stems are the product organs of many important vegetables. To clarify the mechanisms of modified roots or stems formation is not only the main content for plant development biology, but also the guarantee of plant yield and quality improvement. Much progresses have been made in mechanisms of vegetable modified roots or stems development recently. The inheritance and molecular mechanism of modified roots or stems development in vegetable crops including radish, turnip, potato, lotus, mustard, yam and taro were reviewed in this paper. It mainly contained inheritance and QTL of their development associated traits, substances and energy metabolism for morphogenesis, cell cycle and cell expansion, regulation mechanisms including phytohormone, photoperiod and transcription factor effects in modified roots and stems. The related traits of modified roots or stems were controlled by QTL and some molecular markers linked to the important traits have also been developed for marker-assisted selection. Starch, sugar and protein provide the substances, energy and nutrition for modified roots or stems morphogenesis and a set of genes are involved in the metabolism of them. Besides, cell cycle is a temporal regulator of cell division and determines the cell number. Some regulatory proteins including cyclins, cyclin-dependent kinases and RB/E2F transcription factor are involved in cell cycle regulation. In addition, cell expansion, determining the cell size, is regulated by the expansin and xyloglucan endotransglucosylase/hydrolases. Moreover, plant hormones, such as gibberellin, auxin, abscisic acid, cytokinin and jasmonic acid, are the basic regulation factors involved in modified roots or stems development. Furthermore, photoperiod regulation is the dynamic signal for plant development. A large number of photoperiod related genes including Phytochrome, CONSTANS (GO), FLOWERING LOCUS T (FT)and APY are involved in modified roots or stems development. Lastly, the transcription factors, such as MADS-box, ABF/AREBand homeobox, play vital roles in modified roots or stems development. Meanwhile, the methods and technologies including small RNAs, epigenetics, comparative genomics, whole genome sequencing and genome-wide association study in molecular mechanism study of vegetables abnormal organ development were summarized.

Analysis of Expression of KT/HAK/KUP Family Genes and Their Responses to Potassium Fertilizer Application During Peach Flowering

SONG Zhi-zhong, GUO Shao-lei, MA Rui-juan, YU Ming-liang

Scientia Agricultura Sinica. 2015, 48(6):  1177-1185.  doi:10.3864/j.issn.0578-1752.2015.06.13

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【Objective】 The objective of this study is to analyze the transcriptional expression of KT/HAK/KUP family genes and response characteristics to potassium fertilizer application during different flowering stages, and key K⁺ transporter genes and its function. A close relationship between K⁺ nutritional status and flower development was discussed, thus providing a theoretical basis for K fertilization in orchards and genetic improvement and breeding of efficient horticulture crops.【Method】The K fertilizer treatment experiment was conducted via applying 834 g KCl (K₂O content 60%) to each ‘Xiahui6’ peach tree at flower bud expanding stage. The effect of K fertilizer application on flower development, K⁺ nutritional status and blooming date of peach trees was analyzed. The K⁺ concentration of peach flowers at different developmental stages was determined by using ICP-AES apparatus with HNO₃-HClO₄ digestion method. Quantitative real-time PCR was used to analyze the expression profiles of KT/HAK/KUP family genes during the whole flowering process, and the key K⁺ transporter genes were identified. The response of KT/HAK/KUP family genes to K fertilizer application at different developmental stages was also revealed. Functions of the key genes were validated by using heterologous complementation of bacterial function lossing mutant. Coding sequence of KUP11 was cloned into pPAB404 vector to obtain the recombinant expression vector pPAB404-KUP11. Sequencing verified recombinant vector was then transformed into functional mutant E. coli strain TK2420. Whether the recombinant vector pPAB404-KUP11 can restore the ability of TK2420 mutant strain to uptake external K⁺, supplied with either KCl or K₂SO₄, was determined.【Result】Application of K fertilizer treatment favorably induced ‘Xiahui6’ flowers to bloom 2-day earlier, and specifically contributed to flower development at full bloom stage, with an increase of 21.5% in fresh weight. The highest K⁺ accumulation occurred at full-bloom stage, which was followed by begin bloom, bud period and petal fall stages. Potasium application significantly enhanced the K⁺ nutritional status, with an increase of 24.3%, 27.4%, 29.1% and 26.3% of K⁺ concentration, respectively, during four flowering stages. Genes of KUP1-13 were differentially expressed during the four stages, and the highest expression level appeared especially in full-bloom stage. The KT/HAK/KUP family genes were differentially regulated by K, i.e., KUP1 and KUP5 were most sensitive to Kapplication, whose expression was consistently induced from bud swell stage to full-bloom stage. KUP11 was the most expressed gene throughout the whole flowering process, which was highly up-regulated at bud swell stage but greatly reduced at petal fall stage by K treatment. The recombinant expression vector pPAB404-KUP11 can restore the K⁺ uptake capacity in TK2420 bacterial mutant, and can utilize either external KCl or K₂SO₄, indicating that the expression level of KUP11 was positively correlated with the K⁺ uptake of bacterial cells.【Conclusion】Application of K fertilizer favorably promotes peach flower development, improves the K⁺ nutritional status, makes peach flower early to open, and differentially regulated KT/HAK/KUP family genes at different flowering stages. KUP11 transporter possesses the capacity to uptake external K⁺, which may play an important role in peach flowering.

STORAGE·FRESH-KEEPING·PROCESSING

Detection of Endpoint Temperature of Pork, Beef and Mutton by Differential Scanning Calorimetry

LIU Gong-ming, SUN Jing-xin, XU Xing-lian, HUANG Ming, LI Peng

Scientia Agricultura Sinica. 2015, 48(6):  1186-1194.  doi:10.3864/j.issn.0578-1752.2015.06.14

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【Objective】The Differential Scanning Calorimetry (DSC) was used in this test to scan the meat samples of pork, beef and mutton with different heat treatment temperatures. The purpose of this experiment is to study the relationship between the DSC thermogram and the heat treatment temperature of meat samples, to explore a sensitive and high-efficiency method to detect the EPT, in the hope of providing theoretical foundation for EPT detection during the actual production and circulation.【Method】Different heat treatments (for pork and mutton: 50℃, 60℃, 70℃, and 75℃; for beef: 50℃, 55℃, 65℃, 70℃, and 75℃）were carried out on a certain volume (2.0 cm×1.0 cm×1.0 cm) of meat cuboids. The meat cuboids were cooled to 4℃ after the center temperature reached to the aim temperature. The meat samples at 100.0 mg (the raw samples as control) taken from the center of meat cuboid were put into the thermoanalysis aluminium crucible. The crucible was sealed with lid and then balanced for a night at 4℃. A thermal scan was conducted from 40 to 80℃ at a constant heating rate of 1℃/min. The nitrogen flow was 20 mL·min^-1 and the shielding gas flow was 60 mL·min^-1. Finally, DSC thermograms of the meat samples with different center temperatures were obtained.【Result】The result showed that three peaks which had initial temperatures (pork: 50.83℃, 60.54℃, and 71.02℃; mutton: 50.76℃, 59.82℃, and 70.46℃; beef: 50.25℃, 56.29℃, and 71.92℃) and enthalpy of denaturation (pork: 0.4656 J·g^-1, 0.1394 J·g^-1, and 0.2053 J·g^-1; mutton: 0.0899 J·g^-1, 0.3116 J·g^-1, and 0.3842 J·g^-1; beef: 0.1078 J·g^-1, 0.4151 J·g^-1, and 0.3662 J·g^-1), respectively, were obtained from the raw pork, beef and mutton meat samples. The DSC thermograms of the three kinds of meat showed no significant changes when the heat treatment reached 50℃. The first peek vanished when the heat treatment reached 60℃ (for beef it reached 55℃), while, there were no obvious changes (P＞0.05) in the initial temperatures of the second and third peek but the enthalpy of that changed distinctly (P＜0.05). The second peek also disappeared when the heat treatment reached 70℃ (for beef it reached 65℃ and 70℃) and the initial temperatures of the last peeks changed slightly (P＞0.05), but the relevant enthalpy changed significantly (P＜0.05). All the three peaks of pork, beef and mutton meat samples vanished when the heat treatment temperature reached 75℃. It was concluded that the enthalpy of denaturation of the above meat samples gradually decreased and there were significant differences among the DSC thermograms of meat samples dealing with different temperatures. In this study, a success in EPT detection of the meat samples of different heat treatment temperatures was achieved.【Conclusion】Accordingly, the present study demonstrates that the denaturation of the above three kinds of meat has specificity to temperature and DSC can be used in the detection of EPT.

ANIMAL SCIENCE·VETERINARY SCIENCERE·SOURCE INSECT

Expression Profile of IGF-I-calcineurin-NFATc3-Dependent Pathway Genes in Skeletal Muscles and Their Associations with Myofiber Traits During Embryonic and Early Post-Hatching Development in Ducks

SHU Jing-ting, SONG Chi, XU Wen-juan, ZHANG Ming, SHAN Yan-ju, CHEN Wen-feng, SONG Wei-tao, TAO Zhi-yun, LI Hui-fang

Scientia Agricultura Sinica. 2015, 48(6):  1195-1204.  doi:10.3864/j.issn.0578-1752.2015.06.15

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【Objective】Insulin-like growth factor I (IGF-I)-calcineurin (CaN)-NFAT signal pathway have been implicated in the regulation of myocyte hypertrophy and fiber type specificity. In the present study, expression of CnAα, NFATc3 and IGF-I genes was firstly studied in Gaoyou and Jinding ducks differing in their muscle growth rates. 【Method】 Expression of IGF-I, CnAα and NFATc3 was quantified by RT-PCR in the breast muscle (BM) and leg muscle (LM) on days 13, 17, 21, 25 and, 27 of embryonic development, as well as at 7 days post-hatching (PH). Lateral gastrocnemius muscles collected from two duck breeds were cut at -20℃ using a cryotome and then stained with the method of myosin-ATPase in order to analyze muscle fiber type composition. SPSS 20.0 software was used to conduct the significant difference analysis, for investigating the possible regulation mechanism of IGF-I-CaN-NFAT pathway in myofiber type transition. 【Result】 Overall, the percentage of type I fibers increased and that of type IIb fibers decreased consistently. However, the percentage of type IIa fibers was almost constant as development proceeded in both duck breeds. The consistent expression patterns of CnAα, NFATc3 and IGF-I were found in the same anatomical location at different development stages in both duck breeds, showing extremely significant differences in age-specific fashion. However, the three genes were differentially expressed in different anatomical location (BM and LM). CnAα, NFATc3 and IGF-I mRNA could be detected as early as on E 13d, and the highest level was appeared at this stage in both BM and LM, significantly higher than those at the other five development stages, indicating that these three genes might have some effects on the ontogenesis of myofibers. The mRNA expression of duck CnAα in BM showed a tendency as the “V”, the lowest level appeared on E 21d, and then increased continuously up until 7 days PH in both duck breeds, while in LM, CnAα gene expression was variable throughout the course of this study and the lowest level appeared on E 27d. Expression of NFATc3 decreased significantly to a very low level from E 13d to E 17d and maintained this relative low level during late development stages in both BM and LM, the lowest level appeared on E 21d in BM while the expression level on E 21d in LM was significantly higher (P＜0.05) than those on embryonic days 17, 25 and 27, and at 7 days PH. Expression of IGF-I declined to the lowest level just prior to hatch (E 27d), and then elevated a little on 1 week PH in both BM and LM in the two duck breeds. Significant positive relationships were observed for the expression of studied genes in BM and LM of both duck breeds. Meanwhile, the expression of these three genes were all showed positive relationships with the percentage of type IIb fibers and negative relationships with the percentage of type I fibers and type IIa fibers. 【Conclusion】The data of the study indicate that the fiber type of the lateral gastrocnemius muscle may transit from type IIb to type I during late-embryonic and PH development, and differential expression and coordinated developmental regulation of the selected genes that comprise the IGF-I-calcineurin-NFATc3 pathwayin the duck skeletal muscles during embryonic and early PH growth and development, and this signaling pathway might play a role in the regulation of the myofiber type transition.

Safety Evaluation of Feeds from Genetically Modified Crops on Livestock and Poultry

CHEN Liang, HUANG Qing-hua, MENG Li-hui, XING Huan, YAO Bin, YANG Xiao-guang, ZHANG Hong-fu

Scientia Agricultura Sinica. 2015, 48(6):  1205-1218.  doi:10.3864/j.issn.0578-1752.2015.06.16

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The use of transferring foreign genes to plants has led to the dominant agronomic properties of crops, including insect resistance, herbicide tolerance, disease resistance and drought resistance. Since genetically modified (GM) crops were firstly cultivated in 1996, the cultivation area of GM crops has increased more than 100-fold reaching 175 million hectares worldwide in 2013. High portions of these GM crops and their by-products are fed to animals. The degradation and transportation of transgenic DNA and protein for GM feeds in the gastrointestinal tract and the possible effect of GM feeds or feed additive on animal nutrition, growth and health have been the focus of attention. The urgency and necessity of safety evaluation of GM feeds were proposed in the present paper. The difference of safety evaluation between the GM food and feeds were also analyzed. The scientific principles for safety evaluation and the characteristics of transgenic components in crops with insect-resistance, herbicide tolerance and phytase transgenic corn were discussed. This paper mainly reviewed the fate of transgenic DNA and protein, nutrient value and digestibility of GM feeds, and the effects of GM feeds on nutrition, immune response, reproduction performance and intestinal microbiota in livestock and poultry. Based on short-term, long-term, and multigenerational studies, there were no transfers of recombinant dietary DNA or protein to tissues, organs or blood, the transgenic components only presented in foregut digesta of animals, and no adverse effects of GM feeds on nutrition, immune response, reproduction performance and intestinal health of animals were found. The selected experimental materials, description of information, the method to assess the digestion and transportation of transgenic components of GM feeds, and the effects of GM feeds on immune response, reproduction performance and multigenerational effects on livestock and poultry were also analyzed synthetically to provide reference for establishment and further perfection of safety evaluation system of GM feeds.

RESEARCH NOTES

Changes of JA Levels in Floral Organs and Expression Analysis of JA Signaling Genes in Lodicules Before Floret Opening in Rice

HUANG Jun-bao, HE Yong-ming, ZENG Xiao-chun, XIANG Miao-lian, FU Yong-qi

Scientia Agricultura Sinica. 2015, 48(6):  1219-1227.  doi:10.3864/j.issn.0578-1752.2015.06.17

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【Objective】 The rice floret opening is driven by swelling of lodicules, and synchronized with filament elongation and anther dehiscence. The lipid-derived jasmonic acid (JA) is an important phytohormone in regulating plant reproductive development. In this study, the dynamic changes of endogenous jasmonic acid (JA) levels in floral organs and expression of JA signaling genes in lodicules were performed to investigate the roles of JA in rice floret opening. 【Method】 Floral organs (pedicels, lemmas and paleas, stamens, lodicules and pistils) of japonica rice Zhonghua 11 were harvested at 18 h and 0 h before natural floret opening. To quantify JA contents, 100 mg samples were ground in liquid nitrogen, extracted with mixed solution (methanol﹕water﹕acetic acid, 80﹕19﹕1, v/v/v), concentrated with nitrogen gas and filtered through 0.22 μm-pore filters, then measured using ultra-fast liquid chromatography-electrospray ionization tandem mass spectrometry (UFLC-ESI-MS). The rice total RNA was isolated with Trizol reagent. First-strand cDNAs were synthesized from DNaseI-treated total RNA using M-MLV reverse transcriptase. The expression patterns of genes related JA biosynthesis and signaling pathway were analyzed by real-time PCR using SYBR Green as dye. The rice GAPDH gene was used as endogenous control. The experiments were carried out with two biological replications. The statistical significance of differences between variants was estimated by t test.【Result】 At 18 h before floret opening, the highest JA level was found in pedicels (16.0 ng·g^-1 FW), followed by lemmas and paleas (6.1 ng·g^-1 FW), and with a very low accumulation in stamens, lodicules and pistils (less than 4.0 ng·g^-1 FW). During floret opening, JA levels increased by 71% in lemmas and paleas, and sharply increased in pistils, stamens and lodicules (reaching 19.0, 77.2 and 52.4 ng·g^-1 FW, respectively), contrasting with a 69% falling in pedicels. The JA levels in stamens and lodicules were significantly higher than that in other floral organ at floret opening, whereas the lowest JA level was found in pedicels. Consistent with the changes of JA levels, the expressionof OsDAD1, OsAOS1, OsAOC and OsOPR7 involved in JA biosynthesis pathway was sharply up-regulated in stamens and lodicules, and slightly increased in lemmas and paleas, but drastically down-regulated in pedicels during floret opening. Inconsistent with an increased JA level, no obvious expression changes of these JA biosynthetic genes were observed in pistils during floret opening. OsLOX2 and OsAOS2 had a high expression level in pedicels, lemmas and paleas, but a very low expression level in pistils, stamens and lodicules. With the rising of JA level, the expression of OsJAR1, OsCOI1b and 13 OsJAZs involved in JA signaling transduction was obviously up-regulated in lodicules during floret opening. Among them, the expression level of OsJAZ11 increased the most, and exhibited a 520-fold up-regulation. However, the expression level of OsJAR2, OsCOI1a, OsCOI1b, OsJAZ5 and OsJAZ15 was not increased in lodicules.【Conclusion】 The results of study showed that the occurrence of endogenous JA signature was tissue- and developmental stage- specific in rice floret. On the basis of the opening of rice florets induced by application of exogenous JA, the accumulation of JA and the differential activation of key genes in JA biosynthesis and signaling pathway in lodicules during floret opening suggested that endogenous JA was involved in regulation of lodicule swelling.

Identification of Resistance to Main Virus Diseases and Genetic Diversity Study of Tobacco Foundation Parents

DAI Shuai-shuai, REN Min, JIANG Cai-hong, CHENG Ya-zeng, GENG Rui-mei, ZHANG Xing-wei, CHENG Li-rui, YANG Ai-guo

Scientia Agricultura Sinica. 2015, 48(6):  1228-1239.  doi:10.3864/j.issn.0578-1752.2015.06.18

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【Objective】 This study aims to assess the viral disease resistances of the tobacco foundation parents, and to analyze their genetic diversity and phylogenetic relationship. 【Method】 A total of 73 flue-cured tobacco foundation parents were evaluated for resistances to three kinds of virus diseases by artificial inoculation in the green house. Furthermore, the genetic diversity of 29 resistant foundation parents and additional 4 foundation parents were analyzed using 103 pairs of polymorphism SSR markers distributed on the whole tobacco genome. 【Result】 Different cultivars displayed a wide range of variation for resistances to CMV, TMV and PVY. As for CMV, a total of 23 cultivars exhibited high resistances to CMV, although the cultivars exhibited immunity to CMV were not identified. As for TMV, six cultivars exhibited immunity to TMV. As for PVY, five cultivars exhibited immunity to PVY. In sum, two cultivars, Longyan1 and FC8, exhibited immunity to TMV and PVY, respectively. In addition, seven cultivars including CV87, T.T.11, Kang88, CV91, Tailifu1060, Gexin5 and T.I.245, exhibited resistances to three kinds of virus diseases. The genotypes of 29 resistant foundation parents and additional 4 foundation parents were identified with 103 SSR markers. The total numbers of alleles amplified at the 103 SSR loci were 322 and the mean number of alleles detected for each locus was 3.106, ranging from 2 to 6 alleles. The genetic diversity spanned from 0.059 to 0.716, with an average of 0.387. The PIC value ranged from 0.057 to 0.661, with an average of 0.343. According to UPGMA cluster analysis, the 33 tested cultivars were divided into seven clusters with a cut-off of threshold value as 0.672 and the cultivars belonged to the first group were further subdivided into four clusters with a cut-off of threshold value as 0.714. Principle coordinate analysis (PCoA) showed that the 33 tested cultivars were divided into six clusters, which are in agreement with the results of clustering analysis. The results of molecular clustering largely agreed with the pedigree relationship.【Conclusion】 A total of 29 flue-cured tobacco foundation parents exhibited the resistance to tobacco main virus diseases. The genetic relationships among the groups of genotyped cultivars are in agreement with pedigree relationship. The resistant foundation parents from China showed a relatively higher genetic basis.

Analysis of Relationship Between Variations of Main Agronomic Traits and Yield in Garlic

KONG Su-ping, SUN Jing-qiang, WU Xiong, YANG Yan-yan, HUO Yu-meng, XU Kun

Scientia Agricultura Sinica. 2015, 48(6):  1240-1248.  doi:10.3864/j.issn.0578-1752.2015.06.19

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【Objective】Garlic is a clonal propagation crop. This makes it difficult to breed new garlic varieties by conventional method. Accordingly, the purpose of this study was to analyze the variation of agronomic traits and to explore the traits controlling the yielding of garlic, wishing to provide important information for germplasm evaluation and innovation to select the high yielding garlic varieties.【Method】In this study, 16 agronomic traits of 78 garlic varieties were analyzed. The relationship of main agronomic traits, including garlic-scape, weight of bulbs and number of cloves were studied to identify the primary indexes of garlic-scapeand bulb yield using the methods of correlation analysis, principal component analysis, multiple linear regression analysis and path analysis.【Result】The results showed that variations in main agronomic traits of garlic varieties were abundant and its coefficient of variation was ranging from 11.1% to 64%. Among the main agronomic traits, the garlic-scape had the most variation in related traits, the weight of bulbs and number of cloves had less variation, taking the second place while the ideotype traits had the least variation ratio. The bulb weight was positively correlated with other agronomic traits significantly, in which clove-width was not included. A significant positive correlation was clearly established between other agronomic traits, except leaf-angle and clove-number. Principal component analysis showed that plant type factors, garlic-scape factors, leaf and clove factors were largely responsible for the yield of garlic-bulb and garlic-scape . Regression models, which successfully forecasted the relationships not only between agronomic traits but also between garlic yield bulb and scape were established by stepwise regression analysis. Statistical test was performed and the results showed that the correlation coefficient was significant, the coefficients of garlic bulb and scape were 0.8516 and 0.9449, respectively. Furthermore , path analysis indicated that the main factors that influenced bulb yield were cross diameter of bulb (0.5353), clove length (0.1652), number of cloves (0.147), diameter of pseudostem (0.1136) and number of leaves (0.1036). On the other hand, the main factors that influenced garlic-scape yield were diameter of garlic-scape (0.8875), plant height (0.1585) and number of cloves(-0.1382). 【Conclusion】Garlic germplasm had high-level genetic diversity. And the extremely significant correlation between agronomic traits was clearly indicated. The key agronomic traits which had influence on them were still significantly distinguished. The only exception was for the garlic-scape and bulb, the variety which grows higher had higher yield of garlic-scape, and the variety which had wider diameter of pseudostem had higher yield of bulb.