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    Crop Genetics · Breeding · Germplasm Resources
    Quantitative Trait Loci for Grain Chalkiness and Endosperm Transparency Detected in Three Recombinant Inbred Line Populations of Indica Rice
    MEI De-yong, ZHU Yu-jun, YU Yong-hong, FAN Ye-yang, HUANG De-run, ZHUANG Jie-yun
    2013, 12(1): 1-11.  DOI: 10.1016/S2095-3119(13)60199-9
    Abstract ( )   PDF in ScienceDirect  
    Quantitative trait loci (QTL) for percentage of chalky grain, degree of chalkiness, and endosperm transparency were detected using 3 recombinant inbred line populations derived from crosses between parental lines of commercial three-line hybrids of indica rice. Two of the populations showed great variations on heading date, and the other had a short range of heading date variation. A total of 40 QTLs were detected and fell into 15 regions of 10 chromosomes, of which 5 regions were detected for 1 or more same traits over different populations, 2 were detected for different traits in different populations, 3 were detected for 2 or all the 3 traits in a single population, and 5 were detected for a single trait in a single population. Most of these QTLs have been reported previously, but a region located on the long arm of chromosome 10 showing significant effects in all the 3 populations has not been reported before. It was shown that a number of gene cloned, including the Wx and Alk for the physiochemical property of rice grain, and GW2, GS3 and GW5 for grain weight and grain size, could have played important roles for the genetic control of grain chalkiness in rice, but there are many more QTLs exerting stable effects for rice chalkiness over different genetic backgrounds. It is worth paying more attentions to these regions which harbor QTL such as the qPCG5.2/qDC5.2/qET5.2 and qPCG10/qDC10/qET10 detected in our study. Our results also showed that the use of segregating populations having high-uniform heading date could greatly increase the efficiency of the identification of QTL responsible for traits that are subjected to great environmental influence.
    Morphological, Biochemical and Genetic Analysis of a Brittle Stalk Mutant of Maize Inserted by Mutator
    FU Xue-qian, FENG Jing, YU Bin, GAO You-jun, ZHENG Yong-lian, YUE Bing
    2013, 12(1): 12-18.  DOI: 10.1016/S2095-3119(13)60200-2
    Abstract ( )   PDF in ScienceDirect  
    Mutants on stalk strength are essential materials for the studies on the formation of plant cell wall. In this study, a brittle stalk mutant of maize, designated as Bk-x, was screened from a Mutator inserted mutant library. At the germination and early seedling stage, the mutant plants were indistinguishable from the normal ones. However, all of the plant organs were brittle after the 5th-leaf stage and remained brittle throughout the rest of the growing period. Microstructure observation showed that the cell wall in vascular bundle sheath of Bk-x was thinner than that in normal plants. The leaf mechanical strength in Bk-x was 77.9% of that in normal plants growing at Xishuangbanna (BN), Yunnan province and that was 61.7% in Wuhan (WH), Hubei Province, China. The proportion of cellulose was 12.3% in Bk-x, which was significantly lower than that in normal plants (26.7%), while the soluble sugar content was 36.1% in Bk-x, which is significantly higher than that in normal plants (12.4%). Genetic analysis using two F2 populations and one F2:3 families demonstrated that the trait of brittle stalk is controlled by a single recessive gene.
    Combining Ability and Parent-Offspring Correlation of Maize (Zea may L.) Grain b-Carotene Content with a Complete Diallel
    LI Run, XIAO Lan-hai, WANG Jing, LU Yan-li, RONG Ting-zhao, PAN Guang-tang, WU Yuan-qi, TANGQilin , LAN Hai, CAO Mo-ju
    2013, 12(1): 19-26.  DOI: 10.1016/S2095-3119(13)60201-4
    Abstract ( )   PDF in ScienceDirect  
    Vitamin A deficiency has become a worldwide problem. Biofortified foods can potentially be an inexpensive, locally adaptable, and long-term solution to dietary-nutrient deficiency. In order to improve the b-carotene content in maize grain by breeding and minimize vitamin A deficiency, a complete diallel cross was designed with eight inbred lines of maize, and 64 combinations were obtained in this study. The experimental combinations were planted in Yunnan and Sichuan provinces, respectively, with a random complete block design. The b-carotene contents in the grains of the experimental materials were analyzed by high-performance liquid chromatography. Among the tested materials, the effect difference of general combining ability of the b-carotene content was significant; however, the effect difference of the special combining ability and the reciprocal effect were not significant. The b-carotene content of maize grain was not influenced significantly by the cross and the reciprocal cross. There was a significant correlation about the b-carotene content in the maize grains between the F1 and their parents. The combinations with high b-carotene content were obviously influenced by the environment, and the mean value of b-carotene content for the experimental materials planted in Ya’an of Sichuan was higher than that planted in Yuanjiang of Yunnan, with the results being significant at the 0.01 level.
    Molecular Cloning and Functional Characterization of a Salt Tolerance- Associated Gene IbNFU1 from Sweetpotato
    WANG Lian-jun, HE Shao-zhen, ZHAI Hong, LIU De-gao, WANGYan-nan , LIU Qing-chang
    2013, 12(1): 27-35.  DOI: 10.1016/S2095-3119(13)60202-6
    Abstract ( )   PDF in ScienceDirect  
    Iron-sulfur cluster biosynthesis involving the nitrogen fixation (Nif) proteins has been proposed as a general mechanism acting in various organisms. NifU-like protein may play an important role in protecting plants against abiotic and biotic stresses. Based on the EST sequence selected from salt-stressed suppression subtractive hybridization (SSH) cDNA library constructed with a salt-tolerant mutant LM79, a NFU gene, termed IbNFU1, was cloned from sweetpotato (Ipomoea batatas (L.) Lam.) via rapid amplification of cDNA ends (RACE). The cDNA sequence of 1 117 bp contained an 846 bp open reading frame encoding a 281 amino acids polypeptide with a molecular weight of 30.5 kDa and an isoelectric point (pI) of 5.12. IbNFU1 gene contained a conserved Cys-X-X-Cys motif in C-terminal of the iron-sulfur cluster domain. The deduced amino acid sequence had 66.08 to 71.99% sequence identity to NFU genes reported in Arabidopsis thaliana, Eucalyptus grandis and Vitis vinifera. Real-time quantitative PCR analysis revealed that the expression level of IbNFU1 gene was significantly higher in the roots of the mutant LM79 compared to the wild-type Lizixiang. Transgenic tobacco (cv. Wisconsin 38) plants expressing IbNFU1 gene exhibited significantly higher salt tolerance compared to the untransformed control plants. It is proposed that IbNFU1 gene has an important function for salt tolerance of plants.
    Functional Analysis of the Phosphoenolpyruvate Carboxylase on the Lipid Accumulation of Peanut (Arachis hypogaea L.) Seeds
    PAN Li-juan, YANG Qing-li, CHI Xiao-yuan, CHEN Ming-na, YANG Zhen, CHEN Na, WANG Tong, WANG Mian, HE Ya-nan, YU Shan-lin
    2013, 12(1): 36-44.  DOI: 10.1016/S2095-3119(13)60203-8
    Abstract ( )   PDF in ScienceDirect  
    Phosphoenolpyruvate carboxylase (PEPC; EC catalyses phosphoenolpyruvate (PEP) to yield oxaloacetate, which is involved in protein biosynthesis. Pyruvate kinase (PK; EC catalyzes PEP to yield pyruvate, which is involved in fatty acid synthesis. In this study, five PEPC genes (AhPEPC1, AhPEPC2, AhPEPC3, AhPEPC4, and AhPEPC5) from peanut have been cloned. Using a quantitative real-time RT-PCR approach, the expression pattern of each gene was monitored during the seed development of four peanut varieties (E11, Hebeigaoyou, Naihan 1, and Huayu 26). It was found that these five genes shared similar expression behaviors over the developmental stages of E11 with high expression levels at 30 and 40 d after pegging (DAP); whereas these five genes showed irregular expression patterns during the seed development of Hebeigaoyou. In Naihan 1 and Huayu 26, the expression levels of the five genes remained relatively high in the first stage. The PEPC activity was monitored during the seed development of four peanut varieties and seed oil content was also characterized during whole period of seed development. The PEPC activity followed the oil accumulation pattern during the early stages of development but they showed a significantly negative correlation thereafter. These results suggested that PEPC may play an important role in lipid accumulation during the seed development of four peanut varieties tested.
    Spatial and Temporal Characteristics of Rice Potential Productivity and Potential Yield Increment in Main Production Regions of China
    JIANG Xiao-jian, TANG Liang, LIU Xiao-jun, CAO Wei-xing , ZHU Yan
    2013, 12(1): 45-56.  DOI: 10.1016/S2095-3119(13)60204-X
    Abstract ( )   PDF in ScienceDirect  
    The vast area and marked variation of China make it difficult to predict the impact of climate changes on rice productivity in different regions. Therefore, analyzing the spatial and temporal characteristics of rice potential productivity and predicting the possible yield increment in main rice production regions of China is important for guiding rice production and ensuring food security. Using meteorological data of main rice production regions from 1961 to 1970 (the 1960s) and from 1996 to 2005 (the 2000s) provided by 333 stations, the potential photosynthetic, photo-thermal and climatic productivities in rice crop of the 1960s and 2000s in main rice production regions of China were predicted, and differences in the spatial and temporal distribution characteristics between two decades were analyzed. Additionally, the potential yield increment based on the high yield target and actual yield of rice in the 2000s were predicted. Compared with the 1960s, the potential photosynthetic productivity of the 2000s was seen to have decreased by 5.40%, with rates in northeastern and southwestern China found to be lower than those in central and southern China. The potential photo-thermal productivity was generally seen to decrease (2.56%) throughout main rice production regions, decreasing most in central and southern China. However, an increase was seen in northeastern and southwestern China. The potential climatic productivity was observed to be lower (7.44%) in the 2000s compared to the 1960s, but increased in parts of central and southern China. The potential yield increment from the actual yield to high yield target in the 2000s were no more than 6×103 kg ha-1 and ranged from 6×103 to 12×103 kg ha-1 in most of the single- and double-cropping rice growing regions, respectively. The yield increasing potential from the high yield target to the potential photo-thermal productivity in 2000s were less than 10×103 kg ha-1 and ranged from 10×103 to 30×103 kg ha-1 in most of the single- and double-cropping rice growing regions, respectively. The potential yield increment contributed by irrigation was between 5×103 and 20×103 kg ha-1, and between 20×103 and 40×103 kg ha-1 in most of the single- and double-cropping rice growing regions, respectively. These findings suggested that the high yield could be optimized by making full use of climatic resources and through a reasonable management plan in rice crop.
    Performance in Grain Yield and Physiological Traits of Rice in the Yangtze River Basin of China During the Last 60 yr
    ZHANG Hao, CHEN Ting-ting, LIU Li-jun, WANG Zhi-qin, YANG Jian-chang , ZHANG Jian-hua
    2013, 12(1): 57-66.  DOI: 10.1016/S2095-3119(13)60205-1
    Abstract ( )   PDF in ScienceDirect  
    Knowledge on the performance in grain yield and physiological traits is essential to understand the main yield-limiting factor and make strategies for breeding and crop management in rice (Oryza sativa L.). This study investigated the changes in grain yield and associated physiological traits of rice in the Yangtze River Basin of China during the last 60 yr. Thirteen mid-season indica and 12 japonica rice cultivars that were popularly used were grown in the field in 2008 and 2009. The grain yield and yield components, biomass, leaf area, leaf photosynthesis, root oxidation activity, and harvest index were examined. The results showed that grain yield and grain yield per day have progressively increased during the years and such increases are mainly attributed to the expanded sink size as a result of more spikelets per panicle, especially for the case of super rice. Both biomass and harvest index were increased with the improvement of cultivars. Increase in biomass for modern rice cultivars was associated with an enhancement of leaf area and photosynthesis, root dry weight, and root oxidation activity, although the indica super rice cultivars showed a lower leaf photosynthetic rate and root oxidation activity than the semi-dwarf cultivars during the grain filling period. Both indica and japonica super rice cultivars exhibited a low percentage of filled grains, which may limit their great yield potential. All the data suggested that grain yield have been substantially improved during the 60 yr of rice breeding in the Yangtze River Basin. Expanded sink size, increased dry matter production and harvest index, and enhanced leaf area and photosynthesis, root dry weight, and root oxidation activity contribute to the improvement in grain yield. Increase in filling efficiency could realize the great yield potential in super rice.
    Modeling Fiber Fineness, Maturity, and Micronaire in Cotton (Gossypium hirsutum L.)
    ZHAO Wen-qing, ZHOU Zhi-guo, MENG Ya-li, CHEN Bing-lin, WANG You-hua
    2013, 12(1): 67-79.  DOI: 10.1016/S2095-3119(13)60206-3
    Abstract ( )   PDF in ScienceDirect  
    Crop performance is determined by the combined effects of the genotype of the crop and the environmental conditions of the production system. This study was undertaken to develop a dynamic model for simulating environmental (temperature and solar radiation) and N supply effects on fiber fineness, maturity and micronaire. Three different experiments involving genotypes, sowing dates, and N fertilization rates were conducted to support model development and model evaluation. The growth and development duration of fiber fineness, maturity, and micronaire were scaled by using physiological development time of secondary wall synthesis (PDTSWSP), which was determined based on the constant ratio of SWSP/ BMP. PTP (product of relative thermal effectiveness (RTE) and photosynthetically active radiation (PAR), MJ m-2) and subtending leaf N content per unit area (NA, g m-2) and critical subtending leaf N content per unit area (CNA, g m-2) of cotton boll were calculated or simulated to evaluate effects of temperature and radiation, and N supply. Besides, the interactions among temperature, radiation and N supply were also explained by piecewise function. The overall performance of the model was calibrated and validated with independent data sets from three field experiments with two sowing dates, three or five flowering dates and three or four N fertilization rates for three subsequent years (2005, 2007, and 2009) at three ecological locations. The average RMSE and RE for fiber fineness, maturity, and micronaire predictions were 372 m g-1 and 5.0%, 0.11 m g-1 and 11.4%, 0.3 m g-1 and 12.3%, respectively, indicating a good fit between the simulated and observed data. It appears that the model can give a reliable prediction for fiber fineness, maturity and micronaire formation under various growing conditions.
    Respiratory Response of Dormant Nectarine Vegetative Buds to High Temperature Stress
    TAN Yue, LI Ling, LENG Chuan-yuan, LI Dong-mei, CHEN Xiu-de, GAO Dong-sheng
    2013, 12(1): 80-86.  DOI: 10.1016/S2095-3119(13)60207-5
    Abstract ( )   PDF in ScienceDirect  
    High temperature stress (HT) is efficient in breaking endo-dormancy of perennial trees. The effects of HT (50°C) on the respiration of dormant nectarine (Prunus persica var. nectariana cv. Shuguang) vegetative buds were evaluated in the research. We found that bud respiration was transiently inhibited by HT and the pentose phosphate pathway (PPP) and the cytochrome C pathway (CYT) were significantly affected. On the substrate level, PPP was activated in the HT-treated buds compared with the control group. However, the activation did mot occur until hours after HT treatment. The tricarboxylic acid cycle (TCA) in both the HT-treated buds and in the control group proceeded at a low level most of the time compared with total respiration. On the electron transfer level, CYT was transiently inhibited by HT but became significantly active in the later stage. CYT operation in the control group exhibited an attenuation process. The alternative pathway (ALT) fluctuated both in the HT-treated samples and in the control. The results suggest that the temporary CYT inhibition and the following PPP activation may be involved in HT-induced bud dormancy release and budburst mechanisms.
    Assessment of Risk of Establishment of Wheat Dwarf Bunt (Tilletia controversa) in China
    JIA Wen-ming, ZHOU Yi-lin, DUAN Xia-yu, LUO Yong, DING Sheng-li, CAO Xue-ren , Bruce D LFitt
    2013, 12(1): 87-94.  DOI: 10.1016/S2095-3119(13)60208-7
    Abstract ( )   PDF in ScienceDirect  
    Wheat dwarf bunt, caused by Tilletia controversa Kühn (TCK), is an important quarantine wheat disease throughout the world. Based on published research results of the biology and the epidemiology of the disease, the main factors including temperature, humidity, snow cover, and their parameters relating to teliospore germination, infection and epidemics of TCK were determined. The geophytopathological models for the risk analysis of wheat dwarf bunt establishment were modified. Fifty-year meteorologic data from about 500 weather stations in China were used to calculate the probabilities of TCK establishment in different geographic sites with the models. The map that displays the establishment risk of TCK in winter wheat growing regions in China was generated by using geographical information system (GIS). The zones showing high, moderate, low, and very low, including no risk, of TCK establishment accounted for 27.33, 27.69, 38.12, and 6.86% of total winter wheat growing areas in China, respectively. These results will provide useful information to formulate quarantine regulations and wheat importation policy in China.
    ASimpleMethod for the Isolation andPurification of 2,4-Dihydroxy-7-Methoxy- 2H-1,4-Benzoxazin-3(4H)-One (DIMBOA) from Maize (Zea mays L.) Seedlings
    LI Jing, LIU Xin-gang, DONG Feng-shou, XU Jun, GUO Li-qun, KONG Zhi-qiang, TIAN Ying-ying, WU Yan-bin , ZHENG Yong-quan
    2013, 12(1): 95-102.  DOI: 10.1016/S2095-3119(13)60209-9
    Abstract ( )   PDF in ScienceDirect  
    2,4-Dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA), the dominant benzoxazinoid hydroxamic acid in maize (Zea Mays L.), serves as important factors of resistance against insects and microbial diseases, allelochemicals used in competition with other plants. In this paper, a novel and simple method for the isolation and purification of DIMBOA from maize seedlings was developed. Frozen shoots from 7-d-old maize seedlings (1 000×g) were firstly defrosted and then were directly homogenized and extracted with ethyl acetate. The macerate was allowed to stand at room temperature (25±2)°C for 1 h to allow enzymatic release of DIMBOA from DIMBOA-glucoside. Then the ethyl acetate phase was filtered, dried and evaporated to dryness. The resulting light-tan, semicrystalline residue was stored at -20°C for 24 h. Upon recrystallization from acetone-hexane, a relative higher yield (0.58 g) of pure DIMBOA crystals was obtained compared with the yield afforded by Woodward methodology (0.26 g).
    Characterization of Porcine Matrix Metalloproteinase 23 (pMMP-23) Gene and Its Association with Litter Size Traits
    NIU Bu-yue, LAN Xiao-ming, YAN Xiao-hong, DI Sheng-wei, WANG Yang, LI Hai-tao, XIONG Yuanzhu, WANG Xi-biao
    2013, 12(1): 103-109.  DOI: 10.1016/S2095-3119(13)60210-5
    Abstract ( )   PDF in ScienceDirect  
    The matrix metalloproteinase 23 (MMP-23), which might play a role in ovulation in mammals, was one of the promising candidate genes for litter size traits in pigs. In the present research, partial sequence of porcine MMP-23 (pMMP-23) gene, including exons 2-8 (GenBank: EU360790), was obtained. Real-time PCR analysis revealed that pMMP-23 gene was highly expressed in ovary. PCR-Sau3A I-RFLP and PCR-Acc II-RFLP assay were established to detect a C/T mutation in exon 3 (EU360790: g. 269C>T) and an A/G mutation in exon 4 (EU360790: g. 505A>G), respectively. Association study for these two SNPs with litter size was assessed in three independent populations (Minzhu, Landrace I and Landrace II). Statistical analysis demonstrated that for second and subsequent litters, TT sows produced more TNB than CC pigs in Landrace breed (P<0.05) at g. 269C>T locus, and the additive effect was significant (P<0.05); GG sows produced more TNB and NBA than AA pigs in Minzhu (P<0.01) and Landrace breeds (P<0.05) at g. 505A>G locus, and the additive effect was significant (P<0.01 or P<0.05). Our study suggested that the pMMP-23 gene might be a novel candidate gene for litter size traits, and g. 505A>G locus might be a useful molecular marker for marker assisted selection (MAS).
    Fine Mapping QTLs Affecting Milk Production Traits on BTA6 in Chinese Holstein with SNP Markers
    LIU Rui, SUN Dong-xiao, WANG Ya-chun, YU Ying, ZHANG Yi, CHEN Hui-yong, ZHANG Qin, ZHANG Sheng-li , ZHANG Yuan
    2013, 12(1): 110-117.  DOI: 10.1016/S2095-3119(13)60211-7
    Abstract ( )   PDF in ScienceDirect  
    Our previous studies demonstrated that the region around markers BMS470 and BMS1242 on BTA6 showed a linkage to 305-d milk yield and composition traits in the Chinese Holstein population. We herein focused on such narrow region to fine map milk production QTLs with 15 SNPs across 25 Mb with each SNP in 1 Mb within most regions in a Chinese Holstein population with daughter design. 1 449 Holstein cows and 11 sires were genotyped for such SNPs by using TaqMan probe and RFLP assays. Multipoint linkage analysis across family revealed a QTL affecting milk yield between PPARGC1A C4075T and SLC34A2 T1713C. Meanwhile, within family analysis found three milk yield QTLs (two in CR T60984131G-CEP135 C501T and one in PDLIM5 A106C-OPN T3907, a fat yield QTL in UGDH T1670C-CR T60984131G region, and two protein yield QTLs in TBC1D1 G501C-UGDH T1670C and PPARGC1A C4075T-SLC34A2 T1713C, respectively. Associations between aforementioned significant SNP markers and milk production traits were further implemented. We found significant associations of PPARGC1A C4075T, SLC34A2 T1713C with milk yield (P<0.05, P<0.01, P<0.01), UGDH T1670C, and CR T60984131G with fat yield (P<0.01, P<0.01), and PPARGC1A C4075T, SLC34A2 T1713C, UGDH T1670C and OPN T3907 with protein yield (P<0.01, P<0.01, P<0.01, P<0.01). Our findings implied that QTLs affecting milk production traits on BTA6 were pleictropism or multigenic effect and PPARGC1A and OPN may be the causal mutations behind milk production QTLs on BTA6 in the Chinese Holstein population.
    Exploring the Novel Genetic Variant of PITX1 Gene and Its Effect on Milk Performance in Dairy Goats
    LAN Xian-yong, ZHAO Hai-yu, LI Zhuan-jian, ZHOU Rui, PAN Chuan-ying, LEI Chu-zhao, CHEN Hong
    2013, 12(1): 118-126.  DOI: 10.1016/S2095-3119(13)60212-9
    Abstract ( )   PDF in ScienceDirect  
    Paired-like homeodomain transcription factor 1 (PITX1) plays an important role in pituitary development by indirectly regulating the expression of the GH and PRL genes, and therefore PITX1 gene is regarded as a potential candidate gene for building the relationship between the gene polymorphism and milk traits. The aim of this study was to explore the novel genetic variant in PITX1 gene and its effect on milk performance in dairy goats. Herein, a novel genetic variation (NW_00314033: g.201G>A or IVS1+41G>A) located at nt41 position of the first intron of the goat PITX1 gene was reported at the P1 locus, which can be genotyped by the Msp I PCR-RFLP. In the Msp I PCR-RFLP analyis, the GG variant was a major genotype, and the A variant was a minor allele in Guanzhong dairy goats which was at Hardy-Weinberg disequilibrium (chi-square c2=140, P<0.01). The establishment of associations between different genotypes and milk performance was performed in the analyzed population. A total of three significant associations of the polymorphism with average milk fat content (%) (P=0.045), morning milk fat content (%) (P=0.049), and afternoon milk fat content (%) (P=0.050), were found, respectively. A significant relationship between the polymorphism and average total solid content (P=0.029) was also detected. This novel single nucleotide polymorphism (SNP) extended the spectrum of genetic variation of the goat PITX1 gene, and its significant association with milk performance would benefit from the application of DNA markers related to improving milk performance through marker-assisted selection (MAS) in dairy goats.
    Expression of Sex-RelatedGenes in Chicken Embryos During Male-to-Female Sex Reversal Exposure to Diethylstilbestrol
    FANG Li-xiu, XIN Rui, CHEYi , XU Shi-qing
    2013, 12(1): 127-135.  DOI: 10.1016/S2095-3119(13)60213-0
    Abstract ( )   PDF in ScienceDirect  
    Sex emerges out of a delicate dance between a variety of promale, anti-male, and possibly profemale genes. To investigate the role that sex-related genes play in sex determination and gonadal differentiation of fowl, we constructed a male-tofemale sex-reversal model of chick induced by diethylstilbestrol (DES) at onset of incubation (E0). The results of semiquantitative PCR showed that the expression of Sf1, the orphan nuclear receptor steroidogenic factor-1 gene, was put forward from E7d to E5d and up-regulated during E5-7d; the Dmrt1, the double sex and the Mab-3 related to transcription factor 1 gene, was down-regulated during E3-7d. Meanwhile, anti-Müllerian hormone gene (Amh) expressed at a similar level in the genetic females and sex-reversal females before E7d, while no expression products of the three female-specific genes Wpkci, Fet1 and Foxl2 were detected in male-to-female embryos. These findings suggest that the expression of some certain sex-related genes, induced by the exogenous estrogen during period of sex determination and gonadal differentiation, results in the male-to-female sex reversal. Moreover, high activity of Sf1 gene during E5-7d might be related to the profemale process, while low activity of Dmrt1 gene during E3-5d might be anti-male. The expression activity of Amh gene might only contribute to the promale process after E7d, however, it is possibly not an anti-female gene in chick embryos.
    Identification of Novel and Differentially ExpressedMicroRNAs in the Ovaries of Laying and Non-Laying Ducks
    YU De-bing, JIANG Bao-chun, GONG Jing, DONG Fu-lu, LU Ying-lin, YUE Hui-jie, WANG Zhengchao
    2013, 12(1): 136-146.  DOI: 10.1016/S2095-3119(13)60214-2
    Abstract ( )   PDF in ScienceDirect  
    MicroRNAs (miRNAs), which post-transcriptionally regulate gene expression by binding to the 3´ untranslated region of mRNAs to either inhibit or enhance translation, are involved in diverse biological processes. The use of high-throughput Solexa sequencing plays important roles in the discovery of miRNAs. In this study, we used high-throughput Solexa sequencing to identify novel duck miRNAs and compare the miRNA expression profiles in laying and non-laying duck ovaries. Using a bioinformatic analysis, we discovered 86 potential duck miRNAs similar to known chicken miRNAs and 43 unique sequences that matched known miRNAs of other species. We also found that miRNA variations and isoforms were widespread in our two RNA libraries, with most of the variations occurring in the 3´ region of the miRNAs. Furthermore, we detected 55 miRNAs that exhibited significant expression differences between laying and non-laying ducks. Gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) enrichment analyses of the potential targets of the differentially expressed miRNAs indicated these miRNAs may play key roles in the egg laying process. Finally, we confirmed the differential expression of 5 miRNAs in the laying and non-laying samples by qRT-PCR. Cumulatively, our work provides the first look at the miRNA expression profile of the duck ovary and provides novel insight into the roles of miRNAs in egg laying and reproduction.
    Soil & Fertilization · Irrigation · Agro-Ecology & Environment
    Seasonal and Annual Variations of CO2 Fluxes in Rain-Fed Winter Wheat Agro-Ecosystem of Loess Plateau, China
    WANG Wen, LIAO Yun-cheng , GUO Qiang
    2013, 12(1): 147-158.  DOI: 10.1016/S2095-3119(13)60215-4
    Abstract ( )   PDF in ScienceDirect  
    To accurately evaluate the carbon sequestration potential and better elucidate the relationship between the carbon cycle and regional climate change, using eddy covariance system, we conducted a long-term measurement of CO2 fluxes in the rain-fed winter wheat field of the Chinese Loess Plateau. The results showed that the annual net ecosystem CO2 exchange (NEE) was (-71.6±5.7) and (-65.3±5.3) g C m-2 y-1 for 2008-2009 and 2009-2010 crop years, respectively, suggesting that the agro-ecosystem was a carbon sink (117.4-126.2 g C m-2 yr-1). However, after considering the harvested grain, the agroecosystem turned into a moderate carbon source. The variations in NEE and ecosystem respiration (Reco) were sensitive to changes in soil water content (SWC). When SWC ranged form 0.15 to 0.21 m3 m-3, we found a highly significant relationship between NEE and photosynthetically active radiation (PAR), and a highly significant relationship between Reco and soil temperature (Ts). However, the highly significant relationships were not observed when SWC was outside the range of 0.15-0.21 m3 m-3. Further, in spring, the Reco instantly responded to a rapid increase in SWC after effective rainfall events, which could induce 2 to 4-fold increase in daily Reco, whereas the Reco was also inhibited by heavy summer rainfall when soils were saturated. Accumulated Reco in summer fallow period decreased carbon fixed in growing season by 16- 25%, indicating that the period imposed negative impacts on annual carbon sequestration.
    DetectingAgro-Droughts in Southwest of China Using MODIS Satellite Data
    ZHANG Feng, ZHANG Li-wen, WANG Xiu-zhen , HUNG Jing-feng
    2013, 12(1): 159-168.  DOI: 10.1016/S2095-3119(13)60216-6
    Abstract ( )   PDF in ScienceDirect  
    The normalized difference vegetation index (NDVI) has proven to be typically employed to assess terrestrial vegetation conditions. However, one limitation of NDVI for drought monitoring is the apparent time lag between rainfall deficit and NDVI response. To better understand this relationship, time series NDVI (2000-2010) during the growing season in Sichuan Province and Chongqing City were analyzed. The vegetation condition index (VCI) was used to construct a new drought index, time-integrated vegetation condition index (TIVCI), and was then compared with meteorological drought indices-standardized precipitation index (SPI), a multiple-time scale meteorological-drought index based on precipitation, to examine the sensitivity on droughts. Our research findings indicate the followings: (1) farmland NDVI sensitivity to precipitation in study area has a time lag of 16-24 d, and it maximally responds to the temperature with a lag of about 16 d. (2) We applied the approach to Sichuan Province and Chongqing City for extreme drought monitoring in 2006 and 2003, and the results show that the monitoring results from TIVCI are closer to the published China agricultural statistical data than VCI. Compared to VCI, the best results from TIVCI3 were found with the relative errors of -4.5 and 6.36% in 2006 for drought affected area and drought disaster area respectively, and 5.11 and -5.95% in 2003. (3) Compared to VCI, TIVCI has better correlation with the SPI, which indicates the lag and cumulative effects of precipitation on vegetation. Our finding proved that TIVCI is an effective indicator of drought detection when the time lag effects between NDVI and climate factors are taken into consideration.
    Agricultural Policy, Climate Factors and Grain Output: Evidence From Household Survey Data in Rural China
    CHEN Yong-fu, WU Zhi-gang, ZHU Tie-hui, YANG Lei, MA Guo-ying, Chien Hsiao-ping
    2013, 12(1): 169-183.  DOI: 10.1016/S2095-3119(13)60217-8
    Abstract ( )   PDF in ScienceDirect  
    This paper estimates a stochastic frontier function using a panel data set that includes 4 961 farmer households for the period of 2005-2009 to decompose the growth of grain production and the total factor productivity (TFP) growth at the farmer level. The empirical results show that the major contributor to the grain output growth for farmers is input growth and that its average contribution accounts for 60.92% of farmer’s grain production growth in the period of 2006-2009, whereas the average contributions sourced from TFP growth and residuals are only 17.30 and 21.78%, respectively. The growth of intermediate inputs is a top contributor with an average contribution of 44.46%, followed by the planted area (18.16%), investment in fixed assets (1.05%), and labor input (-2.75%), indicating that the contribution from the farmer’s input growth is mainly due to the growth of intermediate inputs and that the decline in labor inputs has become an obstacle for farmers in seeking grain output growth. Among the elements consisting of TFP growth, the contribution of technical progress is the largest (32.04%), followed by grain subsidies (8.55%), the average monthly temperature (4.26%), the average monthly precipitation (-0.88%), the adjusted scale effect (-5.66%), and growth in technical efficiency (-21.01%). In general, the contribution of climate factors and agricultural policy factor are positive and significant.
    Agricultural Production Structure Optimization: ACase Study of Major Grain ProducingAreas, China
    LU Sha-sha, LIU Yan-sui, LONG Hua-lou, GUAN Xing-liang
    2013, 12(1): 184-197.  DOI: 10.1016/S2095-3119(13)60218-X
    Abstract ( )   PDF in ScienceDirect  
    A large number of mathematical models were developed for supporting agricultural production structure optimization decisions; however, few of them can address various uncertainties existing in many factors (e.g., eco-social benefit maximization, food security, employment stability and ecosystem balance). In this study, an interval-probabilistic agricultural production structure optimization model (IPAPSOM) is formulated for tackling uncertainty presented as discrete intervals and/or probability distribution. The developed model improves upon the existing probabilistic programming and inexact optimization approaches. The IPAPSOM considers not only food security policy constraints, but also involves rural households’ income increase and eco-environmental conversation, which can effectively reflect various interrelations among different aspects in an agricultural production structure optimization system. Moreover, it can also help examine the reliability of satisfying (or risk of violating) system constraints under uncertainty. The model is applied to a real case of long-term agricultural production structure optimization in Dancheng County, which is located in Henan Province of Central China as one of the major grain producing areas. Interval solutions associated with different risk levels of constraint violation are obtained. The results are useful for generating a range of decision alternatives under various system benefit conditions, and thus helping decision makers to identify the desired agricultural production structure optimization strategy under uncertainty.