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    Crop Genetics · Breeding · Germplasm Resources
    Analysis of the diversity and function of the alleles of the rice blast resistance genes Piz-t, Pita and Pik in 24 rice cultivars
    WANG Yan, ZHAO Jia-ming, ZHANG Li-xia, WANG Ping, WANG Shi-wei, WANG Hui, WANG Xiao-xi, LIU Zhi-heng, ZHENG Wen-jing
    2016, 15(7): 1423-1431.  DOI: 10.1016/S2095-3119(15)61207-2
    Abstract ( )   PDF in ScienceDirect  
    Understanding the sequence diversity of rice blast resistance genes is important for breeding new resistant rice cultivars against the rice blast fungus Magnaporthe oryzae. In this study, we selected 24 rice cultivars with different genetic backgrounds to study the allelic diversity of rice blast resistance genes Piz-t, Pita and Pik. For Piz-t, a total of 17 allelic types were found within the 24 cultivars. Blast inoculations showed that most of the mutations can affect the function of the resistance gene. For Pita, except for the difference at the 918th amino acid, a majority of the 21 mutations were detected among the cultivars. Inoculations with blast isolates carrying Avr-Pita revealed that cultivars with mutations in other sites except for the 918th amino acid did not affect the function of the Pita gene. For Pik, a total of six allelic types were found within the 24 cultivars, but five of them lost the function of the resistance gene. In addition, we found that Piz-t, Pita and Pik were expressed constitutively in the 24 rice cultivars and the expression level was not related to resistance. Our results have provided the sequence diversity information of the resistance genes Piz-t, Pita and Pik among the popular rice cultivars grown in the northeast region of China.
    Pyramiding blast, bacterial blight and brown planthopper resistance genes in rice restorer lines
    JI Zhi-juan, Yang Shu-dong, ZENG Yu-xiang, LIANG Yan, YANG Chang-deng, QIAN Qian
    2016, 15(7): 1432-1440.  DOI: 10.1016/S2095-3119(15)61165-0
    Abstract ( )   PDF in ScienceDirect  
         Rice blast, bacterial blight (BB) and brown planthopper (BPH) are the three main pests of rice. This study investigated pyramiding genes resistant to blast, BB and BPH to develop restorer lines. Ten new lines with blast, BB and/or BPH resistance genes were developed using marker-assisted selection (MAS) technique and agronomic trait selection (ATS) method. Only HR13 with resistance genes to blast, BB and BPH was obtained. In addition to blast and BB resistance, four lines (HR39, HR41, HR42, HR43) demonstrated moderate resistance to BPH, but MAS for BPH resistance genes were not conducted in developing these four lines. These data suggested that there were unknown elite BPH resistance genes in the Zhongzu 14 donor parent. A more effective defense was demonstrated in the lines with Pi1 and Pi2 genes although the weather in 2012 was favorable to disease incidence. Blast resistance of the lines with a single resistance gene, Pita, was easily influenced by the weather. Overall, the information obtained through pyramiding multiple resistance genes on developing the restorer lines is helpful for rice resistance breeding.
    Identification of a novel gain-of-function mutant allele, slr1-d5, of rice DELLA protein
    ZHANG Yun-hui, BIAN Xiao-feng, ZHANG Suo-bing, LING Jing, WANG Ying-jie, WEI Xiao-ying, FANG Xian-wen
    2016, 15(7): 1441-1448.  DOI: 10.1016/S2095-3119(15)61208-4
    Abstract ( )   PDF in ScienceDirect  
      Controlling the height of crops plays a crucial role for their yields. The large scale utilization of semi-dwarf varieties has greatly improved crop yield, providing an effective support for world food security. In rice, a main food for over half of the world’s population, a number of dwarf loci have been identified. However, most of them are recessive, such as the ‘green revolution’ gene sd1. To gain more beneficial loci for rice breeding programs, exploring new mutations is needed, especially the dominant loci which can be used broadly for hybrid breeding. Here, we isolated a novel dominant dwarf rice mutant, slr1-d5. All of the internodes of slr1-d5 are reduced. We find that the responsiveness of slr1-d5 to gibberellin (GA), GA3, was significantly reduced. Map-based cloning revealed that the dominant dwarfism of slr1-d5 was caused by an amino acid substitution in the N-terminal TVHYNP domain of rice DELLA protein, SLR1, where the conserved amino acid Pro (P) was substituted to His (H). Our findings not only further prove the pivotal role of TVHYNP motif in regulating SLR1 stability, but also provide a new dwarf source for improvement of rice germplasms.
    Evaluation of selenium and carotenoid concentrations of 200 foxtail millet accessions from China and their correlations with agronomic performance
    LIU Min-xuan, ZHANG Zong-wen, REN Gui-xing, ZHANG Qi, WANG Yin-yue, LU Ping
    2016, 15(7): 1449-1457.  DOI: 10.1016/S2095-3119(15)61160-1
    Abstract ( )   PDF in ScienceDirect  
        As selenium and carotenoids are essential micronutrients, the determination of their concentrations in different varieties is important in the breeding of foxtail millet (Setaria italica L. P. Beauv.). To identify selenium- and carotenoid-enriched foxtail millet varieties and to analyze correlations between trace elements and agronomic traits, we measured the selenium and carotenoid concentrations of 200 Chinese accessions by high-performance liquid chromatography and atomic fluorescence spectrometry. Our analysis revealed that lutein concentration in 200 foxtail millet accessions followed normal distribution and average was 3.1 μg g–1. The mean value of zeaxanthin concentration in 200 accessions was 8.6 μg g–1. Lutein and zeaxanthin concentrations were higher in the foxtail millet from Liaoning than in varieties from other locations, with averages of 10.0 and 3.5 μg g–1, respectively. The average measured selenium concentration was 100.3 μg kg–1. The highest average selenium concentration, 110.3 μg kg–1, was found in varieties from Shanxi. Varieties from Inner Mongolia had the lowest average selenium concentration, 84.7 μg kg–1, which was significantly lower (P<0.05) than that of Shanxi. Selenium concentrations of 23 varieties were higher than 117.9 μg kg–1, accounting for 11.5% of the total, thereby were considered to be enriched in selenium. In addition, we identified 29 lutein-enriched varieties (>4.27 μg g–1) and 30 zeaxanthin-enriched ones (>12.63 μg g–1), which corresponded to 14.5 and 15% of tested accessions, respectively. Correlation analysis revealed that selenium concentration was significantly positively correlated with spikelet length (P<0.01), while zeaxanthin concentration was significantly correlated with grass weight (P<0.05) and spikelet length (P<0.01). No correlation was found between lutein concentration and agronomic characters, selenium content or zeaxanthin content. Our results should contribute substantially to the selection of suitable varieties for the development of plants with desired levels of these nutritionally important elements. These results will significantly contribute towards selection of the most suitable varieties for obtaining plants with desired levels of these nutritionally important elements.
    Physiological and molecular characteristics of two ploidy mutants in Myrica rubra cv. Dongkui
    CHEN Fang-yong, NI Hai-zhi, WANG Yin, YAN Bang-guo
    2016, 15(7): 1458-1468.  DOI: 10.1016/S2095-3119(15)61284-9
    Abstract ( )   PDF in ScienceDirect  
        In this study, two ploidy mutant lines of Myrica rubra cv. Dongkui (DK) were identified and named as DB1 and DB2. The floral organ, leaf cell structure, ploidy, and number of chromosomes of the two mutants were investigated. Meanwhile, anthocyanin contents at different developmental stages were analyzed, and the Cy-3-glu contents of DB1 and DB2 at the full ripe stages are significantly higher than that of DK by 27.84 and 23.51%, respectively. Furthermore, 6 RNA libraries at two developmental stages (young fruit stage and full ripe stage) were built for RNA-Seq. By mapping to the reference database, 28 407, 28 043, and 28 683 genes were detected in the young fruit of DB1, DB2, and DK, respectively, while 28 040, 22 256, and 27 351 genes were detected in the full ripe stage, respectively. There were 281 differentially expressed genes between DB1 and DK, with 123 and 158 genes up-regulated and down-regulated, respectively, and 47 differentially expressed genes between DB2 and DK, of which 8 and 39 genes were up-regulated and down-regulated. Using real-time PCR, the expression levels of the eight functional genes at different developmental stages of the fruit were also analyzed. These comprehensive analyses showed that both mutants are different from DK, which is the result of natural doubling of ploidy, thereby generating a pleiotropic effect. As we known, it is the first report to study the relationship between bayberry ploidy alterations and genes involved in regulation of fruit mutations, which will help to identify the morphological and cytological characteristics of M. rubra germplasm, and provide a theoretical basis and technical support for genetic improvement and creation of breeding resources.
    Effects of plant density on cotton yield components and quality
    ZHI Xiao-yu, HAN Ying-chun, LI Ya-bing, WANG Guo-ping, DU Wen-li, LI Xiao-xin, MAO Shu-chun, FENG Lu
    2016, 15(7): 1469-1479.  DOI: 10.1016/S2095-3119(15)61174-1
    Abstract ( )   PDF in ScienceDirect  
         Yield and fiber quality of cotton even varies within locules in a boll, but it is not clear how yield components and quality parameters are altered across seed positions of a locule (SPL). A field experiment was arranged in a split plot design with transgenic insect resistant Bt (Bacillus thuringiensis) cotton hybrid cultivar CRI75 and conventional cultivar SCRC28 as the main plots, and three plant densities (15 000, 51 000 and 87 000 plants ha–1) as the subplots in 2012 and 2013 at Anyang, Henan Province, China. Cotton was hand harvested by node and fruiting position, and then seeds of the first fruiting position bolls from nodes 6–10 were separated by SPL. The effects of plant density on lint yield, fiber quality, especially across SPL were determined. It was showed that plant densities of 51 000 and 87 000 plants ha–1 increased lint yield by 61.3 and 65.3% in 2012 and 17.8 and 15.5% in 2013 relative to low plant density (15 000 plants ha–1), however, no significant difference was observed between 51 000 and 87 000 plants ha–1. The number of bolls (boll density) increased while boll weight decreased as plant density raised, and no significant changes occured in lint percentage in 2013 but increased with plant density in 2012. The number of bolls in upper nodes and distal fruiting positions, the number of seeds per boll, seed area (SA) and seed vigor index increased with decreasing plant density. Seed area was found to be greater from the base to the middle compared to the apex of a locule. Mote frequency (MF) increased as plant density increased, and fiber quality was the best at the middle of the locule regardless of plant density. As the number of fibers per seed area is genetically determined, adjusting plant density to produce more seeds and greater seed area can be a potentially promising alternative to improve lint yield in cotton. These findings might be of great importantance to cotton breeding and filed management.
    Stand establishment, root development and yield of winter wheat as affected by tillage and straw mulch in the water deficit hilly region of southwestern China
    LI Chao-su, LI Jin-gang, TANG Yong-lu, WU Xiao-li, WU Chun, HUANG Gang, ZENG Hui
    2016, 15(7): 1480-1489.  DOI: 10.1016/S2095-3119(15)61184-4
    Abstract ( )   PDF in ScienceDirect  
       Good crop stand establishment and root system development are essential for optimum grain yield of dryland wheat (Triticum aestivum L.). At present, little is known about the effect of tillage and straw mulch on the root system of wheat under dryland areas in southwestern China. The aim of this study was to evaluate the effect of three tillage treatments (no-till, NT; rotary till, RT; conventional till, CT) and two crop residue management practices (straw mulch, ML; non-straw mulch, NML) on stand establishment, root growth and grain yield of wheat. NT resulted in lower soil cover thickness for the wheat seed, higher number of uncovered seeds, lower percentage of seedling-less ridges and lower tiller density compared to RT and CT; ML resulted in higher tiller density compared to NML. Straw mulching resulted in more soil water content and root length density (RLD) at most of the growth stages and soil depths. The maximum RLD, root surface area density and root dry matter density were obtained under NT. In the topmost 10 cm soil layer, higher RLD values were found under NT than those under RT and CT. There were no significant differences in the yield or yield components of wheat among the tillage treatments in 2011–2012, but NT resulted in a significant higher yield compared to RT and CT in 2012–2013. Grain yield was significantly higher in ML compared to in NML. A strong relationship was observed between the water-use efficiency and the grain yield. Both NT and ML proved beneficial for wheat in term of maintaining higher tiller density, better soil water status and root growth, leading to a higher grain yield and enhanced water-use efficiency, especially in a low rainfall year.
    Cytochemical localization of H2O2 in pigment glands of cotton (Gossypium hirsutum L.)
    WANG Ling-li, ZHENG Shuang-shuang, TONG Pan-pan, CHEN Yan, LIU Wen-zhe
    2016, 15(7): 1490-1498.  DOI: 10.1016/S2095-3119(15)61210-2
    Abstract ( )   PDF in ScienceDirect  
        Programmed cell death (PCD) plays a critical role in the development of plant pigment glands, while H2O2, which is a kind of reactive oxygen species (ROS) produced by the aerobic metabolism of cells, acts as an important signal in this process. Here, we investigated the temporal and spatial dynamics of accumulated H2O2 in pigment glands of Gossypium hirsutum L. with 3,3-diaminobenzidine (DAB) staining, 2’,7’-dichlorodihydrofluorescein diacetate (DCFH2)-DA fluorescent labeling and CeCl3 cytochemical localization techniques. The results showed that the pigment glands of G. hirsutum could generate H2O2, and the amount and localization of H2O2 varied at different developmental stages. At the early developmental stage, a small amount of HH2O2 accumulated in the vacuole membrane of pigment gland cells. At the intermediate stage, a large number of H2O2 appeared in the vacuole membrane, while cell walls started to accumulate a small amount of H2O2. When pigment gland cell degraded, H2O2 mainly accumulated on the chloroplast envelope membrane of inner sheath cells. With the degradation of the sheath cells, H2O2 was detected in cell wall and the membrane of secretory vesicles which contains the preliminary contents of pigment gland. With the pigment glands completely maturation, H2O2 would disappeared. The accumulation sites of H2O2 are consistent with the process of PCD of individual gland cells, which started from the degradation of intracellular membrane and ended with the degradation of cell walls. Thus H2O2 probably plays an important role in the development of pigment glands. In addition, the development of pigment glands and the generation of H2O2 are not associated with the light, and no H2O2 was detected in the secretions of pigment glands.
    Comprehensive evaluation of tolerance to alkali stress by 17 genotypes of apple rootstocks
    ZHANG Kun-xi, WEN Tian, DONG Jun, MA Feng-wang, BAI Tuan-hui, WANG Kun, LI Cui-ying
    2016, 15(7): 1499-1509.  DOI: 10.1016/S2095-3119(15)61325-9
    Abstract ( )   PDF in ScienceDirect  
        Alkaline soils have a great influence on apple production in Northern China. Therefore, comprehensive evaluations of tolerance to such stress are important when selecting the most suitable apple rootstocks. We used hydroponics culturing to test 17 genotypes of apple rootstocks after treatment with 1:1 Na2CO3 and NaHCO3. When compared with the normally grown controls, stressed plants produced fewer new leaves, and had shorter roots and shoots and lower fresh and dry weights after 15 d of exposure to alkaline conditions. Their root/shoot ratios were also reduced, indicating that the roots had been severely damaged. For all stressed rootstocks, electrolyte leakage (EL) and the concentration of malondialdehyde (MDA) increased while levels of chlorophyll decreased. Changes in root activity (up or down), as well as the activities of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) were rootstock-dependent, possibly reflecting their differences in alkali tolerance. Using alkali injury index (AI), adversity resistance coefficients (ARC), cluster analysis, and evaluation of their physiological responses, we classified these 17 genotypes into three groups: (1) high tolerance: Hubeihaitang, Wushanbianyehaitang, Laoshanhaitang Ls2, Xiaojinbianyehaitang, and Fupingqiuzi; (2) moderate tolerance: Pingyitiancha, Laoshanhaitang Ls3, Hubeihaitang A1, Deqinhaitang, Balenghaitang, Maoshandingzi, Shandingzi, and Xinjiangyepingguo; or (3) low tolerance: Pingdinghaitang, Hongsanyehaitang, Xiaojinhaitang, and Sanyehaitang. These results will significantly contribute to the selection of the most suitable materials for rootstocks with desired levels of tolerance to alkali stress.
    Plant Protection
    Pathogenicity of Klebsiella pneumonia (KpC4) infecting maize and mice
    HUANG Min, LIN Li, WU Yi-xin, Honhing Ho, HE Peng-fei, LI Guo-zhi, HE Peng-bo, XIONG Guo-ru, YUAN Yuan, HE Yue-qiu
    2016, 15(7): 1510-1520.  DOI: 10.1016/S2095-3119(16)61334-5
    Abstract ( )   PDF in ScienceDirect  
       Recently, a new bacterial top rot disease of maize has frequently appeared in many areas of Yunnan Province, China. The pathogen of the disease was identified as Klebsiella pneumoniae (KpC4), which is well known to cause pulmonary and urinary diseases in humans and animals and occasionally exists as a harmless endophyte in plants. To evaluate the virulence of the maize pathogen to maize and mice, we inoculated maize and mice with routine inoculation and intraperitoneal injection respectively according to Koch’s postulates. The results showed that KpC4 and the clinical strain K. pneumoniae 138 (Kp138) were all highly pathogenic to maize and mice and the strain re-isolated from diseased mice also caused typical top rot symptoms on maize by artificial inoculation. It is highlighting that a seemingly dedicated human/animal pathogen could cause plant disease. This is the first report of K. pneumoniae, an opportunistic pathogen of human/animal, could infect maize and mice. The findings serve as an alert to plant, medical and veterinarian scientists regarding a potentially dangerous bacterial pathogen infecting both plants and animals/humans. The maize plants in the field could serve as a reservoir for K. pneumoniae which might infect animals and probably humans when conditions are favorable. The new findings not only are significant in the developing control strategy for the new disease in Yunnan, but also serve as a starting point for further studies on the mechanism of pathogenesis and epidemiology of K. pneumoniae.
    Effects of Tinospora tuberculata leaf methanol extract on seedling growth of rice and associated weed species in hydroponic culture
    Farzad Aslani, Abdul Shukor Juraimi, Muhammad Saiful Ahmad-Hamdani, Farahnaz Sadat Golestan Hashemi, Md Amirul Alam, Md Abdul Hakim, Md Kamal Uddin
    2016, 15(7): 1521-1531.  DOI: 10.1016/S2095-3119(15)61256-4
    Abstract ( )   PDF in ScienceDirect  
        The study was conducted to evaluate the responses of rice and rice weed seedlings (barnyardgrass and weedy rice) at the three-leaf stage to Tinospora tuberculata leaf methanol extract (3.12, 6.25 and 12.5 g L–1) under hydroponic culture. It shows that the leaf methanol extract had various degrees effects depending on target plant species and each tested index (biomass, root length, shoot length, transpiration volume, chlorophyll a, chlorophyll b and carotenoid contents). The effective concentration of the leaf extract capable of reducing 50% of rice growth was higher than those of target weed species. Moreover, the root length was more tolerant to leaf methanol extract in comparison to the other plant parameters measured. A greater reduction was observed in chlorophyll a content compared to chlorophyll b and carotenoid. The results revealed that the reduction of transpiration volume closely coincided with the magnitude of growth inhibition of tested plants. Ultra-fast liquid chromatography analysis revealed 11 of 32 peaks in chemical profile, including benzoic acid, caffeic acid, chlorogenic acid, isoorientin, isovitexin, orientin, p-anisic acid, syringic acid, trans-cinnamic acid, trans-ferulic acid, and vitexin have the same retention time with those peaks of the extract. The amount of compounds was present in the range of between 4 817 and 115.5 mg kg–1 dry weight (DW). The concentration-response bioassay of all 11 individual compounds and their equimolar mixture against the seeds of barnyardgrass revealed their contribution in the allelopahic activity of T. tuberculata leaf extract. The examined compounds and their combination exhibited various degrees of growth inhibitory effects on the early growth of barnyardgrass. Therefore, the specific number, concentration, combination and inhibitory activity of bioactive compounds leads to allelopathy activity of T. tuberculata leaves which could be employable directly as a natural herbicide and its growth inhibitor compounds can be used as a template for producing new herbicides.
    Development of synthetic volatile attractant for male Ectropis obliqua moths
    SUN Xiao-ling, LI Xi-wang, XIN Zhao-jun, HAN Juan-juan, RAN Wei, LEI Shu
    2016, 15(7): 1532-1539.  DOI: 10.1016/S2095-3119(15)61294-1
    Abstract ( )   PDF in ScienceDirect  
        The tea geometrid Ectropis obliqua is one of the most serious leaf-feeding insect pests in tea (Camellia sinensis) in East Asia. Although several volatile chemicals emitted from tea plants have been reported to be attractive to E. obliqua moths, no synthetic attractants for E. obliqua moths have been developed. By measuring the behavioral responses of the moth to a series of chemicals in the lab, we found that a blend containing a ternary mixture containing (Z)-3-hexenal, (Z)-3-hexenyl hexanoate and benzyl alcohol clearly attracted to E. obliqua moths of both sex and that (Z)-3-hexenyl acetate could enhance the attractiveness of the ternary blend. Moreover, we found that the volatiles emitted from the plant-E. obliqua larva complex have the same attractiveness as: 1) the blend of volatiles containing the ternary mixture and 2) the blend containing (Z)-3-hexenyl acetate plus the ternary mixture to both male and female moths. In a field bioassay, more male moths were observed on traps that were baited with the blend containing (Z)-3-hexenyl acetate plus the ternary mixture than on control traps. Our study raises the tantalizing possibility that synthetic blends could be deployed as attractants for pests in the field.
    Animal Science · Veterinary Science
    Highly efficient generation of GGTA1 knockout pigs using a combination of TALEN mRNA and magnetic beads with somatic cell nuclear transfer
    FENG Chong, LI Xi-rui, CUI Hui-ting, LONG Chuan, LIU Xia, TIAN Xing-hua, PAN Deng-ke, LUO Yuzhu
    2016, 15(7): 1540-1449.  DOI: 10.1016/S2095-3119(16)61347-3
    Abstract ( )   PDF in ScienceDirect  
        The transcription activator-like effector nuclease (TALEN) technique combined with the somatic cell nuclear transfer (SCNT) method has been successfully applied for creating genetically modified pigs. However, methods for isolating cells with biallelic indels requires further improvement because of the relatively low enrichment efficiency of mutated somatic cells. Moreover, little is known regarding the off-target effects of the TALEN system and the heredity of TALEN-modified pigs. In this study, an efficient method to increase the enrichment efficiency of TALEN-mediated biallelic knockout (KO) cells was established, and corresponding genetically modified pigs with the expected genotype were generated whose off-target effect, fertility and heredity characteristics were aslo evaluated. Two TALEN pairs were constructed to target the porcine α-1,3-galactosyltransferase (GGTA1) gene locus. TALEN mRNA was transfected into the ear ?broblasts followed by the enrichment of α-Gal null cells of minipigs using isolectin B4 (IB4) lectin and magnetic beads. A total of 115 cell colonies were formed and validated to be GGTA1 KO cells by sequencing and 10 biallelic KO cell colonies were used as nuclear donors for SCNT. Thirty GGTA1 biallelic KO piglets were successfully delivered and grew normally. Seventeen potential off-target sites were investigated, and no off-target events were detected in the live piglets. To determine the fertility and heredity characteristics of TALEN-modified pigs, 10 mature founders were mated with each other and the mutations were determined to be transmitted to the F1 piglets. We established a robust and safe technology for developing genetically modified pig lines with expected genotypes for agricultural breeding and biomedical application.
    Sensory quality of meat from eight different types of cattle in relation with their biochemical characteristics
    M Gagaoua, E M C Terlouw, D Micol, J-F Hocquette, A P Moloney, K Nuernberg, D Bauchart, A Boudjellal, N D Scollan, R I Richardson, B Picard
    2016, 15(7): 1550-1565.  DOI: 10.1016/S2095-3119(16)61340-0
    Abstract ( )   PDF in ScienceDirect  
        The present study compared eight breeds of cattle differing in gender (heifers, bulls and steers) to determine associations between muscle characteristics and meat sensory qualities of the Longissimus thoracis muscle. Animal types differed in all the muscle characteristics and sensory qualities. Many correlations among muscle characteristics and among sensory qualities were consistent for most animal types. Isocitrate dehydrogenase (ICDH) activities allowed discrimination of muscles with respect to myosin heavy chain (MyHC)-I proportions for all animal types. Lactate dehydrogenase (LDH) and phosphofructokinase (PFK) activities were positively correlated for most animal types. Overall liking was correlated with beef flavour and abnormal flavour in all animal types and with global tenderness for all animal types except for Charolais cross breed steers. For all animal types except for Angus×Friesian heifers, beef flavour and abnormal flavour were negatively correlated. Overall liking was not correlated with juiciness. PFK, ICDH and citrate synthase (CS) activities were strongly associated with tenderness, beef flavour and overall liking when average values for all animal types were used. However, associations between muscle characteristics and sensory qualities within animal types were weak and inconsistent.
    Rumen fermentation and bacterial communities in weaned Chahaer lambs on diets with different protein levels
    YANG Chun-tao, SI Bing-wen, DIAO Qi-yu, JIN Hai, ZENG Shu-qin, TU Yan
    2016, 15(7): 1564-1574.  DOI: 10.1016/S2095-3119(15)61217-5
    Abstract ( )   PDF in ScienceDirect  
       We evaluated the effects of diets with different crude protein (CP) levels on growth performance, rumen fermentation and bacterial communities in weaned Chahaer lambs. 128 weaned Chahaer lambs ((20.56±1.43) kg body weight; ram:ewe 1:1) aged (61±1.85) d were randomly allotted to one of four diets with CP content of 11.17% (T1), 12.06% (T2), 13.40% (T3) or 14.36% (T4). Ruminal fermentation parameters were measured and bacterial communities were analysed using PCR-denaturing gradient gel electrophoresis (PCR-DGGE) and quantitative PCR. The average daily gain and feed utilization efficiency in T3 were higher than those in the other groups (P<0.05), although the dry matter intake and metabolizable energy intake were similar. Total volatile fatty acid concentration in the ruminal fluid of T3 was lower than that of T1 (P=0.011), T2 (P=0.008) or T4 (P=0.309). The ammonia nitrogen concentration and acetate/propionate ratio of ruminal fluid were significantly higher in lambs fed the higher CP diets, whereas the molar concentrations of propionate and butyrate of ruminal fluid were lower. The rumen bacterial community was similar in T2 and T3 which shown more stable and diverse rumen microbes ecosystem compared with the other groups. The DGGE profiles and phylogenetic tree indicated that Bacteroides uniformis, Clostridium alkalicellulosi, Alkalibaculum bacchi and Saccharofermentans sp. were common bacterium of Chahaer lamb rumen. B. uniformis, C. alkalicellulosi, Saccharofermentans sp. and Gracilibacter thermotolerans, which belong to the Bacteroidetes and Firmicutes phyla, were the dominant species in the rumen of lambs fed 13.40% CP. However, Ruminococcus albus, Ruminococcus flavefaciens and Butyrivibrio fibrisolvens were not different in lambs fed different CP diets. Therefore, it could be concluded that B. uniformis, C. alkalicellulosi, A. bacchi and Saccharofermentans sp. were common bacteria of Chahaer lamb rumen. Furthermore, the dietary CP of 13.04% could improve performance and change rumen fermentation model by increasing the dominant species’ peak intensities of B. uniformis, C. alkalicellulosi, Saccharofermentans sp. and Gracilibacter thermotolerans and stabilizing rumen microbial ecosystem.
    Fermentation characteristics of Megasphaera elsdenii J6 derived from pig feces on different lactate isomers
    JIANG Xiao-lin, SU Yong, ZHU Wei-yun
    2016, 15(7): 1575-1583.  DOI: 10.1016/S2095-3119(15)61236-9
    Abstract ( )   PDF in ScienceDirect  
        D-Lactate-utilizing bacteria play important roles in maintaining the balance of gut lactate; however, studies on gut D-lactate-utilizing bacteria have been limited. This study aimed to isolate and identify D-lactate-utilizing bacteria from pig gut using the Hungate roll-tube method, and to investigate their metabolic characteristics in vitro. Six different anaerobes were isolated from pig feces, which were identified as related to Bacteroides fragilis, Bacteroides acidifaciens, Veillonella denticariosi, Veillonella caviae, Bacteroides uniformis, and Megasphaera elsdenii based on the 16S rRNA gene sequences. All strains had a significant ability to utilize D-lactate, which was concluded after in vitro fermentation with 25 mmol L–1 D-lactate as the primary carbon source. Of all 6 strains, M. elsdenii J6 showed the highest efficiency of D-lactate utilization and produced a higher ratio of butyrate in total short chain fatty acids (SCFAs). Thus, the in vitro fermentation characteristics of this strain in D-, L-, and DL-lactate mixtures (D-lactate:L-lactate=1:1 or 1:2) were further studied. The results showed that M. elsdenii J6 preferred utilizing D-lactate, and produced more SCFA when using D-lactate as the primary carbon source. The findings suggest that the administration of D-lactate-utilizing bacteria such as M. elsdenii J6 may have a potential advantage in the alleviation of D-lactic acidosis in the animal gut.
    Tracking domestic ducks: A novel approach for documenting poultry market chains in the context of avian influenza transmission
    Chang-Yong Choi, John Y Takekawa, XIONG Yue, LIU Ying, Martin Wikelski, George Heine, Diann J Prosser, Scott H Newman, John Edwards, Fusheng Guo, Xiangming Xiao
    2016, 15(7): 1584-1594.  DOI: 10.1016/S2095-3119(15)61292-8
    Abstract ( )   PDF in ScienceDirect  
       Agro-ecological conditions associated with the spread and persistence of highly pathogenic avian influenza (HPAI) are not well understood, but the trade of live poultry is suspected to be a major pathway. Although market chains of live bird trade have been studied through indirect means including interviews and questionnaires, direct methods have not been used to identify movements of individual poultry. To bridge the knowledge gap on quantitative movement and transportation of poultry, we introduced a novel approach for applying telemetry to document domestic duck movements from source farms at Poyang Lake, China. We deployed recently developed transmitters that record Global Positioning System (GPS) locations and send them through the Groupe Spécial Mobile (GSM) cellular telephone system. For the first time, we were able to track individually marked ducks from 3 to 396 km from their origin to other farms, distribution facilities, or live bird markets. Our proof of concept test showed that the use of GPS-GSM transmitters may provide direct, quantitative information to document the movement of poultry and reveal their market chains. Our findings provide an initial indication of the complexity of source-market network connectivity and highlight the great potential for future telemetry studies in poultry network analyses.
    Soil & Fertilization﹒Irrigation﹒Plant Nutrition﹒ Agro-Ecology & Environment
    Root carbon consumption and grain yield of spring wheat in response to phosphorus supply under two water regimes
    GUAN Yu, QIAO Zhen, DU Jiu-yuan, DU Yan-lei
    2016, 15(7): 1595-1601.  DOI: 10.1016/S2095-3119(15)61193-5
    Abstract ( )   PDF in ScienceDirect  
       In semiarid areas, cereal crops often allocate more biomass to root at the expense of aboveground yield. A pot experiment was conducted to investigate carbon consumption of roots and its impact on grain yield of spring wheat (Triticum aestivum L.) as affected by water and phosphorus (P) supply. A factorial design was used with six treatments namely two water regimes (at 80–75% and 50–45% field capacity (FC)) and three P supply rates (P1=0, P2=44 and P3=109 µg P g–1 soil). At shooting and flowering stages, root respiration and carbon consumption increased with the elevate of P supply rates, regardless of water conditions, which achieved the minimum and maximum at P1 under 50–45% FC and P3 under 80–75% FC, respectively. However, total aboveground biomass and grain yield were higher at P2 under 80–75% FC; and decreased with high P application (P3). The results indicated that rational or low P supply (80–75% of field water capacity and 44 mg P kg–1 soil) should be recommended to improve grain yield by decreasing root carbon consumption in semiarid areas.
    Buried straw layer and plastic mulching increase microflora diversity in salinized soil
    LI Yu-yi, PANG Huan-cheng, HAN Xiu-fang, YAN Shou-wei, ZHAO Yong-gan, WANG Jing, ZHAI Zhen, ZHANG Jian-li
    2016, 15(7): 1602-1611.  DOI: 10.1016/S2095-3119(15)61242-4
    Abstract ( )   PDF in ScienceDirect  
        Salt stress has been increasingly constraining crop productivity in arid lands of the world. In our recent study, salt stress was alleviated and crop productivity was improved remarkably by straw layer burial plus plastic film mulching in a saline soil. However, its impact on the microflora diversity is not well documented. Field micro-plot experiments were conducted from 2010 to 2011 using four tillage methods: (i) deep tillage with plastic film mulching (CK), (ii) straw layer burial at 40 cm (S), (iii) straw layer burial plus surface soil mulching with straw material (S+S), and (iv) plastic film mulching plus buried straw layer (P+S). Culturable microbes and predominant bacterial communities were studied; based on 16S rDNA, bacterial community structure and abundance were characterized using denaturing gradient gel electrophoresis (DGGE) and polymerase chain reaction (PCR). Results showed that P+S was the most favorable for culturable bacteria, actinomyces and fungi and induced the most diverse genera of bacteria compared to other tillage methods. Soil temperature had significant positive correlations with the number of bacteria, actinomyces and fungi (P<0.01). However, soil water was poorly correlated with any of the microbes. Salt content had a significant negative correlation with the number of microbers, especially for bacteria and fungi (P<0.01). DGGE analysis showed that the P+S exhibited the highest diversity of bacteria with 20 visible bands followed by S+S, S and CK. Moreover, P+S had the highest similarity (68%) of bacterial communities with CK. The major bacterial genera in all soil samples were Firmicutes, Proteobacteria and Actinobacteria. Given the considerable increase in microbial growth, the combined use of straw layer burial and plastic film mulching could be a practical option for alleviating salt stress effects on soil microbial community and thereby improving crop production in arid saline soils.
    Soil nutrient loss due to tuber crop harvesting and its environmental impact in the North China Plain
    YU Han-qing, LI Yong, ZHOU Na, Adrian Chappell, LI Xiao-yu, Jean Poesen
    2016, 15(7): 1612-1624.  DOI: 10.1016/S2095-3119(15)61268-0
    Abstract ( )   PDF in ScienceDirect  
        Soil loss due to crop harvesting (SLCH) is a soil erosion process that significantly contributes to soil degradation in croplands. However, little is known about soil nutrient losses caused by SLCH and its environmental impacts. In the North China Plain area, we measured the losses of soil organic carbon (SOC) and nitrogen as well as phosphorus due to SLCH and assessed their relationship with soil particle size composition, agronomic practices and soil moisture content. Our results show that the losses by harvesting potato of SOC, total nitrogen (TN), available nitrogen (AN), available phosphorus (AP) and total phosphorus (TP) were 1.7, 1.8, 1.8, 15.9 and 14.1 times compared by harvesting sweet potato, respectively. The variation of SOC, N and P loss by SLCH are mainly explained by the variation of plant density (PD) (17–50%), net mass of an individual tuber (Mcrop/p) (16–74%), soil clay content (34–70%) and water content (19–46%). Taking into account the current sewage treatment system and the ratio of the nutrients adhering to the tubers during transportation from the field (NTRP/SP), the loss of TN and TP by harvesting of potato and sweet potato in the North China Plain area amounts to 3% N and 20% P loads in the water bodies of this region. The fate of the exported N and P in the sewage treatment system ultimately controls the contribution of N and P to the pollution of lakes and rivers. Our results suggest that a large amount of SLCH-induced soil nutrient export during transportation from the field is a potential pollutant source for agricultural water for vast planting areas of tuber crops in China, and should not be overlooked.
    Wetting patterns and bacterial distributions in different soils from a surface point source applying effluents with varying Escherichia coli concentrations
    WEN Jie, LI Jiu-sheng, LI Yan-feng
    2016, 15(7): 1625-1637.  DOI: 10.1016/S2095-3119(15)61249-7
    Abstract ( )   PDF in ScienceDirect  
        Understanding bacterial transportation in unsaturated soil is helpful for reducing and avoiding pathogenic contamination that may be induced by irrigation with reclaimed waste water and for developing better irrigation management practices. Experiments were conducted to study the transport of a typical bacterium, Escherichia coli (E. coli), in a sandy and a sandy loam soil under different application rates and input concentrations. A 30° wedge-shaped plexiglass container was used to represent one twelfth of the complete cylinder in the experiments. The apparent cylindrical application rate varied from 1.05 to 5.76 L h–1 and the input concentration of E. coli from magnitude of 102 to 107 colony-forming unit (CFU) mL–1. For a given volume of water applied, an increase in application rate resulted in an increase in the wetted radius and a decrease in the wetted depth. In the sandy loam soil, the water spread out in a circular-arc shaped saturated zone on the surface, and the ultimate saturated entry radius increased with the application rate. An increasing application rate of water suspended bacteria allowed a more rapid transport of bacteria, thus accelerating E. coli transport rate and resulting in a larger distributed volume of E. coli for both soil types. For the sandy soil, more than 70% of the E. coli that was detected within the entire wetted volume concentrated in the range of 10 cm from the point source, and the concentration of E. coli decreased greatly as the distance from the point source increased. More than 98% of the E. coli was detected in a range of 5 cm around the saturated wetted zone for the sandy loam soil. For both soil types tested, an extremely high concentration of E. coli was observed in the proximity of the point source, and the peak value increased with an increased input concentration. In principle, using an emitter with relative lower application rate would be effective to restrict E. coli transport. To reduce bacterial concentration in the sewage effluent during wastewater treatment is important to decrease the risk of soil contamination caused by irrigation with sewage effluent.
    Evaluating the grassland net primary productivity of southern China from 2000 to 2011 using a new climate productivity model
    SUN Cheng-ming, ZHONG Xiao-chun, CHEN Chen, GU Ting, CHEN Wen
    2016, 15(7): 1638-1644.  DOI: 10.1016/S2095-3119(15)61253-9
    Abstract ( )   PDF in ScienceDirect  
        Grassland is the important component of the terrestrial ecosystems. Estimating net primary productivity (NPP) of grassland ecosystem has been a central focus in global climate change researches. To simulate the grassland NPP in southern China, we built a new climate productivity model, and validated the model with the measured data from different years in the past. The results showed that there was a logarithmic correlation between the grassland NPP and the mean annual temperature, and there was a linear positive correlation between the grassland NPP and the annual precipitation in southern China. All these results reached a very significant level (P<0.01). There was a good correlation between the simulated and the measured NPP, with R2 of 0.8027, reaching the very significant level. Meanwhile, both root mean square errors (RMSE) and relative root-mean-square errors (RRMSE) stayed at a relatively low level, showing that the simulation results of the model were reliable. The NPP values in the study area had a decreasing trend from east to west and from south to north, and the mean NPP was 471.62 g C m−2 from 2000 to 2011. Additionally, there was a rising trend year by year for the mean annual NPP of southern grassland and the tilt rate of the mean annual NPP was 3.49 g C m−2 yr−1 in recent 12 years. The above results provided a new method for grassland NPP estimation in southern China.
    Food Science
    Assessing the concentration and potential health risk of heavy metals in China’s main deciduous fruits
    NIE Ji-yun, KUANG Li-xue, LI Zhi-xia, XU Wei-hua, WANG Cheng, CHEN Qiu-sheng, LI An, ZHAO Xu-bo, XIE Han-zhong, ZHAO Duo-yong, WU Yong-long, CHENG Yang
    2016, 15(7): 1645-1655.  DOI: 10.1016/S2095-3119(16)61342-4
    Abstract ( )   PDF in ScienceDirect  
    To assess levels of contamination and human health risk, we analyzed the concentrations of the heavy metals lead (Pb), cadmium (Cd), chromium (Cr), and nickel (Ni) in China’s main deciduous fruits - apple, pear, peach, grape, and jujube. The concentration order of the heavy metals was Ni>Cr>Pb>Cd. In 97.5% of the samples, heavy metal concentrations were within the maximum permissible limits. Among the fruits studied, the heavy metal concentrations in jujube and peach proved to be the highest, and those in grape proved to be the lowest. Only 2.2% of the samples were polluted by Ni, only 0.4% of the samples were polluted by Pb, and no samples were polluted by Cd or Cr. Compared with the other fruits, the combined heavy metal pollution was significantly higher (P<0.05) in peach and significantly lower (P<0.05) in grape. For the combined heavy metal pollution, 96.9% of the samples were at safe level, 2.32% at warning level, 0.65% at light level, and 0.13% at moderate level. In the fruits studied, the contribution of heavy metals to the daily intake rates (DIR) followed the order of Ni>Cr>Pb>Cd. The highest DIR came from apple, while the lowest DIR came from grape. For each of the heavy metals, the total DIR from five studied fruits corresponded to no more than 1.1% of the tolerable daily intake, indicating that no significant adverse health effects are expected from the heavy metals and the fruits studied. The target hazard quotients and the total target hazard quotients demonstrated that none of the analyzed heavy metals may pose risk to consumers through the fruits studied. The highest risk was posed by apple, followed in decreasing order by peach and pear, jujube, and grape. We suggest that the main deciduous fruits (apple, pear, peach, grape, and jujube) of China’s main producing areas are safe to eat.
    Fast determination of multi-mycotoxins in corn by dispersive solid-phase extraction coupled with ultra-performance liquid chromatography with tandem quadrupole time-of-flight mass spectrometry
    WANG Yan, DONG Yan-jie, LI Zeng-mei, DENG Li-gang, GUO Chang-ying, ZHANG Shu-qiu, LI Dapeng, ZHAO Shan-cang
    2016, 15(7): 1656-1666.  DOI: 10.1016/S2095-3119(15)61287-4
    Abstract ( )   PDF in ScienceDirect  
        A fast analytical method for the simultaneous determination of 9 mycotoxins, including aflatoxins (B1, B2, G1, and G2), fumonisins (B1, B2 and B3), zearalenone, and deoxynivalenol in corn using dispersive solid-phase extraction method and ultra-performance liquid chromatography coupled to tandem quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was developed and validated. Samples were extracted with acetonitrile-water (84:16, v:v, containing 1% acetic acid) using ultrasonic extraction. The extracts were purified with a dispersive SPE method using C18 as a cleaning agent. The final clear extracts were dried by nitrogen blowing and subsequently redissolved in methanol-water (5:5, v:v). The samples were then analyzed by UPLC-Q-TOF-MS with 0.1% formic acid in ammonium acetate-methanol as mobile phase. The mean recoveries were ranged from 68.0 to 120.0%, and the relative standard deviation (RSD) ranged from 0.18 to 6.29%. Limits of detections ranged from 0.05 to 50 μg kg−1, and limits of quantification ranged from 0.1 to 200 μg kg−1, which were below the legal limits set by the European Union for the legislated mycotoxins. The developed method was applied to 130 corn samples. Among the mycotoxins studied, aflatoxins B1 and fumonisins B1, B2 and B3 were the most predominant mycotoxins, and their concentrations were 0–593.12, 0–2.01×104, 0–6.94×103 and 0–3.05×103 µg kg–1, respectively.
    Short Communication
    Complete nucleotide sequences of two isolates of Cherry virus A from sweet cherry in China
    GAO Rui, LI Shi-fang, LU Mei-guang
    2016, 15(7): 1667-1671.  DOI: 10.1016/S2095-3119(16)61343-6
    Abstract ( )   PDF in ScienceDirect  
        Cherry virus A (CVA) is a member of the genus Capillovirus, in the family Betaflexiviridae. The infection rate of CVA was high in sweet cherry in China. We determined the complete nucleotide sequences of two isolates of CVA from Tai’an, Shandong Province, China using high fidelity PCR enzymes and specific primer pairs for amplifying long fragments in RT-PCR and RACE. The full-length sequences from isolates ChTA11 and ChTA12 are both 7 382 nucleotide (nt) long, excluding the poly(A) tail, encode two open reading frames (ORFs) and have similar genome organization to the two isolates in GenBank. The complete nucleotide sequence of ChTA11 is 98.2 and 81.2% nt identity to the isolates from Germany and India in GenBank, respectively, and the ChTA12 isolate is 98.2 and 81.0% similar. Analysis of the nucleotide and amino acid sequences showed that the domain of unknown function (DUF1717) is more variable compared with other domains. This is the first report of the complete nucleotide sequences of CVA isolates infecting sweet cherry in China.