Transgenic Melon and Squash Expressing Coat Protein Genes of Aphid-borne Viruses do not Assist the Spread of an Aphid Non- transmissible Strain of Cucumber Mosaic Virus in the Field

Transgenic melon and squash containing the coat protein (CP) gene of the aphid transmissible strain WL of cucumber mosaic cucumovirus (CMV) were grown under field conditions to determine if they would assist the spread of the aphid non-transmissible strain C of CMV, possibly through heterologous encapsidation and recombination. Transgenic melon were susceptible to CMV strain C whereas transgenic squash were resistant although the latter occasionally developed chlorotic blotches on lower leaves. Transgenic squash line ZW-20, one of the parents of commercialized cultivar Freedom II, which expresses the CP genes of the aphid transmissible strains FL of zucchini yellow mosaic (ZYMV) and watermelon mosaic virus 2 (WMV 2) potyviruses was also tested. Line ZW-20 is resistant to ZYMV and WMV 2 but is susceptible to CMV. Field experiments conducted over two consecutive years showed that aphid-vectored spread of CMV strain C did not occur from any of the CMV strain C-challenge inoculated transgenic plants to any of the uninoculated CMV-susceptible non- transgenic plants. Although CMV was detected in 3% (22/764) of the uninoculated plants, several assays including ELISA, RT- PCR-RFLP, identification of CP amino acid at position 168, and aphid transmission tests demonstrated that these CMV isolates were distinct from strain C. Instead, they were non-targeted CMV isolates that came from outside the field plots. This is the first report on field experiments designed to determine the potential of transgenic plants expressing CP genes for triggering changes in virus-vector specificity. Our results indicate that transgenic plants expressing CP genes of aphid transmissible strains of CMV, ZYMV, and WMV 2 are unlikely to mediate the spread of aphid non-transmissible strains of CMV. This finding is of practical relevance because transgenic crops expressing the three CP genes are targeted for commercial release, and because CMV is economically important, has a wide host range, and is widespread worldwide.     

黄瓜Ri T—DNA转化根的植株再生

本文利用发根农杆菌感染黄瓜植体得到的转化根,在不同激素配比的分分培养基上培养,进行再生植株的诱导试验,结果表明,ＮＡＡ和ＢＡ的合适配比,有利于黄瓜植株的再生,转化根及其再生植株检测到冠瘿碱的存在,说明农杆菌Ｒｉ质粒的Ｔ－ＤＮＡ已转移到黄瓜基因组中。     

Global change and root function

Global change includes land-use change, elevated CO₂ concentrations, increased temperature and increased rainfall variability. All four aspects by themselves and in combination will influence the role of roots in linking below- and above-ground ecosystem function via organic and inorganic resource flows. Root-mediated ecosystem functions which may be modified by global change include below-ground resource (water, nutrients) capture, creation and exploitation of spatial heterogeneity, buffering of temporal variations in above-ground factors, supply and storage of C and nutrients to the below-ground ecosystem, mobilization of nutrients and C from stored soil reserves, and gas exchange between soil and atmosphere including the emission from soil of greenhouse gases. The theory of a functional equilibrium between root and shoot allocation is used to explore predicted responses to elevated CO₂ in relation to water or nutrient supply as limiting root function. The theory predicts no change in root:shoot allocation where water uptake is the limiting root function, but substantial shifts where nutrient uptake is (or becomes) the limiting function. Root turnover will not likely be influenced by elevated CO₂, but by changes in regularity of water supply. A number of possible mechanisms for root-mediated N mineralization is discussed in the light of climate change factors. Rhizovory (root consumption) may increase under global change as the balance between plant chemical defense and adapted root consuming organisms may be modified during biome shifts in response to climate change. Root-mediated gas exchange allows oxygen to penetrate into soils and methane (CH₄) to escape from wetland soils of tundra ecosystems as well as tropical rice production systems. The effect on net greenhouse gas emissions of biome shifts (fens replacing bogs) as well as of agricultural land management will depend partly on aerenchyma in roots.     

Variability in susceptibility among cucumber and tomato strains of Tetranychus urticae Koch to 2-tridecanone from tomato trichomes: effects of host plant shift

The effects of secondary plant compounds on different host races/strains of a herbivorous arthropod are not easy to interpret based on dose–response tests alone. This difficulty arises because the responses in a population to a given dose are dictated not only by genetic factors, but also by factors such as feeding history, age and plant. To discriminate between these possibilities different strains of a herbivorous mite (Tetranychus urticae Koch) were exposed to one relevant toxin from glandular hairs on tomato (the methyl ketone, 2-tridecanone) and these strains had a known feeding history on either or both of two host plants (tomato and cucumber). It was hypothesized that tomato is a relatively hostile host plant to spider mites partly due to methyl ketones from glandular hairs and that consequently there will be stronger selection on the tomato strains than on the cucumber strains. However, the expected differences between the tomato and cucumber strains did not show up; three spider mite strains collected from tomato and two strains collected from cucumber appeared to be equally susceptible to 2-tridecanone. This unexpected result cannot result from selection for resistance to 2-tridecanone, but it may be the consequence of cross-resistance to other ketones in cucumber or the bio-accumulation (i.e. metabolic load) of 2-tridecanone prior to the toxicity test. To test this hypothesis, one of the tomato strains was released on cucumber for different time intervals and one of the cucumber strains on tomato. It was found that the resistance of the tomato strain to 2-tridecanone increased 6 months after transfer to cucumber. This increased resistance cannot be the result of selection because 2-tridecanone is absent from cucumber. Hence, it may be due either to selection for resistance to another ketone in cucumber, possibly leading to cross-resistance, or to the absence of 2-tridecanone bioaccumulation on cucumber. Transfer of the cucumber strain from cucumber to tomato also increased the resistance to 2-tridecanone. As this was accompanied by high mortality directly after the transfer, selection for resistance may have played a role. Alternatively, the increased resistance may be due to induction of resistance to secondary plant compounds of tomato, including 2-tridecanone. In conclusion, experiments on host plant transfer show that the tomato strain and the cucumber strain are not equal in their resistance to 2-tridecanone.     

Animal board invited review: genetic possibilities to reduce enteric methane emissions from ruminants

Measuring and mitigating methane (CH₄) emissions from livestock is of increasing importance for the environment and for policy making. Potentially, the most sustainable way of reducing enteric CH₄ emission from ruminants is through the estimation of genomic breeding values to facilitate genetic selection. There is potential for adopting genetic selection and in the future genomic selection, for reduced CH₄ emissions from ruminants. From this review it has been observed that both CH₄ emissions and production (g/day) are a heritable and repeatable trait. CH₄ emissions are strongly related to feed intake both in the short term (minutes to several hours) and over the medium term (days). When measured over the medium term, CH₄ yield (MY, g CH₄/kg dry matter intake) is a heritable and repeatable trait albeit with less genetic variation than for CH₄ emissions. CH₄ emissions of individual animals are moderately repeatable across diets, and across feeding levels, when measured in respiration chambers. Repeatability is lower when short term measurements are used, possibly due to variation in time and amount of feed ingested prior to the measurement. However, while repeated measurements add value; it is preferable the measures be separated by at least 3 to 14 days. This temporal separation of measurements needs to be investigated further. Given the above issue can be resolved, short term (over minutes to hours) measurements of CH₄ emissions show promise, especially on systems where animals are fed ad libitum and frequency of meals is high. However, we believe that for short-term measurements to be useful for genetic evaluation, a number (between 3 and 20) of measurements will be required over an extended period of time (weeks to months). There are opportunities for using short-term measurements in standardised feeding situations such as breath ‘sniffers’ attached to milking parlours or total mixed ration feeding bins, to measure CH₄. Genomic selection has the potential to reduce both CH₄ emissions and MY, but measurements on thousands of individuals will be required. This includes the need for combined resources across countries in an international effort, emphasising the need to acknowledge the impact of animal and production systems on measurement of the CH₄ trait during design of experiments.     

Cattle feed or bioenergy? Consequential life cycle assessment of biogas feedstock options on dairy farms

On‐farm anaerobic digestion (AD) of wastes and crops can potentially avoid greenhouse gas (GHG) emissions, but incurs extensive environmental effects via carbon and nitrogen cycles and substitution of multiple processes within and outside farm system boundaries. Farm models were combined with consequential life cycle assessment (CLCA) to assess plausible biogas and miscanthus heating pellet scenarios on dairy farms. On the large dairy farm, the introduction of slurry‐only AD led to reductions in global warming potential (GWP) and resource depletion burdens of 14% and 67%, respectively, but eutrophication and acidification burden increases of 9% and 10%, respectively, assuming open tank digestate storage. Marginal GWP burdens per Mg dry matter (DM) feedstock codigested with slurry ranged from –637 kg CO₂e for food waste to +509 kg CO₂e for maize. Codigestion of grass and maize led to increased imports of concentrate feed to the farm, negating the GWP benefits of grid electricity substitution. Attributing grass‐to‐arable land use change (LUC) to marginal wheat feed production led to net GWP burdens exceeding 900 kg CO₂e Mg^?1 maize DM codigested. Converting the medium‐sized dairy farm to a beef‐plus‐AD farm led to a minor reduction in GWP when grass‐to‐arable LUC was excluded, but a 38% GWP increase when such LUC was attributed to marginal maize and wheat feed required for intensive compensatory milk production. If marginal animal feed is derived from soybeans cultivated on recently converted cropland in South America, the net GWP burden increases to 4099 kg CO₂e Mg^?1 maize DM codigested – equivalent to 55 Mg CO₂e yr^?1 per hectare used for AD‐maize cultivation. We conclude that AD of slurry and food waste on dairy farms is an effective GHG mitigation option, but that the quantity of codigested crops should be strictly limited to avoid potentially large international carbon leakage via animal feed displacement.     

灌水量和滴灌施肥方式对温室黄瓜产量和品质的影响

以黄瓜为试验材料,研究灌水量和滴灌施肥方式对日光温室黄瓜生长、产量和品质的影响.设两个水分水平(100％ET0,W1;75％ET0,W2)和4种滴灌施肥方式处理,不同滴灌施肥方式处理按推荐施肥量(N∶P2 O5∶K2 O分别为360∶180∶540 kg·hm-2)的100％、66.6％、33.3％、0％(Z100、Z66、Z33、Z0)分8次滴灌施肥,剩余肥料一次性基施;另设不施肥处理为对照(CK).结果表明:滴灌施肥比例和水分与黄瓜的株高、叶面积、干物质量、产量和品质均呈正相关关系.W1 Z100处理的产量最高(67760 kg·hm-2);W2处理的平均水分利用效率比W1处理高9.4％,其中W2Z100处理的水分利用效率最高(47.71 kg·m-3),其产量比最高产量低3.4％却节水25％.与Z0相比,Z100的黄瓜产量和干物质量分别增加15.3％和16.8％;同时,黄瓜果实中维生素C、可溶性蛋白和可溶性糖含量增加;水分利用效率增加19.1％.W2Z100处理为温室黄瓜高产、优质、节水的最佳处理.     

Energy Cost of Living and Associated Pollution for Beijing Residents

China's remarkable economic growth in the last 3 decades has brought about big improvements in quality of life while simultaneously contributing to serious environmental problems. The aim of all economic activities is, ultimately, to provide the population with products and services. Analyzing environmental impacts of consumption can be valuable for illuminating underlying drivers for energy use and emissions in society. This study applies an environmentally extended input‐output analysis to estimate household environmental impact (HEI) of urban Beijing households at different levels of development. The analysis covers direct and indirect energy use and emissions of carbon dioxide (CO₂), sulfur dioxide (SO₂), and nitrogen oxide (NO_x). On the basis of observations of how HEI varies across income groups, prospects for near‐future changes in HEI are discussed. Results indicate that in 2007, an urban resident in Beijing used, on average, 52 gigajoules of total primary energy supply. The corresponding annual emissions were 4.2 tonnes CO₂, 27 kilograms SO₂, and 17 kilograms NO_x. Of this, only 18% to 34% was used or emitted by the households directly. While the overall expenditure elasticity of energy use is around 0.9, there is a higher elasticity of energy use associated with transport. The results suggest that significant growth in HEI can be expected in the near future, even with substantial energy efficiency improvements.     

北京夏植黄瓜内生真菌区系研究

为了解黄瓜植株内生真菌的区系组成及其变化,从而为进一步研究黄瓜内生真菌的生态和功能奠定基础,对采自北京延庆的不同品种和不同生育期的40株黄瓜进行了内生真菌的分离培养。经形态学鉴定和18S rDNA序列分析,分离到的1,024株内生真菌属于18属,其中Exserohilum和Neocosmospora尚未见内生真菌的报道。Alternaria、Aspergillus、Chaetomium、Cladosporium和Fusarium在各生育期和各器官普遍存在。其中,Alternaria在叶中的定殖率达47.0%,远高于在其他器官中的定殖率;Fusarium在根中的定殖率达32.5%,远高于在其他器官中的定殖率。多数真菌类群表现出不同程度的器官偏好性,有些真菌类群则只出现在特定器官中。叶和根的内生真菌类群数量和总定殖率均高于茎和果实。随着黄瓜的生长,各器官内生真菌的类群数在增加,部分真菌的定殖率也呈上升趋势,但Neocosmospora和Chaetomium在各器官中的定殖率则随植株生长呈下降趋势。     

Effects of available surface on gaseous emissions from group-housed gestating sows kept on deep litter

In the European Union, the group-housed pregnant sows have to have a minimal legal available area of 2.25 m²/sow. However, it has been observed that an increased space allowance reduces agonistic behaviour and consecutive wounds and thus induces better welfare conditions. But, what about the environmental impacts of this greater available area? Therefore, the aim of this study was to quantify pollutant gases emissions (nitrous oxide, N₂O, methane, CH₄, carbon dioxide, CO₂ and ammonia, NH₃), according to the space allowance in the raising of gestating sows group-housed on a straw-based deep litter. Four successive batches of 10 gestating sows were each divided into two homogeneous groups and randomly allocated to a treatment: 2.5 v. 3.0 m²/sow. The groups were separately kept in two identical rooms. A restricted conventional cereals based diet was provided once a day in individual feeding stalls available only during the feeding time. Rooms were automatically ventilated. The gas emissions were measured by infra red photoacoustic detection during six consecutive days at the 6th, 9th and 12th weeks of gestation. Sows performance (body weight gain, backfat thickness, number and weight of piglets) was not significantly different according to the space allowance. In the room with 3.0 m²/sow and compared with the room with 2.5 m²/sow, gaseous emissions were significantly greater for NH₃ (6.29 v. 5.37 g NH₃-N/day per sow; P < 0.01) and significantly lower for N₂O (1.78 v. 2.48 g N₂O-N/day per sow; P < 0.01), CH₄ (10.15 v. 15.21 g/day per sow; P < 0.001), CO₂ equivalents (1.11 v. 1.55 kg/day per sow; P < 0.001), CO₂ (2.12 v. 2.41 kg/day per sow; P < 0.001) and H₂O (3.10 v. 3.68 kg/day per sow; P < 0.001). In conclusion, an increase of the available area for group-housed gestating sow kept on straw-based deep litter seems to be ambiguous on an environmental impacts point of view. Compared with a conventional and legal available area, it favoured NH₃ emissions, probably due to an increased emitting surface. However, about greenhouse gases, it decreased N₂O, CH₄ and CO₂ emissions, probably due to reduced anaerobic conditions required for their synthesis, and led to a reduction of CO₂ equivalents emissions.