Agrobacterium tumefaciens-mediated transformation of poinsettia, Euphorbia pulcherrima, with virus-derived hairpin RNA constructs confers resistance to Poinsettia mosaic virus

Agrobacterium-mediated transformation for poinsettia (Euphorbia pulcherrima Willd. Ex Klotzsch) is reported here for the first time. Internode stem explants of poinsettia cv. Millenium were transformed by Agrobacterium tumefaciens, strain LBA 4404, harbouring virus-derived hairpin (hp) RNA gene constructs to induce RNA silencing-mediated resistance to Poinsettia mosaic virus (PnMV). Prior to transformation, an efficient somatic embryogenesis system was developed for poinsettia cv. Millenium in which about 75% of the explants produced somatic embryos. In 5 experiments utilizing 868 explants, 18 independent transgenic lines were generated. An average transformation frequency of 2.1% (range 1.2–3.5%) was revealed. Stable integration of transgenes into the poinsettia nuclear genome was confirmed by PCR and Southern blot analysis. Both single- and multiple-copy transgene integration into the poinsettia genome were found among transformants. Transgenic poinsettia plants showing resistance to mechanical inoculation of PnMV were detected by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). Northern blot analysis of low molecular weight RNA revealed that transgene-derived small interfering (si) RNA molecules were detected among the poinsettia transformants prior to inoculation. The Agrobacterium-mediated transformation methodology developed in the current study should facilitate improvement of this ornamental plant with enhanced disease resistance, quality improvement and desirable colour alteration. Because poinsettia is a non-food, non-feed plant and is not propagated through sexual reproduction, this is likely to be more acceptable even in areas where genetically modified crops are currently not cultivated

A new approach for obtaining rapid uniformity in rice (Oryza sativa L.) via a 3x x 2x cross

A triploid (2n = 3x = 36) rice plant was obtained by screening a twin seedling population in which each seed germinated to two or three sprouts that were then crossed with diploid plants. One diploid plant was chosen among the various F1 progenies and developed into an F 2 population via self-pollination. Compared with the control variety Shanyou 63, this F 2 population had a stable agronomical performance in field trials, as confirmed by the F-test. The stability of the F 2 population was further substantiated by molecular analysis with simple sequence repeat markers. Specifically, of 160 markers assayed, 37 (covering all 12 chromosomes) were polymorphic between the parental lines. Testing the F 1 hybrid individually with these markers showed that each PCR product had only a single band instead of two bands from each parent. The bands were identical to either maternal (23 markers) or paternal (eight markers) bands or distinct from both parents (six markers). The amplified bands of all 60 randomly selected F 2 plants were uniform and identical to those of the F 1 hybrid. These results suggest that the F 1 plant is a non-segregating hybrid and that a stable F 2 population was obtained. This novel system provides an efficient means for shortening the cycle of hybrid rice seed production

Application of heat pump combined two-stage desiccant wheel fresh air system of residential buildings in mixed climate zone

The building requires dehumidification for a long period of time in mixed climate zone of China. As a conventional method for dehumidification, vapor compression systems remove the water vapor by cooling the process air below dew point. This system consumes a lot of energy for reheating the air to meet the requirement of supply air temperature. A heat pump combined with two-stage desiccant wheel (TSDW&HP) is proposed as an air conditioning and dehumidification system in this study. The operation performance of proposed system applied in a hypothetical residence with 3 residents was investigated and simulated by using TRNSYS software. The operation modes of the system are discussed for different scenarios of season and outdoor air humidity ratio. In dehumidification season, fresh air deals with all of the latent load. In air conditioning season, fresh air deals with all of the moisture load with part of the cooling load. When evaporation temperature of HP is reduced and more moisture load is processed by evaporator in air conditioning season, there is a balance point between the performance of DWs and heat pump. The energy consumption of TSDW&HP fresh air system was compared with a conventional fresh air conditioner during dehumidification season and air conditioning season. It was found that the energy-saving potential of this system is 27.3% compared with conventional air conditioner

The climate adaptability evaluation of biogas fermentation assisted by solar greenhouse

The production efficiency of biogas digesters is largely restricted by the low environment temperature in winter, for most regions of China. As a feasible means of warming and heat preservation, solar greenhouse has the ability to expand the application scope and service time of biogas in rural China. The evaluation of climate adaptability of solar greenhouse is of great importance and imminent, due to the fact that both solar energy and biomass resources are affected by climate. In this paper, a complete evaluation index system for climate adaptability of biogas fermentation assisted by solar greenhouse was established. The indicators of the evaluation index system were selected by means of frequency analysis and theoretical analysis. The weights of the indicators, including solar radiation, outdoor air temperature, crop yields and human and animal manure, were determined by analytic hierarchy process combined with literature research, and the scoring rules were based on the objective significance of each indicator. The climate adaptability of typical cities in the Yangtze River Delta was evaluated with the evaluation index system. Among the cities, Hefei shows the best comprehensive adaptability, and then is Xuzhou, Shanghai, Nanjing, and the lowest adaptability, Hangzhou. The comprehensive adaptability results of these cities depend not only on the gas production capacity, but also on the biomass resource and solar radiation

The effect of biogas fermentation assisted by simple solar greenhouse

Biogas fermentation rate is largely affected by environment temperature, causing a much more difficult production of biogas digesters in cold winter, for most regions in China. Combining the abundant solar energy resources and biomass dry anaerobic fermentation together, solar thermal energy can guarantee the production of biogas in winter. With this method, the prediction of the appropriate fermentation temperature is required. In this study, the effect of temperature on biogas fermentation was studied. To predict the fermentation temperature, a heat transfer model of biogas fermentation based on a project in city Xuzhou, which assisted with a simple solar greenhouse, was established according to the heat transfer theory. The maximum difference between the measured and calculated fermentation temperature was 2%. The effect of biogas fermentation assisted by simple solar greenhouse in typical city of different climate zones, including severe cold region, cold region and hot summer and cold winter region, was studied with the combination of heat transfer model and temperature-based biogas production rates prediction model. The results showed that, the gas production rate of biogas fermentation increases with the increase of temperature in a certain range. Assisted by simple solar greenhouse, the biogas digester temperature is increased by 6~8°C compared with the previous one, ensuring a better daily gas production rate of 0.5~0.7m3/m3 in winter