Research on Frequency of Exogenous Gene Flow from Marber-free Insect-resistant Transgenic Rice to Conventional Rice Varieties

[Objective] This study aimed to investigate the frequency of exogenous gene flow to non-transgenic conventional rice cultivars and assess the potential risks of marker-free of insect-resistant transgenic rice to agricultural ecological environment. [Method] Insect-resistant transgenic rice variety HUAHUI No.1 was planted as the experimental material and surrounded by several non-transgenic conventional rice cultivars. F1 non-transgenic rice seeds were collected according to different distances and identified by using PCR technology, the frequency of exogenous gene flow from insect-resistant transgenic rice to non-transgenic conventional rice cultivars was counted and analyzed. [Result] The average frequency of exogenous Bt gene flow to P13381 and CHUNJIANG063 was 0. Transgene flow occurred to varying degrees from insect-resistant transgenic rice HUAHUI No.1 to several non-transgenic rice lines including HEX122-2, TIANXlANG, MINGHUI63 and Pl157, with the maximum average gene flow frequency of 0.875%. The frequency of gene flow was gradually reduced with the increase of distance, and the average transgene flow frequency de- creased to 0 in all the sampling points 7 m away from transgenic rice material. [Conclusion] This study revealed that the exogenous gene flow frequency of insect-re- sistant transgenic rice variety HUAHUI No.1 was very low, leading to very small risk to the eco-environment. Rational distribution in the field for physical isolation, keeping the appropriate distance and scientific farming arrangement to avoid the synchronization of flowering can effectively control the exogenous gene flow from transgenic rice and reduce he ecological risks caused by transgene escape.

Effect of feeding transgenic cry1Ab/cry1Ac rice on indices of immune function in broilers

The safety of feeding transgenic crylAb/crylAc rice （a genetically modified （GM） rice variety） to broilers was examined from an immunological perspective. HatchlingArborAcres chickens （240） were assigned to two dietary treatments （diets containing GM or non-GM rice） with 12 replicates per group and 10 birds per replicate. Traits were measured on one randomly selected bird from each replicate at d 21 and 42. The 42-d feeding trial revealed that crylAb/crylAc rice had no significant effect relative to non-GM rice on body weight and the immune organ indices. No significant pathological lesion in the spleen and bursa of Fabricius was found in the GM rice group. There were no significant differences in serum concentrations of immunoglobulin Y （IgY）, IgM, interleukin 4 （IL-4） and IL-6 between the two groups at d 21 or 42, except for IL-6 being higher （P〈0.05） in the GM- fed chickens at d 42. There were no differences in the T and B lymphocyte transformation rate and CD4＋/CD8＋ ratio between the two groups at d 42. Additionally, there was no significant difference between the two diets in expression of relevant genes viz. the major histocompatibility complex class II beta chain （BLB2）, interferon beta 1 （IFNβ）, tumour necrosis factor alpha-like （TNFa） and toll-like receptor 4 （TLR4）in the spleen and bursa of Fabricius. All the data demonstrated that transgenic crylAb/ crylAc rice had no adverse effect on these aspects of immune function of broilers during 42-d feeding trial. Transgenic rice was therefore indistinguishable from non-GM rice in terms of short-term feeding in chickens.

Indication of Genetic Linkage Map for Sunflower(Helianthus annuus L.) by SSR Markers

In order to investigate the possibility and efficiency of exogenous gene spread in nature and potential ecological risk of transgenic rice, as well as analyze the effect of exogenous Bt gene insertion on ecological fitness of transgenic rice plants, a experiment was carried out with three insect-resistant Bt transgenic rice cultivars Bt63, R1 and R2 and one conventional rice line 11-838 as experimental materials, the insect-resistant transgenic and non-transgenic rice plants were inter- cropped pair-wisely under high and low insect-infestation pressures, and the vegeta- tive growth, seed-setting and the resistance to rice stem borers were compared be- tween transgenic and non-transgenic lines. According to the experimental results, both the tiller number and fresh weight of Bt transgenic rice plants under low insect- infestation pressure showed no significant differences compared with the control, but the plant height, spike length and spike weight were all lower than those of non- transgenic rice plant, and Bt63 and R2 were significantly different compared with the control. On the contrary, under high insect-infestation pressure, the tiller number, spike length and spike weight of three Bt transgenic rice cultivars were significantly higher than those of the control, while the plant height showed different fitness ef- fects among various transgenic rice cultivars, which might be related to the charac- teristics of the receptive cultivars. The individual filled grain number and 1 000-grain weight of three transgenic rice cultivars showed no significant difference compared with the control under two different insect-infestation pressures, suggesting that the effect of exogenous Bt gene on seed setting was not significant. Under insect-infes- tation pressure, the resistance of three Bt transgenic rice cultivars against rice stem borer was significantly superior to non-transgenic rice, indicating that the effect of exogenous Bt gene on insect resistance of receptive plants was distinctly. Further- more, experimental results showed that the fitness cost of Bt transgenic rice was rel- atively low, which implied that exogenous Bt gene in insect-resistant transgenic rice might escape under certain environmental conditions, but this risk was very low.

转cry1Ac和CpTI双基因抗虫水稻对二化螟和大螟的致死效应及田间螟虫构成的影响

就转crylAc＋CpTI双基因抗虫水稻不同生育期对二化螟Chilo suppressalis和大螟Sesamia inferens的室内致死特性及田间螟虫的构成进行了研究。室内测定结果表明，不同生育期转基因水稻对二化螟、大螟都表现明显的致死效应，但水稻生长后期的致死效果降低。转基因水稻对大螟的致死效应显著弱于对二化螟的，其中，二化螟除在齐穗期和成熟期有少量幼虫（0．5％～6．4％）存活到第4天外，其余均在第4天死亡；大螟在两种转基因水稻上的存活率高于二化螟，且少量个体（〈1．6％）还能化蛹、羽化，但化蛹率和羽化率均明显低于在非转基因对照上的。早、晚两季水稻的田间调查结果表明，转基因水稻上两种螟虫虫口数量均显著低于相应的非转基因对照品种，转基因水稻上二化螟虫口减退率〉99％；大螟虫口减退率相对较低，早、晚稻上有所不同，其中早稻〉93％，晚稻仅44％～64％。转基因水稻上残存螟虫中，大螟所占比例明显上升，推测转基因水稻对两种螟虫致死效应差异可能是其主要原因。

转cry1Ac基因抗虫水稻环介导等温扩增检测方法的建立及应用

为了方便快速地检测转cry1Ac基因抗虫水稻的转基因成分,本研究以转cry1Ac基因水稻‘华恢1号’为主要研究对象,根据环介导等温扩增技术的原理,针对人工改造的cry1Ac晶体蛋白毒素基因的6个区段设计4条特异性引物,在65℃条件下,利用链置换DNA聚合酶等温扩增1h,分别通过荧光显色和凝胶电泳完成对转基因作物的检测工作,同时对2种转基因作物和5种非转基因作物进行LAMP检测以检验该方法的特异性。结果表明,该LAMP方法能有效地检测含有cry1Ac的转基因作物,检测结果与常规PCR方法结果一致,灵敏度是PCR方法的10倍,达到0.01%,并且具有高特异性,表明该检测方法适合转cry1Ac基因抗虫作物的快速检测。