转Bt基因玉米对亚洲玉米螟的抗性评价

转Bt基因抗虫玉米为诺华公司含Bt11转化系的杂交种NX4777,能全株表达Cry1Ab杀虫蛋白,以其非转基因受体玉米品种NX4906为对照。在玉米生长至心叶中期(50~60cm高)、抽雄前期和抽丝散粉期分别进行人工接亚洲玉米螟[Ostriniafurnacalis(Guenée)]初孵幼虫40~60头。以食叶级别、存活幼虫数、蛀孔数、隧道长度和雌穗被害级别等,分别作为评价玉米心叶期和穗期的抗性标准。结果表明,Bt玉米食叶级别仅为1级,显著低于对照的7级。Bt玉米平均每株存活幼虫0.04~0.20头、蛀孔0.11~0.15个、隧道长度0.13~0.41cm,雌穗被害级别为0,植株折茎率为0,而对照玉米平均每株存活幼虫6.19~12.41头、蛀孔4.48~7.05个、隧道长度12.41~24.09cm,雌穗被害级别为5.9,植株折茎率高达73.6%~95.5%。室内生测结果亦表明,取食Bt玉米心叶、雄穗的初孵幼虫3d全部死亡,取食花丝7d死亡率达到99%,相比之下取食常规玉米的存活率在88.7%以上。表明表达Cry1Ab杀虫蛋白的Bt对亚洲玉米螟具有很高的抗虫性,能够保护玉米全生育期免受玉米螟的危害。

Transgenic Maize Evaluated for Resistance to the Asian Corn Borer (Lepidoptera: Pyralidae)

A transgenic Bt maize hybrid expressing Bacillus thuringiensis (Bt) toxin, Cry1Ab protein, and its negative isoline hybrid were evaluated for against the Asian corn borer, Ostrinia furnacalis (Guenée), in field trials and laboratory bioassays. The Bt hybrid, NX4777, was developed by Novartis Seeds, using event Bt11, which expresses Bt toxin in green tissue as well as reproductive tissues including the tassel, silk, and kernel. Bt hybrid was compared with the negative isoline control, NX4906. Maize plants were artificially infested with neonate larvae of the Asian corn borer at the mid-whorl, pre-tasselling, and silking stages. Hybrid resistances were based on leaf feeding ratings, larval controls, as well as stalk and ear damages. Bt hybrid sustained significantly less leaf feeding damage (rating 1) than its negative isoline control (rating 7). On average, there were only 0.04~0.20 larvae survived per plant, 0.11~0.15 tunnels per stalk with 0.13~0.41 cm tunnel length per plant, respectively, and none of plants were stems broken or ears damaged on Bt hybrid under different infestations. In contrast, there were 6.19~12.41 larvae survived per plant, 4.48~7.05 tunnels per stalk with 12.41~24.09 cm tunnel length per plant, respectively, and 73.6%~95.5% plants were stems broken and ear damage ratings was 5.9 on the negative isoline control. Laboratory bioassays indicated that there were only 0~1% of larva survived when neonates fed on fresh whorl leaves, young tassel, and fresh silk of Bt hybrid, compared with more than 88.7% of larvae survived on the negative isoline control. These results demonstrate that transgenic Bt maize can provide season-long control of the Asian corn borer.