抗虫内生工程菌对亚洲玉米螟的杀虫效果及其在植株体内的动态变化

Endophytic Engineered Bacterial Insecticidal Activity to Asian Corn Borer and Dynamical Distribution in Corn Plant

利用 3株转 Bt cry1A(c)基因的抗虫工程菌 ,对亚洲玉米螟 Ostrinia furnacalis进行离体生物测定。结果表明 :在相同浓度下 ,工程菌对玉米螟的杀虫活性均高于 Bt野生菌株 ;幼虫死亡率与浓度呈正相关 ,体重、体长与浓度呈负相关 ;工程菌 RPT4 0、RPT5 0、RPT5 5和野生型 Bt菌株 HD- 73对玉米螟的 L C50 值分别为71.2 6 ,36 .33,84 .71和 172 .36μg.g-1。在以 RPT5 0注射接种的活体生测中 ,处理株对玉米螟具有明显的抗性 ,虫体重减轻 2 4 .5 %～ 5 2 .3% ,体长降低 2 2 .6 %～ 6 4.6 %。工程菌 RPT5 0接种玉米 10 d后 ,玉米体内菌量逐步增多 ,2 0 d后菌量迅速增加 ,30 d左右达到最高峰 ,根、茎、叶中的菌量分别达 3.7× 10 6,3.0× 10 6,1.3×10 6cfu.g-1;此后开始回落 ,5 0 d后趋于稳定 ;6 0 d后根、茎、叶中的菌量约保持在 4 .0× 10 5,3.5× 10 5,7.0× 10 4cfu.g-1的水平。该菌在玉米根。

The insecticidal activity of three engineered bacteria strains with Bt cry1A (c) gene to larvae of Asian corn borer, Ostyinia furnacalis, was tested in vitor . Results obtained demonstrated that the engineered stains of RPT40, RPT50 and RPT55 had a higher insecticidal activity to the corn borer than Bt HD 73, a wild Bt strain. Larval mortality was positively, while larval weight and length was negatively correlated to concentration of the bacteria. LC 50 to larval corn borer for stains of RPT40, RPT50, RPT55 and HD 73 was 71.26, 36.33, 84.71 and 172.36 μg·μg -1 respectively A corn plant injected with RPT50 also showedanobvious resistancetothecornborer.Weightandlengthofliving larvae were reduced by 24.5% ～52.3% and 22.6%～64.6%, respectively. The bacteria number of RPT50 increased gradually within 20 days after inoculation (DAI), and attained a peak approximately at 30 DAI, when the number of bacteria in root, stalk and leaf was 3.7×10 6, 3.0 ×10 6, 1.3 ×10 6 cfu·g -1 ,respectively.Since then, the bacterial number was decreased and tended to be stable at 50 DAI. There were approximately 4.0×10 5, 3.5×10 5 and 7.0×10 4 cuf·g -1 in the root, stalk, and leaf at 60 DAI. Based on these results, it seemed clear that the distribution of RPT50 in the root and stalk was strikingly higher than that in the leaf of corn plant.