Bt蛋白在水稻不同遗传背景下的含量及对抗虫性的影响

为明确Bt基因在水稻杂交转育过程中抗虫作用的稳定性,以分别转入cry1C和cry2A基因的抗虫水稻品系T1C-19和T2A-1为供体亲本,与10个恢复系杂交并回交,筛选BC1F3代转基因纯合株系,用ELISA法测定水稻叶片和茎秆中Bt蛋白含量。结果表明,4个转cry1C株系和5个转cry2A株系叶片和茎秆的蛋白含量显著低于亲本,且降低了16.62%~62.03%;相同遗传背景下,叶片和茎秆中的Bt蛋白含量之间呈显著正相关;在室内转cry1C株系和转cry2A株系上二化螟幼虫的校正死亡率分别为62.50%~95.83%和37.50%~83.33%,其中在cry2A株系上的校正死亡率与茎秆中的Cry2A蛋白含量呈极显著正相关;在田间自然发虫条件下,纯合株系的单株卷叶数和枯心率最高仅为3.97和9.37%,受害程度与相应组织中Bt蛋白含量之间存在相关性。表明Bt蛋白含量会受到水稻遗传背景的影响,但杂交后代株系在田间仍能表现出很好的抗性。

Content of Bt protein in different backgrounds of rice and its effect on insect resistance

To clarify the stability of Bt gene in rice hybridization breeding, two insect-resistant rice lines, T1C-19 and T2A-1 generated by introduction of cry1C and cry2A were used as donor parents and transferred into ten restorer lines through hybridization and backcrossing. BC₁F₃ homozygous lines were selected. The amounts of Bt protein in leaves and stems of these homozygous lines were measured by ELISA. The results showed that the concentrations of Bt protein in four cry1C lines and five cry2A lines were much lower than that in the corresponding donor parents. The concentration decreased by 16.62%-62.03%. The concentration of Bt protein in leaf was significantly correlated with Bt protein in stem under the same background. The corrected mortality rates of Chilo suppressalis larvae caused by cry1C and cry2A lines were 62.50%-95.83% and 37.50%-83.33%, respectively. The corrected mortality rates caused by cry2A lines were significantly correlated with the concentration of Cry2A protein in stem. The number of folded leaves per plant and dead heart rate in homozygous lines were 3.97 and 9.37%, respectively. The extent of damage was correlated with the concentration of Bt protein. The results indicated that the concentration of Bt protein was influenced by the background of rice, but all hybrid progenies showed high toxicity to stem borers and leaf folders in the field.