摘要
目前已商品化生产的国内外抗虫棉品种在生产上均存在“苗期抗性强 ,后期抗性减弱”的现象。从DNA、mRNA和蛋白质 3个水平上对双价抗虫棉 139 2 0R4 代植株中Bt杀虫基因及其在整个生长发育期的时空表达进行了系统研究。研究结果表明 ,Bt杀虫基因在抗虫棉中的表达具有时空特异性。同一组织中 ,Bt杀虫蛋白含量在整个生长发育期呈动态下降趋势。这种现象是由于发育前期Bt杀虫基因表达量过高 ,导致转录后水平的基因表达调控引起的 ,是一种发育调控的体细胞转基因沉默现象。同时 ,Bt杀虫基因在抗虫棉生长发育后期的表达变化与 35S启动子的甲基化程度提高有关。这些研究为进一步采取相应措施 ,提高抗虫棉发育后期的抗虫性提供了依据。
The phenomena that“the efficacy of the Bt transgenic cotton in the early stages was high, then it would decrease thereafter” was prevalence in the current commercialized transgenic insect-resistant cotton cultivars both in home and abroad. The changes of Bt gene and its expression at different developmental stages were investigated at DNA, mRNA and protein levels, respectively, in the R 4 generation of GK139-20 insect-resistant transgenic materials. The results indicated that the expression of Bt toxin gene was in tissues and developmental stages specific manner. The content of the Bt crystal protein in the same tissue decreased along with the growth of the transgenic cotton plants because of the decrease of the full length Bt toxin gene transcripts. The over-expression of Bt toxin gene at earlier stages led to the gene regulation at post-transcription level and contributed to the consequent gene silencing that was developmentally regulated. Also the results showed that the lower expression level of Bt insecticidal gene at late developmental stages was correlated with the changes of the methylation state of the 35S promoter region. These results would be helpful in improving the efficacy of the Bt transgenic cotton plant at the late developmental stages.
出处
《作物学报》
CAS
CSCD
北大核心
2005年第2期197-202,共6页
Acta Agronomica Sinica
基金
国家"8 63"高技术研究发展计划 (Z17 0 2 0 1)
农业部"发展棉花生产"专项基金 (990 44 )
中华农业科教基金 (99 0 1 0 4)
关键词
BT抗虫棉
基因表达
转基因沉默
甲基化
Bt transgenic cotton plants
Gene expression
Transgene silencing
DNA methylation
