转新型双抗虫基因棉花的遗传分析

首次用含合成的BtCrylAc活性杀虫蛋白嵌合基因及慈菇蛋白酶抑制剂B(API-B)基因表达框的双抗虫基因植物表达载体，通过土壤根癌杆菌介导转化棉花品种冀合321，获得一批抗虫的转化再生棉花植株。利用叶片涂抹卡那霉素、叶片离体养虫和PCR扩增等检测方法对6个不同转双抗虫基因株系的抗虫性进行遗传分析。结果显示，转化株系自交的T1抗虫性状遗传较为复杂；农杆菌介导获得的转基因抗虫棉在早期世代不易选到纯合系，但是随着对抗虫性状进行单向选择，到T4和T5就能获得抗虫纯合系。利用抗虫性稳定的转化后代材料和转化受体进行田间杂交，发现F2抗虫性分离完全符合一对或两对显性基因的分离规律，并证明了DR248和DR193两个材料为外源基因双拷贝插入。转化株系的Southern杂交也证明了上述结果。

Inheritance and Segregation of Transformants in Cotton with Two Types of Insect-resistant Genes

A plant expression vector containing a chemeric Bt29K gene coding for the active Cry1Ac protein and the arrowhead proteinase inhibition gene API B was introduced into an elite cotton cultivar Jihe 321 by Agrobactertium tumefaciens. Some insect resistant cotton lines were developed.Segregation and stabilization of insect resistant genes in six transformation lines were studied.Based on the results of kanamycin resistant test and insect bioassay using Heliethis armigera, PCR detection and Southern blot,we found that the inheritance and segregation of Bt gene were complicated,some transformants were in accordance with Mendelian patterns of inheritance in the ratio of insect resistant plants to non resistant plants in T 1 progeny,yet others were non Mendelian patterns.But the inheritance and segregation of Bt gene in homozygous transformation lines were one or two pairs of major dominant genes through crossing of insect resistant homozygous lines with non transformation cotton variety.That the insect resistance phenotype was conditioned by one or two pairs of dominant genes was ascertained in this study.There were two copies of Bt genes in two transformation lines DR248 and DR193,which was reported for the first time.The results were confirmed by Southern blot.Through observation of segregation population of transgenic plants at different generations,we found that the exogenous Bt gene in cotton genome showed unstable in inheritance in early generations,but the gene could be stabilized through resistance screening generation by generation.The unstability of Bt gene may mean that it need time for the gene to compatibilize cotton genome.