基因工程技术为改善农作物的许多重要农艺性状提供了机会,包括昆虫抗性。然而,转基因作物可食用组织中的转基因(GM)外源蛋白已成为公众强烈关注的问题。为推进转基因技术在玉米中的应用,开发了一种基于Cre/loxP的策略,用于在绿色组织中操纵转基因,同时将其锁定在非绿色组织中。在战略中,位点特异性切除可用于打开或关闭特定组织中转基因的表达。在这项工作中,两种基本的转基因玉米,名为KEY,携带Cre基因,LOCK,含有带有封闭元素的Vip3A基因,是基于它们单独的融合基因盒获得的。观察到Vip3A的表达水平和浓度在绿色组织(叶和茎)中具有高的特异性积累,在KEY×LOCK杂种的根和籽粒组织中仅观察到少量。转基因玉米对两种常见鳞翅目害虫的抗虫性,OstriniafurnacalisandSpodopterafrugiperda,在实验室和现场进行了评估。结果表明,杂种对两种害虫具有较高的抗性水平,与对照组相比,死亡率高于73.6%,损伤等级低于2.4。我们的结果表明,Cre/loxP介导的基因工程方法在转基因玉米中具有竞争优势。总的来说,这项研究的发现对于提供一种可行的策略来避免转基因在可食部分的表达和探索转基因植物生物安全的新技术具有重要意义。
Genetic engineering technology offers opportunities to improve many important agronomic traits in crops, including insect-resistance. However, genetically modified (GM) exogenous proteins in edible tissues of transgenic crops has become an issue of intense public concern. To advance the application of GM techniques in maize, a Cre/loxP-based strategy was developed for manipulating the transgenes in green tissues while locking them in non-green tissues. In the strategy, the site-specific excision can be used to switch on or off the expression of transgenes at specific tissues. In this work, two basic transgenic maize, named KEY, carrying the Cre gene, and LOCK, containing the Vip3A gene with a blocked element, were obtained based on their separate fusion gene cassettes. The expression level and concentration of Vip3A were observed with a high specific accumulation in the green tissues (leaf and stem), and only a small amount was observed in the root and kernel tissues in the KEY × LOCK hybrids. The insect resistance of transgenic maize against two common lepidopteran pests, Ostrinia furnacalis and Spodoptera frugiperda, was assessed in the laboratory and field. The results indicate that the hybrids possessed high resistance levels against the two pests, with mortality rates above 73.6% and damage scales below 2.4 compared with the control group. Our results suggest that the Cre/loxP-mediated genetic engineering approach has a competitive advantage in GM maize. Overall, the findings from this study are significant for providing a feasible strategy for transgenes avoiding expression in edible parts and exploring novel techniques toward the biosafety of GM plants.