Runo Steven
Kenyatta University, Biochemistry and Biotechnology Department, Nairobi, Kenya.
Bioeng Bugs. 2011 Jul-Aug;2(4):208-13. doi: 10.4161/bbug.2.4.16112. Epub 2011 Jul 1.
RNA interference (RNAi) has rapidly advanced to become a powerful genetic tool and holds promise to revolutionizing agriculture by providing a strategy for controlling a wide array of crop pests. Numerous studies document RNAi efficacy in achieving silencing in viruses, insects, nematodes and weeds parasitizing crops. In general, host derived pest resistance through RNAi is achieved by genetically transforming host plants with double stranded RNA constructs targeted at essential parasite genes leading to generation of small interfering RNAs (siRNAs). Small interfering RNAs formed in the host are then delivered to the parasite and transported to target cells. Delivery can be oral - worms and insects, viral infections, viruses - or through a vascular connections - parasitic plants, while delivery to target cells is by cell to cell systemic movement of the silencing signal. Despite the overall optimism in generating pest resistant crops through RNAi-mediated silencing, some hurdles have recently begun to emerge. Presently, the main challenge is delivery of sufficient siRNAs, in the right cells, and at the right time to mount; a strong, durable, and broad-spectrum posttranscriptional gene silencing (PTGS) signal. This review highlights the novel strategies available for improving host derived RNAi resistance in downstream applied agriculture.
RNA干扰（RNAi）已迅速发展成为一种强大的遗传工具，并有望通过提供一种控制多种作物害虫的策略来彻底改变农业。大量研究证明了RNAi在使寄生于作物的病毒、昆虫、线虫和杂草实现基因沉默方面的有效性。一般来说，通过RNAi实现宿主衍生的害虫抗性是通过用靶向必需寄生虫基因的双链RNA构建体对宿主植物进行基因转化来实现的，从而导致小干扰RNA（siRNA）的产生。在宿主中形成的小干扰RNA随后被传递给寄生虫并运输到靶细胞。传递方式可以是口服（针对蠕虫和昆虫、病毒感染、病毒）或通过维管连接（针对寄生植物），而传递到靶细胞则是通过沉默信号在细胞间的系统性移动。尽管通过RNAi介导的沉默来培育抗害虫作物总体上令人乐观，但最近一些障碍开始显现。目前，主要挑战是在正确的细胞中、在正确的时间递送足够的siRNA，以引发强烈、持久和广谱的转录后基因沉默（PTGS）信号。本综述重点介绍了在下游应用农业中可用于提高宿主衍生的RNAi抗性的新策略。
