Length-dependent accumulation of double-stranded RNAs in plastids affects RNA interference efficiency in the Colorado potato beetle

文献类型： 外文期刊

第一作者： He, Wanwan

作者： He, Wanwan;Xu, Wenbo;Xu, Letian;Bock, Ralph;Zhang, Jiang;Bock, Ralph;Guo, Wenchao;Fu, Kaiyun

作者机构：

关键词： Colorado potato beetle; double-stranded RNA; pest control; plastid engineering; RNA interference; transplastomic plants

期刊名称：JOURNAL OF EXPERIMENTAL BOTANY （ 影响因子：6.992； 五年影响因子：7.86 ）

ISSN： 0022-0957

年卷期： 2020 年 71 卷 9 期

页码：

收录情况： SCI

摘要： Transplastomic potato plants expressing double-stranded RNA (dsRNA) targeted against essential genes of the Colorado potato beetle (CPB) can be lethal to larvae by triggering an RNA interference (RNAi) response. High accumulation levels of dsRNAs in plastids are crucial to confer an efficient RNAi response in the insects. However, whether length and sequence of the dsRNA determine the efficacy of RNAi and/or influence the level of dsRNA accumulation in plastids is not known. We compared the RNAi efficacy of different lengths of dsRNA targeted against the CPB beta-Actin gene (ACT) by feeding in vitro-synthesized dsRNAs to larvae. We showed that, while the 60 bp dsRNA induced only a relatively low RNAi response in CPB, dsRNAs of 200 bp and longer caused high mortality and similar larval growth retardation. When the dsRNAs were expressed from the plastid (chloroplast) genome of potato plants, we found that their accumulation were negatively correlated with length. The level of dsRNA accumulation was positively associated with the observed mortality, suppression of larval growth, and suppression of target gene expression. Importantly, transplastomic potato plants expressing the 200 bp dsRNA were better protected from CPB than plants expressing the 297 bp dsRNA, the best-performing line in our previous study. Our results suggest that the length of dsRNAs is an important factor that influences their accumulation in plastids and thus determines the strength of the insecticidal RNAi effect. Our findings will aid the design of optimized dsRNA expression constructs for plant protection by plastid-mediated RNAi.

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