Department of Entomology, Purdue University, West Lafayette, IN 47907, USA.
J Insect Physiol. 2013 Mar;59(3):367-76. doi: 10.1016/j.jinsphys.2012.11.009. Epub 2012 Dec 8.
Deployment of resistance (R) genes is the most effective control for Hessian fly, Mayetiola destructor (Say); however, deployment of R genes results in an increased frequency of pest genotypes that display virulence to them. RNA interference (RNAi) is a useful reverse genetics tool for studying such insect virulence pathways, but requires a systemic phenotype, which is not found in all species. In an effort to correlate our observed weak RNAi phenotype in M. destructor with a genetic basis, we have aggregated and compared RNAi related genes across M. destructor, three other insect species, and the nematode Caenorhabditis elegans. We report here the annotation of the core genes in the small interfering RNA (siRNA) and microRNA (miRNA) pathways in M. destructor. While most of the miRNA pathway genes were highly conserved across the species studied, the siRNA pathway genes showed increased relative variability in comparison to the miRNA pathway. In particular, the Piwi/Argonaute/Zwille (PAZ) domain of Dicer-2 (DCR-2) had the least amount of sequence similarity of any domain among species surveyed, with a trend of increased conservation in those species with amenable systemic RNAi. A homolog of the systemic interference defective-1 (Sid-1) gene of C. elegans was also not annotated in the M. destructor genome. Indeed, it is of interest that a Sid-1 homolog has not been detected in any dipteran species to date. We hypothesize the sequence architecture of the PAZ domain in the M. destructor DCR-2 protein is related to reduced efficacy of this enzyme and this taken together with the lack of a Sid-1 homolog may account for the weak RNAi response observed to date in this species as well as other dipteran species.
抗（R）基因的部署是防治麦长管蚜（Mayetiola destructor （Say））最有效的方法；然而，R 基因的部署会导致对这些基因具有毒力的害虫基因型的频率增加。RNA 干扰（RNAi）是研究这种昆虫毒力途径的有用反向遗传学工具，但需要系统表型，而不是所有物种都具有这种表型。为了将我们在麦长管蚜中观察到的微弱 RNAi 表型与遗传基础相关联，我们对麦长管蚜、其他三种昆虫物种和线虫秀丽隐杆线虫中的 RNAi 相关基因进行了聚合和比较。我们在这里报告了麦长管蚜中微小 RNA（miRNA）和小干扰 RNA（siRNA）途径的核心基因的注释。虽然大多数 miRNA 途径基因在研究的物种中高度保守，但 siRNA 途径基因与 miRNA 途径相比显示出更高的相对可变性。特别是，Dicer-2（DCR-2）的 Piwi/Argonaute/Zwille（PAZ）结构域在调查的物种中与任何其他物种的同源物相比，具有最少的序列相似性，并且在具有可诱导系统 RNAi 的物种中具有增加的保守性趋势。秀丽隐杆线虫系统性干扰缺陷-1（Sid-1）基因的同源物也未在麦长管蚜基因组中注释。事实上，有趣的是，迄今为止，在任何双翅目物种中都没有检测到 Sid-1 同源物。我们假设麦长管蚜 DCR-2 蛋白的 PAZ 结构域的序列结构与该酶的效力降低有关，再加上缺乏 Sid-1 同源物，这可能解释了迄今为止在该物种以及其他双翅目物种中观察到的微弱 RNAi 反应。
