Haller Angel, Poelstra Jelmer W, Pipatpongpinyo Wirat, Kreuter Nathan, Wilson Jennifer R, Michel Andy
Department of Entomology, The Ohio State University, Wooster, OH, USA.
Molecular and Cellular Imaging Center, The Ohio State University, Wooster, OH, USA.
J Insect Sci. 2025 May 9;25(3). doi: 10.1093/jisesa/ieaf055.
Natural host-plant resistance provides a sustainable solution to control insect outbreaks but can be limited due to insect counter-adaptation. The exact mechanisms of insect adaptation to host-plant resistance remain unclear in most systems. Some insect adaptations are controlled by epigenetic mechanisms, such as through noncoding RNA. PIWI-interacting RNAs are specific noncoding RNAs that bind with PIWI proteins to control a diverse range of gene regulatory functions, particularly in insects. Previous investigation into aphid PIWI gene copies showed expansion in their abundance compared to other insects, which may suggest PIWI genes have additional functions among aphids. We first characterized PIWI gene evolution through a phylogenetic analysis, then investigated the role of PIWIs by examining gene expression in the soybean aphid (Aphis glycines), a significant insect pest of soybean which has adapted to overcome aphid-resistance in host plants. Our data indicated the presence of three PIWI ortholog groups, as well as taxon-specific gene expansions, with gene copy numbers ranging from 3 to 17 across species. To evaluate a potential role of PIWIs in overcoming host-plant resistance, we measured their gene expression in Ap. glycines with (virulent) and without (avirulent) the ability to survive on aphid-resistant soybean. We found that virulent Ap. glycines have significantly higher expression of 2 PIWI genes (Agl1.1 and Agl1.3) compared to the avirulent biotype. These data suggest that gene regulatory mechanisms related to the PIWI pathway, potentially including piRNAs, are important in aphid systems and may enable adaptation to host-plant resistance.
天然宿主植物抗性为控制昆虫爆发提供了一种可持续的解决方案，但由于昆虫的反适应，其效果可能会受到限制。在大多数系统中，昆虫适应宿主植物抗性的确切机制仍不清楚。一些昆虫适应是由表观遗传机制控制的，例如通过非编码RNA。PIWI相互作用RNA是与PIWI蛋白结合以控制多种基因调控功能的特定非编码RNA，特别是在昆虫中。先前对蚜虫PIWI基因拷贝的研究表明，与其他昆虫相比，其丰度有所增加，这可能表明PIWI基因在蚜虫中具有额外的功能。我们首先通过系统发育分析对PIWI基因进化进行了表征，然后通过检测大豆蚜虫（Aphis glycines）中的基因表达来研究PIWI的作用，大豆蚜虫是大豆的一种重要害虫，它已经适应了克服宿主植物中的抗蚜虫性。我们的数据表明存在三个PIWI直系同源组，以及特定分类群的基因扩增，不同物种的基因拷贝数范围为3至17。为了评估PIWI在克服宿主植物抗性中的潜在作用，我们测量了具有（有毒性）和不具有（无毒性）在抗蚜虫大豆上生存能力的大豆蚜虫中PIWI的基因表达。我们发现，与无毒生物型相比，有毒性的大豆蚜虫中2个PIWI基因（Agl1.1和Agl1.3）的表达明显更高。这些数据表明，与PIWI途径相关的基因调控机制，可能包括piRNA，在蚜虫系统中很重要，并且可能使蚜虫能够适应宿主植物抗性。
