mRNA profiles of piRNA pathway genes in emerald ash borer Agrilus planipennis

Recent advances of Piwi-interacting RNAs (piRNAs) have enabled a better understanding of their putative roles in the protection of germ cells against selfish genetic elements. The germ plasm proteins namely, PIWI and VASA, are key players in regulation of piRNAs. However, the biogenesis of piRNAs remains poorly understood. We report the characterization and the transcript profiles of a PIWI and VASA gene in various tissues and developmental stages of the emerald ash borer (Agrilus planipennis), an exotic invasive insect pest that has attained a high impact status worldwide. The deduced amino acid sequences of both these genes (herein referred to ApPIWI and ApVASA) revealed homology with similar proteins from other insect and non-insect taxa. Peak transcript levels for ApPIWI and ApVASA were observed in the ovaries (compared to the other tissues assayed) and in adults (compared to the other developmental stages assayed). To our knowledge this is the first report of profiling piRNA pathway genes in A. planipennis. These results provide new insights into the putative function of the PIWI and VASA proteins in insects.