Project description:Virus infections of insects can easily stay undetected, neither showing typical signs of a disease, nor being lethal. Such a stable and most of the time covert infection with Phthorimaea operculella granulovirus (PhopGV) was detected in a Phthorimaea operculella laboratory colony, which originated from Italy (Phop-IT). This covert virus (named PhopGV-R) was isolated, purified and characterized at the genetic level by full genome sequencing. Furthermore, the insect colony Phop-IT was used to study the crowding effect, double infection with other PhopGV isolates (CR3 and GR1), and co-infection exclusion. An infection with a second homologous virus (PhopGV-CR3) activated the covert virus, while a co-infection with another virus isolate (PhopGV-GR1) led to its suppression. This study shows that stable virus infections can be common for insect populations and have an impact on population dynamics because they can suppress or enable co-infection with another virus isolate of the same species.
Project description:In this research, the complete mitochondrial genome (mitogenome) of Phthorimaea operculella was sequenced and annotated. The mitogenome of P. operculella is 15,269 bp in length and contains 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosome RNA (12s and 16srRNA) genes and 1 control region. In addition, we used Endoclita signifier as the outgroup to analyze phylogenetic relationship, and the phylogenetic tree showed the sister relationship between P. operculella and Tuta absoluta.
Project description:Due to a lack of effective internal references, studies on functional genes in Phthorimaea operculella, a serious Lepidopteran pest attacking potatoes worldwide, have been greatly limited. To select suitable endogenous controls, ten housekeeping genes of actin (ACT), α-tubulin (α-TUB), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), elongation factor 1α (EF1α), 18S and 28S ribosomal RNA (18S, 28S), ribosomal protein genes RPL4, RPL13 and RPL27 and superoxide dismutase (SOD) were tested. Their expression levels were determined under three different experimental conditions (developmental stages, tissues/organs and temperatures) using qRT-PCR technology. The stability was evaluated with five methods (Ct value, geNorm, NormFinder, BestKeeper and RefFinder). The results clarified that RPL13, EF1α and RPL27 are ranked as the best reference gene combination for measuring gene expression levels among different developing stages and under various temperatures; EF1α and RPL13 are recommended to normalize the gene expression levels among diverse tissues. EF1α and RPL13 are the best reference genes in all the experimental conditions. To validate the utility of the selected reference pair, EF1α and RPL13, we estimated the tissue-biased expression level of chitin synthase A gene (PoChSA). As expected, PoChSA was abundantly expressed in ectodermally derived epidermal cells, and lowly transcribed in the midgut. These findings will lay the foundation for future research on the molecular physiology and biochemistry of P. operculella.
