Evolution and diversification of the O-methyltransferase (OMT) gene family in Solanaceae.

O-methyltransferases (OMTs) are a group of enzymes involved in several fundamental biological processes in plants, including lignin biosynthesis, pigmentation, and aroma production. Despite the intensive investigation of the role of OMTs in plant secondary metabolism, the evolution and diversification of this gene family in Solanaceae remain poorly understood. Here, we conducted a genome-wide survey of OMT genes in six Solanaceae species, reconstructing gene phylogenetic trees, predicting the potential involvement in biological processes, and investigating the exon/intron structure and chromosomal location. We identified 57 caffeoyl-CoA OMTs (CCoAOMTs) and 196 caffeic acid OMTs (COMTs) in the studied species. We observed a conserved gene block on chromosome 2 that consisted of tandem duplicated copies of OMT genes. Our results suggest that the expansion of the OMT gene family in Solanaceae was driven by whole genome duplication, segmental duplication, and tandem duplication, with multiple genes being retained by neofunctionalization and subfunctionalization. This study represents an essential first step in unraveling the evolutionary history of OMTs in Solanaceae. Our findings deepen our understanding of the crucial role of OMTs in several biological processes and highlight their significance as potential biotechnological targets.

Four new stink bug mitogenomes corroborate the internal inconsistencies in the classification of Pentatomidae (Hemiptera).

Stink bugs (Pentatomidae) are a speciose group of insects that feed mostly on plants. Many species are considered agricultural pests of economically important crops around the globe. Mitochondrial genomes are valuable for evolutionary and phylogenetic studies, but have been little explored for Pentatomidae. Here, we characterized the mitochondrial genomes of four pentatomid species (Diceraeus melacanthus, Euschistus heros, Piezodorus guildinii, and Stiretrus anchorago) and performed a comparative analysis for this family and its subfamilies. Stink bug mitogenomes disclosed a conserved gene order and content, although we detected two uncommon armless tRNAs in E. heros and D. melacanthus. Phylogenetic results indicate that Pentatominae is polyphyletic, showing that internal relationships of Pentatomidae should be further investigated. Stink bug mitochondrial genes are under strong purifying selection, except for ATP8 which showed signs of positive selection.