[G] Oral presentations in English

[G-13] Parallel evolution of Bacteroidota into highly integrated endosymbionts of scale insects (Hemiptera: Coccomorpha)

◯Jinyeong Choi¹, Cong Liu¹, Pradeep Palanichamy¹, Yumiko Masukagami¹, Filip Husnik¹ (1. OIST, Okinawa)

When symbiotic relationships are established between bacteria and animals, many features of both partners are affected. However, what tends to be the most visible change is the massive reduction of the symbiont genome. Scale insects are plant sap-feeding insects that undergo cyclical replacements of obligate nutritional symbionts. In this study, we analyzed metagenomes of 92 species of scale insects and confirmed 10 different strains of Bacteroidota symbionts. To understand the parallels in genome reduction, we analyzed 21 high-quality genome assemblies of Bacteroidota symbionts with phylogenetic and genomic methods. The symbiont genomes exhibit significant variation in size ranging from 170 kb to 1,600 kb, showing parallel gene loss and pseudogenization in all functional gene categories. Our results recapitulate with many replicates a path of Bacteroidota symbionts from recently acquired bacteria with large genomes to highly specialized partners of insects with minimal gene sets.