Genomic analysis of Wolbachia from Laodelphax striatellus (Delphacidae, Hemiptera) reveals insights into its "Jekyll and Hyde" mode of infection pattern.Genome Biol Evol 2020GB
Wolbachia is a widely distributed intracellular bacterial endosymbiont among invertebrates. The wStriCN, the Wolbachia strain that naturally infects an agricultural pest Laodelphax striatellus, has a "Jekyll and Hyde" mode of infection pattern with positive and negative effects: it kills many offspring by inducing cytoplasmic incompatibility (CI) but also significantly increases host fecundity at the same time. In this study, we assembled the draft genome of wStriCN and compared it to other Wolbachia genomes to look for clues to its Jekyll and Hyde characteristics. The assembled wStriCN draft genome is 1.79 Mb in size, which is the largest Wolbachia genome in supergroup B. Phylogenomic analysis showed wStriCN is closest to Wolbachia from Asian citrus psyllid Diaphorina citri. These strains formed a mono-phylogentic clade within supergroup B. Compared to other Wolbachia genomes, wStriCN contains the most diverse insertion sequence families, the largest amount of prophage sequences and the most ankyrin domain protein coding genes. The wStriCN genome encodes components of multiple secretion systems, including Types I, II, IV, VI, Sec and Tac. We detected three pairs of homologs for CI factors CifA and CifB. These proteins harbor the catalytic domains responsible for CI phenotypes but are phylogenetically and structurally distinct from all known Cif proteins. The genome retains pathways for synthesizing biotin and riboflavin, which may explain the beneficial roles of wStriCN in its host planthoppers, which feed on nutrient-poor plant sap. Altogether, the genomic sequencing of wStriCN provides insight into understanding the phylogeny and biology of Wolbachia.