Genome organization and comparative evolutionary mitochondriomics of rice earhead bug Leptocorisa oratoria (Fabricius)

The rice earhead bug, Leptocorisa oratoria (Fabricius, 1794) is a critical rice pest in India. No mitochondrial genome of L. oratoria has been sequenced earlier, and the mitochondrial data are crucial for phylogenetic and population genetic studies of this significant rice pest. In the present study, the genome of L. oratoria is 17,584 bp long with 73.57% AT content. We observed tandem repeat in the control region. Analyses from genetic distance, sliding window and Ka/Ks ratio revealed a purifying selection of 13 protein-coding genes, with cox1 and nad2 reporting the lowest and highest rate of evolution respectively. Phylogenetic analysis was reconstructed using 65 pentatomid mitogenomes with Bayesian inference and maximum likelihood methods. The results help differentiate the Coreoidea superfamily from Lygaeoidea, Aradoidea and Pentatomoidea. There were two topologies at the family level, i.e. one clade formed with Coreidae + Rhopalidae + Alydidae, and the rest of the families of Pentatomomorpha formed in separate clades. Further, L. oratoria produced an independent subclade from the earlier reported Leptocorisa sp. genome. This study provides a source mitogenome for L. oratoria species to study population demography, individual differences and phylogeography of hemipterans.

Automated summary

This study sequenced the mitochondrial genome of the rice earhead bug and conducted phylogenetic and population genetics analyses. The results showed that purifying selection occurred in 13 protein-coding genes, and different genes had different rates of evolution. Phylogenetic analysis helped distinguish between different mitochondrial genomes. Additionally, the mitochondrial genome of the rice earhead bug differed from that of a closely related species, Leptocorisa sp.