A Comparative Study Of Repeat Sequences In Nine Species Of Orthoptera

Pamphagidae,which belongs to the superfamily Acridoidea,Orthoptera,has four subfamilies,with Pamphaginae and Akicerinae are endemic in China.At present,there are many taxonomic studies on the family Pamphagidae,however,the field of genomic research is still absent.And genome size plays an important role as the most fundamental data of one species.Some comparative studies on genome size of insects have shown that Orthoptera is the only group in the class Insecta with a significantly enlarged genome,but the research on this is still limited.As an important part of genome,repeated sequences vary in types,sequences and contents among different species.And the repeated sequence is the most important factor that affecting genome size.In this study,the genomes of nine species of Pamphagidae were measured by flow cytometry using the internal standards of Locusts migratoria manilensis.At the same time,the next-generation sequencing data of nine species of Pamphagidae with low coverage were analyzed by RepeatExplorer2 software after pre-processing to identify and characterize the repeated sequences in the genomes of each species.Then,we compared and analyzed the types and contents of repeated sequences of 9 species of Pamphagidae to analyze the difference among them.The genome size of the nine species of Pamphagidae we measured are ranged from 13 pg to 15 pg,with an average genomic size of 14.29 pg.And the repeated sequences of the nine species of Pamphagidae accounted for about 44%? 52%of their whole genome.The main repeated types of retrotransposons we detected were LTR,and the main types of DNA transposons were Maverick and Helitron.Among all the detected repeated elements,Ty3_gypsy and LINE accounted for about 15%? 20%and 10%? 14%of the genome respectively with a relatively high proportion,while DIRS were only detected in the genome of Filchnerella beicki.In addition,different rDNA types and contents were detected in different species.By comparative analysis of the genomic repeats of nine species of Pamphagidae,the genomes of Akicerinae were slightly higher than those of Pamphaginae,the contents and differences of the type of repeated sequences were also great.All the nine species of Pamphagidae in this experiment have super-large genome size,but there are little differences in genome size and the content of repeated sequences among species.Meanwhile,the comparative analysis of the repeated sequences among the genomes of nine species of Pamphagidae showed that the types of repeated sequences in the genomes of Pamphaginae were significantly different from Akicerinae.