Horizontal Transfer Between Irinovirus 6 And Rice Planthoppers And Other Organisms

Horizontal transfer of genetic materials between virus and host have been frequently identified.Cross-species HT plays an important role between parasitic organisms and their host evolution.Transposable element(TE)is a kind of DNA fragment that can move through the host genome.At present,it is generally consider that most of the HT events occur at the TE level.Three rice planthoppers,Laodelphax striatellus,Nilaparvata lugens,and Sogatella furcifera are agriculturally important insects in Asia because they are destructive rice pests and also the vector of a number of phytopathogenic viruses.In this study,three reported rice planthopper genomes and all known viral sequences were used to identify a highly homologous and highly copied DNA sequence of iridovirus in the rice planthopper genome.These viral sequences are located at the positions(157,843-158,142)of the ORF 353 L and 354 L of IIV-6 to be inserted into the rice planthopper genome in a sense or antisense orientation.Transposon prediction analysis showed that the sequence contained a conservative transposon sequence SINE3-1_TC,indicating that this sequence(rice planthopper SINEs-like sequences,in rice planthopper,RPSLSs)may be transferred from the rice planthopper to the IIV-6 genome at the level of the transposable process.Further analysis revealed that there were 19(L.striatellus),24(N.lugens)and 178(S.furcifera)RPSLSs transcripts in three rice planthopper transcripts.The results of q RT-PCR showed that these transcripts were expressed in different developmental stages of N.lugens,and might play a regulatory role in different developmental stages of N.lugens.Small RNA analysis showed that RPSLSs could produce small RNA of 26-28 nt which is typical pi RNA feature.At the same time,the HTT(HT of TE)between iridovirus 6 and other species except virus was also identified.The results showed that there was potential HTT between iridovirus 6 and rickettsia,winged insects,yeasts and bacteria.Revealing the potential HT/HTT events of insects and viruses and their mechanisms can help us to reconstruct the long history of co-evolution between vector harmful insects and viruses which will help us to further understand the antiviral mechanism in insects,at the same time,it also provides a theoretical basis for the development of new anti-virus strategies.