Title: Virus-independent and common transcriptome responses of leafhopper vectors feeding on maize infected with semi-persistently and persistent propagatively transmitted viruses Authors
Submitted to: Biomed Central (BMC) Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2014
Publication Date: April 1, 2014
Citation: Cassone, B.J., Wijertine, S., Michel, A., Stewart, L.R., Chen, Y., Yan, P., Redinbaugh, M.G. 2014. Virus-independent and common transcriptome responses of leafhopper vectors feeding on maize infected with semi-persistently and persistent propagatively transmitted viruses. Biomed Central (BMC) Genomics. 15:133. Interpretive Summary: Virus diseases that are moved from plant to plant by insect vectors are among the most common emerging diseases of crops and are among the most difficult to control. This is due, in part, to our lack of information about the mechanisms that viruses use to 'hitch a ride' with these insect vectors and the responses the insects have to the virus that enhance or prevent movement. We know that viruses use a variety of strategies for transmission by insects, that reflect different mechanisms for overcoming defense barriers in the insect. However, little was known about the responses of insect vectors to virus exposure, and no information was available on the responses of insects to viruses that use different transmission strategies. We investigated the responses of leafhoppers to feeding on maize plants infected with either a virus that binds to the surface of the insect gut or one that enters and infects insect cells for transmission using next generation sequencing. We found unexpected similarities in the responses of insects to these two very different viruses, as well as some clear differences. This information will be used to test the importance of genes involved in the common response for virus transmission, and may ultimately be useful for identifying insect factors that disrupt insect-mediated virus transmission to crops.
Technical Abstract: Insects are the most important epidemiological factors of plant virus disease spread, with >75% of the viruses dependent on insects for host transmission. However, little is known regarding the molecular and cellular mechanisms that regulate the processes and efficiency of transmission. The black-faced leafhopper (Graminella nigrifrons) vectors two viruses that use different strategies for host transmission: the semi-persistently transmitted Maize chlorotic dwarf virus and the persistent propagatively transmitted Maize fine streak virus. In this study, next generation sequencing was used to reassemble the G. nigrifrons transcriptome and examine transcript changes in leafhoppers fed on MCDV-infected, MFSV-infected, and healthy maize for 4 h and 7 d. Feeding on MFSV-infected maize induced hemocoel and cell-membrane-linked immune responses in G. nigrifrons that were not elicited when feeding on MCDV-infected or healthy maize. Unexpectedly, feeding on maize infected with either virus for 4 h brought about a substantial, shared induction of core immunity and energy metabolism transcripts. This may indicate that the insect vector is responding to cellular, biochemical, and/or physiological changes in the host plant that are brought about by virus infection rather than directly by virus exposure. Changes in gene expression that occur independent of the mode of pathogen transmission could be important for identifying insect factors that disrupt vector-mediated plant virus transmission.