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Molecular evidence of insect vector manipulation by a plant virus

Jennifer Wilson: Section of Plant Pathology and Plant-Microbe Biology, Cornell University

<div>The vector manipulation hypothesis proposes that plant pathogens manipulate their insect vectors to enhance their spread. <em>Myzus persicae </em>transmits several plant viruses, including the persistent, circulative <em>Potato leafroll virus (PLRV)</em>. We suspected that PLRV may manipulate the aphid’s antiviral immune response and tested our hypothesis using small RNA (sRNA) sequencing. We discovered that production of sRNA in the aphid is changed when aphids fed on PLRV-infected plants. In particular, PLRV altered the antiviral immune response of <em>M. persicae </em>to an aphid-infecting virus, <em>Myzus persicae densovirus </em>(MpDNV)<em>, </em>as evidenced by an abundance of unusually long sRNA against MpDNV, a reduced number of 22-mers, and a higher titer of MpDNV when compared to aphids fed on uninfected plants (p = 0.02). Feeding on plants only expressing P0, the PLRV silencing suppressor protein, recapitulated the increase in MpDNV titer in aphids, suggesting that P0 is the viral protein responsible for this effect. We hypothesize that this manipulation may have evolved to enhance the plant-to-plant spread of the virus. Winged aphids showed higher and more variable MpDNV titer compared to wingless individuals, establishing a connection between MpDNV and wing production, as observed for a densovirus in another aphid species. We hypothesize that the increase of MpDNV titer in aphids mediated by PLRV may result in an increase in the production of winged morphs and hence, long-distance virus dispersal.</div>

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