Genomic analysis of multitrophic interactions between grapevine– the vine mealybug Planococcus ficus and GLRaV-3 virus

Abstract: Little is known about the genetic effects involved in interactions between grapevineplants, their insect herbivores and pathogens transmitted by insect vectors despite the importanceof such information for understanding how defence mechanisms operate at each trophic level.The current study used genomic methods to investigate interactions among grapevine Vitisvinifera, grapevine leafroll associated virus 3 (GLRaV-3) and the GLRaV-3 vector vinemealybug Planococcus ficus. These three species have been intensely researched due to theserious economic injury caused to grapevine by GLRaV-3 and P. ficus. Here we investigatedwhich genes were implicit in the response of grapevine to attack by P. ficus (either vectoringGLRaV-3 or not) as well as which genes were involved in P. ficus attack on grapevine in thepresence of GLRaV-3. Microarrays, cDNA-AFLP analysis and qPCR were used to identifycandidate genes putatively involved in these interactions. Only a small number of genes weredifferentially regulated in each species, although a temporal pattern in the expression behaviourof these genes was evident. These results provide baseline information about the effect of a plantvirus on its insect vector and the response of a plant to simultaneous insect and virus damage.They might also pave the way for a potential manipulation of the grapevine – mealybug – systemto achieve sustainable and ecologically efficient control of P. ficus damage and prevent spread ofGLRaV-3.