Cucumber Mosaic Virusas a carotenoid inhibitorreducingPhelipanche aegyptiacainfectionin tobacco plants

摘要

Cumber Mosaic Virus(CMV) is a highly infectious cucumovirus, which infects more than 800 plant species andcauses major diseases in greenhouse andfield crops worldwide. Parasitic weeds such asPhelipanche aegyptiacaare amajor constraint to the production of many crops in the world and the parasite’s lifestyle makes control extremelydifficult. The parasite seeds can germinate after conditioning and perceiving strigolactones secreted by the host roots.Strigolactones are rhizosphere signaling moleculesin plants that are biosynthesized through carotenoid cleavage. Inthe present study we investigated the possibility of reducingb-carotene and then strigolactone production in the hostroots by blocking carotenoid biosynthesis using CMV-infected tobacco. It was found that CMV downregulated theenzyme phytoene desaturase(PDS) and reduced significantly both carotenoid production andPhelipancheinfection intobacco host roots infected with both CMV andP. aegyptiaca. Based on our results (decrease ofb-caroteneandrepression of PDS transcripts in tobacco roots), we hypothesized that the reduction ofPhelipanchetubercles and shootsoccurred due to an effect of CMV on secondary metabolite stimulators such as strigolacetones. Our study indicated thatmass productionof the host roots was not affected by CMV; however, most inflorescences ofPhelipanchegrown onCMV-infected tobacco developed abnormally (deformed shoots and short nodes). Carotenoid biosynthesis inhibitorssuch as CMV can be used to reduce the production of strigolactones, which will lead to decreasedPhelipancheattachment. Interestingly, attenuated CMV strains may provide a safe means for enhancing crop resistance againstparasitic weeds in a future plan.