Use of Potyvirus Vectors to Produce Carotenoids in Plants

Potyviruses are plus-strand RNA viruses that can be easily transformed into expression vectors to quickly express one carotenogenic enzyme or transcription factor, or more, in plant tissues. Unlike the technically challenging and time-consuming process of plant transformation, manipulation of a roughly 10,000 nt-long viral genome is rather straightforward via common molecular biology techniques. Here I describe how to insert the cDNAs of the proteins of interest into two particular positions of the cDNA of a Tobacco etch virus (TEV) mutant that lacks the viral NIb cistron and only infects the plants in which this protein is expressed. This deletion increases the space to harbor foreign sequences. The selection of the expression site must be made according to subcellular localization requirements. The recombinant virus is then inoculated into Nicotiana benthamiana plants by means of Agrobacterium tumefaciens. The expression of the viral genome entails the production of carotenogenic proteins in the plant tissues with a consequent effect on the plant carotenoid pathway.