Co-infection of Solanum tuberosum with PVX and PVY leads to systemic virus-mediated gene expression

Abstract

Abstract Background Breeding novel crop cultivars can be an extremely laborious and time-consuming process, especially when it comes to highly heterozygous and tetraploid potato (Solanum tuberosum L.). Establishing biotechnological techniques to understand gene functions and to accelerate breeding processes are therefore inevitable to sustain resilient potato cultivars for future food security. Apart from being pathogens, viruses represent suitable vectors for delivering genetic information into plant cells. Taking regulatory obstacles for genetically modified crops into account, RNA viruses provide a convenient tool to introduce desired RNA molecules into plants without the application of foreign DNA. Hence, developing an RNA virus-mediated gene expression system to study and improve crop plants is of great importance. Additionally, plant RNA viruses represent an opportunity to obtain modified crops without the necessity for tissue culture. With this work, we seek to establish a virus-mediated gene expression system for cultivated potato. Results Irrespective of reports claiming successful gene expression or silencing upon infection of potato (S. tuberosum) with RNA viruses, such as potato virus X (PVX), single Agrobacterium-mediated infections with PVX did not lead to a sufficient systemic infection and concomitant expression of a green fluorescent protein (GFP) in various potato cultivars. Using the tuber-bearing species Solanum pinnatisectum for infections, systemic movement of PVX-GFP was detectable throughout the diploid wild potato, pointing out limitations for application in tetraploid potato cultivars. Further, hetero-graftings with Nicotiana benthamiana and S. tuberosum indicated that PVX-GFP can move through the vasculature of potato without leaving the transport tissue. Nonetheless, coinfection of PVX-GFP and potato virus Y (PVY) enabled adequate systemic spreading accompanied by GFP expression in different potato cultivars. Conclusion PVX-mediated gene expression is limited in cultivated potato. Utilizing PVY for co-infections facilitates systemic PVX spreading and accompanying expression of a desired gene. This method allows fast and uncomplicated viral delivery of genetic information into S. tuberosum opening up opportunities not only to express desired proteins but also to silence genes of interest and thereby establish epigenetic modifications serving as tool for basic science and possibly for plant breeding purposes.