Infectivity of Tomato yellow leaf curl virus isolated from imported tomato fruit in Estonia

There is a risk that Tomato yellow leaf curl virus (TYLCV) and its vector, whiteflies of the Bemisia tabaci species complex, will become established in greenhouses in temperate regions of the world, including northern Europe. In this study, TYLCV isolated from imported tomato fruit in Estonia (originating from Spain) was shown to be able to infect plants of tomato and Nicotiana benthamiana using Agrobacterium-mediated inoculation with an infectious clone as well as using biolistic delivery of products from rolling circle amplification (RCA). A 1.8-mer genomic construct of TYLCV was engineered and efficiently agroinfiltrated into plants of tomato and N. benthamiana, and induced symptoms characteristic of natural infection. With Agrobacterium-mediated inoculation, the infection efficiency was 100% for both tomato and N. benthamiana, whereas biolistic inoculation using RCA products resulted in efficiencies of 57% and 36%, respectively. Particle bombardment with monomeric linear genome failed to produce any infection in tomato or N. benthamiana. The genome of TYLCV amplified from tomato fruit was infectious confirming that tomato fruit may serve as a source of virus inoculum. This is the first report of agroinfiltration and particle bombardment assay using TYLCV DNA derived from infected tomato fruit tissue.