Fig 3.
Chlorine treatment of lettuce tissue after TV internalization and dissemination. Feed water was inoculated with TV stock to a starting titer on day 0 of 1.25 × 106 PFU/ml. At days 1, 2, 3, 7, and 14, roots, shoots, and leaves of romaine lettuce were harvested and submerged in 50 ml of chlorine solution (1,000 ppm) for 5 min. Plant tissues were washed with 50 ml of tap water for 5 min by gentle agitation. Following tap water wash, samples were homogenized with liquid nitrogen and mortar and pestle and resuspended in 5 ml of sterile PBS. The residual chlorine was neutralized by 0.25 M sodium thiosulfate. Sample homogenate was then subjected to centrifugation at 1,000 × g for 30 min, and the supernatant was tested for infectious viral particles by plaque assay. Viral titer is reported as PFU/g. Data points were the averages of three replicates. Error bars represent ±1 standard deviation.