Figure 1.

Comparison of accumulation of viroid RNA and severity of symptoms of tomato plants infected with two PSTVd variants and its mutatns. Total RNA was extracted from tomato plants infected with in vitro transcripts of 2 variants of PSTVd and its mutants at 2-, 3- and 4-wpi were used for (A) Northern blot hybridization using digoxigenin (DIG)-labelled PSTVd specific probes to analyze the viroid RNA accumulation. P denotes positive control from PSTVd RNA and Control indicates a mock-inoculated tomato plant. (B) Accumulation of viroid RNA was evaluated by quantifying signals obtained in Northern blot hybridization. Number on the bars represents the nucleotide position that has been mutated. The changes in the viroid RNA accumulation between the time points are shown with dotted lines. (C) At 4-wpi, PSTVd mutants caused an array of symptoms on tomato plants.