FIG.4 (Top).

Susceptibility to PPV of tobacco transgenic lines expressing the 5"-terminal region of the TEV genome with insertions within the P1- and HC-Pro-coding sequences. A diagram of the transgene showing the location of the mutations is shown at the top of the figure. The positions of the amino acids in TEV P1 and HC-Pro flanking the different insertions, as well as the abilities of the mutant transgenes to enhance PVX pathogenicity (taken from reference 59) and to facilitate the long-distance movement of PPV, are indicated below the diagram. Mutants disturbing these two activities are in italics. The lower part of the figure shows the symptoms displayed by upper noninoculated leaves of plants of some of the transgenic lines.