FIGURE 2.

Reassessment of the pathogenicity of PBTS1 and PBTS2 on different hosts. (A) Control (left) and PBTS shoot-inoculated (right) “UCB-1” clonal plants. Note the strongly stunted growth after shoot inoculation with a mixture of PBTS1 and PBTS2 (12 months after infection). (B) Detail of co-infected shoot showing loss of apical dominance and formation of deformed shoots and leaves. (C) Stunted shoot growth and reduced root system of PBTS1 and PBTS2 infected “UCB-1” seedlings (45 days after infection; n = 3). At the end of the experiment, the plants were removed from the pots and the substrate was washed from the roots; root pictures are superimposed on those of the respective plants. (D) Seedling assay to monitor the effect of PBTS1, PBTS2, and D188 on the development of N. tabacum seedling shoots (top) and roots (bottom). The arrows in the PBTS2 panel indicate seedlings with leaf deformations. The average shoot fresh weight (FW) as measured at the end of the experiment is indicated (14 days after infection). Statistical differences between infected plants and the mock-infected control were calculated using Student’s t-tests (*P < 0.01; n = 14–22). (E) Quantification of the growth inhibition effect shown in (D). Category 1, full growth inhibition with arrest at the cotyledon stage; Category 2, intermediate growth inhibition; Category 3, no growth inhibition. (F) Severe stunting of N. benthamiana plants grown in substrate inoculated with PBTS1 or PBTS2 (3 months after infection; n = 5).