(a) Effect of different concentration of VpPR-10.1 protein (25, 50, 75 and 100 µg·mL−1) on cell death. BSA (100 µg·mL−1) was used as a negative control. (b) Prolonged incubation (0, 6, 12 and 24 h) of cultured cells with VpPR-10.1 protein (100 µg·mL−1) showed difference on cell death. (c) Morphology of cells after incubating with different concentration of VpPR-10.1 protein for 24 h (25 µg·mL−1, 50 µg·mL−1, 75 µg·mL−1, 100 µg·mL−1). Blue color indicated cell death. (d) DNA fragmentation analyses of tobacco BY-2 cells treated with recombinant VpPR-10.1 protein. Lane 1, tobacco BY-2 cells were treated with BSA (control; 100 µg·mL−1); lane 2, tobacco BY-2 cells were treated with 100 µg·mL−1 of VpPR-10.1 protein and 100 µL antibody; lane 3, tobacco BY-2 cells were treated with 100 µg·mL−1 of VpPR-10.1 protein.