VAPA, an Innovative “Virus-Acquisition Phenotyping Assay” Opens New Horizons in Research into the Vector-Transmission of Plant Viruses
Figure 3
Protoplast transmission of TuMV.
A. Effect of different acquisition times on TuMV transmission. After 60 min of starving, aphids were allowed different protoplast acquisition periods before being placed on test plants for inoculation. No effect of different acquisition time was observed (P = 0.942; df = 2; Kruskal-Wallis test). The graph combines data from 24 test plants per assay with 6 assays for acquisition times from 15 to 60 min (<90 min), 6 assays for an acquisition time of 90 min, and 4 assays for acquisition times between 120 and 180 min (>90 min). B. Pre-acquisition starving has no effect on TuMV transmission. Aphids were starved for 60, 120, or 180 min before being allowed a 60-min acquisition period on TuMV-infected protoplasts and subsequent transfer to test plants for inoculation. The graph shows that there is no measurable effect of pre-acquisition starving on transmission efficiency (P = 0.193; df = 2; Kruskal-Wallis test). 6 assays of 24 test plants were tested for 60 min starvation, 13 assays for the 120 min time point, and 4 assays for 180 min starvation. C. TuMV acquisition from protoplasts absolutely requires living protoplasts. Aphids were allowed to feed for 60 min on infected intact (control) or dead (sheared) protoplasts before transfer to test plants for inoculation. The difference between transmission rates from living and sheared protoplasts is highly significant (P<0.001; Mann-Whitney test). The graph shows data from 18 assays (9 for each condition) of 24 test plants each. D. Shearing does not inactivate TuMV. Infected protoplasts were homogenised by repeated passage through a syringe needle and then rub-inoculated to turnip test plants. The graph shows that virions from sheared protoplasts were as infectious as those from intact control protoplasts. Three 24 plant cultivation trays were inoculated per condition. All graphs present mean values ± standard deviation.
