Detection of the mild strains of potato spindle tuber viroid from single true potato seed by return electrophoresis
Singh, R.P.; Boucher, A.; Seabrook, J.E.A.
Phytopathology 78(6): 663-667
A modified procedure of return polyacrylamide gel electrophoresis (R-PAGE) was used to detect mild strains of potato spindle tuber viroid (M-PSTV) from single true potato seeds (TPS). Seed lots obtained from field-grown PSTV-infected potato plants varied in their PSTV content. The viroid was detected in both dormant and germinated individual TPS. Dormant TPS contained approximately 0.8-10 ng of viroid RNA per seed. PSTV was detected by R-PAGE in nucleic acid extracts of single seed, diluted to 1:16(about 500 pg). Germinated seed and TPS seedlings grown in vitro at 19 C showed similar rates of seed transmission. There was no change in PSTV detection in TPS seedlings grown for 4-10 wk. In composite samples of infected and healthy TPS, PSTV was detected when one infected TPS was combined with 90-100 healthy seeds. PSTV detection by R-PAGE was comparable or superior to that obtained nucleic acid by hybridization.