The ability of 32P-labeled transcribed cRNA probes to detect tomato ringspot virus (TmRSV) RNA in nucleic acid extracts from roots, bark, and leaves of nectarine (Prunus persica [L.] Batsch) trees with the Prunus stem-pitting disease was assessed and compared with detection of TmRSV antigen by enzyme-linked immunosorbent assay (ELISA) in the same tissues. Neither TmRSV-specific nucleic acid nor antigen was detected in nectarine leaf tissue. ELISA detected TmRSV antigen in root extracts from 71% of the diseased trees, while dot hybridization detected virus-specific nucleic acid in 18% of the same samples. However, ELISA detected TmRSV antigen in only 47% of bark extracts; whereas TmRSV-specific nucleic acid was detected in 100% of the bark extracts from samples collected at or near the soil line. When nucleic acid extracts from bark were prepared from various locations on diseased trees and tested for TmRSV-specific nucleic acid by dot hybridization, there was an almost perfect correlation between the presence of stem-pitting symptoms and the detection of TmRSV nucleic acid. Detection of TmRSV RNA from the bark tissue of rootstock suckers from TmRSV-infected `Delicious'/MM.lO6 apple (Malus × domestica Borkh.) trees was unsuccessful using dot hybridization. The viral RNA, however, was usually detected in either leaf or root tissue of these same trees.
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