DOUBLE-STRANDED TOBACCO MOSAIC VIRUS RNA

Isolation of the double-stranded viral RNA in fractionated cell-free extracts from radioactive tobacco mosaic virus-infected tobacco leaves suggests that the double-stranded tobacco mosaic virus RNA is associated with a cytoplasmic structure or organelle and not with nuclei. Synthesis of double-stranded viral RNA in cell-free extracts from infected leaves also occurred in association with cytoplasmic fractions and not with nuclear fractions. It is concluded that synthesis of tobacco mosaic virus RNA occurs in either mitochondria, in light chloroplasts lacking starch grains, or in some other unidentified sedimentable organelle. Evidence suggesting a nuclear site for tobacco mosaic virus RNA synthesis is discussed. © 1969.