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Time-Course of Tobacco Mosaic Virus-Induced RNA Synthesis in Synchronously Infected Tobacco Leaves. W. O. Dawson, Department of Plant Pathology and Cell Interaction Group, University, of California, Riverside 92502; D. E. Schlegel, Department of Plant Pathology, University of California, Berkeley 94720. Phytopathology 66:437-442. Accepted for publication 22 September 1975. DOI: 10.1094/Phyto-66-437.

The time-course of tobacco mosaic virus (TMV)-induced RNA synthesis was examined in synchronously infected tobacco leaves which were infected at a nonpermissive temperature (3 C) using the differential temperature inoculation procedure. Single-stranded (SS) TMV-RNA, LiCl-soluble double-stranded (LS-DS) RNA, and the double-stranded RNA remaining after RNase treatment of the LiCl- precipitable RNA (LP-DS RNA) each was first detected during the labeling period 6-8 hours after the shift of the infected leaves to the permissive temperature. This coincided with the first detection of infectivity. Afterwards, the rate of synthesis of each species of RNA increased exponentially and in parallel, with the ratios of each species of RNA remaining constant during the early phase of the replication cycle. The maximum rate of synthesis of LS-DS RNA and LP-DS RNA occurred at 18-20 hours, and that of SS TMV-RNA at 24-26 hours. After the maximum rate, the synthesis of SS TMV-RNA declined, but the rate of synthesis of LS-DS RNA continued to increase slightly and the rate of synthesis of LP-DS RNA remained constant.