STUDIES ON BIOSYNTHESIS OF TMV .I. A SYSTEM APPROACHING A SYNCHRONIZED VIRUS SYNTHESIS IN A TOBACCO LEAF

It is shown by quantitative electron-microscopical analysis that veincleared leaves from plants systemically infected with TMV contain a majority of cells in the same stage of infection. Under defined environmental conditions the leaves which will show this synchronized virus synthesis can be determined at the time of inoculation. A standardized procedure for routine use of the system is described. The host-virus system has been used to investigate the sequential development of the virus-induced cytoplasmic differentiations and inclusion bodies. The rapid phase of virus particle formation commences at veinclearing and continues for about 40 hours. The first recognizable cytoplasmic change consists of a local branching and folding of the endoplasmic reticulum. This differentiation develops into the inclusion with diffuse, flexible rods found in late stages of infection together with the virus crystals. © 1969 Springer-Verlag.