VIEW ARTICLE

Radioautographic Studies on the Photosynthetic CO₂ Fixation in Virus-Infected Leaves. N. Doke, Plant Pathology Laboratory, Faculty of Agriculture, Nagoya University, Nagoya, Japan 46400; T. Hirai, Plant Pathology Laboratory, Faculty of Agriculture, Nagoya University, Nagoya, Japan 46400. Phytopathology 60:988-991. Accepted for publication 26 January 1970. DOI: 10.1094/Phyto-60-988.

Radioautograms of virus-inoculated leaves of systemically infected hosts which were exposed to ¹⁴CO₂ in light showed lesions having localized and enhanced radioactivity. Tobacco mosaic virus (TMV), tobacco etch virus (TEV), potato virus X (PVX), and cucumber mosaic virus-Y (CMV-Y) strain were studied. The number of TMV lesions increased in proportion to the concentrations of the virus inoculated. Firstly, lesions were small and compact, then each lesion enlarged into a zone with high radioactivity on the periphery and low radioactivity in the center. As lesions enlarged, the radioactivity at the periphery disappeared. Noninoculated but systemically infected leaves produced almost the same radioactive lesions as inoculated leaves, but a low radioactive center was not detected and the radioactivity at the periphery did not disappear but remained apparent. Leaves with visible mosaic symptoms of TMV showed high radioactivity localized in the yellow-green area. Radioautograms of leaves inoculated with TEV, PVX, and CMV-Y showed almost the same radioactive lesions as those inoculated with TMV. Leaves of local-lesion infection hosts produced radioactive lesions before the appearance of visible local lesions, but produced no additional radioactive lesions after visible lesions developed. Chasing of locally infected leaves which had been exposed in ¹⁴CO₂ caused an accumulation of radioactive substances around the visible lesions, but chasing of systemically infected leaves caused no accumulation.