STUDIES ON THE METABOLISM OF LEAVES WITH LOCALIZED VIRUS INFECTIONS: PARTICULATE FRACTIONS AND SUBSTRATES IN TMV-INFECTED NICOTIANA GLUTINOSA L.

Abstract

When crude homogenates of Nicotiana glutinosa leaves, infected with TMV and showing well-developed lesions, were fractionated by agar gel electrophoresis, the virus band contained very few particles 300 mμ long, as shown by electron microscopy. An equivalent homogenate of N. tabacum systemically infected with TMV and fractionated similarly had about 105times as many particles per unit scanned. This ratio was substantiated by estimating the number of TMV particles per cell in a local lesion and in a systemic infection at a time of comparable development, by means of serology. There were, respectively, 500 to 1000 and 2.5 × 106particles per cell. The electron microscope also showed that a fast electrophoretic band from TMV-infected N. glutinosa was composed of particles shorter than 300 mμ, and that the ribosomal fraction in locally infected tissues had almost disappeared. It is concluded that the abnormal rise in respiration of locally infected tissues is not caused by any great synthesis of virus nor, apparently, by accumulated respirable substrate, as shown by carbohydrate and amino acid analysis.