Respiration Rate, Adenosine Diphosphate and Triphosphate Concentrations of Leaves Showing Necrotic Local Lesions Following Infection by Tobacco Mosaic Virus

The respiration rate of TMV‐infected leaves of Nicotiana tabacum L. variety Xanthi has been shown to be greater than the respiration rate of healthy leaves. 10−5M DNP gave maximum stimulation of the respiration rate of the healthy leaf but had no effect on the respiration of the virus‐infected leaf with dense lesion cover. The concentration of ATP increased with greater lesion density while the ADP concentration decreased. The increase in ATP concentration was greater than could be accounted for by the decrease in ADP concentration. Thus, increased respiration in the virus‐infected leaf is accompanied by a decrease in the ADP/ATP ratio. Illumination of the virus infected leaf increased the ADP/ATP ratio.