Influence of Virus Inflections on Impedance Parameters

This paper deals with investigations of some electrical parameters in four host-virus interactions. (1) With gradient corrections from healthy plants, injury was detected by the resistance ratio at a distance ≈ 1.5 mm external to the localized necrotic lesions caused by tobacco mosaic virus (TMV) in leaves of Nicotiana glutinosa, and was interpreted as evidence of an altered metabolism possibly associated with limiting cell-to-cell spread of the virus. (2) The influence of systemic infections of virus X was examined in potato tubers. In one of the two varieties, viz. Bismarck, the magnitude of three parameters allowed the diagnosis of the presence of the virus. (3) Systemic infections of tomato spotted wilt (TSW) in leaves of N. glutinosa caused very marked changes, affecting 21 out of 24 parameters. (4) Systemic infections of TMV in petioles of N. tabacum caused less pronounced changes than those of TSW in leaves of N. glutinosa. On the basis of changes in major parameters, infection of TSW in leaves of N. glutinosa and infections of virus X in potato tubers var. Bismarck are considered to have certain features in common as regards influence on host metabolism. Possible explanations are given for some of the parameter changes.