MEASUREMENT OF EXOTHERMIC HEAT-FLOW AND LEAF TEMPERATURE OF TMV-INFECTED AND CMV-INFECTED PLANTS BY MICROCALORIMETRY AND INFRARED DETECTIONTECHNIQUE

In TMV-infected N. tabacum cv. Xanthi nc. leaves considerably higher h eat production could be detected only during lesion formation. Similar ly, 14 h after temperature shift from 33-degrees-C to 25-degrees-C, wh en a very quick confluent necrotization of tissue takes place, we foun d higher heat flow from infected leaf samples as compared to control o nes. In N. tabacum cv. Samsun plants (compatible interaction) only upp er leaves (bearing mosaic symptoms) showed extra heat production. Simi lar results were found in cucumber mosaic virus (CMV) infected soybean leaves: after the development of symptoms we detected increased leaf temperature. These data suggest that both hypersensitive necrotization and systemic virus infection may lead to energy dissipation of plant cells as heat. However, this phenomenon does not seem to be useful too l for the prediction of infection. The possible source(s) of heat over production will be hypothesized.