Simultaneous Activation of Pentose Phosphate Shunt Enzymes in a Virus-infected Local Lesion Host Plant

Abstract

IN the course of work on the biochemical basis of plant virus localization it has been found that around the necrotic lesions of Nicotiana glutinosa leaves infected with tobacco mosaic virus (TMV) the dehydrogenases are highly activated as shown by the in vivo application of the triphenyl tetrazolium chloride (TTC) technique¹. Because of the possible implication of oxidative metabolism, in resistance phenomena, the nature of the enzymes involved was examined. Our attention was directed to the pentose phosphate cycle enzymes as alterations in their activities were recently reported to occur in host tissues infected by fungal pathogens^2,3. Isotope investigations also suggested an increased in vivo role of the pentose phosphate cycle in these hosts^4,5. Virus diseases have not been investigated from this point of view so far, although the host–virus systems offer distinct advantages; the direct contribution of the pathogen to the enzymatic changes occurring in the host was in this way excluded.