Influence of temperature upon levels of virus and an induced antiviral principle in tomato plants systemically infected with tobacco mosaic virus.

Abstract

The levels of tobacco mosaic virus (TMV) and an associated antiviral principle (AVP) in infected tomato plants incubated at temperatures ranging from 15.5 C to 32 C were determined. Yield of TMV, as measured spectrophotometrically, reached a maximum at 26.5 C, but fell off markedly at 32 C. Infectivity, as indicated by local-lesion counts on Nicotiana glutinosa, reached its maximum at 23 C then declined substantially at the higher incubation temperatures. Production of AVP in the diseased plants reached a maximum at 26 C and was maintained at a high level at 32 C. Temperatures most favorable for the induction of AVP had an influence both on the quantity and the quality of the virus produced. It is suggested that the presence of a critical level of AVP in the diseased plant not only lowers the yield of TMV, but profoundly reduces the infectivity of the virus which is present.