Developmental Biology and Molecular Pathology, University of Bielefeld, D-33501 Bielefeld, Germany
We analyzed, with respect to heat shock proteins (HSPs), systemically reacting tobacco leaves inoculated with Tobacco mosaic virus (TMV), wild-type vulgare, and temperature-sensitive coat protein (CP) mutants Ni 118 (P20L) and flavum (D19A), kept at 23 or 30°C. HSP18 and HSP70 mRNAs and proteins were induced with temperature-sensitive CP mutants after 1 to 2 days at 30°C. After 4 to 6 days, HSP70 was also induced at 23°C. The induction of HSPs paralleled the amount of insoluble TMV CP in leaf extracts, indicating that denatured TMV CP by itself induces a heat-shock response.