Abstract
It has been revealed that cytosolic Hsp90 is essential for steady-state accumulation of R proteins. Reduction of Hsp90 level compromises R gene-dependent defense responses. p50, which is a truncated gene product of TMV, is the Avr component of N resistance gene inducing HR like cell death in NN tobacco. The specific inhibitor geldanamycin (GDA) for Hsp90 inhibited TMV- and p50-mediated cell death but not the cell death by Bax which is a mammalian pro-apoptotic protein inducing HR like cell death in plants. TMV- and p50-mediated cell death was accompanied with the activation of WIPK and SIPK, but Bax-mediated cell death was not. In WIPK and SIPK double silenced plants, p50- but not Bax-mediated cell death was suppressed. These results indicate that p50 induces cell death via activation of WIPK and SIPK but Bax induces cell death in the pathway which is independent on WIPK and SIPK.
