Abstract
The NPR1 plays a central role in salicylic acid (SA)-mediated systemic acquired resistance (SAR) in Arabidopsis. NPR1 is localized in the cytoplasm as an oligomer in uninduced state. Upon SAR induction or SA treatment, NPR1 translocates to the nuclei as a monomer leading to upregulation of its target genes. Overexpression of NH1, a rice ortholog of NPR1, increases rice resistance against a bacterial pathogen, Xanthomonas. However, the role of NH1 in defense responses of rice remains obscure.
We showed that RNAi-mediated knockdown of NH1 compromised BTH-inducible resistance against rice blast. Immunodetection using anti-NH1 antibody revealed that NH1 proteins were accumulated in the cytoplasm as a monomer. Moreover, NH1 localization was not affected by BTH treatments. These data strongly suggest that the mechanism controlling NH1 localization is different from that of NPR1 in Arabidopsis. Experiments are in progress to identify NH1-dependent BTH-inducible genes using gene expression profiling.
