Figure 8.

Proposed Model for BTH/SA Signaling Pathway in Rice.

In Arabidopsis, most BTH-responsive genes are regulated downstream of NPR1, and this regulation is mediated by several WRKY TFs acting downstream of NPR1. In rice, WRKY45 and NH1 constitute apparently independent signaling pathways. GST and cytochrome P450 genes are regulated by WRKY45 but not by NH1. PR-1a and PR-1b are dependent on NH1 and are conditionally dependent also on WRKY45. Posttranslational signal flow from WRKY45 to NH1 (dashed arrow) would account for the dependence of these genes on both NH1 and WRKY45. The lipoxygenase gene does not appear to depend on either NH1 or WRKY45, so it might be regulated by another regulator. An environmental factor acts downstream of WRKY45 transcription and might also act on the NH1-dependent pathway (gray arrows).