The activation of the signal transduction cascade leading to HR cell death, influx of calcium ions, and other immune reactions in rice is correlated with biochemical modifications and other cellular events (Pontier et al., 1998). Phosphorylation and other intracellular and extracelluar reactions serve to elicit the expression of immunity genes (genes having antimicrobial activity.) According to the amino acid sequences obtained from the cDNA data, Xb10 is a transcriptional factor that may directly promote the expression of defense genes (genes involved in immunity such as the HR) (Dardick, unpublished material). Transcription factors often dimerize with themselves or other transcriptional factors to elicit gene expression. However, in Y2H experiments, Xb10 was not shown to bind to itself. This result is not expected since Xb10 was found to interact with transcription factors very similar to itself (WRKY1, WRKY2, and WRKY3.) This implicates a more specific plant defense response �V WRKY��s form different combinations of transcription factor complexes to induce defense genes.