The transcriptional factor WRKY proteins contain the highly conserved amino acid sequence WRKYGQK as well as the novel zinc-finger-like motifs Cys(2)His(2) or Cys(2)HisCys. A search of the rice genome identified 97 genes encoding WRKY proteins. Of these 97 WRKY homologs found in rice, 13 cDNAs encoding WRKY proteins were consequently isolated from a rice cDNA library constructed from 4degreesC-treated shoots by probing for the conserved WRKY domain. Northern blotting analysis revealed that 10 of 13 OsWRKY genes were differentially regulated in plants that were treated by the four following abiotic stress factors: NaCl, PEG, cold (4degreesC) and heat (42degreesC). The resulting expression profiles exhibited great differences in both the manner and timing of their response to the four different abiotic treatments. The difference of gene expression profiles suggested the different physiological functions among the WRKY genes.