Transcription Factor WRKY Superfamily:Origin, Structure and Function

The transcription factor WRKY protein superfamily so far is found exclusively in plants.There exist at least 74 and 97 members in Arabidopsis and rice,respectively.The most archaic WRKY transcription factors,which may originate some 1.5-2 billion years ago in eukaryotes,contain two highly conserved WRKY domains.Although all WRKY proteins regulate mainly the expression of target genes by specifically binding to the (T)TGACC(A/T) (W box) sequences of their promoter,the biological function of each member is specific.In this review,we summarize in detail the molecular biological function of WRKY proteins in regulating specific signaling pathways during development or in response to stress factors.