LuxR homologues are the main components of LuxR/LuxI circuit in Quorum Sensing(QS)of Gram-negative bacteria.A luxR homologue,designated as xooR,was cloned from Ⅹ.oryzae pv.oryzae.The xooR gene is atranscription factor with 765 bp inlength,and encodes a 254-amino acid putative protein with a molecular weight and an isoelectric point of 28.3 ku and 8.72 respectively.Amino acids 15 to 171 from the N-terminus are the Autoin-bind domain of XooR whereas amino acids 191 to 245 form a helix-tu-helix(HTH)motif that serves as the DNA-binding domain.In this study,XooR was expressed as a fusion protein along with green fluorescent protein(GFP),using pET-24a-d(+),a prokaryotic expression vector.Weste blot showed that the xooR gene was successfully expressed in vitro in E.coli as a XooR-GFP fusion protein with a size of 54 ku.