Abstract: Pathogenesis-related (PR) proteins are commonly used as markers of plant defense responses. To examine the expression patterns of rice PR proteins, we used western blot analysis to investigate rice PR1 family proteins and found 6 of 7 tested PR1 proteins expressed in rice leaves under normal growth. We examined the expression pattern of PR1 proteins in the interaction between rice and the bacterium Xanthomonas oryzae pv. oryzae (Xoo) and found PR1#052, PR1#072, PR1#073 and PR1#121 upregulated or induced in the later stage of Xa21-mediated incompatible interactions and PR1#071 downregulated. The comparison among resistance, susceptible and mock treatments demonstrated that the alteration in abundance was greater with resistance and susceptible than mock treatment, so PR1 proteins may play a role in rice under biotic stress. In addition, we predicted cis elements in the upstream promoter region of PR1 genes. We reveal the expression spectrum of rice PR1 family proteins and provide useful clues for the functional investigation of rice PR1 proteins.

Key words: PR1, rice, western blot, Xanthomonas oryzae pv. oryzae (Xoo)