Stress repressive expression of rice SRZ1 and characterization of plant SRZ gene family

A zinc finger protein gene was cloned from rice and designated as SRZ1 (stress repressive zinc finger protein 1). SRZ1 encodes a protein with three C2C2-type zinc finger motifs that are structurally similar to human ZNF265 zinc finger motifs. SRZ1 was expressed with high level in leaves and markedly repressed by salt, cold, drought and abcisic acid stresses but not by salicylic acid and blast inoculation in rice seedlings. Ectopic expression of SRZ1 in tobacco plants repressed expression of abiotic stress-related genes including osmotin, NtERB10B, NtERB10C, and increased plant sensitivity to cold and salt stresses. Database searches showed SRZ genes were widely distributed among plant species and their expressions in rice and Arabidopsis were significantly down-regulated by at least one type of abiotic stresses. This study indicates that SRZ1 and its relatives in plants may play negative roles in abiotic stress signaling and the down-regulation of them might be crucial for plant tolerance against stresses.