Isolation and characterization of maize gene promoter in drought-response.

The clade A members of serine/threonine protein phosphatase 2Cs (PP2Cs) play crucial roles in plant growth, development, and stress response via the ABA signaling pathway. But little is known about other PP2C clades in plants. Our previous study showed that maize the , a clade B member of , negatively regulated drought tolerance in transgenic . However, the upstream regulatory mechanism of remains unclear. In the present study, the expression of gene in maize was analyzed by quantitative real time PCR (qRT-PCR). The results showed that the expression of in shoot and root was both significantly inhibited by drought stress. Subsequently, a 2175 bp promoter of was isolated from maize genome ( ). To validate whether the promoter possess some key -element and negatively drive expression in drought stress, three 5´-deletion fragments of 1505, 1084 and 215 bp was amplified from and were fused to β-glucuronidase () and luciferase gene () to produce and constructs, and transformed into tobacco, respectively. Transient expression assays indicated that all promoters could drive and expression. The GUS and LUC activity were both significantly inhibited by PEG-6000 treatment. Notably, the - 1084 to - 215 bp promoter possess one MBS element and inhibits the expression of and under drought stress. Meanwhile, we found that the 215 bp length is enough to drive expression. These findings will provide insights into understanding the transcription-regulatory mechanism of negatively regulating drought tolerance.