[The inductive activation of the promoter of pib gene].

ABSTRACT

A 5.7 kb putative promoter region of pib gene was isolated from the pib genomic clone and substituted for the 35S promoter upstream of gus gene in plasmid pCAMBIA1301 to construct a new plant expression vector pNAR604 (putative pib promoter-GUS + 35S-hpt). From Agrobacterium-mediated transformation and hygromycin selective culture in vitro, hygromycin resistant calli and 36 transgenic rice (Oryza sativa L.) plants were obtained. Histochemical assays of GUS activity showed that no expression was observed in the resistant calli and roots from transgenic rice if cultured under light, but after 24 h dark treatment there was strong GUS staining. Fluorimetric quantitative analysis indicated that GUS expression was organ-specific in transgenic rice. Without the dark treatment, GUS activity in roots and stems were about 7 and 3 times higher than in leaves in which GUS activity was only trace detected. After 24 h dark treatment, GUS activity in roots, stems and leaves of transgenic plants were all promoted and the largest increase was observed in leaves. Twenty-four hours after spraying with 5 mmol/L SA (Salicylic Acid) or 0.3 mol/L NaCl, GUS activity in leaves of the transgenic plants was 2.7 or 3.6 times respectively higher than untreated control. It was confirmed that an inductive promoter was involved in this 5.7 kb upstream region of pib gene, and dark, SA and NaCl treatments were inductive factors for pib promoter.