Abstract
Expression of some α‐amylase genes in cereals is suppressed by sugars and activated by sugar starvation. A 100‐bp sugar response sequence (SRS) identified in the promoter of a rice α‐amylase gene, αAmy3, contains three essential motifs: the GC box, the G box, and the TATCCA element. To study the mechanism of sugar regulation of αAmy3 transcription, an ABA‐responsive bZIP protein, OsBZ8, which binds specifically to the G box in αAmy3 SRS was characterized and function analysed. In sucrose‐starved rice suspension cells and embryos, decline in OsBZ8 mRNA levels coincided with the induction of αAmy3 mRNA accumulation. In vivo gain‐ and loss‐of‐function studies by transient expression assays in rice embryos revealed that OsBZ8 suppresses SRS activity through the G box and overrides the activity of an activator, OsMYBS1, which binds to the TATCCA element. Gel mobility shift assays revealed that OsBZ8 binds specifically to the G box in vitro. These studies suggest that OsBZ8 is a suppressor responsible for sugar repression of αAmy3 expression, and OsMYBS1 is responsible for sugar starvation induced expression of αAmy3.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
