Combinatorial interaction of two adjacent cis-active promoter regions mediates the synergistic induction of Bt2 gene by sucrose and ABA in maize endosperm. (September 2018)

• Record Type: Journal Article
• Authors: Li, Yangping; Yu, Guowu; Lv, Yanan; Long, Tiandan; Li, Ping; Hu, Yufeng; Liu, Hanmei; Zhang, Junjie; Liu, Yinghong; Li, Wan-Chen; Huang, Yubi
• Is Part Of: Plant science. Volume 274(2018)
• Page Start: 332
• Page End: 340
• Publication Date: 2018-09
• Subjects: Abscisic acid -- Bt2 -- Maize endosperm -- Promoter regions -- Sucrose -- Synergistic induction; Botany -- Periodicals; Botanique -- Périodiques; 580
• DOI: 10.1016/j.plantsci.2018.06.003
• Languages: English
• ISSNs: 0168-9452

Abstract

Highlights: Sucrose and ABA synergistically increase the starch content and AGPase activity of maize endosperm. The Bt 2 promoter regions −370/−186 and −186/−43 are involved in sucrose and ABA response, respectively. ABA response in the promoter region (−186/−43) requires the presence of the sucrose-responsive region (−370/−186). The combination of these two promoter regions mediates the synergistic induction from sucrose and ABA on Bt 2 expression. Abstract: The accumulation of starch in cereal endosperm is a key process that determines crop yield and quality. Research has reported that sucrose and abscisic acid (ABA) synergistically regulate the synthesis of crop starch. However, little is known about the molecular mechanisms behind this synergistic effect. In this study, the effect of sucrose and ABA on starch synthesis in maize endosperm was investigated. The starch content, the ADP-Glc pyrophosphorylase (AGPase) concentration, and the expression of AGPase-encoding genes were found to be enhanced slightly by sucrose or ABA alone, but were elevated significantly by the co-treatment of sucrose and ABA. Truncation analysis of the Bt2 promoter via transient expression in maize endosperm showed that the promoter region (−370/−186) is involved in sucrose response, and that an adjacent region (−186/−43) responds to ABA. The synergistic induction of sucrose and ABA on Bt2 promoter activity requires interaction with both of these regions. Interestingly, removal of the sucrose-responsive region (−370 to −186) abolishes ABA responsiveness in the Bt2 promoter, even in the presence of ABA-responsive region (−186 to −43). This study provides novel insights into the regulatory mechanisms that underlie the synergistic regulation of starch synthesis and grain filling from sucrose and ABA in cereal endosperm.