title: Promoter analysis of the sweet potato ADP-glucose pyrophosphorylase gene IbAGP1 in Nicotiana tabacum.
abstract: The IbAGP1 gene of sweet potato ( Ipomoea batatas ) encodes the sucrose-inducible small subunit of ADP-glucose pyrophosphorylase. Through expression analysis of 5'-truncations and synthetic forms of the IbAGP1 promoter in transgenic tobacco, we show that SURE-Like elements and W-box elements of the promoter contribute to the sucrose inducibility of this gene. Sweet potato (Ipomoea batatas) contains two genes (IbAGP1 and IbAGP2) encoding the catalytically active small subunits of ADP-glucose pyrophosphorylase, an enzyme with an important role in regulating starch synthesis in higher plants. Previous studies have shown that IbAGP1 is expressed in the storage roots, leaves, and stem tissues of sweet potato, and its transcript is strongly induced by applying sucrose exogenously to detached leaves. To investigate the tissue-specific expression of the IbAGP1 promoter, a series of 5'-truncated promoters extending from bases -1913, -1598, -1298, -1053, -716, and -286 to base +75 were used to drive the expression of the β-glucuronidase reporter gene (GUS) in tobacco plants (Nicotiana tabacum). Histochemical and fluorometric GUS assays showed that (1) GUS expression driven by the longest fragment (1989 bp) of the IbAGP1 promoter was detected in vegetative tissues (roots, stems, leaves), (2) fragments extending to -1053 or beyond retained strong GUS expression in roots, stems, and leaves, whereas further 5'-deletions resulted in considerable reduction in GUS activity, and (3) the series of 5'-truncated promoters responded differently to exogenously applied sucrose. The 1989-bp IbAGP1 promoter contains five sequences (two AATAAAA, one AATAAAAAA, and two AATAAATAAA) that are similar to sucrose-responsive elements (SURE). These SURE-Like sequences are found at nucleotide positions -1273, -1239, -681, -610, and -189. Moreover, putative W-box elements are found at positions -1985, -1434, -750, and -578. Synthetic promoters containing tandem repeats of the 4X SURE-Like or 4X W-box upstream from a minimal CaMV35S promoter-GUS fusion showed significant expression in transgenic tobacco in response to exogenous sucrose. These results show that SURE-Like elements and W-box elements of the IbAGP1 promoter contribute to the sucrose inducibility of this gene.
authors.affiliation: School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China.
authors.forename: Xuelian
authors.initials: X
authors.lastname: Zheng
authors.affiliation: School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
authors.affiliation: School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China.
authors.forename: Dongqing
authors.initials: D
authors.lastname: Liu
authors.affiliation: School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Zang
authors.affiliation: School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China.
authors.forename: Kaiyue
authors.initials: K
authors.lastname: Zhang
authors.affiliation: School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China.
authors.forename: Kejun
authors.initials: K
authors.lastname: Deng
authors.affiliation: School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China.
authors.forename: Shixin
authors.initials: S
authors.lastname: Yang
authors.affiliation: School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China.
authors.forename: Zhengyang
authors.initials: Z
authors.lastname: Xie
authors.affiliation: School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Tang
authors.affiliation: Department of Biology, East Carolina University, Greenville, NC, 27858, USA. qiy@ecu.edu.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Qi
authors.affiliation: School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China. zhangyong916@uestc.edu.cn.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D018506:Gene Expression Regulation, Plant / Q000235:genetics; D051599:Glucose-1-Phosphate Adenylyltransferase / Q000235:genetics* / Q000378:metabolism*; D027723:Ipomoea batatas / Q000201:enzymology* / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics; D030821:Plants, Genetically Modified / Q000201:enzymology; D011401:Promoter Regions, Genetic / Q000235:genetics*; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics
chemical_list: D010940:Plant Proteins; D051599:Glucose-1-Phosphate Adenylyltransferase
keywords: GUS expression; IbAGP1; Ipomoea batatas; Nicotiana tabacum; Promoter analysis