Poster: Transcription Regulation

Abs # 1046: A transcriptional activator of the Isoamylase 1 gene in barley

Presenter:	Palmqvist, Sara K, Sara.Palmqvist@vbsg.slu.se
Authors	Palmqvist, Sara K (A)   Olsson, Helena  (A)   Borén, Mats  (A)   Mutisya, Joel  (A)   Baguma, Yona  (A)   Ghebremedhin, Haile  (A)   Venkateshaiah, Laxmi  (A)   Sun, Chuanxin  (A)   Jansson, Christer  (A)
Affiliations:	(A): Swedish University of Agricultural Sciences, SLU

Starch is an important industrial raw material for both food and non-food purposes. In plants starch is deposited in the leaf and storage tissues such as seed endosperm, roots or tubers. Starch is a glucose polymer and its synthesis involves four groups of enzymes, ADP-glucose-pyrophosphorylase (AGPase), starch synthases (SS), starch branching enzymes (SBE), and starch debranching enzyme (DBE). The regulation of several of these starch synthetic enzymes have been studied in barley, expression of the debranching enzyme, Isoamylase 1, and branching enzyme, SBE IIb, have previously shown to be induced by sucrose. This indicates that sucrose is involved in the signaling pathway of starch biosynthesis and sugar-sensing play an important role in the regulation of the starch synthetic enzymes. Recently, several transcription factors involved in sugar-sensing have been cloned in our laboratory. One of them, SUSIBA2 (SUgar SIgnaling in BArley), has been extensively characterized. It belongs to the WRKY superfamily of transcription factors. By the use of a ODN (oligodeoxynucleotide) decoy and a GFP transient expression system, it has been confirmed that a sugar responsive element (SURE) of the iso1 promoter is required for high iso1 expression.