OsttaSBEIII expression alters granule size and increases starch levels and its degradability in Arabidopsis

HEDIN, NICOLAS; BARCHIESI, JULIETA; ZANOR, MARIA I.; PERMINGEAT, HUGO R.; GOMEZ-CASATI, DIEGO F.; BUSI, MARIA V.

Current Research in Biotechnology

Elsevier B.V.

Año: 2023 vol. 5

The physicochemical properties of starches from different botanical origin, such as viscosity, gelatinization temperature, solubility and degradability depend on the amylose/amylopectin ratio and the length and frequency of the α-1,6-glycosidic bonds in amylopectin. These branches depend on the action of the starch branching enzymes (SBEs), which are highly structurally conserved in plants. We recently identified a novel gene from Ostreococcus tauri (OsttaSBEIII) which codes for a protein showing starch branching activity (OsttaSBEIII) and with a different structure than other known SBEs from plants, containing two in-tandem carbohydrate binding modules (CBM41-CBM48) at its N-terminus. OsttaSBEIII overexpression in A. thaliana plants resulted in a higher starch content and smaller granules with an increased degradability. OEOsttaSBE lines showed also an increase in the expression and activity of starch degradative enzymes and a higher content of glucose and inorganic phosphate, which suggests a remodeling of the granule structure in response to the expression of OsttaSBEIII. These results allow us to propose the use of OsttaSBEIII as a new strategy to obtain starches with greater degradability that would be useful for different biotechnological applications.