Leqing Qu’s group revealed the mechanism of plastidial disproportionating enzyme participating in rice storage starch synthesis
The starch accumulated in cereal endosperm is the most important dietary source of energy for humans. Rice is a staple cereal crop and has a total of 27 genes encoding starch-biosynthesizing enzymes: six for AGPase, two for granule-bound starch synthase, eight for soluble starch synthase, three for starch-branching enzyme, four for starch-debranching enzyme, two for α-glucan phosphorylase, and two for disproportionating enzyme (DPE). The functions of the former six groups have been studied intensively; however, little is known about the precise role of plastidial DPE1 in starch metabolism in developing rice endosperm.
Recently, Dr. Leqing Qu’s group investigated the function of DPE1 in storage starch synthesis in rice by endosperm-specific gene overexpression and suppression. Overexpression or suppression of DPE1 altered the amylose content, starch structure, and morphological and physicochemical properties of starch granules. The activities of other major starch synthesizing enzymes were not changed in DPE1-overexpressed or -suppressed seeds. They demonstrated that DPE1 participates in starch synthesis in rice endosperm by transferring maltooligosyl groups from amylose and amylopectin to amylopectin. This transferring of maltooligosyl groups may be a complement for the model of stacking glucose one after another during the chain elongation of amylopectin.
This work has been published in Plant Physiology(http://www.plantphysiol.org/content/169/4/2496.full.pdf+html). Dr. Xiangbai Dong is the first author of this paper. This work was supported by the Natural Science Foundation of China (31070226) and the National Program of Transgenic Variety Development of China (2014ZX08001-006).
Recently, Dr. Leqing Qu’s group investigated the function of DPE1 in storage starch synthesis in rice by endosperm-specific gene overexpression and suppression. Overexpression or suppression of DPE1 altered the amylose content, starch structure, and morphological and physicochemical properties of starch granules. The activities of other major starch synthesizing enzymes were not changed in DPE1-overexpressed or -suppressed seeds. They demonstrated that DPE1 participates in starch synthesis in rice endosperm by transferring maltooligosyl groups from amylose and amylopectin to amylopectin. This transferring of maltooligosyl groups may be a complement for the model of stacking glucose one after another during the chain elongation of amylopectin.
This work has been published in Plant Physiology(http://www.plantphysiol.org/content/169/4/2496.full.pdf+html). Dr. Xiangbai Dong is the first author of this paper. This work was supported by the Natural Science Foundation of China (31070226) and the National Program of Transgenic Variety Development of China (2014ZX08001-006).