title: Characterization of the time evolution of starch structure from rice callus.
abstract: Callus (formed when a plant tissue is wounded) is a promising system for studying starch biosynthesis and bioengineering; however the molecular structure of callus starch has been poorly characterized. Size-exclusion chromatography was used in this study to characterize the starch structure in rice calli from two cultivars and a mutant of one cultivar lacking starch branching enzyme IIb. There were major qualitative differences in the chain-length and whole-molecule size distributions between starch from grain and from callus. However callus starch was found to be able to simulate the starch metabolism from both leaves and endosperm and reveal the structural development of starch granules, and this was dependent on the culture system. During synthesis, trans-lamellar amylopectin chains in callus are synthesized earlier than single-lamella chains, while enzymatic degradation starts from outer to inner amylopectin chains. The outer layers of the callus-starch granules have larger molecules with lower amylose content and shorter amylopectin chains compared to further inside the callus-starch granules. Controlling starch granular number and size thus has potential for improving both the quantity and quality of plant starch.
authors.affiliation: Tongji School of Pharmacy, Huazhong University of Science and Technology, Wuhan 430030, China; The University of Queensland, Centre for Nutrition and Food Sciences, Queensland Alliance for Agricultural and Food Innovation, Brisbane, QLD 4072, Australia.
authors.forename: Cheng
authors.initials: C
authors.lastname: Li
authors.affiliation: The University of Queensland, School of Agriculture and Food Sciences, Brisbane, QLD 4072, Australia.
authors.forename: Guoquan
authors.initials: G
authors.lastname: Liu
authors.affiliation: Key Laboratories of Crop Genetics and Physiology of the Jiangsu Province and Plant Functional Genomics of the Ministry of Education, Yangzhou University, Yangzhou 225009, China.
authors.forename: Qiaoquan
authors.initials: Q
authors.lastname: Liu
authors.affiliation: The University of Queensland, School of Agriculture and Food Sciences, Brisbane, QLD 4072, Australia.
authors.forename: Ian D
authors.initials: ID
authors.lastname: Godwin
authors.affiliation: Tongji School of Pharmacy, Huazhong University of Science and Technology, Wuhan 430030, China; The University of Queensland, Centre for Nutrition and Food Sciences, Queensland Alliance for Agricultural and Food Innovation, Brisbane, QLD 4072, Australia. Electronic address: b.gilbert@uq.edu.au.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Gilbert
mesh_terms: D000687:Amylopectin / Q000096:biosynthesis / Q000737:chemistry*; D012275:Oryza / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000687:Amylopectin
keywords: Callus; Molecular size distribution; Size-exclusion chromatography (SEC); Starch