Label-Free Proteomics of Starch Granule-Associated Proteins Reveals Starch Molecular Modification during Rice Grain
Xiaoning Liu1, Xinyu Zhang1, Zekun Xu1
1Department of Food Science & Technology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China.
Journal of Agricultural and Food Chemistry
|February 16, 2026
Summary
Rice starch structure changes during grain filling, with molecular weight and amylopectin size varying. Starch granule-associated proteins (SGAPs) play a key role in regulating these dynamic changes in starch synthesis.
Area of Science:
- Plant Biology
- Biochemistry
- Molecular Biology
Background:
- Rice starch structure, including molecular weight (MW) and amylopectin (AP) size, undergoes dynamic changes during grain filling.
- Starch granule-associated proteins (SGAPs) are implicated in regulating starch synthesis and granule structure.
Purpose of the Study:
- To investigate the dynamic changes in rice starch structure during grain filling.
- To identify and characterize the role of SGAPs in modulating starch granule structure and synthesis.
Main Methods:
- Label-free quantitative proteomics was employed to analyze SGAPs.
- Differential protein expression analysis was performed between early, mid, and late grain filling stages.
Main Results:
- Proteomics identified 286 differentially expressed proteins (DEPs) between early and mid-filling stages, with only seven DEPs between mid and late stages.
- Co-increased debranching and branching enzymes with reduced granule-bound starch synthase correlated with smaller AP size and higher MW.
- Altered abundances of proteins involved in glycolysis, lipid metabolism, tubulin, and ribosomal functions suggest enhanced starch synthesis, transport, and translation.
Conclusions:
- SGAPs play a crucial role in regulating rice starch granule structure and synthesis during development.
- Specific enzymes and metabolic pathways associated with SGAPs directly and indirectly influence starch molecular architecture.
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