Proteomic Dissection of Endosperm Starch Granule Associated Proteins Reveals a Network Coordinating Starch Biosynthesis and Amino Acid Metabolism and Glycolysis in Rice Endosperms

Abstract

Starch biosynthesis and starch granule packaging in cereal endosperms involve a coordinated action of starch biosynthesis enzymes and coordination with other metabolisms. Because directly binding to starch granules, starch granule-associated proteins (SGAPs) are essential to understand the underlying mechanisms, however the information on SGAPs remains largely unknown. Here, we dissected developmentally changed SGAPs from developing rice endosperms from 10 to 20 days after flowering (DAF). Starch granule packaging was not completed at 10 DAF, and was finished in the central endosperm at 15 DAF and in the whole endosperm at 20 DAF. Proteomic analysis with two-dimensional differential in-gel electrophoresis and mass spectrometry revealed 115 developmentally changed SGAPs, representing 37 unique proteins. 65% of the unique proteins had isoforms. 39% of the identified SGAPs were involved in starch biosynthesis with main functions in polyglucan elongation and granule structure trimming. Almost all proteins involved in starch biosynthesis, amino acid biosynthesis, glycolysis, protein folding, and PPDK pathways increased abundance as the endosperm developed, and were predicted in an interaction network. The network represents an important mechanism to orchestrate carbon partitioning among starch biosynthesis, amino acid biosynthesis and glycolysis for efficient starch and protein storage. These results provide novel insights into mechanisms of starch biosynthesis and its coordination with amino acid metabolisms and glycolysis in cereal endosperms.

Physiological and Proteomic Analyses Reveal Adaptive Mechanisms of Ryegrass (Annual vs. Perennial) Seedlings to Salt Stress

“…Amino acid biosynthesis and metabolism is of critical importance for plant growth, development, and response to stress condition [56,57]. Our results reflected that the proteins associated with cellular processes (including amino acid metabolism and cellular structure) were differentially accumulated in annual ryegrass and perennial ryegrass under salt stress.…”

Remobilisation of phosphorus fractions in rice flag leaves during grain filling: Implications for photosynthesis and grain yields

“…The concerted activity of several day length sensitive gene products inhibit flowering in rice [ 29 ] and when inhibition of stage in rice reproduction is released, a cascade of irreversible events and physiological processes are initiated which result in flowering and ultimately grain filling. The cell structures required for grain filling are achieved through a cell differentiation that is completed six days after flowering and followed by physiological maturity at 20 days after flowering [ 30 , 31 ]. As a result of the tight regulation of the flowering and seed set processes, when P was withdrawn from the nutrient solution at anthesis or 8 DAA in the present work, plants did not invest energy or P in late tillers which enabled them to sustain or increase grain yield.…”

Rice starch biotechnology: Rice endosperm as a model of cereal endosperms

“…The developing endosperm includes a network of several metabolic pathways, such as intermediate carbon metabolism including sugars, phosphorylated compounds, and organic acids, amino acid metabolism, glycolysis, lipid metabolism, and carbohydrate metabolism including starch and cell wall biosynthesis, all of which are very active and coordinated differently from each other during the course of endosperm development . In addition, the central vacuole functions as a large reservoir of sucrose, hexoses, organic acids, and ions.…”