Biosynthesis and Regulation of Wheat Amylose and Amylopectin from Proteomic and Phosphoproteomic Characterization of Granule-binding Proteins.

Guan-Xing Chen,Jian-Wen Zhou,Yue-Ming Yan,Cai-Xia Han,Xiao-Bing Lu,Wen-Ying Zhang,Yan-Hao Xu,Yan-Lin Liu

doi:10.1038/srep33111

Guan-Xing Chen, Jian-Wen Zhou + Show 6 more

Open Access

https://doi.org/10.1038/srep33111

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Journal: Scientific Reports	Publication Date: Sep 8, 2016
Citations: 42	License type: CC BY 4.0

Affiliation: Capital Normal University, Yangtze University

Abstract

Waxy starch has an important influence on the qualities of breads. Generally, grain weight and yield in waxy wheat (Triticum aestivum L.) are significantly lower than in bread wheat. In this study, we performed the first proteomic and phosphoproteomic analyses of starch granule-binding proteins by comparing the waxy wheat cultivar Shannong 119 and the bread wheat cultivar Nongda 5181. These results indicate that reduced amylose content does not affect amylopectin synthesis, but it causes significant reduction of total starch biosynthesis, grain size, weight and grain yield. Two-dimensional differential in-gel electrophoresis identified 40 differentially expressed protein (DEP) spots in waxy and non-waxy wheats, which belonged mainly to starch synthase (SS) I, SS IIa and granule-bound SS I. Most DEPs involved in amylopectin synthesis showed a similar expression pattern during grain development, suggesting relatively independent amylose and amylopectin synthesis pathways. Phosphoproteome analysis of starch granule-binding proteins, using TiO2 microcolumns and LC-MS/MS, showed that the total number of phosphoproteins and their phosphorylation levels in ND5181 were significantly higher than in SN119, but proteins controlling amylopectin synthesis had similar phosphorylation levels. Our results revealed the lack of amylose did not affect the expression and phosphorylation of the starch granule-binding proteins involved in amylopectin biosynthesis.

Highlights

Wheat is one of the most important grain crops in the world, and the dry seeds have approximately 65–75% starch[1]
Our results revealed the expression profiles of the key genes and enzymes, and their phosphorylated characterization in vivo involved in amylose and amylopectin synthesis, which provides new insights into the mechanisms of wheat grain starch biosynthesis
Most differentially expressed protein (DEP) involved in amylopectin synthesis showed a similar expression pattern during grain development, suggesting the amylose and amylopectin synthesis pathways to be independent

Summary

Introduction

Wheat is one of the most important grain crops in the world, and the dry seeds have approximately 65–75% starch[1]. Null alleles of SS IIa in each of the A, B and D genomes were identified and combined to produce a wheat variety with a 10% increase in amylose content, from 25 to 35%. The phosphoprotein detection of starch granule-binding proteins is accomplished primarily by three methods: Pro-Q Diamond staining, in vitro phosphorylation isotope labeling by γ-32P-ATP, and LC-MS/MS technology[19,20,21,22,23,24]. Tetlow et al.[20] showed that binding of enzymes to starch granules labeled by γ-32P-ATP in vitro resulted in enhanced amylase activity and increased amylose synthesis[19,20,21]. Our results revealed the expression profiles of the key genes and enzymes, and their phosphorylated characterization in vivo involved in amylose and amylopectin synthesis, which provides new insights into the mechanisms of wheat grain starch biosynthesis

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