Journal article
Re‐programming of gene expression in the CS8 rice line over‐expressing ADPglucose pyrophosphorylase induces a suppressor of starch biosynthesis
The Plant journal : for cell and molecular biology, Vol.97(6), pp.1073-1088
03/2019
Handle:
https://hdl.handle.net/2376/104314
PMID: 30523657
Abstract
Summary
The CS8 transgenic rice (Oryza sativa L.) lines expressing an up‐regulated glgC gene produced higher levels of ADPglucose (ADPglc), the substrate for starch synthases. However, the increase in grain weight was much less than the increase in ADPglc levels suggesting one or more downstream rate‐limiting steps. Endosperm starch levels were not further enhanced in double transgenic plants expressing both glgC and the maize brittle‐1 gene, the latter responsible for transport of ADPglc into the amyloplast. These studies demonstrate that critical processes within the amyloplast stroma restrict maximum carbon flow into starch. RNA‐seq analysis showed extensive re‐programming of gene expression in the CS8 with 2073 genes up‐regulated and 140 down‐regulated. One conspicuous gene, up‐regulated ~15‐fold, coded for a biochemically uncharacterized starch binding domain‐containing protein (SBDCP1) possessing a plastid transit peptide. Confocal microscopy and transmission electron microscopy analysis confirmed that SBDCP1 was located in the amyloplasts. Reciprocal immunoprecipitation and pull‐down assays indicated an interaction between SBDCP1 and starch synthase IIIa (SSIIIa), which was down‐regulated at the protein level in the CS8 line. Furthermore, binding by SBDCP1 inhibited SSIIIa starch polymerization activity in a non‐competitive manner. Surprisingly, artificial microRNA gene suppression of SBDCP1 restored protein expression levels of SSIIIa in the CS8 line resulting in starch with lower amylose content and increased amylopectin chains with a higher degree of polymerization. Collectively, our results support the involvement of additional non‐enzymatic factors such as SBDCP in starch biosynthesis.
Significance Statement
Transcriptome analysis of a rice CS8 line that expressed an up‐regulated glgC (ADPglucose pyrophosphorylase) gene revealed extensive re‐programming especially of genes associated with starch synthesis including a previously uncharacterized, amyloplast‐localized SBDCP1. This CBM20 domain‐containing protein interacts with SSIIIa and inhibits its catalytic activity and, thereby, restraining maximum carbon flow into starch.
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Details
- Title
- Re‐programming of gene expression in the CS8 rice line over‐expressing ADPglucose pyrophosphorylase induces a suppressor of starch biosynthesis
- Creators
- Bilal Cakir - Washington State UniversityLi Tian - Washington State UniversityNaoko Crofts - Akita Prefectural University, Shimoshinjo‐NakanoHong‐Li Chou - Washington State UniversityKaan Koper - Washington State UniversityChun‐Yeung Ng - Washington State UniversityAytug Tuncel - Washington State UniversityMahmoud Gargouri - Washington State UniversitySeon‐Kap Hwang - Washington State UniversityNaoko Fujita - Akita Prefectural University, Shimoshinjo‐NakanoThomas W Okita - Washington State University
- Publication Details
- The Plant journal : for cell and molecular biology, Vol.97(6), pp.1073-1088
- Academic Unit
- Biological Chemistry, Institute of
- Number of pages
- 16
- Grant note
- USDA‐NIFA (0590; 0119) Agricultural Research Center College of Agricultural, Human, and Natural Resource Sciences, Washington State University Japan Society for the Promotion of Science (15J40176) Molecular Plant Science Graduate Program
- Identifiers
- 99900546659301842
- Language
- English
- Resource Type
- Journal article