Coalescence and directed anisotropic growth of starch granule initials in subdomains of Arabidopsis thaliana chloroplasts


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Date

2021-12

Publication Type

Journal Article

ETH Bibliography

yes

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Data

Abstract

Living cells orchestrate enzyme activities to produce myriads of biopolymers but cell-biological understanding of such processes is scarce. Starch, a plant biopolymer forming discrete, semi-crystalline granules within plastids, plays a central role in glucose storage, which is fundamental to life. Combining complementary imaging techniques and Arabidopsis genetics we reveal that, in chloroplasts, multiple starch granules initiate in stromal pockets between thylakoid membranes. These initials coalesce, then grow anisotropically to form lenticular granules. The major starch polymer, amylopectin, is synthesized at the granule surface, while the minor amylose component is deposited internally. The non-enzymatic domain of STARCH SYNTHASE 4, which controls the protein’s localization, is required for anisotropic growth. These results present us with a conceptual framework for understanding the biosynthesis of this key nutrient.

Publication status

published

Editor

Book title

Volume

12 (1)

Pages / Article No.

6944

Publisher

Nature

Event

Edition / version

Methods

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Geographic location

Date collected

Date created

Subject

3-D reconstruction; Chloroplasts; Plant physiology; Polysaccharides

Organisational unit

03707 - Zeeman, Samuel C. / Zeeman, Samuel C. check_circle

Notes

Funding

166487 - Multi-dimensional imaging to visualize starch biosynthesis in plants. (SNF)
182570 - Understanding the Cell Biology of Starch Metabolism in Plants (SNF)

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