Journal Article

Septum Formation in Amyloplasts Produces Compound Granules in the Rice Endosperm and is Regulated by Plastid Division Proteins

Min-Soo Yun and Yasushi Kawagoe

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 51, issue 9, pages 1469-1479
Published in print September 2010 | ISSN: 0032-0781
Published online August 2010 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcq116
Septum Formation in Amyloplasts Produces Compound Granules in the Rice Endosperm and is Regulated by Plastid Division Proteins

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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Storage tissues such as seed endosperm and tubers store starch in the form of granules in the amyloplast. In the rice (Oryza sativa) endosperm, each amyloplast produces compound granules consisting of several dozen polyhedral, sharp-edged and easily separable granules; whereas in other cereals, including wheat (Triticum aestivum), barley (Hordeum vulgare) and maize (Zea mays), each amyloplast synthesizes one granule. Despite extensive studies on mutants of starch synthesis in cereals, the molecular mechanisms involved in compound granule synthesis in rice have remained elusive. In this study, we expressed green fluorescent protein (GFP) fused to rice Brittle1 (BT1), an inner envelope membrane protein, to characterize dividing amyloplasts in the rice endosperm. Confocal microscopic analyses revealed that a septum-like structure, or cross-wall, containing BT1–GFP divides granules in the amyloplast. Plastid division proteins including FtsZ, Min and PDV2 play significant roles not only in amyloplast division, but also in septum synthesis, suggesting that amyloplast division and septum synthesis are related processes that share common factors. We propose that successive septum syntheses which create sections inside the amyloplast and de novo granule synthesis in each section are primarily responsible for the synthesis of compound granules.

Keywords: Amyloplast division; Compound granule; FtsZ; Min; Septum; Starch

Journal Article.  5534 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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