EARLY STARVATION 1 Is a Functionally Conserved Protein Promoting Gravitropic Responses in Plants by Forming Starch Granules
Open Access
- 23 July 2021
- journal article
- research article
- Published by Frontiers Media SA in Frontiers in Plant Science
Abstract
Starch granules in the endodermis of plant hypocotyls act as statoliths that promote hypocotyl negative gravitropism—the directional growth of hypocotyls against gravity—in the dark. To identify the molecular components that regulate hypocotyl negative gravitropism, we performed a mutagenesis screen and isolated reduced gravitropic 1 (rgv1) mutants that lack starch granules in their hypocotyl endodermis and show reduced hypocotyl negative gravitropism in the dark. Using whole genome sequencing, we identified three different rgv1 mutants that are allelic to the previously reported early starvation 1 mutant, which is rapidly depleted of starch just before the dawn. ESV1 orthologs are present in starch-producing green organisms, suggesting ESV1 is a functionally conserved protein necessary for the formation of starch granules. Consistent with this, we found that liverwort and rice ESV1 can complement the Arabidopsis ESV1 mutant phenotype for both starch granules and hypocotyl negative gravitropism. To further investigate the function of ESV1 in other plants, we isolated rice ESV1 mutants and found that they show reduced levels of starch in their leaves and loosely packed starch granules in their grains. Both Arabidopsis and rice ESV1 mutants also lack starch granules in root columella and show reduced root gravitropism. Together, these results indicate ESV1 is a functionally conserved protein that promotes gravitropic responses in plants via its role in starch granule formation.Keywords
Funding Information
- National Research Foundation of Korea (2018R1A3B1052617)
This publication has 85 references indexed in Scilit:
- PIFs: pivotal components in a cellular signaling hubTrends in Plant Science, 2011
- Phytochromes inhibit hypocotyl negative gravitropism by regulating the development of endodermal amyloplasts through phytochrome-interacting factorsProceedings of the National Academy of Sciences of the United States of America, 2011
- Gravity-induced PIN transcytosis for polarization of auxin fluxes in gravity-sensing root cellsProceedings of the National Academy of Sciences of the United States of America, 2010
- Starch Synthesis in Arabidopsis Is Achieved by Spatial Cotranscription of Core Starch Metabolism GenesPlant Physiology, 2009
- Phytochromes promote seedling light responses by inhibiting four negatively-acting phytochrome-interacting factorsProceedings of the National Academy of Sciences of the United States of America, 2009
- The Two Plastidial Starch-Related Dikinases Sequentially Phosphorylate Glucosyl Residues at the Surface of Both the A- and B-Type Allomorphs of Crystallized Maltodextrins But the Mode of Action DiffersPlant Physiology, 2009
- Phosphorylation of C6‐ and C3‐positions of glucosyl residues in starch is catalysed by distinct dikinasesFEBS Letters, 2006
- A novel isoform of glucan, water dikinase phosphorylates pre‐phosphorylated α‐glucans and is involved in starch degradation in ArabidopsisThe Plant Journal, 2005
- Identification of a Novel Enzyme Required for Starch Metabolism in Arabidopsis Leaves. The Phosphoglucan, Water DikinasePlant Physiology, 2005
- T‐DNA insertional mutagenesis for functional genomics in riceThe Plant Journal, 2000