RT Journal Article
SR Electronic
T1 STARCH SYNTHASE 4 is required for normal starch granule initiation in amyloplasts of wheat endosperm
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.01.29.428798
DO 10.1101/2021.01.29.428798
A1 Erica Hawkins
A1 Jiawen Chen
A1 Alexander Watson-Lazowski
A1 Jennifer Ahn-Jarvis
A1 J. Elaine Barclay
A1 Brendan Fahy
A1 Matthew Hartley
A1 Frederick J. Warren
A1 David Seung
YR 2021
UL http://biorxiv.org/content/early/2021/01/31/2021.01.29.428798.abstract
AB Starch granule initiation is poorly understood at the molecular level. The glucosyltransferase, STARCH SYNTHASE 4 (SS4), plays a central role in granule initiation in Arabidopsis leaves, but its function in cereal endosperms is unknown. We investigated the role of SS4 in wheat, which has a distinct spatiotemporal pattern of granule initiation during grain development.We generated TILLING mutants in tetraploid wheat (Triticum turgidum) that are defective in both SS4 homoeologs. The morphology of endosperm starch was examined in developing and mature grains.SS4 deficiency led to severe alterations in endosperm starch granule morphology. During early grain development, while the wild type initiated single ‘A-type’ granules per amyloplast, most amyloplasts in the mutant formed compound granules due to multiple initiations. This phenotype was similar to mutants deficient in B-GRANULE CONTENT 1 (BGC1). SS4 deficiency also reduced starch content in leaves and pollen grains.We propose that SS4 and BGC1 are required for the proper control of granule initiation during early grain development that leads to a single A-type granule per amyloplast. The absence of either protein results in a variable number of initiations per amyloplast and compound granule formation.Competing Interest StatementThe authors have declared no competing interest.