The overexpression of rice ACYL-CoA-BINDING PROTEIN2 increases grain size and bran oil content in transgenic rice

A - Papers appearing in refereed journals

Guo, Z.-H., Haslam, R. P., Michaelson, L. V., Young, E. C., Lung, S. C., Napier, J. A. and Chye, M.L. 2019. The overexpression of rice ACYL-CoA-BINDING PROTEIN2 increases grain size and bran oil content in transgenic rice. The Plant Journal.

AuthorsGuo, Z.-H., Haslam, R. P., Michaelson, L. V., Young, E. C., Lung, S. C., Napier, J. A. and Chye, M.L.
Abstract

As Oryza sativa (rice) seeds represent food for over three billion people worldwide, the identification of genes that enhance grain size and composition is much desired. Past reports have indicated that Arabidopsis thaliana acyl-CoA-binding proteins (ACBPs) are important in seed development but did not affect seed size. Herein, rice OsACBP2 was demonstrated not only to play a role in seed development and germination, but also to influence grain size. OsACBP2 mRNA accumulated in embryos and endosperm of germinating seeds in qRT-PCR analysis, while b-glucuronidase (GUS) assays on OsACBP2pro::GUS rice transformants showed GUS expression in embryos, as well as the scutellum and aleurone layer of germinating seeds. Deletion analysis of the OsACBP2 5’-flanking region revealed five copies of the seed cis-element, Skn-I-like motif (1486/1482, 956/952, 939/935, 826/822, and 766/762), and the removal of any adversely affected expression in seeds, thereby providing a molecular basis for OsACBP2 expression in seeds. When OsACBP2 function was investigated using osacbp2 mutants and transgenic rice overexpressing OsACBP2 (OsACBP2-OE), osacbp2 was retarded in germination, while OsACBP2-OEs performed better than the wild-type and vector-transformed controls, in germination, seedling growth, grain size and grain weight. Transmission electron microscopy of OsACBP2-OE mature seeds revealed an accumulation of oil bodies in the scutellum cells, while confocal laser scanning microscopy indicated oil accumulation in OsACBP2-OE aleurone tissues. Correspondingly, OsACBP2-OE seeds showed gain in triacylglycerols and long-chain fatty acids over the vector-transformed control. As dietary rice bran contains beneficial bioactive components, OsACBP2 appears to be a promising candidate for enriching seed nutritional value.

Keywordsaleurone layer; lipid profiling; oil body; Oryza sativa ; scutellum; Skn-I-like motif
Year of Publication2019
JournalThe Plant Journal
Digital Object Identifier (DOI)doi:10.1111/tpj.14503
Open accessPublished as bronze (free) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeTailoring Plant Metabolism
Designing oilseeds for nutrition and health
Publisher's version
Copyright license
Publisher copyright
Output statusE-publication ahead of print
Publication dates
Online22 Aug 2019
Publication process dates
Accepted05 Aug 2019
PublisherWiley-Blackwell
ISSN0960-7412

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