Wheat amino acid transporters highly expressed in grain cells regulate amino acid accumulation in grain

A - Papers appearing in refereed journals

Wan, Y., Wang, Y., Shi, Z., Rentsch, D., Ward, J. L., Hassall, K. L., Sparks, C. A., Huttly, A. K., Buchner, P. H., Powers, S. J., Shewry, P. R. and Hawkesford, M. J. 2021. Wheat amino acid transporters highly expressed in grain cells regulate amino acid accumulation in grain. PLOS ONE. 16 (2), p. e0246763. https://doi.org/10.1371/journal.pone.0246763

AuthorsWan, Y., Wang, Y., Shi, Z., Rentsch, D., Ward, J. L., Hassall, K. L., Sparks, C. A., Huttly, A. K., Buchner, P. H., Powers, S. J., Shewry, P. R. and Hawkesford, M. J.
Abstract

Amino acids are delivered into developing wheat grains to support the accumulation of storage proteins in the starchy endosperm, and transporters play important roles in regulating this process. RNA-seq, RT-qPCR, and promoter-GUS assays showed that three amino acid transporters (TaAAP2, TaAAP13, and TaAAP21) are differentially expressed in the endosperm transfer cells, starchy endosperm cells, aleurone cells and the embryo of the developing grain, respectively. Yeast complementation revealed that all three transporters can transport a broad spectrum of amino acids. RNAi-mediated suppression of TaAAP13 expression in the starchy endosperm did not reduce the total nitrogen content of the whole grain, but significantly altered the composition and distribution of metabolites in the starchy endosperm, with increasing concentrations of some amino acids (especially glutamine and glycine) from the outer to inner starchy endosperm cells. Overexpression of TaAAP13 under the endosperm-specific HMW-GS promoter significantly increased grain size, grain nitrogen concentration, and thousand grain weight, indicating that the sink strength for nitrogen improvement was increased by manipulation of amino acid transporters. However, the total grain number was reduced, suggesting that source nitrogen remobilized from leaves is a limiting factor for productivity. Therefore, simultaneously increasing loading of amino acids into the phloem and delivery to the spike would be required to increase protein content while maintaining grain yield.

KeywordsAmino acid transporter; Wheat grain; Overexpression; RNAi; Grain nitrogen; Grain metabolites; Grain size
Year of Publication2021
JournalPLOS ONE
Journal citation16 (2), p. e0246763
Digital Object Identifier (DOI)https://doi.org/10.1371/journal.pone.0246763
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeDesigning Future Wheat - WP1 - Increased efficiency and sustainability
Publisher's version
Accepted author manuscript
Output statusPublished
Publication dates
Online19 Feb 2021
Publication process dates
Accepted25 Jan 2021
PublisherPublic Library of Science (PLOS)
ISSN1932-6203

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