Contrasting gene expression patterns in grain of high and low asparagine wheat genotypes in response to sulphur supply

A - Papers appearing in refereed journals

Curtis, T., Raffan, S., Wan, Y., King, R., Gonzalez-Uriarte, A. and Halford, N. G. 2019. Contrasting gene expression patterns in grain of high and low asparagine wheat genotypes in response to sulphur supply. BMC Genomics. 20, p. 628.

AuthorsCurtis, T., Raffan, S., Wan, Y., King, R., Gonzalez-Uriarte, A. and Halford, N. G.

Background: Free asparagine is the precursor for acrylamide formation during cooking and processing of grains, tubers, beans and other crop products. In wheat grain, free asparagine, free glutamine and total free amino acids accumulate to high levels in response to sulphur deficiency. In this study, RNA-seq data were acquired for the embryo and endosperm of two genotypes of bread wheat, Spark and SR3, growing under conditions of sulphur sufficiency and deficiency, and sampled at 14 and 21 days post anthesis (dpa). The aim was to provide new knowledge and understanding of the genetic control of asparagine accumulation and breakdown in wheat grain.
Results: There were clear differences in gene expression patterns between the genotypes. Sulphur responses were greater at 21 dpa than 14 dpa, and more evident in SR3 than Spark. TaASN2 was the most highly expressed asparagine synthetase gene in the grain, with expression in the embryo much higher than in the endosperm, and higher in Spark than SR3 during early development. There was a trend for genes encoding enzymes of nitrogen assimilation to be more highly expressed in Spark than SR3 when sulphur was supplied. TaASN2 expression in the embryo of SR3 increased in response to sulphur deficiency at 21 dpa, although this was not observed in Spark. This increase in TaASN2 expression was accompanied by an increase in glutamine synthetase gene expression and a decrease in asparaginase gene expression. Asparagine synthetase and asparaginase gene expression in the endosperm responded in the opposite way. Genes encoding regulatory protein kinases, SnRK1 and GCN2, both implicated in regulating asparagine synthetase gene expression, also responded to sulphur deficiency. Genes encoding bZIP transcription factors, including Opaque2/bZIP9, SPA/bZIP25 and BLZ1/OHP1/bZIP63, all of which contain SnRK1 target sites, were also expressed. Homeologues of many genes showed differential expression patterns and responses, including TaASN2.
Conclusions: Data on the genetic control of free asparagine accumulation in wheat grain and its response to sulphur supply showed grain asparagine levels to be determined in the embryo, and identified genes encoding signalling and metabolic proteins involved in asparagine metabolism that respond to sulphur availability.

KeywordsAsparagine synthetase; Amino acid metabolism; Acrylamide; bZIP; Crop composition; Food safety; RNA-seq; Sulphur; Triticum aestivum; Wheat
Year of Publication2019
JournalBMC Genomics
Journal citation20, p. 628
Digital Object Identifier (DOI)
Web address (URL)
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeBBSRC LINK: Genetic improvement of wheat to reduce the potential for acrylamide formation during processing
Designing Future Wheat (DFW) [ISPG]
DFW - Designing Future Wheat - Work package 1 (WP1) - Increased efficiency and sustainability
SWBio DTP PhD studentship
Publisher's version
Copyright license
Output statusPublished
Publication dates
Online01 Aug 2019
Publication process dates
Accepted23 Jul 2019
PublisherBiomed Central Ltd

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