The sulphur response in wheat and its implications for acrylamide formation and food safety

A - Papers appearing in refereed journals

Raffan, S., Oddy, J. and Halford, N. G. 2020. The sulphur response in wheat and its implications for acrylamide formation and food safety. International Journal Of Molecular Sciences. 21 (11), p. 3876. https://doi.org/10.3390/ijms21113876

AuthorsRaffan, S., Oddy, J. and Halford, N. G.
Abstract

Free (soluble, non-protein) asparagine concentration can increase many-fold in wheat grain in response to sulphur deficiency. This exacerbates a major food safety and regulatory compliance problem for the food industry because free asparagine may be converted to the carcinogenic contaminant, acrylamide, during baking and processing. Here we describe the predominant route for the conversion of asparagine to acrylamide in the Maillard reaction. The effect of sulphur deficiency and its interaction with nitrogen availability is reviewed, and we reiterate our advice that sulphur should be applied to wheat being grown for human consumption at a rate of 20 kg per hectare. We describe the genetic control of free asparagine accumulation, including genes that encode metabolic enzymes (asparagine synthetase, glutamine synthetase, glutamate synthetase and asparaginase), regulatory protein kinases (SnRK1 and GCN2) and bZIP transcription factors, and how this genetic control responds to sulphur, highlighting the importance of asparagine synthetase-2 (ASN2) expression in the embryo. We show that expression of glutamate-cysteine ligase is reduced in response to sulphur deficiency, probably compromising glutathione synthesis. Finally, we describe unexpected effects of sulphur deficiency on carbon metabolism in the endosperm, with large increases in expression of sucrose synthase-2 (SuSy2) and starch synthases.

KeywordsWheat; Triticum aestivum; Asparagine metabolism; Maillard reaction; Acrylamide; Food safety; Amino acid metabolism; Glutathione; Starch synthesis; Sulphur deficiency
Year of Publication2020
JournalInternational Journal Of Molecular Sciences
Journal citation21 (11), p. 3876
Digital Object Identifier (DOI)https://doi.org/10.3390/ijms21113876
Web address (URL)https://www.mdpi.com/1422-0067/21/11/3876
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeDesigning Future Wheat (DFW) [ISPG]
SWBio DTP PhD studentship
Collaborative Training Partnership Studentship with Mondelez International
Publisher's version
Output statusPublished
Publication dates
Online29 May 2020
Publication process dates
Accepted28 May 2020
PublisherMDPI
ISSN1422-0067

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