Food safety: Structure and expression of the asparagine synthetase gene family of wheat.
Asparagine is an important nitrogen storage and transport molecule, but its accumulation as a free amino acid in crops has implications for food safety because free asparagine is a precursor for acrylamide formation during cooking and processing. Asparagine synthesis occurs by the amidation of aspartate, catalysed by asparagine synthetase, and this study concerned the expression of asparagine synthetase (TaASN) genes in wheat. The expression of three genes,TaASN1-3, was studied in different tissues and in response to nitrogen and sulphur supply. The expression ofTaASN2in the embryo and endosperm during mid to late grain development was the highest of any of the genes in any tissue. BothTaASN1andTaASN2increased in expression through grain development, and in the grain of field-grown plants during mid-development in response to sulphur deprivation. However, onlyTaASN1was affected by nitrogen or sulphur supply in pot-based experiments, showing complex tissue-specific and developmentally-changing responses. A putative N-motif or GCN4-like regulatory motif was found in the promoter ofTaASN1genes from several cereal species. As the study was completed, a fourth gene,TaASN4, was identified from recently available genome data. Phylogenetic analysis showed that other cereal species have similar asparagine synthetase gene families to wheat.
Biotechnology Research Institute, Shanghai Academy of Agricultural Sciences, 2901 Beidi Road, Minhang District, Shanghai, 201106, PR China; Plant Biology and Crop Science Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom.
Runhong
R
Gao
Plant Biology and Crop Science Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom.
Tanya Y
TY
Curtis
Computational and Systems Biology Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom.
Stephen J
SJ
Powers
Biotechnology Research Institute, Shanghai Academy of Agricultural Sciences, 2901 Beidi Road, Minhang District, Shanghai, 201106, PR China; Plant Biology and Crop Science Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom.
Hongwei
H
Xu
Biotechnology Research Institute, Shanghai Academy of Agricultural Sciences, 2901 Beidi Road, Minhang District, Shanghai, 201106, PR China.
Jianhua
J
Huang
Plant Biology and Crop Science Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom.
Nigel G
NG
Halford
Acrylamide; Crop composition and food safety; Nitrogen metabolism; Nutritional regulation of gene expression