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Metabolic consequences of knocking out UGT85B1, the gene encoding the glucosyltransferase required for synthesis of dhurrin in Sorghum bicolor (L. Moench)

Blomstedt, Cecilia K., O'Donnell, Natalie H., Bjarnholt, Nanna, Neale, Alan D., Hamill, John D., Møller, Birger Lindberg and Gleadow, Roslyn M. 2016, Metabolic consequences of knocking out UGT85B1, the gene encoding the glucosyltransferase required for synthesis of dhurrin in Sorghum bicolor (L. Moench), Plant and cell physiology, vol. 57, no. 2, Special issue : marchantia polymorpha, pp. 373-386, doi: 10.1093/pcp/pcv153.

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Title Metabolic consequences of knocking out UGT85B1, the gene encoding the glucosyltransferase required for synthesis of dhurrin in Sorghum bicolor (L. Moench)
Author(s) Blomstedt, Cecilia K.
O'Donnell, Natalie H.
Bjarnholt, Nanna
Neale, Alan D.
Hamill, John D.
Møller, Birger Lindberg
Gleadow, Roslyn M.
Journal name Plant and cell physiology
Volume number 57
Issue number 2
Season Special issue : marchantia polymorpha
Start page 373
End page 386
Total pages 14
Publisher Oxford University Press
Place of publication Oxford, Eng.
Publication date 2016-02
ISSN 0032-0781
1471-9053
Keyword(s) cyanogenic glucoside
detoxification
dhurrin
metabolic turnover
sorghum
UDP-glycosyltransferase
Summary Many important food crops produce cyanogenic glucosides as natural defense compounds to protect against herbivory or pathogen attack. It has also been suggested that these nitrogen-based secondary metabolites act as storage reserves of nitrogen. In sorghum, three key genes, CYP79A1, CYP71E1 and UGT85B1, encode two Cytochrome P450s and a glycosyltransferase, respectively, the enzymes essential for synthesis of the cyanogenic glucoside dhurrin. Here, we report the use of targeted induced local lesions in genomes (TILLING) to identify a line with a mutation resulting in a premature stop codon in the N-terminal region of UGT85B1. Plants homozygous for this mutation do not produce dhurrin and are designated tcd2 (totally cyanide deficient 2) mutants. They have reduced vigor, being dwarfed, with poor root development and low fertility. Analysis using liquid chromatography-mass spectrometry (LC-MS) shows that tcd2 mutants accumulate numerous dhurrin pathway-derived metabolites, some of which are similar to those observed in transgenic Arabidopsis expressing the CYP79A1 and CYP71E1 genes. Our results demonstrate that UGT85B1 is essential for formation of dhurrin in sorghum with no co-expressed endogenous UDP-glucosyltransferases able to replace it. The tcd2 mutant suffers from self-intoxication because sorghum does not have a feedback mechanism to inhibit the initial steps of dhurrin biosynthesis when the glucosyltransferase activity required to complete the synthesis of dhurrin is lacking. The LC-MS analyses also revealed the presence of metabolites in the tcd2 mutant which have been suggested to be derived from dhurrin via endogenous pathways for nitrogen recovery, thus indicating which enzymes may be involved in such pathways.
Language eng
DOI 10.1093/pcp/pcv153
Field of Research 060702 Plant Cell and Molecular Biology
Socio Economic Objective 929999 Health not elsewhere classified
HERDC Research category C1 Refereed article in a scholarly journal
ERA Research output type C Journal article
Copyright notice ©2015, The Authors
Persistent URL http://hdl.handle.net/10536/DRO/DU:30084190

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