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Plant Mol Biol. 2019 Mar;99(4-5):477-497. doi: 10.1007/s11103-019-00831-z. Epub 2019 Feb 5.

Opposite fates of the purine metabolite allantoin under water and nitrogen limitations in bread wheat.

Author information

1
School of Agriculture Food and Wine, The University of Adelaide, Urrbrae, SA, 5064, Australia.
2
Strube Research GmbH & Co. KG, 38387, Söllingen, Germany.
3
School of Agriculture and Food, The University of Melbourne, Parkville, VIC, 3010, Australia.
4
Metabolomics Australia, The University of Melbourne, Parkville, VIC, 3052, Australia.
5
Max Plank Institute of Molecular Plant Physiology, 14476, Potsdam, Golm, Germany.
6
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan.
7
School of Agriculture Food and Wine, The University of Adelaide, Urrbrae, SA, 5064, Australia. sigrid.heuer@rothamsted.ac.uk.
8
Rothamsted Research, Plant Science Department, Harpenden, Hertfordshire, AL5 2JQ, UK. sigrid.heuer@rothamsted.ac.uk.

Abstract

Degradation of nitrogen-rich purines is tightly and oppositely regulated under drought and low nitrogen supply in bread wheat. Allantoin is a key target metabolite for improving nitrogen homeostasis under stress. The metabolite allantoin is an intermediate of the catabolism of purines (components of nucleotides) and is known for its housekeeping role in nitrogen (N) recycling and also for its function in N transport and storage in nodulated legumes. Allantoin was also shown to differentially accumulate upon abiotic stress in a range of plant species but little is known about its role in cereals. To address this, purine catabolic pathway genes were identified in hexaploid bread wheat and their chromosomal location was experimentally validated. A comparative study of two Australian bread wheat genotypes revealed a highly significant increase of allantoin (up to 29-fold) under drought. In contrast, allantoin significantly decreased (up to 22-fold) in response to N deficiency. The observed changes were accompanied by transcriptional adjustment of key purine catabolic genes, suggesting that the recycling of purine-derived N is tightly regulated under stress. We propose opposite fates of allantoin in plants under stress: the accumulation of allantoin under drought circumvents its degradation to ammonium (NH4+) thereby preventing N losses. On the other hand, under N deficiency, increasing the NH4+ liberated via allantoin catabolism contributes towards the maintenance of N homeostasis.

KEYWORDS:

Allantoin; Drought; Nitrogen deficiency; Nutrient recycling; Purine catabolism; Triticum aestivum

PMID:
30721380
DOI:
10.1007/s11103-019-00831-z
[Indexed for MEDLINE]

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