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ID 21456
file
creator
Nakagawa, Ayami
Sakamoto, Saori
Morikawa, Hiromichi
subject
Arabidopsis (Arabidopsis thaliana)
plant growth and development
purine metabolism
senescence
xanthine dehydrogenase
NDC
Biology
abstract
Xanthine dehydrogenase (XDH) is a ubiquitous enzyme involved in purine metabolism which catalyzes the oxidation of hypoxanthine and xanthine to uric acid. Although the essential role of XDH is well documented in the nitrogen-fixing nodules of leguminous plants, the physiological importance of this enzyme remains uncertain in non-leguminous species such as Arabidopsis. To evaluate the impact of an XDH deficiency on whole-plant physiology and development in Arabidopsis, RNA interference (RNAi) was used to generate transgenic lines of this species in which AtXDH1 and AtXDH2, the two paralogous genes for XDH in this plant, were silenced simultaneously. The nearly complete reduction in the total XDH protein levels caused by this gene silencing resulted in the dramatic overaccumulation of xanthine and a retarded growth phenotype in which fruit development and seed fertility were also affected. A less severe silencing of XDH did not cause these growth abnormalities. The impaired growth phenotype was mimicked by treating wild-type plants with the XDH inhibitor allopurinol, and was reversed in the RNAi transgenic lines by exogenous supplementation of uric acid. Inactivation of XDH is also associated with precocious senescence in mature leaves displaying accelerated chlorophyll breakdown and by the early induction of senescence-related genes and enzyme markers. In contrast, the XDH protein levels increase with the aging of the wild-type leaves, supporting the physiological relevance of the function of this enzyme in leaf senescence. Our current results thus indicate that XDH functions in various aspects of plant growth and development.
journal title
Plant and Cell Physiology
volume
Volume 48
issue
Issue 10
start page
1484
end page
1495
date of issued
2007-10
publisher
Oxford University Press
issn
0032-0781
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
author
rights
Copyright(c) 2007 Oxford University Press
relation is version of URL
http://dx.doi.org/10.1093/pcp/pcm119
department
Graduate School of Science