JXB Advance Access originally published online on February 27, 2004
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Journal of Experimental Botany, Vol. 55, No. 398, pp. 791-801, April 1, 2004
© 2004 Oxford University Press
Cell and Molecular Biology, Biochemistry and Molecular Physiology |
The auxin conjugate 1-O-indole-3-acetyl-ß-D-glucose is synthesized in immature legume seeds by IAGlc synthase and may be used for modification of some high molecular weight compounds
Received 17 July 2003; Accepted 16 December 2003
Nicholas Copernicus University, Institute of General and Molecular Biology, Department of Biochemistry, ul. Gagarina 9, 87-100 Toruñ, Poland
* To whom correspondence should be addressed. Fax: +48 56 611 44 72. E-mail: anjakubo{at}cc.uni.torun.pl
Abbreviations: IAA, indole-3-acetic acid; 1-O-IAGlc, 1-O-(indole-3-acetyl)-ß-D-glucose; IAInos, indole-3-acetyl-myo-inositol; IAGlc synthase, UDP-glucose:indole-3-acetate glucosyltransferase; IAInos synthase, 1-O-(indole-3-acetyl)-glucose:myo-inositol indoleacetyl transferase.
Immature seeds of some dicotyledonous plants contain IAGlc synthase catalysing the synthesis of 1-O-IAGlc. This enzyme activity is comparable with 1-O-IAGlc synthase activity investigated earlier in liquid endosperm of Zea mays. Polyclonal antibodies against maize 1-O-IAGlc synthase cross-react with partially purified 1-O-IAGlc synthase from immature pea and rape seeds. Single immunoreactive bands were observed at a locus corresponding to 45.7 kDa and 43.7 kDa from pea and rape enzyme preparations, respectively, unlike that from the 50 kDa molecular mass of the maize enzyme. It was also observed that some high molecular weight compounds of pea seeds are labelled in vivo by [14C] IAA, and unlabelled 1-O-IAGlc inhibits that labelling. In immature pea seeds 43–49.8% of the IAA-modified high molecular weight compounds, obtained after ultracentrifugation, was found in the soluble fraction and 50.1–57% in the insoluble fraction. Ester-linked IAA accounted for about 6–9% and 38–45.6% in soluble and insoluble material, respectively, estimated after hydrolysis in 1 N NaOH. Enzymatic hydrolysis of IAA-labelled high molecular weight compounds gives free IAA and compound(s) corresponding to IAGlc isomers. These results suggest that 1-O-IAGlc synthesized in legume seeds may be used for the modification of some high molecular weight compounds.
Key words: High molecular weight indole-3-acetic acid conjugates, IAA-glucose synthase, indole-3-acetic acid, indole-3-acetic acid glucose, legume plants.
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  A. W. WOODWARD and B. BARTEL Auxin: Regulation, Action, and Interaction Ann. Bot., April 1, 2005; 95(5): 707 - 735. [Abstract] [Full Text] [PDF]
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