This Article Full Text Full Text (PDF) All Versions of this Article: 141/1/121    most recent pp.106.078592v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by Chehab, E.W. Articles by Dehesh, K. Search for Related Content PubMed PubMed Citation Articles by Chehab, E.W. Articles by Dehesh, K. Agricola Articles by Chehab, E.W. Articles by Dehesh, K.

ENVIRONMENTAL STRESS AND ADAPTATION TO STRESS

Rice HYDROPEROXIDE LYASES with Unique Expression Patterns Generate Distinct Aldehyde Signatures in Arabidopsis¹

Section of Plant Biology, University of California, Davis, California 95616

HYDROPEROXIDE LYASE (HPL) genes encode enzymes that catalyze the cleavage of fatty acid hydroperoxides into aldehydes and oxoacids. There are three HPLs in rice (Oryza sativa), designated OsHPL1 through OsHPL3. To explore the possibility of differential functional activities among these genes, we have examined their expression patterns and biochemical properties of their encoded products. Transcript analysis indicates that these genes have distinct patterns and levels of expression. OsHPL1 is ubiquitously expressed, OsHPL2 is expressed in the leaves and leaf sheaths, whereas OsHPL3 is wound inducible and expressed exclusively in leaves. OsHPLs also differ in their substrate preference as determined by in vitro enzyme assays using 9-/13-hydroperoxy linolenic and 9-/13-hydroperoxy linoleic acids as substrates. OsHPL1 and OsHPL2 metabolize 9-/13-hydroperoxides, whereas OsHPL3 metabolizes 13-hydroperoxy linolenic acid exclusively. Sequence alignments of the HPL enzymes have identified signature residues potentially responsible for the substrate specificity/preference of these enzymes. All three OsHPLs are chloroplast localized as determined by chloroplast import assays and green fluorescent protein (GFP) fusion studies. Aldehyde measurements in transgenic Arabidopsis (Arabidopsis thaliana) plants overexpressing individual OsHPL-GFP fusions indicate that all rice HPLs are functional in a heterologous system, and each of them generates a distinct signature of the metabolites. Interestingly, these aldehydes were only detectable in leaves, but not in roots, despite similar levels of OsHPL-GFP proteins in both tissues. Similarly, there were undetectable levels of aldehydes in rice roots, in spite of the presence of OsHPL1 transcripts. Together, these data suggest that additional tissue-specific mechanism(s) beyond transcript and HPL enzyme abundance, regulate the levels of HPL-derived metabolites.

² Present address: Pacific Northwest National Laboratories, P.O. Box 999, Richland, WA 99352.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: K. Dehesh (kdehesh{at}ucdavis.edu).

Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.106.078592.

^* Corresponding author; e-mail kdehesh{at}ucdavis.edu; fax 530–752–5410.

Received February 2, 2006; returned for revision March 1, 2006; accepted March 2, 2006.

This article has been cited by other articles:

				E. W. Chehab, E. Eich, and J. Braam Thigmomorphogenesis: a complex plant response to mechano-stimulation J. Exp. Bot., January 1, 2009; 60(1): 43 - 56. [Abstract] [Full Text] [PDF]