Plant Physiol, May 2002, Vol. 129, pp. 72-84
Tissue Localization of a
Submergence-Induced 1-Aminocyclopropane-1-Carboxylic Acid
Synthase in Rice1
Zhongyi
Zhou,2
Janice
de Almeida Engler,
Dominique
Rouan,
Frank
Michiels,
Marc
Van Montagu, and
Dominique
Van Der
Straeten*
Department of Plant Systems Biology, Flanders Interuniversity
Institute for Biotechnology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium (Z.Z., J.d.A.E., M.V.M., D.V.D.S.); and Aventis
CropScience, B-9000 Ghent, Belgium (D.R., F.M.)
At least two 1-aminocyclopropane-1-carboxylic acid synthase
genes (ACS) are implicated in the submergence response
of rice (Oryza sativa). Previously, the
OS-ACS5 gene has been shown to be induced during short-
as well as long-term complete submergence of seedlings and to be
controlled by a balance of gibberellin and abscisic acid in both
lowland and deepwater rice. This study demonstrates that
OS-ACS5 mRNA is localized in specific tissues and cells
both during normal development and in response to complete submergence.
The temporal and spatial regulation of OS-ACS5
expression is presented by in situ hybridization and histochemical
analysis of 
-glucuronidase (GUS) activity in transgenic rice
carrying an OS-ACS5-gus fusion. Whole-mount in situ
hybridization revealed that in air-grown rice seedlings,
OS-ACS5 was expressed at a low level in the shoot apex,
meristems, leaf, and adventitious root primordia, and in vascular
tissues of nonelongated stems and leaf sheaths. In response to complete
submergence, the expression in vascular bundles of young stems and leaf
sheaths was strongly induced. The results of histochemical GUS assays
were consistent with those found by whole-mount in situ hybridization.
Our findings suggest that OS-ACS5 plays a role in
vegetative growth of rice under normal conditions and is also recruited
for enhanced growth upon complete submergence. The possible implication
of OS-ACS5 in root-shoot communication during
submergence stress and its putative role in aerenchyma formation upon
low-oxygen stress are discussed.
1
This work was supported by the European Union
(grant no. ISC China CI1*-CT93-0082) and by the Geconcerteerde
Overlegde Acties (grant no. GOA 96016).
2
Present address: CropDesign N.V., Technologiepark 3, B-9052 Ghent, Belgium.
*
Corresponding author; e-mail dostr{at}gengenp.rug.ac.be; fax
32-9-2645333.
© 2002 American Society of Plant Physiologists
