Reference "Cloning and characterization of the rice CatA catalase gene, a homologue of the maize Cat3 gene"

Reference ID

1401

Title

Cloning and characterization of the rice CatA catalase gene, a homologue of the maize Cat3 gene

Source

Plant molecular biology, 1996, vol. 30, pp. 505-521

Authors (2)

Higo-K

Higo-H

Abstract

We isolated and sequenced a genomic clone (CatA) encoding CAT-A catalase, a
homologue of the maize catalase isozyme 3 (CAT-3) from rice (Oryza sativa L.).
The 5'-upstream non-coding region had very low similarity with the maize Cat3
gene and possible cis elements and sequence motifs in the maize Cat3 gene were
not evident, except for TATA and CAAT motifs. Several sequence motifs found in
the promoters of plant seed-specific genes were identified in the 5'-upstream
non-coding region of the CatA gene. Northern blotting showed that the CatA gene
is expressed at high levels in seeds during early development and also in young
seedlings. Methyl viologen (paraquat) resulted in the 3-fold induction of the
CatA gene in the leaves of young seedlings, whereas abscisic acid, wounding,
salicylic acid, and hydrogen peroxide had no or only slight effects. The 1.9 kb
5'-upstream fragment (-1559 to +342) of the CatA gene was fused with the
Escherichia coli beta-glucuronidase (GUS) gene and introduced by electroporation
into protoplasts prepared from rice suspension-cultured cells, then the
transient expression of the GUS gene was examined. Deletion analysis of this
chimeric gene suggested that a weak silencer is located in the region between
-1564 to -699. Abscisic acid (ABA) at a final concentration of 10(-6) M doubled
GUS activity in protoplasts electroporated with the chimeric DNAs having 1.9 to
1.2 kb 5'-upstream regions. A sequence highly similar to the Sph box, a motif
found in genes modulated by ABA, was found at -266 to -254. Deletion of this
region however, did not eliminate the responsiveness to ABA. Expression of the
chimeric gene in the protoplasts was not enhanced by stress such as low and high
temperature, hydrogen peroxide, methyl viologen, salicylic acid, elicitor, and
UV light. The chimeric CatA-GUS plasmid DNAs amplified in the methylation-
positive strain, E. coli DH5alpha, showed GUS gene activities, whereas all the
chimeric DNAs amplified in the methylation-deficient E. coli JM110 were
completely inactive in the presence or absence of ABA in the culture medium. DNA
methylation, especially of either one or both of the deoxyadenosines at the two
GATC motifs (one in the first exon and the other in the first intron of the rice
CatA gene), appeared to be responsible for the CatA promoter activity identified
in the transient assay.