Transcriptional Regulation of ABI3- and ABA-responsive Genes Including RD29Band RD29Ain Seeds, Germinating Embryos, and Seedlings of Arabidopsis

ABA-responsive elements (ABREs) are cis-acting elements and basic leucine zipper (bZIP)-type ABRE-binding proteins (AREBs) are transcriptional activators that function in the expression of RD29Bin vegetative tissue of Arabidopsisin response to abscisic acid (ABA) treatment. Dehydration-responsive elements (DREs) function as coupling elements of ABRE in the expression of RD29Ain response to ABA. Expression analysis using abi3and abi5mutants showed that ABI3 and ABI5 play important roles in the expression of RD29Bin seeds. Base-substitution analysis showed that two ABREs function strongly and one ABRE coupled with DRE functions weakly in the expression of RD29Ain embryos. In a transient transactivation experiment, ABI3, ABI5 and AREB1 activated transcription of a GUSreporter gene driven by the RD29Bpromoter strongly but these proteins activated the transcription driven by the RD29Apromoter weakly. In 35S::ABI3 Arabidopsisplants, the expression of RD29Bwas up-regulated strongly, but that of RD29Awas up-regulated weakly. These results indicate that the expression of RD29Bhaving ABREs in the promoter is up-regulated strongly by ABI3, whereas that of RD29Ahaving one ABRE coupled with DREs in the promoter is up-regulated weakly by ABI3. We compared the expression of 7000 Arabidopsisgenes in response to ABA treatment during germination and in the vegetative growth stage, and that in 35S::ABI3plants using a full-length cDNA microarray. The expression of ABI3- and/or ABA-responsive genes and cis-elements in the promoters are discussed.ABA-responsive elements (ABREs) are cis-acting elements and basic leucine zipper (bZIP)-type ABRE-binding proteins (AREBs) are transcriptional activators that function in the expression of RD29Bin vegetative tissue of Arabidopsisin response to abscisic acid (ABA) treatment. Dehydration-responsive elements (DREs) function as coupling elements of ABRE in the expression of RD29Ain response to ABA. Expression analysis using abi3and abi5mutants showed that ABI3 and ABI5 play important roles in the expression of RD29Bin seeds. Base-substitution analysis showed that two ABREs function strongly and one ABRE coupled with DRE functions weakly in the expression of RD29Ain embryos. In a transient transactivation experiment, ABI3, ABI5 and AREB1 activated transcription of a GUSreporter gene driven by the RD29Bpromoter strongly but these proteins activated the transcription driven by the RD29Apromoter weakly. In 35S::ABI3 Arabidopsisplants, the expression of RD29Bwas up-regulated strongly, but that of RD29Awas up-regulated weakly. These results indicate that the expression of RD29Bhaving ABREs in the promoter is up-regulated strongly by ABI3, whereas that of RD29Ahaving one ABRE coupled with DREs in the promoter is up-regulated weakly by ABI3. We compared the expression of 7000 Arabidopsisgenes in response to ABA treatment during germination and in the vegetative growth stage, and that in 35S::ABI3plants using a full-length cDNA microarray. The expression of ABI3- and/or ABA-responsive genes and cis-elements in the promoters are discussed.