Abstract
We have isolated and characterized Arabidopsis mutants that show reduced sensitivity to abscisic acid during seed germination. Among them, chotto1 (cho1) mutants were analyzed by genetic and genomic approaches. We identified the CHO1 gene that encodes a novel AP2 transcription factor and was expressed predominantly during seed development and germination. The phenotypic and gene expression analysis indicated that CHO1 acts downstream of ABI4. The cho1 mutants showed the resistance to high concentration of glucose in a similar manner to the abi4 mutants. In addition, the cho1 mutants were also resistant to high concentration of nitrate. The gene expression analysis using Affymetrix ATH1 GenomeArray indicated that the expression of some metabolism-related genes was induced earlier in cho1 than in wild type during seed germination with the high concentration of nitrate. These results suggested that CHO1 participates in the growth repression to delay the seed germination under the high nitrate conditions.
