Arabidopsis F-box gene FOAl involved in ABA signaling

The expression of FOAl （F-box overexpressed/oppressed ABA signaling） in different organs of Arabidopsis, and in response to ABA and NaCI, was analyzed. The expression level of FOAl is higher in the root and is lower in the stem, and is induced rapidly by ABA and NaC1. The phenotypes of T-DNA insertion mutant foal and FOAl overexpression lines FOAloxl and FOAlox2 were analyzed. The foal mutant exhibited a lower germination rate, shorter root length, more stomatal opening, in- creased proline accumulation and hypersensitivity to ABA compared with the wild type. In contrast, the overexpression lines showed lower sensitivity to ABA than the wild type. The expression levels of several ABA and stress-responsive transcription factors and genes were altered in the foal mutant in response to ABA. Compared with the wild type, the expression levels of ABA-responsive transcription factors were higher, but ABA and stress-responsive genes were lower in foal mutant. This study demonstrates that FOAl is an ABA signaling-related gene, and may play a negative role in ABA signaling.