Lin, Wan-chi , Ho, Tuan-hua David .
Dissection of GA/ABA signaling pathways in cereal aleurone cells via chemical genetics.
The synthesis of sevral hydrolytic enzymes, such as alpha-amylases, in cereal aleurone cells is up-regulated by GA and down-regulated by ABA. A library of 10,000 small chemicals has been screened for the ability to affect the GA induction or ABA inhibition of alpha-amylase synthesis/secretion from rice endosperm half-seeds. Two GA modulators and two ABA modulators have been repeatedly shown to inhibit GA and ABA action, respectively. The GA modulators were further studied to pinpoint their site of action relative to the known intermediates in GA/ABA signaling pathways. These GA modulators inhibited the GA up-regulation of Amy32b::GUS reporter construct, but did not affect either the ABA down regulation of the same reporter construct or the ABA up-regulation of LEA promoter::GUS reporter construct, indicating that the action of these modulators is quite specific. These GA modulators had no effect on the up-regulation of the Amy32b::GUS reporter construct by the transcription factor, GAMYB. On the other hand, the same modulators could inhibit the de-repression of Amy32b::GUS when the synthesis of endogenous repressor, SLN (SLR), was partially reduced by a specific RNAi. Taken together, these observations suggest that the action of these GA modulators act down-stream from SLN, but upstream of GAMYB. Since they mimic the action of an ABA-induced protein kinase PKABA1 (SnRK2), they could be useful tools in further elucidating the action of ABA.
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1 - Academia Sinica, Institute of Plant and Microbial Biology
2 - Academia Sinica, Institute of Plant and Microbial Biology, Nankang, Taipei, 115, Taiwan
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM