Structural analogs of ABA reveal novel features of ABA perception and signaling in Arabidopsis.
Changes in gene expression produced by the application of (+)-abscisic acid (ABA) to Arabidopsis thaliana plants were compared with changes produced by the ABA structural analogs (-)-ABA, (+)-8'-acetylene ABA and (-)-2',3'-dihydroacetylenic abscisyl alcohol. The maximum expression of many rapidly (+)-ABA-induced genes occurred prior to peak hormone accumulation, suggesting negative feedback regulation that may be mediated by the induction of genes encoding PP2C-type protein phosphatases. For most rapidly (+)-ABA-induced genes, expression was delayed in ABA analog treatments although analogs accumulated to higher levels than did (+)-ABA. For each analog, some genes exhibited a hypersensitive response to the analog and some genes were less sensitive to the analog than to (+)-ABA. Variations in the sensitivity of gene expression to (+)-ABA and analogs reflect the different structural requirements of two or more classes of hormone receptors. By using ABA analogs to reveal and confirm weakly (+)-ABA-regulated genes, we estimate that 14% of Arabidopsis genes are ABA-regulated in aerial tissues. Treatments with the analog (+)-8'-acetylene ABA (PBI425) led to the identification of new ABA-regulated genes. As an example, the transcription factor MYBR1 was significantly induced by PBI425, but not by (+)-ABA, and is shown to play a role in ABA signaling by phenotypic analysis of gain-of-function and loss-of-function mutants.
Huang
Daiqing
D
Plant Biotechnology Institute, National Research Council of Canada, 110 Gymnasium Place, Saskatoon S7N 0W9, Canada.
Jaradat
Masrur R
MR
Wu
Weiren
W
Ambrose
Stephen J
SJ
Ross
Andrew R
AR
Abrams
Suzanne R
SR
Cutler
Adrian J
AJ
D000040:Abscisic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D015394:Molecular Structure; D005810:Multigene Family; D011401:Promoter Regions, Genetic / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; D014157:Transcription Factors; D000040:Abscisic Acid