Structural analogs of ABA reveal novel features of ABA perception and signaling in Arabidopsis

Abstract

SummaryChanges 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.

Molecular and Physiological Analysis of Drought Stress in Arabidopsis Reveals Early Responses Leading to Acclimation in Plant Growth

“…These results of mDr and pDr are consistent and reveal the similarity in significance of ABA-and non-ABA-related or -dependent pathways in drought responses. In genome-wide oligonucleotide microarray studies of Arabidopsis soil water deficit pDr responses (Huang et al, 2008), a higher level of drought-regulated genes was found in comparison with ABA responses using a more response-eliciting ABA analog (Huang et al, 2007).…”

Understanding the Biochemical Basis of Temperature-Induced Lipid Pathway Adjustments in Plants

“…Primer specificity was checked with BLASTn searches against TAIR10 transcripts (http://www.arabidopsis.org/) as well as by monitoring melt curve using the ABI StepOne Real-time PCR systems (Applied Biosystems). ACTIN2 (At3g18780) was used as an endogenous control for standardization (Huang et al, 2007). Real-time qRT-PCR was performed with Power SYBR Green PCR Master Mix (Applied Biosystems), and amplification was monitored with StepOne real-time PCR systems.…”

TheArabidopsisC2H2 Zinc Finger INDETERMINATE DOMAIN1/ENHYDROUS Promotes the Transition to Germination by Regulating Light and Hormonal Signaling during Seed Maturation

“…A similar GA-hypersensitive phenotype was also observed in RAB18:ENY seedlings when grown under 10 mM GA 3 and 0.45 mM (+)-ABA to induce ENY, but only with respect to increased hypocotyl elongation (see Supplemental Figure 12 online). A mild phenotype was not unexpected, however, as ENY expression would not be sustained under the RAB18 promoter, partly because ABA was applied at a low concentration and would be rapidly metabolized (Huang et al, 2007).…”