Functional interactions of lanthanum and phospholipase D with the abscisic acid signaling effectors VP1 and ABI1-1 in rice protoplasts.
cis,trans-Abscisic acid (ABA) plays an important role in plant growth and development, regulation of seed maturation, germination, and adaptation to environmental stresses. Knowledge of ABA mechanisms of action and the interactions of components required for ABA signal transduction is far from complete. Using transient gene expression in rice protoplasts, we observed additive and inhibitory effects between maize VP1 (Viviparous-1, a transcriptional activator) and a dominant-negative mutant protein phosphatase, ABI1-1 (ABA-insensitive-1-1), from Arabidopsis. Lanthanide ions were shown to be specific agonists of ABA-inducible gene expression and to interact synergistically with ABA and overexpressed VP1. Both VP1 and lanthanum activities could be antagonized by coexpression of ABI1-1, which demonstrates the specific ABA dependence of these effectors on ABA-regulated gene expression. We obtained pharmacological evidence that phospholipase D (PLD) functions in ABA-inducible gene expression in rice. Antagonism of ABA, VP1, and lanthanum synergy by 1-butanol, a specific inhibitor of PLD, was similar to the inhibition by coexpression of ABI1-1. These results demonstrate that ABA, VP1, lanthanum, PLD, and ABI1 are all involved in ABA-regulated gene expression and are consistent with an integrated model whereby La(3+) acts upstream of PLD.
Gampala
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Department of Biology, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Hagenbeek
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Rock
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D020001:1-Butanol / Q000494:pharmacology; D000040:Abscisic Acid / Q000737:chemistry / Q000378:metabolism*; D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D018506:Gene Expression Regulation, Plant; D005799:Genes, Dominant; D007477:Ions / Q000378:metabolism; D007811:Lanthanum / Q000378:metabolism*; D012275:Oryza / Q000187:drug effects / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000737:chemistry* / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000378:metabolism*; D010940:Plant Proteins; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D015398:Signal Transduction; D015534:Trans-Activators; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D007477:Ions; D010940:Plant Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D007811:Lanthanum; D000040:Abscisic Acid; D020001:1-Butanol; C087434:ABI1 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases; D010744:Phosphoric Monoester Hydrolases; D010739:Phospholipase D