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GrainGenes Reference Report: PMB-47-437

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Reference	PMB-47-437
Title	Dissection of abscisic acid signal transduction pathways in barley aleurone layers
Journal	Plant Molecular Biology
Year	2001
Volume	47
Pages	437-448
Author	Thum KE [ Show all 12 ]
Abstract	Summary: Abscisic acid (ABA) induces genes that are highly expressed during late embryogenesis, but suppresses gibberellin (GA)-responsive genes essential for seed germination and seedling growth. Promoter elements necessary and sufficient for ABA up- and down-regulation of gene expression have been previously defined in barley aleurone layers. We have studied the effect of a protein phosphatase 2C, ABI1, an ABA-inducible protein kinase, PKABA1, and a transcription factor, VP1, on ABA action in a barley aleurone transient expression system. The observations have allowed us to dissect ABA signal transduction pathways leading to either induction or suppression of gene expression. The ABA induction of embryogenesis genes is highly inhibited in the presence of a mutated protein phosphatase 2C, encoded by the abi1-1 dominant mutant gene that is known to block ABA responses in Arabidopsis. However, the abi1-1 gene product has no effect on the ABA suppression of a GA-responsive alpha-amylase gene. On the other hand, PKABA1 suppresses the expression of alpha-amylase genes, but has little effect on ABA upregulated genes. Therefore, it appears that ABA induction and suppression follow two separate signal transduction pathways with the former inhibited by ABI1 and the latter modulated by PKABA1. The presence of VP1 enhances the ABA induction of late embryogenesis genes, but also suppresses germination specific genes. A schematic model based on these observations is presented to explain the effect of these regulatory proteins on ABA-mediated gene expression
Keyword	[ Hide all but 1 of 101 ] aba aba signal transduction abi1 abscisic acid acid activation aleurone aleurone layer alpha-amylase alpha-amylase gene amylase arabidopsis barley barley aleurone barley aleurone layer blue light chloroplast chloroplast gene expression circadian rhythms deletion dna binding factor dominant down-regulation element embryogenesis extension gene gene expression gene product genome germination gibberellin growth homologous recombination hordeum hordeum vulgare illuminated barley in vivo induced transcription induction kinase late embryogenesis layer leaf development light light quality light regulation light-responsive promoter maize messenger rna model mutant mutation negative regulator nicotiana nicotiana tabacum organelle genome pathway phosphatase photosystem ii pkaba1 plant science plastid plastid transformation primer primer extension promoter promoter analysis protein protein kinase protein phosphatase protein phosphatase 2c reaction center recombination regulation regulatory protein reporter reporter gene response complex responses seed seed germination seed maturation seedling growth sequence signal signal transduction suppression system tobacco transcript transcription transcription factor transduction transduction pathway transient transient expression transient expression system vp1 wheat chloroplasts white

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