Membrane-associated transcription factor peptidase, site-2 protease, antagonizes ABA signaling in Arabidopsis

• Published in: The New phytologist 2015-10, Vol.208 (1), p.188-197
• Main Authors: Zhou, Shun‐Fan, Sun, Le, Valdés, Ana Elisa, Engström, Peter, Song, Ze‐Ting, Lu, Sun‐Jie, Liu, Jian‐Xiang
• Format: Article
• Language: English
• Subjects: ABA response; Abscisic acid; Abscisic Acid - metabolism; Arabidopsis; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Base Sequence; Basic-Leucine Zipper Transcription Factors - metabolism; Biological Transport; Desensitization; Dormancy; Endoplasmic reticulum; Fluorescence; Gene expression; Gene expression regulation; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Genes; Genes, Plant; Genetic analysis; Germination; Germination - genetics; Gibberellins; Green fluorescent protein; Greening; Membrane Proteins - metabolism; membrane-associated transcription factor; Membranes; Molecular Sequence Data; Myc protein; Peptidase; Peptide Hydrolases - genetics; Peptide Hydrolases - metabolism; Phenotypes; Phosphatases; Plant Development - genetics; Plant Dormancy - genetics; Plant Growth Regulators - metabolism; Plant growth substances; Plant hormones; Protease; Proteinase; Proteins; regulated intramembrane proteolysis; Regulator genes; Regulators; Seed dormancy; Seed germination; Seeds; Seeds - growth & development; Seeds - metabolism; Signal Transduction; Signaling; site‐2 peptidase (S2P); Transcription; Transcription factors; Transcription Factors - metabolism; Transcriptional regulatory elements; Up-Regulation
• ISSN: 0028-646X; 1469-8137; 1469-8137
• DOI: 10.1111/nph.13436

Abscisic acid plays important roles in maintaining seed dormancy while gibberellins (GA) and other phytohormones antagonize ABA to promote germination. However, how ABA signaling is desensitized during the transition from dormancy to germination is still poorly understood. We functionally characterized the role of membrane-associated transcription factor peptidase, site-2 protease (S2P), in ABA signaling during seed germination in Arabidopsis. Genetic analysis showed that loss-of-function of S2P conferred high ABA sensitivity during seed germination, and expression of the activated form of membrane-associated transcription factor bZIP17, in which the transmembrane domain and endoplasmic reticulum (ER) lumenfacing C-terminus were deleted, in the S2P mutant rescued its ABA-sensitive phenotype. MYC and green fluorescent protein (GFP)-tagged bZIP17 were processed and translocated from the ER to the nucleus in response to ABA treatment. Furthermore, genes encoding negative regulators of ABA signaling, such as the transcription factor ATHB7 and its target genes HAB1, HAB2, HAI1 and AHG3, were up-regulated in seeds of the wild-type upon ABA treatment; this up-regulation was impaired in seeds of S2P mutants. Our results suggest that S2P desensitizes ABA signaling during seed germination through regulating the activation of the membrane-associated transcription factor bZIP17 and therefore controlling the expression level of genes encoding negative regulators of ABA signaling.