The RCC1 family protein SAB1 negatively regulates ABI5 through multidimensional mechanisms during postgermination in Arabidopsis

Abscisic acid-insensitive 5 (ABI5) is an essential and conserved plant basic leucine zipper transcription factor whose level controls seed germination and postgerminative development. It has been demonstrated that activity of ABI5 is transcriptionally and post-translationally regulated. However, tra...

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Bibliographic Details
Published in:The New phytologist 2019-04, Vol.222 (2), p.907-922
Main Authors: Ji, Hongtao, Wang, Shuangfeng, Cheng, Chunhong, Li, Ran, Wang, Zhijuan, Jenkins, Gareth I., Kong, Fanjiang, Li, Xia
Format: Article
Language:English
Subjects:
ABI5 (ABA insensitive 5)
Abscisic acid
abscisic acid (ABA)
Abscisic Acid - pharmacology
Arabidopsis
Arabidopsis - drug effects
Arabidopsis - genetics
Arabidopsis - growth & development
Arabidopsis - metabolism
Arabidopsis Proteins - isolation & purification
Arabidopsis Proteins - metabolism
Basic-Leucine Zipper Transcription Factors - isolation & purification
Binding
Chromatin
Chromatin - metabolism
DNA methylation
Gene regulation
Gene silencing
Germination
Germination - drug effects
Histones
Identification
Leucine
Leucine zipper proteins
Models, Biological
Mutation
Mutation - genetics
Phosphoamino Acids - metabolism
Phosphorylation
Phosphorylation - drug effects
postgermination growth
Promoters
Protein Binding - drug effects
Protein Biosynthesis - drug effects
Protein Stability - drug effects
Proteins
RCC1 (Regulator of Chromatin Condensation 1)
RNA, Messenger - genetics
RNA, Messenger - metabolism
Seed germination
Seedlings
Seeds - growth & development
Sensitivity enhancement
Stability
Transcription
Transcription, Genetic - drug effects
Vesicular Transport Proteins - isolation & purification
Vesicular Transport Proteins - metabolism
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Summary:Abscisic acid-insensitive 5 (ABI5) is an essential and conserved plant basic leucine zipper transcription factor whose level controls seed germination and postgerminative development. It has been demonstrated that activity of ABI5 is transcriptionally and post-translationally regulated. However, transcriptional regulation of ABI5 is not fully understood. Here, we identified SAB1 (Sensitive to ABA 1) as a novel negative regulator of ABI5 that simultaneously regulates its stability, promoter binding activity and histone methylationmediated gene silencing of ABI5. SAB1 encodes a Regulator of Chromatin Condensation 1 (RCC1) family protein and is expressed in an opposite pattern to that of ABI5 during early seedling growth in response to abscisic acid (ABA). SAB1 mutation results in enhanced ABA sensitivity and acts upstream of ABI5. SAB1 physically interacts with ABI5 at phosphoamino acid Ser-145, and reduces the phosphorylation of ABI5 and the protein stability. SAB1 reduces ABI5 binding activity to its own promoter, leading to reduced transcriptional level of ABI5. SAB1 inactivates ABI5 transcription by increasing the level of histone H3K27me2 in the ABI5 promoter. Our findings have identified SAB1 as a crucial new component of ABA signaling which modulates early development of plant by precisely controlling ABI5 activity through multiple mechanisms.
ISSN:0028-646X
1469-8137
DOI:10.1111/nph.15653