An Arabidopsis PWI and RRM motif-containing protein is critical for pre-mRNA splicing and ABA responses.

Xiangqiang Zhan,Wenwu Wu,Stephanie L Dunn,Qingmei Guan,Jian-Kang Zhu,Temiloluwa A Okusolubo,Fengqiu Cao,Jianhua Zhu,Lan Yang,Xianbin Gu,Pengcheng Wang,Bilian Qian

doi:10.1038/ncomms9139

Abstract

The phytohormone abscisic acid (ABA) is important for growth, development and stress responses in plants. Recent research has identified ABA receptors and signalling components that regulate seed germination and stomatal closure. However, proteins that regulate ABA signalling remain poorly understood. Here we use a forward-genetic screen to identify rbm25-1 and rbm25-2, two Arabidopsis mutants with increased sensitivity to growth inhibition by ABA. Using RNA-seq, we found that RBM25 controls the splicing of many pre-mRNAs. The protein phosphatase 2C HAB1, a critical component in ABA signalling, shows a dramatic defect in pre-mRNA splicing in rbm25 mutants. Ectopic expression of a HAB1 complementary DNA derived from wild-type mRNAs partially suppresses the rbm25-2 mutant phenotype. We suggest that RNA splicing is of particular importance for plant response to ABA and that the splicing factor RBM25 has a critical role in this response.

Highlights

The phytohormone abscisic acid (ABA) is important for growth, development and stress responses in plants
Splicing is important for all cellular processes involving gene expression, the splicing factor RBM25 is essential for root growth and leaf development in response to ABA but appears not to be required for normal growth and development
The rbm[25] mutants are hypersensitive to ABA in the growth medium, indicating that RBM25 may be involved in mediating signal transduction events downstream of ABA

Summary

Results

Roa[1] mutants are hypersensitive to ABA. Identification of a large number of mutants defective in seed germination or guard cell movements has led to the discovery of genes involved in ABA biosynthesis and its downstream signalling events[3]. The genes carrying defective alternative splicing patterns in rbm[] plants under control or ABA treatment conditions encode proteins with diverse functions in many biological processes, and the predicted roles of a good portion of these genes involve responses to abiotic or biotic stresses (Supplementary Data 3). Thirty genes involved in transcription were found to have splicing defects in their transcripts in rbm[] mutant under ABA treatment (Supplementary Data 3) These genes include the largest subunit of DNA-dependent RNA polymerase II, TATA-binding proteins, a nuclear factor, promoter-specific transcription factors and the subunits of the mediator complex. Genes carrying splicing defects in rbm[] mutant under ABA treatment encode proteins involved in diverse biological processes, a substantial portion of the genes encode proteins that are predicted to function in biotic or abiotic stress-response pathways (Supplementary Data 3). Cell organisation and biogenesis Developmental processes DNA or RNA metabolism Electron transport or energy pathways Other biological processes Other metabolic processes Other cellular processes Protein metabolism Response to stress Signal transduction Transcription, DNA dependent Transport Unknown biological process

At4g33720

Discussion

Findings

Methods