The Arabidopsis spliceosomal protein SmEb modulates ABA responses by maintaining proper alternative splicing of HAB1

Yechun Hong,Yunjuan Chen,Juanjuan Yao,Jian-Kang Zhu,Zhen Wang,Huazhong Shi

doi:10.1007/s44154-021-00006-1

Abstract

Abscisic acid (ABA) signaling is critical for seed germination and abiotic stress responses in terrestrial plants. Pre-mRNA splicing is known to regulate ABA signaling. However, the involvement of canonical spliceosomal components in regulating ABA signaling is poorly understood. Here, we show that the spliceosome component Sm core protein SmEb plays an important role in ABA signaling. SmEb expression is up-regulated by ABA treatment, and analysis of Arabidopsis smeb mutant plants suggest that SmEb modulates the alternative splicing of the ABA signaling component HAB1 by enhancing the HAB1.1 splicing variant while repressing HAB1.2. Overexpression of HAB1.1 but not HAB1.2 rescues the ABA-hypersensitive phenotype of smeb mutants. Mutations in the transcription factor ABI3, 4, or 5 also reduce the ABA hypersensitivity of smeb mutants during seed germination. Our results show that the spliceosomal component SmEb plays an important role in ABA regulation of seed germination and early seedling development.

Highlights

Abscisic acid (ABA) signaling is critical for seed germination and abiotic stress responses in terrestrial plants
After 12 h of ABA treatment, the accumulation of HYPERSENSITIVE TO ABA1 (HAB1).1, 1.3, 1.4, and 1.5 transcripts were clearly lower in smeb mutants than in Col-0 wild type, whereas the transcript level of HAB1.2 was higher in smeb mutants than in Col-0 wild type plants (Fig. 2c - g)
Since the expression level of HAB1.3 is very low compared with the other four variants (Fig. 2e), and the HAB1.1 and HAB1.2 proteins function antagonistically (Wang et al 2015), it is likely that the reduction of HAB1.1 and HAB1.4 transcripts and the decreased level of HAB1.1 protein contributes to the ABA hypersensitive phenotype of smeb mutants

Summary

Introduction

Abscisic acid (ABA) signaling is critical for seed germination and abiotic stress responses in terrestrial plants. Phenotyping of smeb-1 and smeb-2 showed that these two mutants were much more sensitive to ABA treatment than the Col-0 wild type plants in cotyledon greening during seed germination (Fig. 1d).

Results

Conclusion