GSE200895
Modulation of Plant Development and Chilling Stress Responses by An Sm Core Protein Controlled Pre-mRNA Splicing in Arabidopsis
Cold stress resulting from chilling and freezing temperatures substantially inhibits plant growth and reduces crop production worldwide. Tremendous research efforts have been focused on elucidating the molecular mechanisms of freezing tolerance in plants. Little is known about the molecular nature of chilling stress responses in plants. Here we found that two allelic mutants in a spliceosome component gene SmEb (smeb-1 and smeb-2) are defective in development and responses to chilling stress. RNA-seq analysis revealed that SmEb controls the splicing of many pre-mRNAs under chilling stress. The intron retentive COP1b splicing variant was dramatically induced by chilling stress in the smeb mutants. This nuclear-depleted COP1b lacks the nuclear speckle-localization capacity, supporting the regulatory role of COP1-HY5 interaction in hypocotyl elongation during chilling stress. Genetic evidence indicates that chilling-sensitive phenotype of the smeb mutants are partially rescued by the hy5 mutation. The transcription factor BES1 shows a dramatic defect in pre-mRNA splicing in the smeb mutants. Ectopic expression of the two BES1 splicing variants enhances the chilling sensitivity of the smeb-1 mutant. Biochemical and genetic analysis showed that CBFs act as negative upstream regulators of SmEb by directly suppressing its transcription. Together, our results demonstrate that proper alternative splicing of pre-mRNAs controlled by the spliceosome component SmEb is critical for plant development and chilling stress responses. Cold stress resulting from chilling and freezing temperatures substantially inhibits plant growth and reduces crop production worldwide. Tremendous research efforts have been focused on elucidating the molecular mechanisms of freezing tolerance in plants. Little is known about the molecular nature of chilling stress responses in plants. Here we found that two allelic mutants in a spliceosome component gene SmEb (smeb-1 and smeb-2) are defective in development and responses to chilling stress. RNA-seq analysis revealed that SmEb controls the splicing of many pre-mRNAs under chilling stress. The intron retentive COP1b splicing variant was dramatically induced by chilling stress in the smeb mutants. This nuclear-depleted COP1b lacks the nuclear speckle-localization capacity, supporting the regulatory role of COP1-HY5 interaction in hypocotyl elongation during chilling stress. Genetic evidence indicates that chilling-sensitive phenotype of the smeb mutants are partially rescued by the hy5 mutation. The transcription factor BES1 shows a dramatic defect in pre-mRNA splicing in the smeb mutants. Ectopic expression of the two BES1 splicing variants enhances the chilling sensitivity of the smeb-1 mutant. Biochemical and genetic analysis showed that CBFs act as negative upstream regulators of SmEb by directly suppressing its transcription. Together, our results demonstrate that proper alternative splicing of pre-mRNAs controlled by the spliceosome component SmEb is critical for plant development and chilling stress responses. Overall design: Twelve-day-old smeb-1, smeb-2, and Col-0 seedlings grown on 0.5× MS medium were treated at 4°C for 0 or 24 h.