SPLICING FACTOR1 Is Important in Chloroplast Development under Cold Stress.

Area of Science:

• Plant molecular biology
• RNA splicing mechanisms
• Stress response in plants

Background:

• RNA Splicing Factor1 (SF1) recognizes branch point sites (BPS) for pre-mRNA splicing.
• Arabidopsis AtSF1 retains conserved function, yet null mutants are viable.
• The function of SF1's conserved domain remains largely unknown.

Purpose of the Study:

• Identify novel alleles of Arabidopsis SF1 (AtSF1).
• Investigate the role of AtSF1 in plant development and stress response.
• Elucidate the molecular mechanism of AtSF1-mediated splicing.

Main Methods:

• Mutant screening and characterization (sot4 allele identification).
• Transcriptomic profiling and RT-qPCR for gene expression analysis.
• RNA electrophoresis mobility shift assays (EMSA) for direct binding studies.

Main Results:

• The sot4 mutant exhibits leaf virescence and reduced plastid rRNA accumulation, especially under cold stress.
• A conserved AtSF1 mutation mirrors yeast SF1/Msl5p cold hypersensitivity and impaired splicing of suboptimal introns.
• AtSF1 directly binds to the BPS consensus sequence 5'-CU(U/A)AU-3', influencing gene expression via intron retention.

Conclusions:

• AtSF1 plays a critical role in regulating intron splicing efficiency in Arabidopsis.
• Efficient intron splicing mediated by AtSF1 is essential for plant acclimation to cold stress.
• The identified sot4 allele provides a valuable tool for studying AtSF1 function in vivo.