ENAapplication/xmlftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR299/005/SRR2993035/SRR2993035.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR299/003/SRR2993033/SRR2993033_1.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR299/004/SRR2993034/SRR2993034.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR299/002/SRR2993032/SRR2993032_1.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR299/003/SRR2993033/SRR2993033_2.fastq.gzftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR299/002/SRR2993032/SRR2993032_2.fastq.gzprimaryOK200GenomicsJohn Innes Centrehttps://www.ebi.ac.uk/ena/browser/view/PRJNA305860Arabidopsis thalianaxref:PubMed:26721863Nuclear-localized RNA binding proteins are involved in various aspects of RNA metabolism, which in turn modulates gene expression. However, the functions of nuclear-localized RNA binding proteins in plants are poorly understood. Here we report the functions of two proteins containing RNA recognition motifs, At RZ-1B and At RZ-1C, in Arabidopsis. At RZ-1B and At RZ-1C were localized to nuclear speckles and interacted with a spectrum of serine/arginine-rich (SR) proteins through their C-termini. At RZ-1C preferentially bound to purine-rich RNA sequences in vitro through its N-terminal RNA recognition motif. Disrupting the RNA-binding activity of At RZ-1C with SR proteins through over-expression of the C-terminus of At RZ-1C conferred defective phenotypes similar to those observed in At rz-1b/At rz-1c double mutants, including delayed seed germination, reduced stature, and serrated leaves. Loss of function of At RZ-1B and At RZ-1C was accompanied by defective splicing of many genes and global perturbation of gene expression. In addition, we found that At RZ-1C directly targeted FLC, promoting efficient splicing of FLC introns and likely also repressing FLC transcription. Our findings highlight the critical role of At RZ-1B/1C in regulating RNA splicing, gene expression, and many key aspects of plant development via interaction with proteins including SR proteins. Overall design: mRNA-seq to look at the transcriptome and splicing differences between wild type and At rz-1b At rz-1c mutant of Arabidopsis thalianaENAfalseArabidopsis thalianamRNA-seq data of 14 days old Arabidopsis seedlings in Col-0 and At rz-1b At rz-1c double mutant2025-09-242015-12-15PRJNA305860GSE75959370226721863