Ali, Gul , Palusa, Saiprasad , Golovkin, Maxim , Prasad, Jayendra , Manley, James , Reddy, Anireddy S. N. .
A novel plant-specific splicing factor regulates Flowering in Arabidopsis.
Serine/arginine-rich (SR) proteins play important roles in constitutive and alternative splicing and other aspects of mRNA metabolism. We have previously isolated a unique plant SR protein (SR45) with atypical domain organization. Unlike typical SR proteins, SR 45 contains two RS domains, one on either side of the RNA recognition motif. However, the biological and molecular functions of this novel SR protein are not known. Using an in vitro splicing complementation assay, we showed that SR45 functions as an essential splicing factor. A T-DNA insertion mutant, sr45-1, exhibited developmental abnormalities, including altered number of petals and stamens and delayed flowering time. The late flowering phenotype was observed under both long days and short days and was rescued by vernalization. Expression analysis of several flowering time genes using RT-PCR and microarrays revealed that FLC, a key flowering repressor, is up-regulated in sr45-1 demonstrating that SR45 influences the autonomous flowering pathway. Furthermore, the alternative splicing patterns of several other SR genes was altered in sr45-1 in a tissue-specific manner. Hence, the observed phenotypic abnormalities are likely due to altered levels of SR protein isoforms, which in turn modulate splicing of other pre-mRNAs. Changes in the alternative splicing of SR genes and the flowering time in the mutant were rescued by expressing full-length SR45 cDNA, further confirming that the observed defects in the mutant are due to the lack of SR45. These results indicate that SR45 is a novel plant-specific splicing factor that plays a crucial role in flowering.
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1 - Colorado State University, Department of Biology and Program in Molecular Plant Biology, Fort Collins, Colorado, 80523, USA
2 - Colorado State University, Department of Biology and Program in Molecular Plant Biology
3 - Thomas Jefferson University
4 - Cleveland Clinic Foundation, Department of Immunology
5 - Columbia University, Department of Biological Sciences
Presentation Type: ASPB Minisymposium
Location: International Ballroom/Hilton
Date: Tuesday, July 10th, 2007
Time: 3:20 PM