SPF45-related splicing factor for phytochrome signaling promotes photomorphogensis by regulating pre-mRNA splicing in arabidopsis

Authors: XIN, RUIJIAO - University Of Texas At Austin; ZHU, LING - University Of Texas At Austin; SALOME, PATRICE - Max Planck Institute Of Molecular Plant Physiology; MANCINI, ESTEFANIA - Consejo Nacional De Investigaciones Científicas Y Técnicas(CONICET); MARSHALL, CARINE - University Of California; Harmon, Frank; YANOVSKY, MARCELO - Consejo Nacional De Investigaciones Científicas Y Técnicas(CONICET); WEIGEL, DETLEF - Max Planck Institute Of Molecular Plant Physiology; HUQ, ENAMUL - University Of Texas At Austin

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2017
Publication Date: 7/31/2017
Citation: Xin, R., Zhu, L., Salome, P.A., Mancini, E., Marshall, C.M., Harmon, F.G., Yanovsky, M.J., Weigel, D., Huq, E., 2017. SPF45-related splicing factor for phytochrome signaling promotes photomorphogensis by regulating pre-mRNA splicing in Arabidopsis. Proceedings of the National Academy of Sciences(PNAS). 114(33):E7018-E7027. https://doi.org/10.1073/pnas.1706379114.
DOI: https://doi.org/10.1073/pnas.1706379114

Interpretive Summary: Plant continuously monitor their environment and use this information to make important decisions about their growth and development. These decisions have a large effect on the size, shape, and fertility of many crop plants, which directly influences production of these crops. Light is a major environmental information source for plants. Specialized photoreceptors proteins detect light signals and these activated photoreceptors trigger changes in gene expression that ultimately produce appropriate growth and development. This study found that a gene known as SPLICING FACTOR FOR PHYTOCHROME SIGNALING (SFPS) is critical for making changes in gene expression when light activates a specific photoreceptor. Ultimately, the SFPS gene plays a key part in plant processes controlled by light signals, including the growth of young seedlings and how quickly plants produce flowers once mature. Since many food products rely on the proper growth of crop plants, this discovery provides plant researchers and plant breeders with a deeper understanding of the molecular activities required for crop plants to reach their final form.

Technical Abstract: Light signals regulate plant growth and development by controlling a plethora of gene expression changes. Post-transcriptional regulation, especially pre-mRNA processing, is a key modulator of gene expression; however, the molecular mechanisms linking pre-mRNA processing and light signaling are not well understood. Here we report a splicing factor, SPLICING FACTOR FOR PHYTOCHROME SIGNALING (SFPS), that directly interacts with the photoreceptor phytochrome B (phyB). In response to light, SFPS-RFP colocalizes with phyB-GFP in photobodies. sfps loss-of-function plants are hyposensitive to red, far-red and blue light, and flower precociously. SFPS colocalizes with U2 snRNP associated factors including U2AF65B, U2A’, and U2AF35A in nuclear speckles, suggesting that SFPS might be involved in the 3’ splice site determination. SFPS regulates pre-mRNA splicing of a large number of genes, of which many are involved in regulating light signaling, photosynthesis and the circadian clock under both dark and light conditions. In vivo RNA immunoprecipitation (RIP) assays revealed that SFPS associates with EARLY FLOWERING 3 (ELF3) mRNA, a critical link between light signaling and the circadian clock. Moreover, PHYTOCHROME INTERACTING FACTORs (PIFs) transcription factor genes act downstream of SFPS, as the quadruple pif mutant pifq suppresses defects of sfps mutants. Taken together, these data strongly suggest that SFPS modulates light-regulated developmental processes by controlling pre-mRNA splicing of light signaling and circadian clock genes.