Abstract
BackgroundPlant glycine-rich proteins are categorized into several classes based on their protein structures. The glycine-rich RNA binding proteins (GRPs) are members of class IV subfamily possessing N-terminus RNA-recognition motifs (RRMs) and proposed to be involved in post-transcriptional regulation of its target transcripts. GRPs are involved in developmental process and cellular stress responses, but the molecular mechanisms underlying these regulations are still elusive.ResultsHere, we report the functional characterization of rice GLYCINE-RICH PROTEIN 3 (OsGRP3) and its physiological roles in drought stress response. Both drought stress and ABA induce the expression of OsGRP3. Transgenic plants overexpressing OsGRP3 (OsGRP3OE) exhibited tolerance while knock-down plants (OsGRP3KD) were susceptible to drought compared to the non-transgenic control. In vivo, subcellular localization analysis revealed that OsGRP3-GFP was transported from cytoplasm/nucleus into cytoplasmic foci following exposure to ABA and mannitol treatments. Comparative transcriptomic analysis between OsGRP3OE and OsGRP3KD plants suggests that OsGRP3 is involved in the regulation of the ROS related genes. RNA-immunoprecipitation analysis revealed the associations of OsGRP3 with PATHOGENESIS RELATED GENE 5 (PR5), METALLOTHIONEIN 1d (MT1d), 4,5-DOPA-DIOXYGENASE (DOPA), and LIPOXYGENASE (LOX) transcripts. The half-life analysis showed that PR5 transcripts decayed slower in OsGRP3OE but faster in OsGRP3KD, while MT1d and LOX transcripts decayed faster in OsGRP3OE but slower in OsGRP3KD plants. H2O2 accumulation was reduced in OsGRP3OE and increased in OsGRP3KD plants compared to non-transgenic plants (NT) under drought stress.ConclusionOsGRP3 plays a positive regulator in rice drought tolerance and modulates the transcript level and mRNA stability of stress-responsive genes, including ROS-related genes. Moreover, OsGRP3 contributes to the reduction of ROS accumulation during drought stress. Our results suggested that OsGRP3 alleviates ROS accumulation by regulating ROS-related genes’ mRNA stability under drought stress, which confers drought tolerance.
Highlights
Plant glycine-rich proteins are categorized into several classes based on their protein structures
The RNArecognition motif (RRM) was highly conserved in both rice and Arabidopsis glycine-rich RNA binding proteins (GRPs), but the length of the glycine-rich domain was diverse between the analyzed protein sequences (Fig. S1a)
These results indicate that OsGRP3 is highly expressed in rice plants and is further induced by drought and ABA treatments
Summary
Plant glycine-rich proteins are categorized into several classes based on their protein structures. The glycine-rich RNA binding proteins (GRPs) are members of class IV subfamily possessing N-terminus RNA-recognition motifs (RRMs) and proposed to be involved in post-transcriptional regulation of its target transcripts. Since the plant glycine-rich (GR) proteins were first discovered in petunia 30 years ago (Condit and Meagher 1986), multifunctional roles of these proteins have been reported in development and response to several biotic and abiotic stimuli (Ciuzan et al 2015; Magdalena and Michal 2018). The glycine-rich RNA binding proteins (GRPs) are members of class IV subfamily possessing N-terminus RRMs in addition to C-terminal GR regions, and proposed to be involved in post-transcriptional regulation of its target transcripts (Kang et al 2013; Ciuzan et al 2015; Magdalena and Michal 2018)
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