Perception and transduction of salt stress signals are critical for plant survival, growth, and propagation. Thus, identification of components of the salt stress-signaling pathway is important for rice () molecular breeding of salt stress resistance. Here, we report the identification of an apetala2/ethylene response factor transcription factor INDETERMINATE SPIKELET1 (IDS1) and its roles in the regulation of rice salt tolerance. By genetic screening and phenotype analysis, we demonstrated that IDS1 conferred transcriptional repression activity and acted as a negative regulator of salt tolerance in rice. To identify potential downstream target genes regulated by IDS1, we conducted chromatin immunoprecipitation (ChIP) sequencing and ChIP-quantitative PCR assays and found that IDS1 may directly associate with the GCC-box-containing motifs in the promoter regions of abiotic stress-responsive genes, including () and (), which are key genes regulating rice salt tolerance. IDS1 physically interacted with the transcriptional corepressor topless-related 1 and the histone deacetylase HDA1, contributing to the repression of and expression. Analyses of histone H3 acetylation status and RNA polymerase II occupation on the promoters of and further defined the molecular foundation of the transcriptional repression activity of IDS1. Our findings illustrate an epigenetic mechanism by which IDS1 modulates salt stress signaling as well as salt tolerance in rice.
<p><strong>Abstract.</strong> Dust plumes emitted from the narrow Arabian Red Sea coastal plain are often observed on satellite images and felt in local population centers. Despite its relatively small area, the coastal plane could be a significant dust source, however, its effect is not well quantified as it is not well approximated in global or even regional models. In addition, because of close proximity to the Red Sea, a significant amount of dust from the coastal areas could be deposited into the Red Sea and serve as a vital component of the nutrient balance of marine ecosystems. <br><br> In the current study, we apply the off-line fine-resolution version of the Community Land Model version-4 (CLM4) land surface model to better quantify dust emission from the coastal plain. We verify the spatial and temporal variability of model results using independent station reports. We also compare the results with the MERRA Aerosol Reanalysis (MERRAero) reanalysis. We show that the best results are obtained with 1-km spatial resolution and dust source function based on Meteosat Second Generation Spinning Enhanced Visible and InfraRed Imager (SEVIRI) measurements. We present the dust emission spatial pattern, estimates of seasonal and diurnal variability of dust event frequency and intensity, and discuss the emission regime in the major dust generation hot spot areas. We demonstrate the contrasting seasonal dust cycles in the northern and southern parts of the coastal plain and discuss the physical mechanisms responsible for dust generation. <br><br> The total dust emission from the coastal plain appears to be 7.5&#8201;Mt per year, with over 65&#8201;% of dust emitted from its northern part. The mineralogical composition analysis suggests that the coastal plain generates around 76&#8201;Kt of iron oxides and 6&#8201;Kt of phosphorus annually. Given the structure of wind circulation in this area and close proximity of the dust hot spots to the sea, we can expect that a significant amount of emitted dust is deposited to the sea, almost matching the annual deposition from major dust storms.</p>
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