Arsenic (As) is accumulated in rice grain due to environmental reasons such as polluted ground water and soil, and As toxicity constitutes a serious threat to human health. However, the accurate information required for understanding As-responsive mechanisms remain mostly unknown in rice. Here, we performed the comparative genome-wide transcriptome analysis between As tolerance type (ATT) rice mutant induced by γ-irradiation and its wild type (WT). As compared to WT after As treatment of 150 ppm, ATT exhibited the phenotypic differences such as vigorous growth in shoots and root hairs, and low accumulation of H2O2 in rice roots. In transcriptome analysis, we found between WT and ATT that As toxicity commonly affected to inhibit gene regulations involved in photosynthesis, mitochondrial electron transport and lipid biosynthesis metabolism. While, many genes associated with cysteine synthesis metabolism considerably up regulated in both As-treated plants. Additionally, we found the potential As tolerance-related genes involved in abiotic stress-responsive mechanism and RNA-protein synthesis for protein degradation and modification. To further analyzes the genetic variations of As-responsive genes, the DNA polymorphic DEGs associated with oxidoreductase significantly distributed in ATT more than in WT.

As sessile organisms, plants have evolved mechanisms that allow them to adapt and survive periods of various environmental stresses including high salinity and drought. The ubiquitin-proteasome system (UPS) is an integral player in plant response and adaptation to various abiotic stresses. Understanding UPS function has centered mainly on defining the role of E3 ubiquitin ligases, which are the substrate-recruiting component of the ubiquitination pathway. Here, we report on Ring finger E3 ligase, Oryza sativa salt- and drought-induced RING finger protein1 gene (OsSDRFP1) in defense responses to osmotic stresses. Results of qRT-PCR and In vitro ubiquitination assay demonstrated that OsSDRFP1 act as an E3 ligase in response to salt and drought stresses. in this study, Subcellular localizations showed that the OsSDRFP1 was observed in cytosol (66%) and nucleus (34%) under non-treated conditions. However, the florescence signals of rice protoplasts after salt treatments detected in nucleus (60%) higher than in cytosol (30%). The Arabidopsis plants overexpressing OsSDRFP1 clearly exhibited hypersensitive responses to salt stress. whereas, OsSDRFP1-overexpressing plants were more tolerant to both drought- and ABA-stresses than the wild-type plants. These results might suggest that OsSDRFP1 has a dual function as a regulator of high salt- and drought-stresses.

In this study, we report that the development of a multiplex PCR method using species-specific primers for the simultaneous detection of Poaceae family members, including adlay, barley, maize, rice and wheat, based on the sequence polymorphism of the DNA-directed RNA polymerase beta'' chain (rpoC2) genes Species-specific primers were constructed with common forward primer and each reverse primers which have differences on the basis of sequences. Each primer pairs could amplify PCR products of 443 bp for rice, 346 bp for barley, 278 bp for adlay, 221 bp for wheat and 96 for maize, respectively, from the five chloroplast DNAs. The series of template DNA concentrations were identified by the sensitivity of multiplex PCR. The band of products were clearly amplified from the DNA concentration range of 0.01 to 10 ng/μL. In addition, the species-specific primers were examined for the detection of seven commercial flour mixed products. The combination of the sensitivity of a multiplex PCR with the specificity of the primers for the detection of species would allow to be applied in analyses of processed foods.

Recently, the increased consumption of mixed-grain flour products have led to improved human health in busy modern life. For this reason, the verification of commercial food authenticity is one of important subjects. The development of DNA techniques such as real-time PCR has led to the increasing efficiency of illegal food product detection. Here, we have developed a comprehensive method for detecting the grain flour of various rice cultivars in commercial food products derived from different plant species. In the genetic variation analysis of different protein coding genes on various chloroplast genomes, we found the high numbers of segregating sites in rpoB and rpoC2 more than in other genes. Thus, we have attempted to develop chloroplast DNA (cpDNA) markers, which were Os_m_rpoB in rpoB, and Os_m1_rpoC2 and Os_m2_rpoC2 in rpoC2. To assess the applicability of three cpDNA markers, we have identified the appropriate statistical measurements of each marker in various mixed-grain flour samples derived from rice cultivars and different plant species by real-time PCR, In addition, the three cpDNA markers successfully applied for detecting of nonexistent rice flour in different commercial food products.

Exposure to ionizing radiation is regarded as a kind of abiotic stresses that can change the expression of genes in living organisms. This study aimed on investigating the variations in gene expressions induced by two different types of irradiations with different doses, which were low linear energy transfer (LET) gamma rays (100, 200, and 400 Gy) and high LET ion-beams (20, 40, and 80 Gy) on rice. RNA sequencing was carried out using the Illumina HiSeq-2500 platform. The average amount of reads were 4.8 Gb per individual, and 5 to 8% of the reads were removed after quality control. More than 90% of the RNA-seq reads were mapped to the rice reference genome sequence (IRGSP-1.0). A total of 247 differentially expressed genes (DEGs) were identified by comparison of the gene expression levels between the wildtype and the irradiated individuals. The 247 DEGs were divided into five modules and 27 intra-modular hub genes were found using the weighted correlation network analysis (WGCNA) method. The MEturquiose module had the most number of genes with 75 related to carbohydrate and small molecule metabolic processes. The co-expression network reconstructed using ARACNE (algorithm for reconstruction of accurate cellular networks) showed specific up- or down-regulation of the genes in each module according to the types and doses of radiation. This study will contribute to understanding the gene expression responses to ionizing irradiation.

Recently, the importance of food safety is increasing due to numerous junk food. Junk food means to violate the law in stage such as production, manufacture, distribution, and sale of food. Many crop plants are processing as foods including bread, noodle, and other foods for supporting nutrition to human. For example, rice is one of the most well-known food crops in the world, and processed rice is being mixed with other processed crops to health food. The object of this study is to detect amount of specific grains, i.e. rice from processed foods mixed with other cereals. This experiment was performed to the following two steps: 1) designed the specific primer sets based on chloroplast DNAs, 2) amplified products using real-time PCR. We designed eleven primer sets within chloroplast DNA of rice, and then the confirmation of primer efficiency was to amplified with rice genomic DNA using real-time PCR. In addition, these primer sets were applied in other crops such as wheat, maize, and adlay to confirm specificity to rice. The rice specific primer sets were determined by the number of amplification and the melting peak through real-time PCR. As a result, five primer sets were confirmed to uniqueness in the rice genome. In conclusion, the specific primer sets would be useful for identifying rice grain from the processed foods to eliminate junk foods and for contribution of food safety.

Rice is a staple food for over one-half of the world population, especially in Asian countries. Recently, the growth and yield of crop plants was affected by various abiotic stresses, such as salt, drought, and high temperature due to change of climate environment. To study molecular functions of Oryza sativa nuclear-targeted RING Finger Proteins (OsNRFPs) in response to abiotic stresses, we selected 44 OsNRFPs genes, whose subcelluar localizations are predicted to the nucluear, on the basis of expression patterns of a microarray dataset. A total of 44 OsNRFPs were grouped into two types such as RING-HC and RING-H2 via phylogeneitc analysis of their RING domains structures. Subsequently, we surveyed the expression patterns of 44 genes in response to salt stress via qRT-PCR in roots. We found 10 salt stress-induced OsNRFPs and then examined their subcellular localizations. These genes were clearly localized to the nucleus (OsNRFPHC-10), cytoplasm (OsNRFPHC-17 and OsNRFPH2-16) and microtuble (OsNRFPHC-23, OsNRFPH2-17 and OsNRFPH2-05), respectively. These results might provide a key clue for understanding moleuclar functions of the OsNRFP genes associated with salt stress-related signaling pathway

In order to select a rice population with useful trait such as arsenic tolerance for crop improvement, we have developed 3000 M7 Targeting Induced Local Lesions IN Genomes (TILLING) lines by gamma ray (GR) irradiation treatment to a rice variety (cv. Donganbyeo). A total of 2 M7 lines exhibited the arsenic (AsV) tolerant phenotype (hereafter, named Arsenic Tolerant TILLING line 1 and 2, and designed as ATT1 and 2), in which the shoots and roots length of ATT lines were significantly longer than those of wild type (WT) during As(V) treatment. To survey the DNA polymorphism of these plants, we conducted the Whole genome resequencing with 10x coverage in ATT lines. By comparative analysis among ATT lines, we have identified the common DNA polymorphism such as 11,817 SNPs (49.83% in ATT1 and 48.35% in ATT2) and 30,618 InDels (86.72% in ATT1 and 86.23% in ATT2). Also, these mutants were showed the close relationships more than WT. To further study the changed amino acids of genes, we commonly identified the 758 genes for non-synonymous SNPs and 249 genes for changed codon InDels. These genes were mainly exhibited the enriched GO functions such as catalytic activity, nucleic acid binding and transferring phosphorus-containing groups. To determine the genes associated with arsenic-related mechanism in DNA polymorphism of ATT lines, we have retrieved the two structurally altered genes (Os11g47870 and Os03g19900) for metalloid As(V) detoxification toward induced genes in response to arsenic treatments by public microarray datasets. We suggest that As(V) tolerant phenotypes of ATT lines are certainly affected by structurally altered genes associated with phosphorus transferring and As(V) detoxification during GR treatment

The metalloid arsenic (As) and the hevy metal cadmium (Cd) are ubiquitously found at low concentrations in the earth, while high concentrations of the both elements in soil and crop are severe dangerous to human health. We have tried to retrieve RING E3 ligase gene, which is believed to regulate substrate proteins in As or Cd uptake via ubiquitin 26S proteasome pathway, related to inhibit metal ion transport system. A total of 48 rice RING E3 ligases were randomly selected and then conducted semi-quantitative RT-PCR for their expression patterns as exposed to As and Cd treatments. We discovered one gene, Oryza sativa heavy metal induced RING E3 ligase 1 (OsHIR1) that was significantly up-regulated against both treatments. A total of 31 positive interaction clones with OsHIR1 were screened depending on their strong α-galactosidase activity via yeast-two hybrid screen. Bimolecular fluorescence complementation analysis evidenced that the OsHIR1 protein was clearly interacted with each of six partner protein including aquaporin tonoplast intrinsic protein 4;1 (OsTIP4;1) in the plasma membrane. Protein degradation assay showed that OsHIR1 strongly degraded the protein level of OsTIP4;1 via ubiquitin 26S proteasome system. Heterogeneous overexpression of OsHIR1 in Arabidopsis showed As- and Cd-insensitive phenotype. In addition, the transgenic plant showed low levels of As and Cd accumulation than the control plant in leaf and root. Here, we report the novel finding that OsHIR1 E3 ligase positively regulates OsTIP4;1 related to As and Cd uptake.

Plant growth under water-deficit conditions adversely affects many key processes. Efforts to understand drought stress-related defense mechanisms have revealed a host of plant genes using molecular approaches in rice. Here, we report the novel finding that OsCTR1 E3 ligase regulates both chloroplast-localized chloroplast protein 12 (OsCP12) and ribosomal protein 1 (OsRP1) in protein levels and subcellular localization. The results of a yeast-two hybrid assay, bimolecular fluorescence complementation assay, ubiquitination assay, subcellular localization, and a protein degradation assay support the hypothesis that OsCTR1 functions in trafficking inhibition and proteolysis of OsCP12 and OsRP1 via the ubiquitin 26S proteasome pathway. Heterogeneous overexpression of OsCTR1 in Arabidopsis showed ABA-hypersensitive phenotype in seed germination, seedling growth, and stomatal closure. The transgenic plants also exhibited improvement of water-deficit tolerance with an accumulation of hydrogen peroxide production. These results demonstrate that the OsCTR1 E3 ligase might positively regulate the cellular functions of OsCP12 and RP1 related to photosynthesis under drought stress conditions in rice.

Low temperature is a major factor restrict to growth and limiting productivity of rice crops. We used a cDNA microarray approach to monitor the expression profile of rice (Oryza sativa) under chilling stress and identified 20 chilling inducible genes in previously study. Ten such genes encoding bHLH, metal transporter and, zinc finger protein with unknown functions showed a significant change in expression under various abiotic stresses. Among them, OsCHI1 (Os07g15460), OsCHI2 (Os02g43660), and OsCHI3 (Os01g61160), were selected for further study. They have structural features such as metal-binding signature sequences in their protein sequences, and OsCHI genes were expressed in root of rice seedling and induced in chilling and salt or drought. Expression of OsCHI1, OsCHI3 and OsCHI2 were targeted to membrane and ER when transiently expressed in tobacco cell, respectively. The Arabidopsis (Arabidopsis thaliana) transgenic plants overexpressing showed increased tolerance to salt and drought stress in the seed germination and root elongation than that of wild type. This comprehensive study provides insight into the biological function of OsCHIs, which may be useful in understanding how rice plants adapt to unfavorable environmental conditions.

We used a microarray dataset that is deposited in the public database to evaluate plant responses to heat stress and selected two genes, OsSHSP1 (Os03g16030) and OsSHSP2 (Os01g04380), that are highly expressed under heat stress in rice. OsSHSP1 and OsSHSP2 gene transcripts were highly induced in response to salt and drought. In addition, OsSHSP1 and OsSHSP2 gene transcripts were induced under ABA and SA. Subcellular localization of proteins of 35S::OsSHSP1 were associated with the cytosol, whereas those of and 35S::OsSHSP2 were associated with the cytosol and nucleus. Heterogeneous overexpression of both genes exhibited higher germination rates than those of wild-type plants under the salt treatment, but not under heat or drought stress. The network of both genes harboring 9 sHSPs as well as at least 13 other chaperone genes might support the idea of a role for sHSPs in the chaperone network. Our findings might provide clues to shed light on the molecular functions of OsSHSP1 and OsSHSP2 in response to abiotic stresses, especially heat stress.

In order to better understand the biological systems that are affected in response to cosmic ray, we conducted the weighted gene co-expression network analysis with module detection method. By using the Pearson’s correlation coefficient value, we were evaluated the complex gene-gene functional interactions between 680 CR-response probes from integrated microarray datasets, which included large-scale transcriptional profiling of 918 microarray samples. These probes were divided into 6 distinct modules that contained 20 enriched function such as oxidoreductase activity, response to stimulus and stress, and hydrolase activity. Especially, module 1 and 2 commonly showed the enriched annotation categories such as oxidoreductase activity, including the enriched cis-regulatory elements known as ROS specific regulator. These results suggest in module1 and 2 that ROS-mediated irradiation response pathway are affected by CR. We found the 243 irradiation-dependent probes, which were exhibited the similarities of differentially expressed patterns in various irradiation microarray datasets, and RT-PCR for confirmations of several irradiation-dependent genes were exhibited the similar expressed patterns in rice by CR, gamma ray and Ion beam treatments. Interestingly, these genes were differentially expressed by non-gravity. Moreover, we were identified the co-regulations between several irradiation-dependent genes and functional interacted genes in the CR-responsive network by various GA treatments such as different conditions of dose and treatment time. These results of network-based analysis might provide a clue to understanding the complex biological system of CR.

Rice is one of the most important food crops in the world, and has been used as model monocots for genetic studies, because of its relatively small genome size. We have previously reported the different functions of several RING (Really Interesting New Gene) proteins to respond the various abiotic stresses. In order to study a regulation of RING proteins in rice under ionizing irradiation such as gamma ray (GA), we have identified the expression patterns of these genes by RT-PCR. We found Gamma-ray induced RING finger protein (OsGRP) gene, which were associated with cytosol by subcellular localization analysis. in vitro ubiquitination assay revealed that OsGRP possess E3 ligase activity. Also, we demonstrate that C196A point mutation in the RING finger domain of OsGRP can have a critical effect to the breakdown of structural integrity in RING constructs. To identify the interaction partners for OsGRP in protein-protein interactions, we found the seven genes interacted with OsGRP by Yeast Two Hybrid method. To examine the GA-influence of interaction partners by RT-PCR, two genes were specifically down-regulated in rice during GA treatment. These interaction partners were identified the reliable interactions and subcellular localizations via BiFC method. Interestingly, five genes associated with plastid, while two down-regulated genes associated with cytosol and plastid. These results of OsGRP based on genetic approach might provide a clue to understanding the GA responsive mechanism in rice.

Ionizing radiation is known to cause chromosomal alterations such as inversions and deletions and affects gene expression within the plant genome. To monitor the genome-wide transcriptome changes by ionizing radiation, we used rice Affimetrix GeneChip microarray to identify genes that are up- or down regulated by gamma-ray (200 Gy, 60Co source), cosmic-ray and ion beam (40 Gy, 220 MeV carbon ion). The overall expression patterns between gamma-ray and ion beam were similar but cosmic-ray was regulated differently. Combined results from all 3 radiations identified 27 up-regulated genes and 188 down regulated genes. These results mean the induction of similar mechanism changes in treatments of gamma ray and ion beam. However the different expression in treatment of cosmic-ray might be due to the other environmental conditions. Among the commonly up- or down- regulated genes, we chose highly up- or down- regulated several genes and confirmed its regulation in response to ionizing radiation exposure by RT-PCR analysis. Moreover, we showed that specific co-expression networks of candidate radio marker genes by ARACNE algorithm. Our results present profiles of gene expression related to different ionizing radiation and marker gene to predict sensitivity to ionizing radiation, such as GS (glutelin subunit) and FBX322.

The application of next generation sequencing technologies allows us to discover the high levels of DNA polymorphism throughout a genome, e.g., single nucleotide polymorphisms (SNPs), and insertions and deletions (InDels). We performed whole-genome resequencing of a Korean rice cultivar (cv. Donganbyeo) and then obtained the sequences of covered 366,042,872 bp (96.63%) with average mapped read depth of 34.17 on 382,788,128 bp of the Japanese cultivar genome (cv. Nipponbare). We characterized the polymorphisms of 173,711 SNPs, 295,334 insertions and 40,642 deletions based on the comparison of both genomes. About 11.5% and 17.8% of the annotated total SNPs were presented in the regions of 1kb upstreams and genes, respectively. The annotated InDels in gene regions were similar with 15.5% insertion (4,588) and 15.9% (5,100) deletions, but not in 1kb upstream regions with 9.0% insertion (2,662) and 14.3% deletions (5,100). In addition, the Korea rice genome sequences were mapped on individual chromosome, resulted that SNPs were shown with different frequencies from each chromosome. The InDels distributions on individual chromosomes exhibited similar pattern as compared to those of SNPs. Some gene families such as NB-ARC (NB-LRR), F-box, RLK (serine/threonine protein kinase) and Zinc-finger (RING) for SNPs occurred the similar pattern with those of Arabidopsis. These results might be useful for better understanding the genome structure and genetic diversity of the Korean rice cultivars.

Plants are known to have homeostatic cellular mechanisms to control the concentration of heavy metal inside the cell. We tried to retrieve rice RING finger protein genes, which are believed to regulate substrates via ubiqitinations, related to metal ions detoxification mechanisms. A total of 48 rice RING finger proteins were randomly selected and then examined for their expression patterns as exposed to cadmium and arsenic treatments. We discovered a RING finger protein gene that was significant up-regulated against both treatments and then named Oryza sativa heavy metal induced 1 (OsHMI1). We tested subsequently OsHMI1 expression patterns against to salinity, dehydration, cold, heat stress and phytohormones treatments. In addition, we evaluated its subcellular localization and determined E3 ligase activity. The interaction partner proteins were screened via yeast-two hybridization. These results might shed further light on the understanding of homeostatic cellular mechanisms to control heavy metal detoxification via protein degradation in plants.