Analysis of microbial communities in solid and liquid pig manure during the fertilization process.

Utilizing livestock manure as organic fertilizer in sustainable agriculture is crucial and should be developed through an appropriate manufacturing process. Solid-liquid separation contributes to reducing odor, managing nutrients in livestock excretions, and lowering the cost of transporting manure to arable soil. To investigate the impact of fermentation after solid-liquid separation, we examined the specific correlation between chemical properties and bacterial communities in solid-liquid manures before and after the fermentation process. In terms of chemical properties before fermentation, the levels of electrical conductivity, nitrogen, ammonium nitrogen (NH4+-N), potassium, sodium, and chloride were higher in the liquid sample than in the solid sample. However, the chemical components of the liquid sample decreased during fermentation, which could be attributed to the low organic matter content. Many chemical components increased in the solid samples during fermentation. Fifty-six bacterial species were significantly correlated with NH4+-N and phosphorus. Following fermentation, their abundance increased in the solid samples and decreased in the liquid samples, indicating the potential for NH4+-N release or phosphorus mineralization from organic matter. These results provide information regarding changes in nutrient and bacterial formation when applying the fermentation process after solid-liquid separation.

Effects of Hanwoo (Korean cattle) manure as organic fertilizer on plant growth, feed quality, and soil bacterial community.

Introduction: The development of organic manure from livestock excreta is a useful source for sustainable crop production in environment-friendly agriculture. Organic manure increases soil microbial activity and organic matter (OM) supply. The excessive use of chemical fertilizers (CFs) leads to air and water pollution caused by toxic chemicals and gases, and soil quality degradation via nutrient imbalance due to supplying specific chemical components. Thus, the use of organic manure will serve as a long-term supply of various nutrients in soil via OM decomposition reaction as well as the maintenance of environment. Methods: In this study, we aimed to analyze the diverse effects of Hanwoo manure (HM) on plant growth, feed quality, and soil bacterial communities in comparison with CFs, commercial poultry manure (CM), and the combined use of chemical fertilizer and Hanwoo manure (HM+CF). We analyzed the contents of crude matter (protein, fat, fiber, and ash), P, acid detergent fiber (ADF), and neutral detergent fiber (NDF) through feed quality analysis, and the contents or activities of total phenol, total flavonoid, ABTS, nitrite scavenging, and reducing power via the antioxidant assay. Furthermore, the soil microbial communities were determined using 16S rRNA sequencing. We compared the soil bacteria among different soil samples by using amplicon sequence variant (ASV) analysis. Results and discussion: We observed increased OM in the soil of the HM group compared to that of the CF and non-treated groups over a period of two years. Moreover, HM+CF treatment enormously improved plant growth. Organic manure, especially HM, caused an increase in the content of crude ash and phosphorus in plants. There were no significant differences in total polyphenol, total flavonoid, ABTS, nitrite scavenging, and reducing power in plants between HM and CF groups. Finally, we detected 13 soil bacteria (Acidibacter, Algisphaera, Cystobacter, Microvirga, Ohtaekwangia, Panacagrimonas, Pseudarthrobacter, Reryanella, Rhodoligotrophos, Solirubrobacter, Stenotrophobacter, Tellurimicrobium, and Thermomarinilinea) that were considerably correlated with OM and available phosphorus, and three considerably correlated bacteria were specifically distributed in CF or organic manure. The results suggest that HM is a valuable source of organic manure that can replace CF for sustainable crop production.

Elevated CO2 concentration induces changes in plant growth, transcriptome, and antioxidant activity in fennel (Foeniculum vulgare Mill.).

Introduction: Fennel (Foeniculum vulgare Mill.) is widely used to produce natural bio-materials. Elevated CO2 (eCO2) concentrations in the atmosphere improve the net photosynthesis of plants. Methods: The aim of the present study was to investigate distinct changes in fennel growth characteristics and phytonutrient contents under different CO2 concentrations. The effects of 400 and 800 ppm concentrations on plant growth and antioxidant activity were observed under hydroponics. Results and Discussion: Plant growth was improved by eCO2 concentrations. We also observed diverse changes in nutrient solution (pH, electrical conductivity, and dissolved oxygen) and environmental factors (temperature and humidity) in greenhouse under light or dark conditions. Electrical conductivity increased under dark and eCO2 conditions, whereas the pH decreased. Additionally, we performed transcriptome analysis and identified CO2-responsive differentially expressed genes. In the 800 ppm group, genes involved in photosynthesis and Karrikin response were upregulated whereas those involved in syncytium formation were downregulated. Four upregulated differentially expressed genes involved in flavonoid biosynthesis and total flavonoid content were relatively increased under the 800 ppm CO2 condition. In contrast, antioxidant activity, including total phenolic content, scavenging activity, ferric ion reducing antioxidant power, and reducing power were decreased in fennel under relatively high eCO2 concentrations. Moreover, different light intensities of 12 or 24 lx did not affect the growth and antioxidant activity of fennel, suggesting eCO2 has a stronger effect on plant improvement than light intensity. The results of the present study enhance our understanding of the positive effects of CO2 on the growth and antioxidant activity of fennel.

Transcriptomic Analysis of Testicular Gene Expression in a Dog Model of Experimentally Induced Cryptorchidism.

Cryptorchidism, a condition in which testes fail to descend from the abdomen into the scrotum, is a risk factor for infertility and germ cell cancer. Normally, tight junctions between adjacent Sertoli cells in the testes form a blood-testes barrier that regulates spermatogenesis; however, the effect of cryptorchidism on tight junctions is not well-understood. We established a model of heat-induced testicular damage in dogs using surgical cryptorchidism. We sequenced RNA to investigate whether certain transcripts are expressed at higher rates in heat-damaged versus normally descended testes. Claudins, cell adhesion molecules, were relatively highly expressed in cryptorchid testes: claudins 2, 3, 5, 11, and 18 were significantly increased in cryptorchid testes and reduced by orchiopexy. SOX9-positive Sertoli cells were present in the seminiferous tubules in both cryptorchid and control testes. Using real-time PCR and Western blot analysis to compare Sertoli cells cultured at 34 °C and 37 °C, we found that Sertoli cell claudins 2, 3, 5, 11, and 18 were significantly increased at 37 °C; however, accumulation was higher in the G0/G1 phase in Sertoli cells cultured at 34 °C. These results indicate that testicular hyperthermia caused by cryptorchidism affects claudin expression, regulated germ cell death, and the proliferation of Sertoli cells.

Host-microbial interactions between PTGR2 and Bifidobacterium in the early life gut of atopic dermatitis children.

BACKGROUND: Gut microbiota dysbiosis is linked to the development and responses of the immune system and can play an important role in the onset of allergic diseases including atopic dermatitis (AD). This study investigated the association between host genetics and the gut microbiota in AD. METHODS: A global gene expression profiling of the gut epithelial colonocytes, genetic variations analysis, and the gut microbial composition analysis were performed. RESULTS: This study identified the upregulation of PTGR2 (p = .028), a gene involved in prostaglandin catalysis and inflammatory responses, as a potential risk factor for AD. In subsequent fine mapping analysis using 17 single nucleotide polymorphisms (SNPs) of PTGR2 in 864 Korean subjects (420 AD patients and 444 unaffected controls), several SNPs and haplotypes showed significant associations with AD and its SCORing AD (SCORAD) values (p = .002). To investigate host-microbial interactions, further gut microbiota data and genotypes were obtained from an independent cohort of 176 subjects (91 AD patients and 85 controls). From correlation analysis, a significantly negative association between SNP and Bifidobacterium abundance was observed in AD patients (p = .005). In additional observations of PTGR2-associated downstream molecules, NRF2 (p = .004) and several antioxidant genes (GSTT1, GCLC, GPX1; p < .05) showed significantly reduced expression in AD patients. CONCLUSIONS: Our current findings suggest that the interaction between PTGR2 dysregulated expression and a Bifidobacterium abundance affects a higher risk of AD and a more severe onset.

Contribution of common and rare variants to bipolar disorder susceptibility in extended pedigrees from population isolates.

Current evidence from case/control studies indicates that genetic risk for psychiatric disorders derives primarily from numerous common variants, each with a small phenotypic impact. The literature describing apparent segregation of bipolar disorder (BP) in numerous multigenerational pedigrees suggests that, in such families, large-effect inherited variants might play a greater role. To identify roles of rare and common variants on BP, we conducted genetic analyses in 26 Colombia and Costa Rica pedigrees ascertained for bipolar disorder 1 (BP1), the most severe and heritable form of BP. In these pedigrees, we performed microarray SNP genotyping of 838 individuals and high-coverage whole-genome sequencing of 449 individuals. We compared polygenic risk scores (PRS), estimated using the latest BP1 genome-wide association study (GWAS) summary statistics, between BP1 individuals and related controls. We also evaluated whether BP1 individuals had a higher burden of rare deleterious single-nucleotide variants (SNVs) and rare copy number variants (CNVs) in a set of genes related to BP1. We found that compared with unaffected relatives, BP1 individuals had higher PRS estimated from BP1 GWAS statistics (P = 0.001 ~ 0.007) and displayed modest increase in burdens of rare deleterious SNVs (P = 0.047) and rare CNVs (P = 0.002 ~ 0.033) in genes related to BP1. We did not observe rare variants segregating in the pedigrees. These results suggest that small-to-moderate effect rare and common variants are more likely to contribute to BP1 risk in these extended pedigrees than a few large-effect rare variants.

Overexpression of rice F-box protein OsFBX322 confers increased sensitivity to gamma irradiation in Arabidopsis.

Ionizing radiation has a substantial effect on physiological and biochemical processes in plants via induction of transcriptional changes and diverse genetic alterations. Previous microarray analysis showed that rice OsFBX322, which encodes a rice F-box protein, was downregulated in response to three types of ionizing radiation: gamma irradiation, ion beams, and cosmic rays. In order to characterize the radiation-responsive genes in rice, OsFBX322 was selected for further analysis. OsFBX322 expression patterns in response to radiation were confirmed using quantitative RT-PCR. Transient expression of a GFP-OsFBX322 fusion protein in tobacco leaf epidermis indicated that OsFBX322 is localized to the nucleus. To determine the effect of OsFBX322 expression on radiation response, OsFBX322 was overexpressed in Arabidopsis. Transgenic overexpression lines were more sensitive to gamma irradiation than control plants. These results suggest that OsFBX322 plays a negative role in the defense response to radiation in plants. In addition, we obtained four co-expression genes of OsFBX322 by specific co-expression networks using the ARANCE. Quantitative RT-PCR showed that the four genes were also downregulated after exposure to the three types of radiation. These results imply that the co-expressed genes may serve as key regulators in the radiation response pathway in plants.

Transcriptome analysis for identifying possible gene regulations during maize root emergence and formation at the initial growth stage.

The root plays an important role during plant development and growth, i.e., the plant body maintenance, nutrient storage, absorption of water, oxygen and nutrient from the soil, and storage of water and carbohydrates, etc. The objective of this study was attempted to determine root-specific genes at the initial developmental stages of maize by using network-based transcriptome analysis. The raw data obtained using RNA-seq were filtered for quality control of the reads with the FASTQC tool, and the filtered reads were pre-proceed using the TRIMMOMATIC tool. The enriched BINs of the DEGs were detected using PageMan analysis with the ORA_FISHER statistical test, and genes were assigned to metabolic pathways by using the MapMan tool, which was also used for detecting transcription factors (TFs). For reconstruction of the co-expression network, we used the algorithm for the reconstruction of accurate cellular networks (ARACNE) in the R package, and then the reconstructed co-expression network was visualized using the Cytoscape tool. RNA-seq. was performed using maize shoots and roots at different developmental stages of root emergence (6-10 days after planting, VE) and 1 week after plant emergence (V2). A total of 1286 differentially expressed genes (DEGs) were detected in both tissues. Many DEGs involved in metabolic pathways exhibited altered mRNA levels between VE and V2. In addition, we observed gene expression changes for 113 transcription factors and found five enriched cis-regulatory elements in the 1-kb upstream regions of both DEGs. The network-based transcriptome analysis showed two modules as co-expressed gene clusters differentially expressed between the shoots and roots during plant development. The DEGs of one module exhibited gene expressional coherence in the maize root tips, suggesting that their functional relationships are associated with the initial developmental stage of the maize root. Finally, we confirmed reliable mRNA levels of the hub genes in the potential sub-network related to initial root development at the different developmental stages of VE, V2, and 2 weeks after plant emergence.

Genome-wide transcriptome profiling of genes associated with arsenate toxicity in an arsenic-tolerant rice mutant.

The presence of arsenic (As) in polluted environments, such as ground water, affects the accumulation of As in rice grains and causes a serious threat to human health. However, the precise molecular regulations related to As toxicity and tolerance in rice remain largely unknown. In the present study, we developed an arsenic-tolerant type 1 (ATT1) rice mutant by γ-irradiation mutagenesis and performed genome-wide transcriptome analysis for the characterization of As-responsive genes. Toxicity inhibited transcriptional regulation of putative genes involved in photosynthesis, mitochondrial electron transport, and lipid biosynthesis metabolism in wild-type (WT) and ATT1 rice mutant. However, many cysteine biosynthesis-related genes were significantly upregulated in both plants. We also attempted to elucidate the putative genes associated with As tolerance by comparing transcriptomes and identified ATT1-specific transcriptional regulation of genes involved in stress and RNA-protein synthesis. This analysis identified 50 genes that had DNA polymorphisms in upstream regions that differed from those in the exon regions, which suggested that genetic variations in the upstream regions might enhance As tolerance in the mutants. Therefore, the expression profiles of the genes evaluated in this study may improve understanding of the functional roles of As-related genes in response to As tolerance mechanisms and could potentially be used in molecular breeding to limit As accumulation in rice grains.

Molecular characterization of rice arsenic-induced RING finger E3 ligase 2 (OsAIR2) and its heterogeneous overexpression in Arabidopsis thaliana.

Arsenic (As) accumulation adversely affects the growth and productivity of plants and poses a serious threat to human health and food security. In this study, we identified one As-responsive Really Interesting New Gene (RING) E3 ubiquitin ligase gene from rice root tissues during As stress. We named it Oryza sativa As-Induced RING E3 ligase 2 (OsAIR2). Expression of OsAIR2 was induced under various abiotic stress conditions, including heat, salt, drought and As exposure. Results of an in vitro ubiquitination assay showed that OsAIR2 possesses an E3 ligase activity. Within the cell, OsAIR2 was found to be localized to the Golgi apparatus. Using yeast two-hybrid (Y2H) assay, the 3-ketoacyl-CoA thiolase (KAT) protein was identified as an interaction partner. We found that the O. sativa KAT1 (OsKAT1) is localized to the cytosol and peroxisomes. Moreover, in vitro pull-down assay verified the physical interaction between OsAIR2 and OsKAT1. Interestingly, in vitro ubiquitination assay and in vivo proteasomal degradation assay revealed that OsAIR2 ubiquitinates OsKAT1 and promotes the degradation of OsKAT1 via the 26S proteasome degradation pathway. Heterogeneous overexpression of OsAIR2 in Arabidopsis improved the seed germination and increased the root length under arsenate stress conditions. Therefore, these results suggest that OsAIR2 may be associated with the plant response to As stress and acts as a positive regulator of As stress tolerance.

Transcriptome analysis of reproductive-stage Arabidopsis plants exposed gamma-ray irradiation at various doses.

PURPOSE: Gamma rays (GR) induce significant changes in the structure and expression of genes involved in the regulation of diverse biochemical and physiological processes. Arabidopsis plants exhibit different growth and development patterns in response to exposure to GR. The effects on gene expression of different radiation doses of GR (100 and 800 Gy) administered to Arabidopsis plants were examined at the reproductive stage. MATERIALS AND METHODS: We irradiated 26-day-old plants with three replications [developmental stages 5.1-6.0, according to Boyes et al. ( 2001 )] using a GR irradiator (60 Co, ca. 150 TBq capacity, Atomic Energy of Canada Limited, Ontario, Canada) at the Korea Atomic Energy Research Institute. Plants were treated with 100, 200, 300, 400, 800, 1200, 1600, or 2000 Gy, and the doses were made from varying the distance to the source. RESULTS: We conducted a high-throughput screening analysis and detected 883 GR-responsive genes that showed significant changes; these were involved in several putative metabolic pathways related to biotic stress. Additionally, five overrepresented cis-regulatory elements were identified in the 1-kb upstream regions of GR-responsive genes by using motif enrichment analysis. We also detected three GR-responsive genes associated with stamen development and confirmed their co-regulation with functionally interacting genes. CONCLUSIONS: This finding suggests that a network-based analysis is a viable approach to identify significant GR-responsive genes associated with the reproductive stage of Arabidopsis. Our results provide further insights into the complex biological systems involved in the response to different doses of GR in plants.

Molecular dissection of Oryza sativa salt-induced RING Finger Protein 1 (OsSIRP1): possible involvement in the sensitivity response to salinity stress.

Ubiquitination-mediated protein degradation via Really Interesting New Gene (RING) E3 ligase plays an important role in plant responses to abiotic stress conditions. Many plant studies have found that RING proteins regulate the perception of various abiotic stresses and signal transduction. In this study, Oryza sativa salt-induced RING Finger Protein 1 (OsSIRP1) gene was selected randomly from 44 Oryza sativa RING Finger Proteins (OsRFPs) genes highly expressed in rice roots exposed to salinity stress. Transcript levels of OsSIRP1 in rice leaves after various stress treatments, including salt, heat, drought and hormone abscisic acid (ABA), were observed. Poly-ubiquitinated products of OsSIRP1 were investigated via an in vitro ubiquitination assay.35S:OsSIRP1-EYFP was distributed in the cytosol of untreated and salt-treated rice protoplasts. Heterogeneous overexpression of OsSIRP1 in Arabidopsis reduced tolerance for salinity stress during seed germination and root growth. Our findings indicate that OsSIRP1 acts as a negative regulator of salinity stress tolerance mediated by the ubiquitin 26S proteasome system.

Molecular characterization of Oryza sativa arsenic-induced RING E3 ligase 1 (OsAIR1): Expression patterns, localization, functional interaction, and heterogeneous overexpression.

High levels of arsenic (As) in plants are a serious threat to human health, and arsenic accumulation affects plant metabolism and ultimately photosynthesis, growth, and development. We attempted to isolate As-responsive Really Interesting New Gene (RING) E3 ubiquitin ligase genes from rice, and we have designated one such gene Oryza sativa arsenic-induced RING E3 ligase 1 (OsAIR1). OsAIR1 expression was induced under abiotic stress conditions, including drought, salt, heat, and As exposure. Results from an in vitro ubiquitination assay showed that OsAIR1 possesses E3 ligase activity. Within the cell, the expression of this gene was found to be localized to the vacuole. In a network-based analysis, we found significantly enriched gene ontology (GO) functions, which included ribonucleoprotein complexes such as ribosomes, suggesting that the function of OsAIR1 are related to translation. Differences in the proportion of seedlings with expanded cotyledons and root lengths, and the lack of differences in germination rates between OsAIR1-overexpressing lines and control plants under AsV stress, suggest that OsAIR1 may positively regulate post-germination plant growth under stress conditions.

Identification of novel therapeutic target genes in acquired lapatinib-resistant breast cancer by integrative meta-analysis.

Acquired resistance to lapatinib is a highly problematic clinical barrier that has to be overcome for a successful cancer treatment. Despite efforts to determine the mechanisms underlying acquired lapatinib resistance (ALR), no definitive genetic factors have been reported to be solely responsible for the acquired resistance in breast cancer. Therefore, we performed a cross-platform meta-analysis of three publically available microarray datasets related to breast cancer with ALR, using the R-based RankProd package. From the meta-analysis, we were able to identify a total of 990 differentially expressed genes (DEGs, 406 upregulated, 584 downregulated) that are potentially associated with ALR. Gene ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the DEGs showed that "response to organic substance" and "p53 signaling pathway" may be largely involved in ALR process. Of these, many of the top 50 upregulated and downregulated DEGs were found in oncogenesis of various tumors and cancers. For the top 50 DEGs, we constructed the gene coexpression and protein-protein interaction networks from a huge database of well-known molecular interactions. By integrative analysis of two systemic networks, we condensed the total number of DEGs to six common genes (LGALS1, PRSS23, PTRF, FHL2, TOB1, and SOCS2). Furthermore, these genes were confirmed in functional module eigens obtained from the weighted gene correlation network analysis of total DEGs in the microarray datasets ("GSE16179" and "GSE52707"). Our integrative meta-analysis could provide a comprehensive perspective into complex mechanisms underlying ALR in breast cancer and a theoretical support for further chemotherapeutic studies.

Identification of altered metabolic pathways of γ-irradiated rice mutant via network-based transcriptome analysis.

In order to develop rice mutants for crop improvement, we applied γ-irradiation mutagenesis and selected a rice seed color mutant (MT) in the M14 targeting-induced local lesions in genome lines. This mutant exhibited differences in germination rate, plant height, and root length in seedlings compared to the wild-type plants. We found 1645 different expressed probes of MT by microarray hybridization. To identify the modified metabolic pathways, we conducted integrated genomic analysis such as weighted correlation network analysis with a module detection method of differentially expressed genes (DEGs) in MT on the basis of large-scale microarray transcriptional profiling. These modules are largely divided into three subnetworks and mainly exhibit overrepresented gene ontology functions such as oxidation-related function, ion-binding, and kinase activity (phosphorylation), and the expressional coherences of module genes mainly exhibited in vegetative and maturation stages. Through a metabolic pathway analysis, we detected the significant DEGs involved in the major carbohydrate metabolism (starch degradation), protein degradation (aspartate protease), and signaling in sugars and nutrients. Furthermore, the accumulation of amino acids (asparagine and glutamic acid), sucrose, and starch in MT were affected by gamma rays. Our results provide an effective approach for identification of metabolic pathways associated with useful agronomic traits in mutation breeding.

Topological network analysis of differentially expressed genes in cancer cells with acquired gefitinib resistance.

BACKGROUND/AIM: Despite great effort to elucidate the process of acquired gefitinib resistance (AGR) in order to develop successful chemotherapy, the precise mechanisms and genetic factors of such resistance have yet to be elucidated. MATERIALS AND METHODS: We performed a cross-platform meta-analysis of three publically available microarray datasets related to cancer with AGR. For the top 100 differentially expressed genes (DEGs), we clustered functional modules of hub genes in a gene co-expression network and a protein-protein interaction network. We conducted a weighted correlation network analysis of total DEGs in microarray dataset GSE 34228. The identified DEGs were functionally enriched by Gene Ontology (GO) function and KEGG pathway. RESULTS: We identified a total of 1,033 DEGs (510 up-regulated, 523 down-regulated, and 109 novel genes). Among the top 100 up- or down-regulated DEGs, many genes were found in different types of cancers and tumors. Through integrative analysis of two systemic networks, we selected six hub DEGs (Pre-B-cell leukemia homeobox1, Transient receptor potential cation channel subfamily C member 1, AXL receptor tyrosine kinase, S100 calcium binding protein A9, S100 calcium binding protein A8, and Nucleotide-binding oligomerization domain containing 2) associated with calcium homeostasis and signaling, apoptosis, transcriptional regulation, or chemoresistance. We confirmed a correlation of expression of these genes in the microarray dataset. CONCLUSION: Our study may lead to comprehensive insights into the complex mechanism of AGR and to novel gene expression signatures useful for further clinical studies.

Molecular characterization of the cold- and heat-induced Arabidopsis PXL1 gene and its potential role in transduction pathways under temperature fluctuations.

LRR-RLK (Leucine-Rich Repeat Receptor-Like Kinase) proteins are believed to play essential roles in cell-to-cell communication during various cellular processes including development, hormone perception, and abiotic stress responses. We isolated an LRR-RLK gene previously named Arabidopsis PHLOEM INTERCALATED WITH XYLEM-LIKE 1 (AtPXL1) and examined its expression patterns. AtPXL1 was highly induced by cold and heat stress, but not by drought. The fluorescence signal of 35S::AtPXL1-EGFP was closely localized to the plasma membrane. A yeast two-hybrid and bimolecular fluorescence complementation assay exhibited that AtPXL1 interacts with both proteins, A. thaliana histidine-rich dehydrin1 (AtHIRD1) and A. thaliana light-harvesting protein complex I (AtLHCA1). We found that AtPXL1 possesses autophosphorylation activity and phosphorylates AtHIRD1 and AtLHCA1 in an in vitro assay. Subsequently, we found that the knockout line (atpxl1) showed hypersensitive phenotypes when subjected to cold and heat during the germination stage, while the AtPXL1 overexpressing line as well as wild type plants showed high germination rates compared to the knockout plants. These results provide an insight into the molecular function of AtPXL1 in the regulation of signal transduction pathways under temperature fluctuations.

Overexpression of the OsChI1 gene, encoding a putative laccase precursor, increases tolerance to drought and salinity stress in transgenic Arabidopsis.

In a previous study, we identified a number of genes induced by chilling using a microarray approach. In order to investigate the molecular mechanism underlying chilling tolerance and possible crosstalk with other abiotic stresses, we selected a rice gene, OsChI1 (Os01g61160), for further analysis. The OsChI1 gene encodes a putative laccase precursor protein. In accordance with our previous results, its transcript is highly accumulated during a 12-day period of chilling treatment. Higher expression of the OsChI1 gene was also detected in roots and tissues at the vegetative and productive stages. In addition, we also observed increased transcript levels of the OsChI1 gene during dehydration and high salinity conditions. Transient expression of OsChI1 proteins tagged with fluorescence protein in rice protoplasts revealed that OsChI1 is localized in the plasma membrane. The Arabidopsis transgenic plants overexpressing OsChI1-EGFP resulted in an increased tolerance to drought and salinity stress. In silico analysis of OsChI1 suggests that several genes coexpressed with OsChI1 in the root during various abiotic stresses, such as chilling, drought and salt stress, may play an important role in the ROS signaling pathway. Potential roles of OsChI1 in response to abiotic stresses are discussed.

Identification of rice genes associated with cosmic-ray response via co-expression gene network analysis.

In order to better understand the biological systems that are affected in response to cosmic ray (CR), we conducted weighted gene co-expression network analysis using the module detection method. By using the Pearson's correlation coefficient (PCC) value, we evaluated complex gene-gene functional interactions between 680 CR-responsive probes from integrated microarray data sets, which included large-scale transcriptional profiling of 1000 microarray samples. These probes were divided into 6 distinct modules that contained 20 enriched gene ontology (GO) functions, such as oxidoreductase activity, hydrolase activity, and response to stimulus and stress. In particular, modules 1 and 2 commonly showed enriched annotation categories such as oxidoreductase activity, including enriched cis-regulatory elements known as ROS-specific regulators. These results suggest that the ROS-mediated irradiation response pathway is affected by CR in modules 1 and 2. We found 243 ionizing radiation (IR)-responsive probes that exhibited similarities in expression patterns in various irradiation microarray data sets. The expression patterns of 6 randomly selected IR-responsive genes were evaluated by quantitative reverse transcription polymerase chain reaction following treatment with CR, gamma rays (GR), and ion beam (IB); similar patterns were observed among these genes under these 3 treatments. Moreover, we constructed subnetworks of IR-responsive genes and evaluated the expression levels of their neighboring genes following GR treatment; similar patterns were observed among them. These results of network-based analyses might provide a clue to understanding the complex biological system related to the CR response in plants.

Genome-wide DNA polymorphism and transcriptome analysis of an early-maturing rice mutant.

In order to develop a rice population with improved important traits such as flowering time, we developed 2,911 M2 targeting-induced local lesions in genomes (TILLING) lines by irradiating rice seeds with γ-rays. In all, 15 M3 lines were obtained from 3 different M2 lines that exhibited an early-maturing phenotype: these plants matured approximately 25 days faster than wild-type (WT) plants. To identify genome-wide DNA polymorphisms, we performed whole-genome resequencing of both the plant types, i.e., WT and early-maturing TILLING 1 (EMT1), and obtained mapped reads of 118,488,245 bp (99.53 %) and 128,489,860 bp (99.72 %), respectively; Nipponbare was used as the reference genome. We obtained 63,648 and 147,728 single nucleotide polymorphisms (SNPs) and 33,474 and 31,082 insertions and deletions (InDels) for the WT and EMT1, respectively. Interestingly, there was a higher number of SNPs (2.6-fold) and slightly lower number of InDels (0.9-fold) in EMT1 than in WT. The expression of at least 202 structurally altered genes was changed in EMT1, and functional enrichment analysis of these genes revealed that their molecular functions were related to flower development. These results might provide a critical insight into the regulatory pathways of rice flowering.