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.

Overexpression of rice jacalin-related mannose-binding lectin (OsJAC1) enhances resistance to ionizing radiation in Arabidopsis.

BACKGROUND: Jacalin-related lectins in plants are important in defense signaling and regulate growth, development, and response to abiotic stress. We characterized the function of a rice mannose-binding jacalin-related lectin (OsJAC1) in the response to DNA damage from gamma radiation. RESULTS: Time- and dose-dependent changes of OsJAC1 expression in rice were detected in response to gamma radiation. To identify OsJAC1 function, OsJAC1-overexpressing transgenic Arabidopsis plants were generated. Interestingly, OsJAC1 overexpression conferred hyper-resistance to gamma radiation in these plants. Using comparative transcriptome analysis, genes related to pathogen defense were identified among 22 differentially expressed genes in OsJAC1-overexpressing Arabidopsis lines following gamma irradiation. Furthermore, expression profiles of genes associated with the plant response to DNA damage were determined in these transgenic lines, revealing expression changes of important DNA damage checkpoint and perception regulatory components, namely MCMs, RPA, ATM, and MRE11. CONCLUSIONS: OsJAC1 overexpression may confer hyper-resistance to gamma radiation via activation of DNA damage perception and DNA damage checkpoints in Arabidopsis, implicating OsJAC1 as a key player in DNA damage response in plants. This study is the first report of a role for mannose-binding jacalin-related lectin in DNA damage.

Functional Mechanisms Underlying the Antimicrobial Activity of the Oryza sativa Trx-like Protein.

Plants are constantly subjected to a variety of environmental stresses and have evolved regulatory responses to overcome unfavorable conditions that might reduce or adversely change a plant's growth or development. Among these, the regulated production of reactive oxygen species (ROS) as a signaling molecule occurs during plant development and pathogen defense. This study demonstrates the possible antifungal activity of Oryza sativa Tetratricopeptide Domain-containing thioredoxin (OsTDX) protein against various fungal pathogens. The transcription of OsTDX was induced by various environmental stresses known to elicit the generation of ROS in plant cells. OsTDX protein showed potent antifungal activity, with minimum inhibitory concentrations (MICs) against yeast and filamentous fungi ranging between 1.56 and 6.25 and 50 and 100 µg/mL, respectively. The uptake of SYTOX-Green into fungal cells and efflux of calcein from artificial fungus-like liposomes suggest that its killing mechanism involves membrane permeabilization and damage. In addition, irregular blebs and holes apparent on the surfaces of OsTDX-treated fungal cells indicate the membranolytic action of this protein. Our results suggest that the OsTDX protein represents a potentially useful lead for the development of pathogen-resistant plants.

Prevalence and predictors of tricyclic antidepressant use among elderly Koreans in primary-care and specialty clinics.

OBJECTIVES: Tricyclic antidepressants (TCAs) are prescribed with caution in the elderly due to diverse side effects. We analyzed the patterns of TCA use in elderly patients in primary-care and specialty clinics and investigated factors influencing TCA prescriptions. MATERIALS AND METHODS: Elderly patients (≥ 65 years old) prescribed antidepressants in primary-care clinics in 2013 were included from the Health Insurance Review and Assessment Service-Aged Patient Sample (HIRA-APS). Prevalence of TCA prescriptions was assessed by insurance coverage status, clinical specialty, and region. Multiple logistic regression analysis was performed to compute odds ratios (ORs) and 95% confidence intervals (CIs) for factors associated with TCA prescriptions. RESULTS: TCAs and selective serotonin reuptake inhibitors (SSRIs) comprised 45.2% and 15.0% of all antidepressant prescriptions, respectively. TCAs comprised 61.5% and 20.7% of antidepressant prescriptions for pain and depression, respectively. Patients aged ≥ 85 years were less likely to be treated with TCAs (OR 0.81, 95% CI 0.79 - 0.84) than those aged 65 - 69 years. The odds for being prescribed TCAs were higher for patients residing in cities (OR 1.20, 95% CI 1.18 - 1.23), treated in nonpsychiatric clinics (OR 5.64, 95% CI 5.53 - 5.76), and those covered by Veteran's Health (OR 1.62, 95% CI 1.37 - 1.90) when compared to patients residing in the Seoul metropolitan area, treated in psychiatric clinics, or covered by National Health Insurance, respectively. The prescriptions of TCAs with pain diagnoses were much higher than prescriptions for depression (OR 1.87, 95% CI 1.82 - 1.93). CONCLUSIONS: Compared with a 2005 report, the prevalence of TCA prescriptions in elderly patients in Korea has decreased substantially, but remains high. Various efforts should be considered to reduce TCA prescriptions in the elderly.
.

Individual class evaluation and effective teaching characteristics in integrated curricula.

BACKGROUND: In an integrated curriculum, multiple instructors take part in a course in the form of team teaching. Accordingly, medical schools strive to manage each course run by numerous instructors. As part of the curriculum management, course evaluation is conducted, but a single, retrospective course evaluation does not comprehensively capture student perception of classes by different instructors. This study aimed to demonstrate the need for individual class evaluation, and further to identify teaching characteristics that instructors need to keep in mind when preparing classes. METHODS: From 2014 to 2015, students at one medical school left comments on evaluation forms after each class. Courses were also assessed after each course. Their comments were categorized by connotation (positive or negative) and by subject. Within each subject category, test scores were compared between positively and negatively mentioned classes. The Mann-Whitney U test was performed to test group differences in scores. The same method was applied to the course evaluation data. RESULTS: Test results for course evaluation showed group difference only in the practice/participation category. However, test results for individual class evaluation showed group differences in six categories: difficulty, main points, attitude, media/contents, interest, and materials. That is, the test scores of classes positively mentioned in six domains were significantly higher than those of negatively mentioned classes. CONCLUSIONS: It was proved that individual class evaluation is needed to manage multi-instructor courses in integrated curricula of medical schools. Based on the students' extensive feedback, we identified teaching characteristics statistically related to academic achievement. School authorities can utilize these findings to encourage instructors to develop effective teaching characteristics in class preparation.

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.

Selection and molecular characterization of a lipoxygenase-free soybean mutant line induced by gamma irradiation.

KEY MESSAGE: A lipoxygenase-free soybean mutant line (H70) induced by gamma ray was selected and its detailed information about the lipoxygenase was analyzed by comparison of DNA sequence. Soybean seeds contain three lipoxygenase enzymes, which induce a beany or grassy flavor. The elimination of lipoxygenases can reduce the poor stability and off-flavors of soybean oil and protein products. In this study, we selected a soybean mutant (H70) in which the three lipoxygenases had been mutated using gamma rays. To obtain detailed information about the lipoxygenase, we investigated the sequences of the Lox1, Lox2 and Lox3 genes in H70 compared to the original cultivar, Hwanggum. Comparisons of the sequences of the Lox1 and Lox2 genes in H70 with those in a line with normal lipoxygenase (HG) showed that the mutations in these genes affected a highly conserved group of six histidine residues necessary for enzymatic activity. Lox1 in H70 contained a 74 bp deletion in exon 8, creating a stop codon that prematurely terminates translation. A single point mutation (T-A) in exon 8 of Lox2 changed histidine (H532, one of the iron-binding ligands essential for Lox2 activity) to glutamine. The mutation in the Lox3 gene in H70 was a single-point mutation in exon 6 (A-G), which changed the amino acid from histidine to arginine. This amino acid alteration in Lox3 was located in the N-terminal barrel, which might play a role in molecular recognition during catalysis and/or proteolysis. These results suggest that gene analysis based on DNA sequencing could be useful for elucidating the lipoxygenase content in soybean mutant lines. Additionally, the soybean mutant line selected in this study could be used to develop soybean cultivars with improved flavor.

DREB2C acts as a transcriptional activator of the thermo tolerance-related phytocystatin 4 (AtCYS4) gene.

Phytocystatins are proteinaceous inhibitors of cysteine proteases. They have been implicated in the regulation of plant protein turnover and in defense against pathogens and insects. Here, we have characterized an Arabidopsis phytocystatin family gene, Arabidopsis thaliana phytocystatin 4 (AtCYS4). AtCYS4 was induced by heat stress. The heat shock tolerance of AtCYS4-overexpressing transgenic plants was greater than that of wild-type and cys4 knock-down plants, as measured by fresh weight and root length. Although no heat shock elements were identified in the 5'-flanking region of the AtCYS4 gene, canonical ABA-responsive elements (ABREs) and dehydration-responsive elements (DREs) were found. Transient promoter activity measurements showed that AtCYS4 expression was up-regulated in unstressed protoplasts by co-expression of DRE-binding factor 2s (DREB2s), especially by DREB2C, but not by bZIP transcription factors that bind to ABREs (ABFs, ABI5 and AREBs). DREB2C bound to and activated transcription from the two DREs on the AtCYS4 promoter although some preference was observed for the GCCGAC DRE element over the ACCGAC element. AtCYS4 transcript and protein levels were elevated in transgenic DREB2C overexpression lines with corresponding decline of endogenous cysteine peptidase activity. We propose that AtCYS4 functions in thermotolerance under the control of the DREB2C cascade.

Transcriptome profiling in response to different types of ionizing radiation and identification of multiple radio marker genes in rice.

Ionizing radiation (IR) affects gene expression from plant genomes. To monitor the genome-wide transcriptional changes induced by three types of IR, we used the rice Affymetrix GeneChip microarray to identify genes that are up- or down-regulated by gamma rays (GAs), cosmic rays (CRs) and ion beams (IBs). The overall expression patterns in rice seedlings generated from seeds exposed to GAs and IBs were similar but differed for CRs exposure. Expression profiles of genes involved in metabolic pathways and cellular response were identified using MapMan analysis. This result revealed that IRs induced gene expression related to sucrose-starch metabolisms; sugar and starch accumulation was significantly increased in response to three types of IR in rice. In addition, we compared the genes commonly up- or down-regulated by exposure to three types of IR and identified 53 candidate radio marker genes (RMGs) that were differentially regulated by radiation exposure but not by other stresses. Among these genes, we selected six RMGs commonly applicable to different types of IR by specific coexpression networks using the algorithm for the reconstruction of accurate cellular networks (aracne) and confirmed the expression of these genes by reverse transcription-polymerase chain reaction (RT-PCR) analysis. Our results provided insight into the mechanisms of the responses to different types of IR and identified multiple marker genes to predict sensitivity to three types of IR.

Selection and molecular characterization of a high tocopherol accumulation rice mutant line induced by gamma irradiation.

Tocopherols are micronutrients with antioxidant properties. They are synthesized by photosynthetic bacteria and plants, and play important roles in animal and human nutrition. In this study, we isolated a new rice mutant line with elevated tocopherol content (MRXII) from an in vitro mutagenized population induced by gamma irradiation. The mutant exhibited greater seed longevity than the control, indicating a crucial role for tocopherols in maintaining viability during quiescence, and displayed faster seedling growth during the early growth stage. To study the molecular mechanism underlying vitamin E biosynthesis, we examined the expression patterns of seven rice genes encoding vitamin E biosynthetic enzymes. Accumulation levels of the OsVTE2 transcript and OsVTE2 protein in the MRXII mutant were significantly higher than in the control. Sequence analysis revealed that the MRXII mutant harbored a point mutation in the OsVTE2 promoter region, which resulted in the generation of MYB transcription factor-binding cis-element. These results help identify the promoter regions that regulate OsVTE2 transcription, and offer insights into the regulation of tocopherol content.

UAV telephotography elucidates floristic variability and beta diversity of island cliffs under grazing interventions.

Cliffs contain one of the least known plant communities, which has been overlooked in biodiversity assessments due to the inherent inaccessibility. Our study adopted the unmanned aerial vehicle (UAV) with the telephoto camera to remotely clarify floristic variability across unreachable cliffs. Studied cliffs comprised 17 coastal and 13 inland cliffs in Gageodo of South Korea, among which 9 and 5 cliffs were grazed by the introduced cliff-dwelling goats. The UAV telephotography showed 154 and 166 plant species from coastal and inland cliffs, respectively. Inland cliffs contained more vascular plant species (P < 0.001), increased proportions of fern and woody species (P < 0.05), and decreased proportion of herbaceous species (P < 0.001) than coastal cliffs. It was also found that coastal and inland cliffs differed in the species composition (P < 0.001) rather than taxonomic beta diversity (P = 0.29). Furthermore, grazed coastal cliffs featured the elevated proportions of alien and annual herb species than ungrazed coastal cliffs (P < 0.05). This suggests that coastal cliffs might not be totally immune to grazing if the introduced herbivores are able to access cliff microhabitats; therefore, such anthropogenic introduction of cliff-dwelling herbivores should be excluded to conserve the native cliff plant communities.

The identification of candidate radio marker genes using a coexpression network analysis in gamma-irradiated rice.

Plant physiological and biochemical processes are significantly affected by gamma irradiation stress. In addition, gamma-ray (GA) differentially affects gene expression across the whole genome. In this study, we identified radio marker genes (RMGs) responding only to GA stress compared with six abiotic stresses (chilling, cold, anoxia, heat, drought and salt) in rice. To analyze the expression patterns of differentially expressed genes (DEGs) in gamma-irradiated rice plants against six abiotic stresses, we conducted a hierarchical clustering analysis by using a complete linkage algorithm. The up- and downregulated DEGs were observed against six abiotic stresses in three and four clusters among a total of 31 clusters, respectively. The common gene ontology functions of upregulated DEGs in clusters 9 and 19 are associated with oxidative stress. In a Pearson's correlation coefficient analysis, GA stress showed highly negative correlation with salt stress. On the basis of specific data about the upregulated DEGs, we identified the 40 candidate RMGs that are induced by gamma irradiation. These candidate RMGs, except two genes, were more highly induced in rice roots than in other tissues. In addition, we obtained other 38 root-induced genes by using a coexpression network analysis of the specific upregulated candidate RMGs in an ARACNE algorithm. Among these genes, we selected 16 RMGs and 11 genes coexpressed with three RMGs to validate coexpression network results. RT-PCR assay confirmed that these genes were highly upregulated in GA treatment. All 76 genes (38 root-induced genes and 38 candidate RMGs) might be useful for the detection of GA sensitivity in rice roots.

Asymbiotic Seed Germination and In Vitro Seedling Development of the Endangered Orchid Species Cypripedium guttatum.

Cypripedium guttatum is a highly restricted terrestrial orchid that faces increasing endangerment owing to its habitat destruction and illegal collection. Compared to epiphytic orchids, terrestrial orchids such as C. guttatum have harder seed coats and more demanding in vitro germination conditions. This study aimed to develop an effective in vitro propagation system for C. guttatum to aid in its conservation. Seeds from mature capsules were subjected to various conditions, including sterilization using 1% sodium hypochlorite (NaOCl) and different light conditions, culture media, hormones, and organic supplements, to assess germination and early seedling development in vitro. Sterilization with 1% NaOCl significantly improved the germination rate, especially under dark conditions. Germination initiation occurred at 2 and 3 months in orchid seed sowing medium (OSM) and Murashige and Skoog (MS) medium, respectively. The addition of 1 mg/L naphthaleneacetic acid (NAA) further enhanced germination. However, the inclusion of organic supplements, such as apple and banana homogenates, in the culture medium led to substantial growth inhibition after 12 months. Notably, orchid maintenance medium (OMM) without organic additives proved to be the most suitable for seedling growth. The results of this study show that sterilization, appropriate light, and optimal NAA concentrations are beneficial for seed germination.

A proximal promoter region of Arabidopsis DREB2C confers tissue-specific expression under heat stress.

The dehydration-responsive element-binding factor 2C (DREB2C) is a member of the CBF/DREB subfamily of proteins, which contains a single APETALA2/Ethylene responsive element-binding factor (AP2/ERF) domain. To identify the expression pattern of the DREB2C gene, which contains multiple transcription cis-regulatory elements in its promoter, an approximately 1.4 kb upstream DREB2C sequence was fused to the ß-glucuronidase reporter gene (GUS) and the recombinant p1244 construct was transformed into Arabidopsis thaliana (L.) Heynh. The promoter of the gene directed prominent GUS activity in the vasculature in diverse young dividing tissues. Upon applying heat stress (HS), GUS staining was also enhanced in the vasculature of the growing tissues. Analysis of a series of 5'-deletions of the DREB2C promoter revealed that a proximal upstream sequence sufficient for the tissue-specific spatial and temporal induction of GUS expression by HS is localized in the promoter region between -204 and -34 bps relative to the transcriptional start site. Furthermore, electrophoretic mobility shift assay (EMSA) demonstrated that nuclear protein binding activities specific to a -120 to -32 bp promoter fragment increased after HS. These results indicate that the TATA-proximal region and some latent trans-acting factors may cooperate in HS-induced activation of the Arabidopsis DREB2C promoter.

Population genetic structure and conservation management of hill pigeons (Columba rupestris) recently endangered in South Korea.

BACKGROUND: Hill pigeons (Columba rupestris) are close to local extinction (ca. less than 100 individuals) in South Korea where a variety of conservation management procedures are urgently required. OBJECTIVE: This study was aimed at determining the conservation direction of captive propagation and reintroduction of hill pigeons using genetic information based on mitochondrial DNA. We also evaluated the extent of hybridization between hill pigeons and cohabiting domestic pigeons. METHODS: We used 51 blood samples of hill pigeons from Goheung (GH), Gurye (GR), and Uiryeong (UR), and domestic pigeons cohabiting with hill pigeon populations. Genetic diversity, pairwise Fst, analysis of molecular variance, and haplotype network analysis were used to examine the genetic structure of hill pigeons. RESULTS: Hill pigeons that inhabited South Korea were not genetically distinct from Mongolian and Russian populations and showed relatively low genetic diversity compared with other endangered species in Columbidae. The GR population that exhibited the largest population size showed lower genetic diversity, compared to the other populations, although the pairwise Fst values of the three populations indicated low genetic differentiation. The GH and GR populations were confirmed to lack hybridization, relatively, whereas the UR population was found to exhibit some degrees of hybridization. CONCLUSION: To conserve hill pigeons with low genetic diversity and differentiation in South Korea, the conservation process of captive propagation and reintroduction may require artificial gene flows among genetically verified populations in captivity and wildness. The introduction of foreign individuals from surrounding countries is also considered an alternative strategy for maintaining genetic diversity.

Association between ranitidine use with potential NDMA impurities and risk of cancer in Korea.

N-Nitrosodimethylamine (NDMA) detected above the acceptable level in ranitidine products has been a great global concern. To examine the risk of cancer among people treated with ranitidine, we conducted a cohort study using the National Health Insurance Service-National Sample Cohort data (2002-2015) of South Korea. Patients were aged 40 or above as of January 2004 and began receiving ranitidine or other histamine-2 receptor antagonist (H2RA), active comparator, without a history of H2RAs prescription during the prior 2-years. The lag time was designated up to 6 years. The outcomes were an overall incident cancer risk and the risk of major single cancers during the follow-up. The association between ranitidine use and cancer risk was examined by Cox regression model. After exclusion and propensity score matching, 25,360 patients were available for analysis. The use of ranitidine was not associated with the overall cancer risk and major individual cancers [overall cancer: incidence rate per 1000 person-years, 2.9 vs 3.0 among the ranitidine users and other H2RAs users, respectively; adjusted hazard ratio (HR) and 95% confidence interval (95% CI) for all cancers, 0.98 (0.81-1.20)]. The higher cumulative exposure to ranitidine did not increase the cancer risk. Given the insufficient follow-up period, these findings should be interpreted carefully.

Development of InDel markers for interspecific hybridization between hill pigeons and feral pigeons based on whole-genome re-sequencing.

Interspecific hybridization occurs among birds, and closely related sister taxa tend to hybridize at a high rate. Genomic hybridization markers are useful for understanding the patterns and processes of hybridization and for conserving endangered species in captivity and the wild. In this study, we developed genomic hybridization markers for the F1 progeny of the sister taxa feral pigeons (Columba livia var. domestica) and endangered hill pigeons (Columba rupestris) (family Columbidae). Using whole-genome re-sequencing data, we performed genome-wide analysis for insertion/deletion (InDel) polymorphisms and validated using primers. We conducted polymerase chain reaction (PCR) and agarose gel electrophoresis to identify species-specific InDels. We produced eight F1 hybrids of hill and feral pigeons, and their samples were tested by re-performing analyses and sequencing using 11 species-specific InDel polymorphisms. Eight InDel markers simultaneously amplified two DNA fragments from all F1 hybrids, and there was no abnormality in the sequencing results. The application of genomic tools to detect hybrids can play a crucial role in the assessment of hybridization frequency in the wild. Moreover, systematic captive propagation efforts with hybrids can help control the population decline of hill pigeons.

Endangered plant species under differing anthropogenic interventions: how to preserve Pterygopleurum neurophyllum in Wondong wetland?

Endangered wetland plants are important as the potential keystone species and mediators for plant-soil interactions. Establishing conservation strategies for endangered plants is also prioritized because of the elevating extinction risk by human-induced wetland disturbances. The present study examined the factors controlling the incidence of Pterygopleurum neurophyllum, the endangered wetland plant experiencing severe habitat loss throughout Northeast Asia. Here, P. neurophyllum populations and their surrounding environments were addressed in the last natural Korean habitat to assess the possible influential factors (vegetation coverage, species richness, exotic plant species, coarse rock content, soil bulk density, and soil electroconductivity and pH) under anthropogenic wetland interventions (with or without soil disturbance). Our results showed that P. neurophyllum occurred 6 out of 32 plots in the study area. All P. neurophyllum were found in Miscanthus-dominated area, but preferred microhabitats featuring reduced vegetation coverage, increased species richness, and undisturbed soils under vegetation removal. Multimodel inference also indicated that vegetation coverage (relative importance = 1.00) and coarse rock content (relative importance = 0.70) were the major influential factors for P. neurophyllum population size, and the surviving P. neurophyllum were strictly limited to where both of them were kept lowered. Furthermore, the wetland intervention with soil disturbance had a negative effect on P. neurophyllum by creating the rocky and compacted soil surface as a result of land reclamation treatments. Conversely, the wetland intervention without soil disturbance enhanced the P. neurophyllum incidence by decreasing vegetation coverage of the overcrowding competitive plants. Overall findings reflect that the strategies to counteract habitat loss and manage the overly dense competitive plants should be necessary for conserving P. neurophyllum, as well as other wetland plants threatened by the human-induced disturbances and excessive competition intensities.

Effects of Light Condition on Growth and Physiological Characteristics of the Endangered Species Sedirea japonica under RCP 6.0 Climate Change Scenarios.

This study was conducted to evaluate the physiological and growth responses of Sedirea japonica cultured in chambers under RCP 6.0 and different light conditions. S. japonica was grown in a soil-plant daylight system chamber under two treatments, a control (CO2 = 400 ppm) and a climate change treatment (CCT) (CO2 = 650 ppm, temperature = control + 3 °C), and three different shading treatments (60%, 90%, and no-shading). S. japonica showed the characteristics of typical Crassulacean acid metabolism (CAM) plants. As the shading rate increased, it increased chlorophyll content, leaf area, and leaf dry weight to efficiently absorb and use light. The CCT had a lower CO2 absorption rate, stomatal conductance, and growth rate and slightly higher water utilization efficiency than the control. This was because stomatal closure occurred in the CCT to reduce water loss due to a relatively higher temperature. As CO2 fixation decreased and consumption increased due to respiration, the overall growth was inhibited. The CCT without shading revealed a dynamic photoinhibition phenomenon showing a significant increase in ABS/RC, TRo/RC, ETo/RC, and DIo/RC and a decrease in PI ABS and DF ABS. In this group, leaf, root, and total dry weight, chlorophyll content, and carotenoid content were the worst growth indices.

Effects of Different Growth Media on In Vitro Seedling Development of an Endangered Orchid Species Sedirea japonica.

Sedirea japonica is becoming endangered, and even extinct, due to habitat destruction and illegal collection, and the development of an optimized artificial propagation system is necessary for its conservation and reintroduction. Thus, the effects of plant growth medium strength (Murashige and Skoog (MS) and Hyponex media) and the addition of activated charcoal (AC) and organic supplements on seedling growth of S. japonica were investigated through in vitro seed culture. The results showed that seedling growth was higher in half-strength (1/2) media than in full-strength media. After the addition of AC, the highest leaf area (2.14 cm2) was recorded in the seedlings grown in 1/2 Hyponex medium, and after the addition of organic supplements, root development increased regardless of the media type. Among the sixteen suitable media tested at later seedling growth stages, 1/2 MS medium with the addition of 0.6 g·L-1 AC, 30 g·L-1 banana homogenate and 10 g·L-1 apple homogenate was generally effective in fresh weight (6.13 g) and root length (9.59 cm). We demonstrated which organic supplements are preferred for in vitro growth of seedlings developed from S. japonica protocorms by asymbiotic seed culture, which can be used for mass production and conservation of this rare epiphytic orchid.