Development of a Rapid and Accurate Vapor Generation System for Real-Time Monitoring of a Chemical Warfare Agent (CWA) by Coupling Fourier Transform Infrared (FT-IR) Spectroscopy.

Developing an accurate chemical warfare agent (CWA) vapor generator is critical for homeland security because it enables real-time monitoring of target agent concentration for testing and evaluation. We designed and built an elaborate CWA vapor generator that offers reliable long-term stability and real-time monitoring capabilities by coupling it with Fourier transform infrared (FT-IR) spectroscopy. We evaluated the reliability and stability of the vapor generator using a gas chromatography-flame ion detector (GC-FID) and conducted a comparison between the experimental and theoretical results of sulfur mustard (HD, bis-2-chloroethylsulfide), a real CWA, at concentrations ranging from 1 to 5 ppm. Our FT-IR-coupled vapor generation system showed real-time monitoring ability, which enables rapid and accurate evaluation of chemical detectors. The vapor generation system was able to generate CWA vapor continuously for over 8 h, demonstrating its long-term vapor generation capability. In addition, we vaporized another representative CWA, viz., GB (Sarin, propan-2-yl ethylphosphonofluoridate), and conducted real-time monitoring of GB vapor concentration with high accuracy. This versatile vapor generator approach can enable the rapid and accurate evaluation of CWAs for homeland security against chemical threats and can be used in constructing a versatile real-time monitoring vapor generation system for CWAs.

Detection of hazardous chemical using dual-wavelength Raman spectroscopy in the ultraviolet region.

This study proposes a stand-off Raman spectroscopy system using dual-wavelength in the ultraviolet (UV) region to detect hazardous chemicals. The Raman spectrum generated by the UV excitation source avoids solar background noise during daytime for chemical detection as the spectrum is in the solar blind range. Wavelengths of 213 and 266 nm by 5th and 4th harmonics are generated from Nd:YAG laser. However, Raman spectra of chemicals exhibit different signal-to-noise ratios for both the excitation wavelengths; therefore, to detect such chemicals, Raman spectra by two sources are required. Raman spectra were acquired using a dual-wavelength laser and spectrometer with a single grating and detector at the wavelengths of 213 and 266 nm simultaneously. The Raman spectra of sulfuric acid, 2-chloroethyl ethyl sulfide, and dimethyl methylphosphonate were acquired and analyzed, thus highlighting the application of dual-wavelength Raman spectroscopy. For efficient chemical detection in the field, we have ensured that the system developed in this study is robust.

Identification of strA-strB Genes in Streptomycin-Resistant Pseudomonas syringae pv. actinidiae Biovar 2 Strains Isolated in Korea.

Bacterial canker is a devastating disease of kiwifruit caused by the bacterium Pseudomonas syringe pv. actinidiae. Canker disease of kiwifruit in Korea has been controlled using streptomycin for more than two decades. Four streptomycin-resistant strains, belonging to biovar 2, which are found only in Korea, were collected between 2013 and 2014 from different orchards located in Jeju, Korea. The genetic background for streptomycin resistance among P. syringe pv. actinidiae strains were determined by examining the presence of strA-strB or aadA, which are genes frequently found in streptomycin-resistant bacteria, and a point mutation at codon 43 in the rpsL gene. All four streptomycin-resistant strains of P. syringe pv. actinidiae investigated in this study contained strA-strB as a resistant determinant. The presence of the aadA gene and a mutation in codon 43 of the rpsL gene was not identified.

Genomic analyses of Pseudomonas syringae pv. actinidiae isolated in Korea suggest the transfer of the bacterial pathogen via kiwifruit pollen.

Introduction. The bacterial pathogen, Pseudomonas syringae pv. actinidiae (Psa), has emerged as a major threat to kiwifruit cultivation throughout the world. One pandemic strain (from the Psa3 group) has occurred in various geographical regions. It is important to understand how this pathogen is being transmitted.Aim. Although Psa has been found in Korea since 1992, the isolates were until recently of a distinct type (Psa2). Recently, the more virulent Psa3 type has been detected. The purpose of this study was to describe the variety of Psa3 now found in Korea.Methodology. Strains were isolated from kiwifruit plants in Korea and from pollen imported into Korea from New Zealand. The genomes of 10 isolates were sequenced using the Illumina platform and compared to the completely assembled genomes of pandemic Psa3 strains from New Zealand and China. Comparisons were also made with pandemic strains from Chile and non-pandemic Psa3 isolates from China.Results. Six of the 10 Psa3 isolates from Korea show a clear relationship with New Zealand isolates. Two isolates show a distinct relationship to isolates from Chile; one further isolate has a sequence that is highly similar to that of M228, a strain previously isolated in China; and the last isolate belongs to the Psa3 group, but is not a member of the pandemic lineage.Conclusion. This analysis establishes that there have been multiple routes of transmission of the Psa3 pandemic strain into Korea. One route has involved the importation of pollen from New Zealand. A second route probably involves importation from Chile.

An Integrated Modeling Approach for Predicting Potential Epidemics of Bacterial Blossom Blight in Kiwifruit under Climate Change.

The increasing variation in climatic conditions under climate change directly influences plant-microbe interactions. To account for as many variables as possible that may play critical roles in such interactions, the use of an integrated modeling approach is necessary. Here, we report for the first time a local impact assessment and adaptation study of future epidemics of kiwifruit bacterial blossom blight (KBB) in Jeonnam province, Korea, using an integrated modeling approach. This study included a series of models that integrated both the phenological responses of kiwifruit and the epidemiological responses of KBB to climatic factors with a 1 km resolution, under the RCP8.5 climate change scenario. Our results indicate that the area suitable for kiwifruit cultivation in Jeonnam province will increase and that the flowering date of kiwifruit will occur increasingly earlier, mainly due to the warming climate. Future epidemics of KBB during the predicted flowering periods were estimated using the Pss-KBB Risk Model over the predicted suitable cultivation regions, and we found location-specific, periodic outbreaks of KBB in the province through 2100. Here, we further suggest a potential, scientifically-informed, long-term adaptation strategy using a cultivar of kiwifruit with a different maturity period to relieve the pressures of future KBB risk. Our results clearly show one of the possible options for a local impact assessment and adaptation study using multiple models in an integrated way.

Genetic Diversity of the Pear Scab Fungus Venturia nashicola in Korea.

Scab disease caused by Venturia nashicola is of agroeconomic importance in cultivation of Asian pear. However, little is known about the degree of genetic diversity in the populations of this pathogen. In this study, we collected 55 isolates from pear scab lesions in 13 major cultivation areas in Korea and examined the diversity using sequences of internal transcribed spacer (ITS) region, ß-tubulin (TUB2), and translation elongation factor-1α (TEF-1α) genes as molecular markers. Despite a low level of overall sequence variation, we found three distinctive subgroups from phylogenetic analysis of combined ITS, TUB2, and TEF-1α sequences. Among the three subgroups, subgroup 1 (60% of isolates collected) was predominant compared to subgroup 2 (23.6%) or subgroup 3 (16.4%) and was distributed throughout Korea. To understand the genetic diversity among the subgroups, RAPD analysis was performed. The isolates yielded highly diverse amplicon patterns and none of the defined subgroups within the dendrogram were supported by bootstrap values greater than 30%. Moreover, there is no significant correlation between the geographical distribution and the subgroups defined by molecular phylogeny. Our data suggest a low level of genetic diversification among the populations of V. nashicola in Korea.

Epidemiological Characteristics of Scab of Japanese Apricot in Korea.

Scabs caused by Venturia carpophila greatly reduce the quality of the fruits of the Japanese apricot (Prunus mume) when the disease is not properly managed. The disease produces a superficial blemish that is unlikely to affect the overall yield of processed fruit, but reduce the value of fruit intended for the fresh market. Incidence rates of scab at sprayed and unsprayed orchards range from 0% to 21.5% and from 30.2% to 100%, respectively, in the major cultivation regions of Jeonnam Province during the growing season of 2009. The trends in disease progress were quite similar, regardless of regions, and cultivar Namgo was relatively less damaged by scab compared to cultivar Cheonmae among the tested Japanese apricot cultivars. The fruits on branches 1.5 m above the infected Japanese apricot trees and the stem-end parts of the infected fruits were more severely damaged by scabs, possibly because of rain and run-off facilitate dissemination of conidia of V. carpophila and subsequent infection of the fruits or branches. The conidia of V. carpophila were dispersed from March 24 to April 26 in 2010, and more conidia were dispersed from 2-year-old branches than 1-year-old branches. Since the control efficacies were higher than 90% after more than two applications of Trifloxystrobin WG at 10-day-intervals from mid April, it is that effective fungicides be applied at least two times at 10-day-intervals from the middle of April to manage scabs of Japanese apricot in orchards.

Occurrence and Epidemics of Bacterial Canker of Kiwifruit in Korea.

Bacterial canker is the largest limiting factor in the cultivation and production of kiwifruit worldwide. Typical symptoms comprise necrotic spots on leaves, canker and dieback on canes and trunks, twig wilting, and blossom necrosis. Pseudomonas syringae pv. actinidiae (Psa), which is the causal agent of kiwifruit bacterial canker, is divided into four biovars based on multilocus sequence analysis of different genes, additional PCR testing of pathogenic genes (argKtox cluster, cfl, and various effector genes), and biochemical and physiological characterization. Bacterial canker caused by Psa biovar 2 designated Psa2 was detected for the first time on the green-fleshed kiwifruit cultivar Hayward in 1988 and the yellow-fleshed kiwifruit cultivar Hort16A in 2006 in Korea. Psa biovar 3 designated Psa3, responsible for the current global pandemics of kiwifruit bacterial canker, began to appear in Korea in 2011 and caused tremendous economic losses by destroying many vines or orchards of yellow-fleshed kiwifruit cultivars in one or several growing seasons. Bacterial canker epidemics caused by both Psa2 and Psa3 are prevalent in Korea in recent years. In this review, we summarize the symptomatology, etiology, disease cycle, diagnosis, and epidemiology of kiwifruit bacterial canker in Korea.

Incidence Rates of Major Diseases of Kiwiberry in 2015 and 2016.

Incidence rates of diseases in kiwiberry orchards were investigated monthly from late June to late September in Gwangyang and Boseong in 2015 and 2016. The impact of postharvest fruit rot was investigated during ripening after harvest. Bacterial canker was only observed on one single tree in 2015, but black rot, powdery mildew, leaf spot and blight, and postharvest fruit rot diseases were problematic throughout the study period in both 2015 and 2016. Incidence rates of the diseases varied with kiwiberry cultivar, region and sampling time. Incidence rates of powdery mildew, leaf spot and blight diseases increased significantly during the late growing stages near fruit harvest, while black rot peaked in late August. Incidence rate of postharvest fruit rot on fruit without fruit stalks was less than half of fruit with fruit stalks, regardless of kiwiberry cultivars. Among the four cultivars, Mansu was relatively resistant to black rot and postharvest fruit rot diseases. In our knowledge, this is the first report of various potential pathogens of kiwiberry in Korea.

Development of Carrot Medium Suitable for Conidia Production of Venturia nashicola.

The causal fungus of pear scab, Venturia nashicola, grows slowly and rarely produces conidia on artificial media in the laboratory, but it produced conidia on the Cheongah medium containing Cheongah powder. V. nashicola grew too slow to produce conidia until 15 days after cultivation but produced conidia with 4 × 104 conidia/plate 30 days after cultivation on the Cheongah medium containing 1% Cheongah powder. V. nashicola showed a peak production of conidia with 4.5 × 105 conidia/plate 60 days after cultivation on the carrot medium containing 2% carrot powder, one of the constituents of Cheongah powder. The carrot medium is considered to be the best medium to obtain conidia of V. nashicola in the laboratory until now. This is the first report on the development of a suitable medium for conidia production of V. nashicola, as far as we know.

Outbreak and Spread of Bacterial Canker of Kiwifruit Caused by Pseudomonas syringae pv. actinidiae Biovar 3 in Korea.

A bacterial pathogen, Pseudomonas syringae pv. actinidiae (Psa), is a causal agent of kiwifruit bacterial canker worldwide. Psa biovar 3 (Psa3) was first detected in 2011 at an orchard in Dodeok-myeon, Goheunggun, Jeonnam Province in Korea. In this study, we present the results of an epidemiological study regarding Psa3 occurrence on kiwifruit orchards in Korea for the period of 2013 to 2015. Since the first detection of Psa3 in 2011, there was no further case reported by 2013. However, Psa3 was rapidly spreading to 33 orchards in 2014; except for three orchards in Sacheonsi, Gyeongnam Province, most cases were reported in Jeju Island. Entering 2015, bacterial canker by Psa3 became a pandemic in Korea, spreading to 72 orchards in Jeju Island, Jeonnam, and Gyeongnam Provinces. Our epidemiological study indicated that the first Psa3 incidence in 2011 might result from an introduction of Psa3 through imported seedlings from China in 2006. Apart from this, it was estimated that most Psa3 outbreaks from 2014 to 2015 were caused by pollens imported from New Zealand and China for artificial pollination. Most kiwifruit cultivars growing in Korea were infected with Psa3; yellow-fleshed cultivars (Yellow-king, Hort16A, Enza-gold, Zecy-gold, and Haegeum), red-fleshed cultivars (Hongyang and Enza-Red), green-fleshed cultivars (Hayward and Daeheung), and even a kiwiberry (Skinny-green). However, susceptibility to canker differed among cultivars; yellow- and red-fleshed cultivars showed much more severe symptoms compared to the green-fleshed cultivars of kiwifruit and a kiwiberry.

Development of Specific Markers for Identification of Biovars 1 and 2 Strains of Pseudomonas syringae pv. actinidiae.

Pseudomonas syringae pv. actinidiae, the causal agent of canker in kiwifruit, can be divided into three biovars (biovars 1, 2, and 3). Strains belonging to biovar 1 produce phaseolotoxin and were isolated in Japan and Italy before 2008. Strains of biovar 2 produce coronatine instead of phaseolotoxin and have been isolated only in Korea. Strains belonging to biovar 3 produce neither phaseolotoxin nor coronatine and are responsible for the global outbreak of bacterial canker of kiwifruit in recent years. The biovar 3-specific primer set was developed in a previous work. In this study, two sets of PCR primers specific to strains of biovars 1 and 2, respectively, were developed based on random amplified polymorphic DNA analyses. Primers PsaJ-F and PsaJ-R produced a 481-bp region with genomic DNA of biovar 1 strains, whereas primers PsaK-F and PsaK-R amplified a 413-bp region present only in the genome of biovar 2 strains.

Isolation and Characterization of Bacteriophages Against Pseudomonas syringae pv. actinidiae Causing Bacterial Canker Disease in Kiwifruit.

Pseudomonas syringae pv. actinidiae causes bacterial canker disease in kiwifruit. Owing to the prohibition of agricultural antibiotic use in major kiwifruit-cultivating countries, alternative methods need to be developed to manage this disease. Bacteriophages are viruses that specifically infect target bacteria and have recently been reconsidered as potential biological control agents for bacterial pathogens owing to their specificity in terms of host range. In this study, we isolated bacteriophages against P. syringae pv. actinidiae from soils collected from kiwifruit orchards in Korea and selected seven bacteriophages for further characterization based on restriction enzyme digestion patterns of genomic DNA. Among the studied bacteriophages, two belong to the Myoviridae family and three belong to the Podoviridae family, based on morphology observed by transmission electron microscopy. The host range of the selected bacteriophages was confirmed using 18 strains of P. syringae pv. actinidiae, including the Psa2 and Psa3 groups, and some were also effective against other P. syringae pathovars. Lytic activity of the selected bacteriophages was sustained in vitro until 80 h, and their activity remained stable up to 50°C, at pH 11, and under UV-B light. These results indicate that the isolated bacteriophages are specific to P. syringae species and are resistant to various environmental factors, implying their potential use in control of bacterial canker disease in kiwifruits.

Outbreaks of Yuzu Dieback in Goheung Area: Possible Causes Deduced from Weather Extremes.

Starting in 2012, severe diebacks usually accompanied by abundant gum exudation have occurred on yuzu trees in Goheung-gun, Jeonnam Province, where severely affected trees were occasionally killed. On-farm surveys were conducted at 30 randomly-selected orchards located at Pungyang-myeon, Goheung-gun, and the resulting disease incidences were 18.5% and 39.6% for dieback and gumming symptoms, respectively. Black spots on branches and leaves also appeared on infected trees showing a typical dieback symptom. Morphological and molecular identifications of the isolated fungal organisms from lesions on the symptomatic leaves and branches revealed that they are identical to Phomopsis citri, known to cause gummosis. In order to find the reason for this sudden epidemic, we investigated the weather conditions that are exclusively distinct from previous years, hypothesizing that certain weather extremes might have caused the severe induction of pre-existing disease for yuzu. There were two extreme temperature drops beyond the yuzu's cold hardiness limit right after an abnormally-warm-temperature-rise during the winter of 2011-12, which could cause severe frost damage resulting in mechanical injuries and physiological weakness to the affected trees. Furthermore, there was an increased frequency of strong wind events, seven times in 2012 compared to only a few times in the previous years, that could also lead to extensive injuries on branches. In conclusion, we estimated that the possible damages by severe frost and frequent strong wind events during 2012 could cause the yuzu trees to be vulnerable to subsequent fungal infection by providing physical entries and increasing plant susceptibility to infections.

Molecular Characteristics of Pseudomonas syringae pv. actinidiae Strains Isolated in Korea and a Multiplex PCR Assay for Haplotype Differentiation.

The molecular features of Pseudomonas syringae pv. actinidiae strains isolated in Korea were compared with strains isolated in Japan and Italy. Sequencing of eight P. syringae pv. actinidiae and three P. syringae pv. theae strains revealed a total of 44 single nucleotide polymorphisms across 4,818 bp of the concatenated alignment of nine genes. A multiplex PCR assay was developed for the detection of P. syringae pv. actinidiae and for the specific detection of recent haplotype strains other than strains isolated since the 1980s in Korea. The primer pair, designated as TacF and TacR, specifically amplified a 545-bp fragment with the genomic DNA of new haplotype of P. syringae pv. actinidiae strains. A multiplex PCR conducted with the TacF/TacR primer pair and the universal primer pair for all P. syringae pv. actinidiae strains can be simultaneously applied for the detection of P. syringae pv. actinidiae and for the differentiation of new haplotype strains.

The lichen genus sticta in South Korea.

Sticta (Schreber.) Ach. is one of the common lichen genera in tropical and subtropical regions, but not in the Korean Peninsula. For almost two decades, no detailed taxonomic or revisionary study has been done on this genus. This study was based on the specimens deposited in the lichen herbarium at the Korean Lichen Research Institute, and the samples were identified on the basis of recent literature. In this revisionary study, a total of eight species of Sticta, including a newly recorded one are documented. These species include Sticta fuliginosa (Dicks.) Ach., Sticta gracilis (Müll. Arg.) Zahlbr., Sticta limbata (Sm.) Ach., Sticta nylanderiana Zahlbr., Sticta sublimbata (J. Steiner) Swinscow & Krog, Sticta weigelii (Ach.) Vain., Sticta wrightii Tuck., and Sticta yatabeana Müll. Arg. Detailed descriptions of S. nylanderiana, S. sublimbata, S. weigelii, and S. yatabeana with their morphological, anatomical, and chemical characteristics are provided. A key description of all known Sticta species of the Korean Peninsula is also presented.

Coffee consumption and bone mineral density in korean premenopausal women.

BACKGROUND: Although Asian people are known to have lower bone mass than that of Caucasians, little is known about coffee-associated bone health in Asian. This study aimed to assess the relationship between coffee consumption and bone mineral density (BMD) in Korean premenopausal women. METHODS: Data were obtained from the Fourth Korea National Health and Nutrition Examination Survey 2008-2009. The study population consisted of 1,761 Korean premenopausal women (mean age 36 years) who were measured for lumbar spine and femoral neck BMD and who completed a standardized questionnaire about coffee intake frequency. We excluded the participants who took hormone replacement therapy or medication for osteoporosis. The cross-sectional relationship between coffee consumption and impaired bone health (osteopenia or osteoporosis) was investigated by bone densitometry. RESULTS: Coffee consumption showed no significant association with BMD of either femoral neck or lumbar spine, independent of other factors. The adjusted odds ratios for BMD for those who consumed once in a day, twice a day and three times a day were 0.94 (0.70-1.26), 0.93 (0.67-1.28), and 1.02 (0.69-1.50), respectively (P for trend = 0.927). CONCLUSION: This study does not support the idea that coffee is a risk factor for impaired bone health in Korean premenopausal women.

Functional characterization of the sucrose isomerase responsible for trehalulose production in plant-associated Pectobacterium species.

Fifty-three plant-associated microorganisms were investigated for their ability to convert sucrose to its isomers. These microorganisms included one Dickeya zeae isolate and 7 Enterobacter, 3 Pantoea, and 43 Pectobacterium species. Eleven out of the 53 strains (21%) showed the ability to transform sucrose to isomaltulose and trehalulose. Among those, Pectobacterium carotovorum KKH 3-1 showed the highest bioconversion yield (97.4%) from sucrose to its isomers. In this strain, the addition of up to 14% sucrose in the medium enhanced sucrose isomerase (SIase) production. The SIase activity at 14% sucrose (47.6 U/mg dcw) was about 3.6-fold higher than that of the negative control (13.3 U/mg dcw at 0% sucrose). The gene encoding SIase, which is comprised a 1776 bp open reading frame (ORF) encoding 591 amino acids, was cloned from P. carotovorum KKH 3-1 and expressed in Escherichia coli. The recombinant SIase (PCSI) was shown to have optimum activity at pH 6.0 and 40 °C. The reaction temperature significantly affected the ratio of sucrose isomers produced by PCSI. The amount of trehalulose increased from 47.5% to 79.1% as temperature was lowered from 50 °C to 30 °C, implying that SIase activity can be controlled by reaction temperature.

Lichen mycota in South Korea: the genus usnea.

Usnea Adans. is a somewhat rare lichen in South Korea, and, in nearly two decades, no detailed taxonomic or revisionary study has been conducted. This study was based on the specimens deposited in the lichen herbarium at the Korean Lichen Research Institute, and the samples were identified using information obtained from recent literature. In this study, a total of eight species of Usnea, including one new record, Usnea hakonensis Asahina, are documented. Detailed descriptions of each species with their morphological, anatomical, and chemical characteristics are provided. A key to all known Usnea species in South Korea is also presented.

Notes on the lichen genus hypotrachyna (parmeliaceae) from South Korea.

Hypotrachyna (Vainio) Hale is a somewhat rare lichen genus found on the Korean Peninsula. Since it was first recorded more than two decades ago, no detailed taxonomic or revisionary study of the genus has been conducted. Thus, the present study was conducted to carry out a detailed taxonomic and revisionary study of Hypotrachyna in South Korea. This study was based on specimens deposited in the Korean Lichen Research Institute (KoLRI). Detailed taxonomic studies and a literature review confirmed the presence of seven species of Hypotrachyna from South Korea, including one new record, Hypotrachyna nodakensis (Asahina) Hale. Descriptions of each species with their morphological, anatomical and chemical characters together with a key to all known Hypotrachyna species are presented.