V. vulnificus는 그람음성의 호염성균으로 감염 되었을 경우, 복통과 발열 등의 급성 위장염을 일으키며 만성질환자에게 급성 패혈증을 일으키는 매우 높은 치사율의 식중 독균이다. 식품 중에서 V. vulnificus를 분석하는 방법으로 는 TCBS agar와 같은 선택배지를 이용하는 방법과 PCR 을 이용한 방법이 있으나 온도, 염 및 pH 등과 같은 환경요인에 민감한 V. vulnificus의 특성을 고려하였을 때 정확한 균수 정량을 위한 정량분석법 확립의 필요성이 요구된 다. 본 연구에서는 배지 및 염 차이에 따른 V. vulnificus 생육 특성 차이에 대한 연구를 진행하였다. 그 결과, V. vulnificus 균수 정량분석에 APW 증균 배양을 이용한 MPNPCR 방법이 적합하였다. 본 연구에서 제시된 방법은 해수뿐만 아니라 어패류 등의 시료에서 V. vulnificus 균수 정 량분석에 유용하게 사용될 것으로 기대된다.

We discuss the influence of few-walled carbon nanotubes (FWCNTs) treated with nitric acid and/or sulfuric acid on field emission characteristics. FWCNTs/tetraethyl orthosilicate (TEOS) thin film field emitters were fabricated by a spray method using FWCNTs/TEOS sol one-component solution onto indium tin oxide (ITO) glass. After thermal curing, they were found tightly adhered to the ITO glass, and after an activation process by a taping method, numerous FWCNTs were aligned preferentially in the vertical direction. Pristine FWCNT/TEOS-based field emitters revealed higher current density, lower turn-on field, and a higher field enhancement factor than the oxidized FWCNTs-based field emitters. However, the unstable dispersion of pristine FWCNT in TEOS/N,N-dimethylformamide solution was not applicable to the field emitter fabrication using a spray method. Although the field emitter of nitric acid-treated FWCNT showed slightly lower field emission characteristics, this could be improved by the introduction of metal nanoparticles or resistive layer coating. Thus, we can conclude that our spray method using nitric acid-treated FWCNT could be useful for fabricating a field emitter and offers several advantages compared to previously reported techniques such as chemical vapor deposition and screen printing.

We present the effect of a coupling agent on the optoelectrical properties of few-walled carbon nanotube (FWCNT)/epoxy resin hybrid films fabricated on glass substrates. The FWCNT/epoxy resin mixture solution was successfully prepared by the direct mixing of a HNO3-treated FWCNT solution and epoxy resin. FWCNT/binder hybrid films containing different amounts of the coupling agent were then fabricated on UV-ozone-treated glass substrates. To determine the critical binder content (Xc), the effects of varying the binder content in the FWCNT/silane hybrid films on their optoelectrical properties were investigated. In this system, the Xc value was approximately 75 wt%. It was found that above Xc, the coupling agent effectively decreased the sheet resistance of the films. From microscopy images, it was observed that by adding the coupling agent, more uniform FWCNT/binder films were formed.

The synthetic methods for high yield of multiwalled carbon nanotube (MWNT) and singlewalled carbon nanotube (SWNT) with high purity by arc discharge have been investigated. MWNTs were synthesized under different pressures of helium and the gas mixture of argon and hydrogen. Relatively high pressure of 300-400 torr was required for high yield MWNTs synthesis at low bias voltage of about 20 V and 55 A, whereas low pressure of about 100 torr was required for SWNTs. The introduction of hydrogen gases during the synthesis of MWNTs improved the yield and purity of the samples. The SWNTs were synthesized by the assistance of a small amount of mixture of transition metals, which played as a catalyst during the formation process. The purity and yield of SWNTs were higher at a lower pressure and enhanced by mixing more components of the transition metals.

Plant breeding requires genetic diversity of useful traits for crop improvement. EMS-induced mutation is practiced to generate mutations at loci regulating economically important traits and/or to knock out the genes to elucidate their functions. The present study was aimed to induce mutations in a Korean local land race Capsicum annuum ‘Yuwol-cho’. This accession is pungent and also has advantage to mature early. A total of about 1,500 M2 families were screened and three non-pungent mutants were identified and crossed with wild type ‘Yuwol-cho’. After phenotyping of F2 population for pungency, MutMap approach will be used to identify the genes controlling the pungency in mutants. In addition to this, another C. annuum accession “Micro-Pep” was used to develop a mutant population. Micro-Pep is a small, pungent pepper generally used as ornamental purpose. Having compact growth habit, and small size, it has advantage to handle and utilize easily in mutation study and molecular research. On the basis of preliminary experiment 1.3% of mutagen was used for treatment of pepper seeds and 30% less germination percentage was observed in EMS treated seeds in comparison to control seeds. A total of 4,674 M1 plants are grown under greenhouse condition and M2 population will be studied for characterization of phenotypic variation including fruit color and pungency. Newly constructed mutant populations will be valuable assets for identification of functional genes and molecular breeding of pepper.

Next-generation sequencing (NGS) technology and fast improvement in plant genetics have elevated to massive development of molecular genetic markers through fast analysis of huge molecular biological data. Furthermore, in domestic commercial breeding of horticultural crops, the application of marker assisted breeding (MAB) has been introduced recently. For effective improvement of cultivar breeding, in this research, transcriptome analysis and single nucleotide polymorphism (SNP) comparison with high density pepper map in UC-DAVIS were performed using four lines of Capsicum annuum and C. chinense. For rapid analysis of MAB of tolerant pepper lines, 412 Fluidigm probes were newly designed in this study. These designed probes and SSR and COSII markers were applied for background selection through the MAB program. In addition, powdery mildew (PM), tomato spot wilt virus (TSWV) resistance related markers were subjected to foreground selection of BC1, BC2, and BC3 progenies. The MAB system using Fluidigm probes, and trait-related and common markers was introduced into domestic pepper breeding, which will rapidly approach to a new elite line and a commercial tolerant cultivar.

Capsinoids which were found recently in non-pungent pepper show the same biological effects as capsaicinoid including anticancer and anti-obesity. A precursor of capsaicinoids, vanillyl alcohol, is known to be produced by mutations in the p-aminotransferase (pAMT) gene. In the previous study, we showed that capsinoid production is also controlled by the capsaicin synthase (CS) gene. However correlation between the CS gene expression and capsinoids contents has not been fully understood. This study was conducted to elucidate correlation between the expression level of CS gene and capsinoids contents. Through germplasm screening, we identified one C. chinese pepper cultivar, SNU11-001, which contained capsinoids as much as C. annuum ‘CH-19 Sweet’. SNU11-001 was crossed with five Capsicum cultivars (ECW, Takanotsume, Yuwolcho, Habanero and Jolokia) containing different levels of capsaicin, ‘ECW’ is non-pungent pepper line, and ‘Takanotsume’ and ‘Yuwolcho’ have mild pungency, and ‘Habanero’ and ‘Jolokia’ is known to be included in the most pungent pepper lines. When we analyzed the expression of CS and pAMT genes using the six Capsicum cultivars, the expression levels of CS were higher in pungent Capsicum cultivars. To test whether the expression levels of CS also control capsinoids contents, we will analyze several F2 populations derived from crosses between SNU11-001 and Capsicum cultivars containing different levels of capsaicin.

Capsicum diversity is getting lower in modern crops because of the genetic erosion. In Capsicum, breeders have been mainly focused on agriculturally important traits such as disease resistances, high yield and pungency. However, this narrow breeding pool hampered to develop improved cultivars. It has become a hot issue to conservation of genetic diversity and exploitation of wild germplasm in Capsicum. Analysis of genetic diversity and construction of core collection is the first step to make efficient use of germplasm. Although there have been several attempts to construct core collections in Capsicum, most of these works were limited due to handling small number of samples, relying mainly on the characterization of morphological traits or focusing only C. annuum species. To expand understanding of the structure and genetic diversity of germplasm in Capsicum, we need to have a highly efficient genotyping tool to handle large number of samples. Toward this end, we are analyzing 3,599 germplasm accessions including other cultivated species and wild species in Capsicum with 48 single nucleotide polymorphism (SNP) markers.

Mutant lines induced by ethyl methane sulfonate (EMS) have been used for crop improvement and functional genomics. Since pepper is very recalcitrant to be transformed, EMS mutagenesis could be an alternative method to generate useful mutant lines and to characterize the function of genes. We have developed mutant lines consisting of about 3,938 M2 mutant lines using Korea local landrace, C. annuum ‘Yuwolcho’. Yuwolcho has suitable traits for mutagenesis such as early flowering and maturation, large number of seeds per fruit, and susceptibility to various diseases. Up to now, 917 M2 mutant lines were evaluated to confirm the effect of EMS. M2 mutant lines have shown variations in plant stature (small size, dwarfism, and early death), leaf development (light color, variegation and morphological change) and flower (inflorescence, morphological change) and fruit (size and color). We observed the largest morphological variation in leaf development. Most of these mutant phenotypes were inherited recessively. In addition, we are applying cel1-based TILLING to identify useful mutant lines. We will apply cel1-based TILLING to identify useful mutant lines. We are expecting that these mutant lines will be very useful to study the function of genes in C. annuum.

In pepper, investigation of important traits such as disease resistances, high yield and pungency were mostly focused on a cultivated species, Capsicum annuum. This narrow breeding pool hampered to develop improved cultivars. Exploitation of wild germplasm in Capsicum has been recognized as an important issue. The construction of core collection and analysis of genetic diversity in Capsicum is the first step to make full use of germplasm. Although there have been several attempts to construct core collections in Capsicum, most of the works were limited due to handling small number of samples, relying mainly on the characterization of morphological traits and focusing on C. annuum species. Therefore, the comprehensive studies for genetic diversity and structure of Capsicum including phenotypic data, molecular marker patterns and evaluation of useful alleles are very necessary to understand the structure and patterns of genetic diversity in Capsicum. We are developing for a core collection set in Capsicum using molecular markers and phenotypic data with over 3,000 germplasm accessions.

The Korean people consume a lot of hot peppers. Despite its popularity and importance, genetic mechanism determining the content of capsaicinoid has not been understood yet. Since the inheritance of capsaicinoid content is thought to be controlled by quantitative trait loci (QTLs), a well-constructed genetic population and well-organized approach method to study genetic inheritance are required. Here we show the scheme to find the QTLs controlling capsaicinoid content using a recombinant inbred lines (RILs) obtained from a cross between C. annuum, Perennial and C. annuum, Dempsey. We measured capsaicinoid contents of each line for QTL analysis. In addition, total 24 qualitative and quantitative traits of RILs were phenotyped. Phenotyping data can be used to construct another QTL map controlling agricultural trait. An ultra high density linkage map constructed by sequencing RILs will used for QTL nalaysis. We are expecting that this study will be useful to breed high-quality and pungent pepper cultivars by molecular breeding method.

Mutant populations generated by ethyl methanesulfonate (EMS) have been used for crop improvement and functional genomics. Since pepper is very recalcitrant to be transformed, EMS mutagenesis can be a very useful to generate useful alleles and to characterize the function of genes. We have been developing a mutant population aiming at 5,000 mutants by treating EMS on seeds of C. annuum ‘Yuwolcho’. A total of 4,300 M1 mutants have been developed until now. Among the 4,300 M1 population, almost 800 M2 mutant lines have been phenotyped and evaluated to confirm the effect of EMS. We categorized seven key organ development and subdivided them into twenty secondary categories. Among them, 50 and 72 families have been shown variations in plant growth and leaf development, respectively. In addition, we detected nucleotide variations using HRM analysis in eIF4E and putative aminotransferase genes. These results demonstrated that our mutant population can be very useful for study function of genes in near future.