Anthocyanins, providing the bright red-orange to blue-violet colors, flavonoid-derived pigments with strong antioxidant activity that have benefits for human health. We isolated RsMYB1, which encodes an R2R3 MYB transcription factor (TF), from red radish plants (Raphanus sativus L.) that accumulate high levels of anthocyanins. RsMYB1 shows higher expression in red radish than in common white radish, in both leaves and roots, at different growth stages. regulatory genes. Transient expression of RsMYB1 in tobacco showed that RsMYB1 is a positive regulator of anthocyanin production. Also, the synergistic effect of RsMYB1 with B-Peru was larger than the effect of Arabidopsis plants stably expressing RsMYB1 produced red pigmentation throughout the plant, accompanied by up-regulation of the six structural and two regulatory genes for anthocyanin production. This broad transcriptional activation of anthocyanin biosynthetic machinery in Arabidopsis included up-regulation of TRANSPARENT TESTA 8, which encodes a bHLH-type TF. These results suggest that overexpression of RsMYB1 promotes anthocyanin production by triggering the expression of endogenous bHLH genes as potential binding partners for RsMYB1. In addition, RsMYB1-overexpressing Arabidopsis plants had a higher antioxidant capacity than did non-transgenic control plants. Taken together, RsMYB1 is an actively positive regulator for anthocyanins biosynthesis in radish plants and it might be one of the best targets for anthocyanin production by single gene manipulation being applicable in diverse plant species.

For purposes of studying intron structures and predicting consensus splice motifs, a total of 102 legume species were used to isolate introns across the family. Of 196 gene-targeted PCR primer pairs, we successfully amplified 118 intron-containing genes (60.2%) and obtained a total of 1,870 introns with an average size of 143 nucleotides. Species-based compilation of 5’- and 3’-splicing motifs showed lineage-specific conservation in each splicing motif. Compilation of the entire intron set permitted prediction of the consensus sequences of splicing signal motifs in legumes, AYGWGTABABGH and TVNC/TAGGHTV for the 5’- and 3’-splicing motifs, respectively. Interestingly, these consensus motifs are very similar to the corresponding splicing signals of two model systems, Arabidopsis and rice. This result is suggestive of conservation of pre-mRNA splicing mechanisms in higher plants. Multiple alignments of CALTL introns demonstrated that the region from the branch point to 3’ splice site was relatively more conserved than the region from5’ splice site to the branch point. Phylogenetic analysis demonstrated that each of three splicing motifs, 5’-splice sites, 3’-splice sits, and branch site, was relevant to evolutionary divergence of species and phylogenetically informative, suggesting that splice signal sequences would be useful as a potential tool for the molecular phylogenetic analysis.

Natural and artificially induced mutants have provided valuable resources for plant genetic studies and crop improvement. Some variations induced in the process of plant transformation have often been observed in regenerated plants. In this study, we investigated the insertion number of transgene and the flanking sequences of T-DNA in tall-induced line BP23, which was unexpectedly gained in the process of transformation of insect-resistant rice with cryBP1 gene, and also analyzed the whole-genome sequencing by using the NGS technologies to gain a better understanding of the sequence and structural changes between tall line or natural cultivar and rice reference. than others, was confirmed with two copies of foreign gene insertion, which was inserted in one genomic site facing each other between the position 2,430,152~2,430,151 of rice chromosome 12 without any deletion of genomic sequences. Sequencing analysis also revealed that 18bp-unknown sequences were added in the 5′ insertion site of T-DNA. This position in rice genome was confirmed with none of expressed gene sites. By the NGS analysis, we detected 86560 SNPs and 1091/1472 large insertion/deletion (indel) sites (100bp) between BP23 and rice reference, and 84743 SNPs and 1094/1451 large indels between natural cultivar Nagdong and rice reference. The possible mechanisms for the gene mutation, the developmental and tissue expression of the taller height in BP23 line may need to be scrutinized a few more.

Chrysanthemum (Chrysanthemum morifolium) is one of the most popular ornamental species in the world due to the great diversity of inflorescence form and color. There has been increasing demands for various types of chrysanthemums, such as cut flowers, potted plants and bedding plants. However, the genomic studies of this species have been not extensively conducted relative to other ornamental species due to high levels of polyploidy (2n = 4x =36 or 2n = 6x = 54) and heterozygosity as well as large genome size. In this work, we developed a molecular tool for cultivar identification using simple sequence repeats (SSRs) and investigated genetic diversity in 127 chrysanthemum cultivars. Of the 150 SSR primer pairs tested in this study, 62 primers were obtained from previous studies, while 88 primers were designed using the unigene sequences of C. nankingense and the Expressed Sequence Tag (EST) sequences of C. morifolium in the NCBI database. Thirty SSR primers were selected based on polymorphism and banding patterns in a subset of 8 cultivars and used to amplify the DNA of 127 chrysanthemum cultivars. The UPGMA dendrogram based on these 30 SSR markers showed that most of chrysanthemum cultivars were divided into five clusters. These results will benefit chrysanthemum research community to develop elite cultivars.

Citrus canker caused by Xanthomonas citri is a notorious disease affecting a decrease in fruit productivity and quality. Citrus export to USA is also prohibited by the disease. Therefore, development of citrus canker resistant variety is essential and exploitation of markers for molecular breeding is urgent. To develop DNA molecular markers, we performed whole genome resequencing for 8 varieties: 4 citrus canker resistant varieties including C. hybrid ‘Kioymi’ and 4 citrus canker susceptible varieties including C. iyo ‘Miyauchiiyokan’. In total, 642 polymorphic SNPs were detected between resistant and susceptible varieties. Of the 642 SNPs, 50 SNPs were preferably selected based on integrative genomics viewer. To apply the markers in a broad range of citrus variety, we performed genotyping with 6 other varieties very well known as citrus canker resistant and susceptible varieties in addition to previous mentioned 8 varieties. Three of the 50 SNPs were identified as a marker to distinguish citrus canker resistant varieties from susceptible varieties. Secondly, we developed molecular markers to apply for F1 lines crossed by ‘Kiyomi’ and ‘Miyauchiiyokan’. Of the 50 SNPs, we identified 2 SNP markers to distinguish between F1 resistant and susceptible lines. One of them is a resistance gene that plays a role in plant defense mechanism. In this study, we developed 5 molecular marker candidates possible to apply for molecular breeding to develop citrus canker resistant variety. We are working on development of candidate markers related to citrus canker.

The plant-specific transcription factor, LEAFY (LFY) is considered to be a master regulator of flower development in the model plant, Arabidopsis. This protein plays a dual role in plant growth, integrating signals from the floral inductive pathways and acting as a floral meristem identity gene by activating genes for floral organ development. Although LFY occupies an important position in flower development, the functional divergence of LFY homologues has been demonstrated in several plants including monocots and gymnosperms. In particular, the functional roles of LFY genes from orchid species such as Phalaenopsis that contain unique floral morphologies with distinct expression patterns of floral organ identity genes remain elusive. Here, PaLFY, a orthologue of Arabidopsis LFY from Phalaenopsis aphrodite subsp. formosana, a Taiwanese native monopodial orchid was isolated and characterized through analyses of expression and protein activity. PaLFY transcripts accumulated in the floral primordia of developing inflorescences and the PaLFY protein had transcriptional autoactivation activity forming as a homodimer. Furthermore, PaLFY rescues the aberrant floral phenotypes of Arabidopsis lfy mutants. Over-expression of PaLFY alone or together with PaFT1, a P. aphrodite subsp. formosana homologue of Arabidopsis FLOWERING LOCUS T (FT) in rice caused precocious heading. Consistently, higher chlorophyll content in the sepals and morphological changes in epidermal cells were observed in the floral organs of PaLFY knock-down orchids generated by virus-induced gene silencing. Taken together, these results suggest that PaLFY is functionally distinct from RICE FLORICAULA/LEAFY (RFL) but similar to Arabidopsis LFY based on phenotypes of our transgenic Arabidopsis and rice plants.

The transposable element is a DNA sequence that can be changed its position within the genome, sometimes it can create or reverse mutations and altering the cell's genome size. Target region amplification polymorphism (TRAP) is a rapid and efficient PCR-based marker technique, which uses bioinformatics tools and expressed sequence tag (EST) database information to generate polymorphic markers around targeted candidate gene sequences. TE-TRAP is a new marker system which used terminal inverted repeat (TIR) instead of targeted candidate gene sequences. Sorghum holds a good potential plant organism for transposon tagging due to its small genome size, low amount of repetitive DNA and co-linearity with other cereal genomes, which allows the use of information derived from sorghum in other cereal grasses. IS2868 of sorghum accession was treated Gamma irradiation on seed. To define availability and utilization of TE-TRAP, twenty-one accessions were used to evaluate the genetic diversity and underlying relationships. One-thousand thirty-three TE-TRAP markers were amplified by thirty-one primer combination. Altogether, 712 (62.8%) markers were observed polymorphic segregation, whereas 421 (37.2%) showed monomorphic patterns. To estimate genetic differentiation of population by various gamma radiation doses, the analysis of molecular variance (AMOVA) was performed using 4 to 5 different radiation doses population of M1 sorghum individuals. This study and marker system will provide valuable information to assist radiation mutation breeding.

Grain weight is the most important target not only as a major component of grain yield, but also of the cooking qualities in rice breeding program. In a previous study, a high-resolution physical map targeting a cluster of yield-related QTLs for grain weight, spikelets per panicle has been constructed using series of BC3F4 nearly isogenic lines (NILs) derived from a cross between the Korean japonica cultivar Hwaseong and O. rufipogon. The QTLs including grain weight trait have been mapped in a 25.5kb region containing three genes. Based on GenBank database, these genes include male sterility 5 (OsMs5, LOC_Os09g36740), similar ascorbate peroxidase (OsApx, LOC_Os09g36750) and glutelin family protein (OsGlu, LOC_Os09g36760). Their endogenous expression patterns were analyzed in various rice tissues (2-week seedling, flag leaf, root and panicle) from the parental lines, Hwaseong and NIL-gw9. Semi-quantitative RT-PCR and qRT-PCR were performed using gene specific primer sets. The cDNAs of the similar OsApx gene of Hwaweong and NIL-gw9 were cloned. Over-expression and RNAi knock-down transgenic plants using three genes are under construction for the functional characterization of the genes. The results will be discussed.

Regulation of fruit ripening may help extend fruit shelf life and prevent losses due to spoilage. Here, we investigated whether sound treatment could delay tomato fruit ripening. We treated harvested tomato fruits with low-frequency sound waves (1 kHz) for 6 h, and then monitored various characteristics of the fruits over 14-day period at 23±1°C. Seven days after the treatment, 85% of the treated fruits were green, versus fewer than 50% of the non-treated fruits. Most of the tomato fruits had switched to the red ripening stage by 14 days after treatment. Ethylene production and respiration rate were lower in the treated than non-treated tomatoes. Furthermore, changes in surface color and flesh firmness were delayed in the treated fruits. To investigate how sound wave treatment affects fruit ripening, we analyzed the expression of ethylene-related genes by quantitative real-time RT-PCR analysis. We found that the expression level of several ethylene biosynthetic and ethylene signaling pathway-related genes was influenced by sound wave treatment. These results demonstrate that sound wave treatment delays tomato fruit ripening by altering the expression of important genes in the ethylene biosynthesis and ethylene signaling pathways.

Major loci controlling flowering time and maturity of short-day plant soybean, E1, E2, E3, E4, E5, E6, E7 and E8, have been identified in soybean. The gene corresponding to E2 locus is a homolog of Arabidopsis GIGANTEA (AtGI). We identified three GI homologs in soybean and are verifying their roles in day-length dependent flowering. Expression anlysis indicated that GmGIs are ubiquitously expressed at all developmental stages of soybean plants. Diurnal expression of GmGIs fluctuates within light/dark cycles of long-day (LD) and short-day (SD). GmGI2 and GmGI3 have identical expression patterns under both day length conditions with the highest peak at zeitgeber time 8 h (ZT8) under LD and at ZT4 under SD. GmGI1 shows the peak at ZT12 under LD and at ZT8 under SD. All of GmGIs exhibit the earlier peak and the shorter phase under SD than LD. The results indicated that day length affects expressions of GmGIs. Subcellular localization analysis showed that GmGIs are mainly targeted to nucleus, similar to the localization of AtGI. Overexpression of GmGIs in Arabidopsis transgenic plants showed no significant effect on flowering time nor rescue of gi-2 mutant phenotype. The results suggested that GmGIs have different molecular functions in flowering time regulation of short-day plant soybean compared to long-day plant Arabidopsis. To investigate the molecular mechanisms of GmGIs’ functions in soybean flowering time control, we intend to identify target gene of GmGIs and interacting proteins by using yeast two-hybrid assay.

This experiment was carried out to enhance plantlet conversion and ex vitro survival of encapsulated somatic embryos of Siberian ginseng. Cotyledonary somatic embryos were encapsulated with 3.0% sodium alginate and 96% of conversion rate in terms of plantlet with well-developed epicotyl marked when the encapsulated embryos were placed on perlite soils wetted with sucrose solution as for carbon source. However, post-germinative growth of encapsulated embryos was suppressed in case of sucrose did not added. Instead of sucrose alone, the addition of both sucrose and starch to the sodium alginate enhanced the post-germinative growth of the embryos. In sodium alginate matrix with 2% sucrose, the survival rate of the encapsulated embryos was more than twice (23.5%) that of ones without sucrose (10.0%). Embryos encapsulated with both 2% sucrose and 1% starch showed the highest percentage (42.1%) of survival rate was shown. In analysis of Iodine staining and starch content in the sodium alginate matrix, the starch component was decomposed when the embryos started to germinte. This result indicated that the carbohydrate treatments (starch and sucrose) in the encapsulation matrix enhanced the survival rate of post-germinative growth of encapsulated embryos in Siberian ginseng.

The high quality of gene set is necessary to study the functional research of genes. Although perilla is cultivated as an oil crop and as a vegetable crop in Asian countries such as Korea, Japan, northeast China and Nepal, the reference genome is absent. To assembly perilla gene set, we sequenced the various tissues of perilla (Perilla citriodora) RNA-seq with Illumina HiSeq platform, generating 548,549,314 short reads. When de novo transcriptome assembly was performed with five samples, 86,396 and 38,413 transcripts were assembled as total and representative transcripts, respectively. Using 1,917,424 proteins at Phytozome ver. 9.1, we annotated the perilla assembled transcripts, and 66,139(76.55%) and 24,030(62.55%) transcripts showed the similarity with known plant proteins (E-value < 1e-10) as total and representative transcripts, respectively. Among the diverse molecular functions, we were interested in the regulatory components, such as transcription factor and transcription regulator. Using this data, we identified 499 transcripts annotated the putative transcription factor differentially expressed transcripts. 165 putative transcription factors were significantly expressed in perilla flower and 121 putative transcription factors in both leaf and flower. This study provides the perilla reference gene set and the understanding of the molecular regulation of transcription factor dependent on the tissue.

Ionizing radiation affects gene expression from plant genomes. To monitor the genome-wide transcriptional changes induced by three types of ionizing radiation, we used the rice RNA sequencing to identify genes that are up- or down-regulated by gamma rays (GAs), proton (PRs) and ion beams (IBs). The Oryza sativa jacalin-like lectin domain containing proteins (OsJAC1) gene was highly induced by GAs, PRs and IBs. OsJAC1 was selected based on the expression patterns of a genome-wide dataset of RNA sequencing. Many jacalin-related lectin genes have been shown to be associated with disease resistance, biotic and abiotic stress signaling. Therefore, we studied its expression pattern in response to different abiotic stress and phytohormone treatments. The expression patterns of OsJAC1 under two different abiotic stress conditions (salt and heat stress) and phytohormones (salicylic acid and methyl jasmonate) were examined. The transcripts of OsJAC1 were significantly induced in response to abiotic stress conditions, including salt and heat treatments. In addition, it was induced in response to the salicylic acid and methyl jasmonate treatments, respectively. To investigate the sub-cellular localization of OsJAC1, the gene was expressed as a fusion protein tagged with GFP, in tobacco leaf epidermis and examined under confocal microscope. The OsJAC1 was clearly localized at the nucleus. These results provide critical insights into the molecular functions of the rice jacalin-like lectin domain containing proteins as receptors of external signals.

Senna tora (L.) Roxb. belongs to Leguminosae and its seeds are usually roasted and boiled in water to produce tea in Korea. Also the plants are well known for the treatment of Hypertension, Hepatitis, Constipation and Conjunctivitis. This study was conducted to investigate the morphological characteristics and pollen germination rates of Senna tora with the aim of genetic mapping of this species. First, we investigated morphological characteristics of domestic and international genotypes containing 51 lines in Korea and 2 lines in China. No significant differences in growth characteristics were observed among 53 genotypes. However, ST-9 line which was collected in Pyung-chang showed high growth rate at the early stage. The flower of Senna tora consists of 5 petals, 10 surgeries (7 main surgeries, 3 small surgeries), 1 pistil, and 5 sepals. After bud emergence, each petal was white in 1-2 days, turn into ivory in a week, then yellow in 8-9 days and finally bloomed in 9-10 days. Although the average flowering times of the plants were July 24, ST9 flowered in July 12. In addition, the flowers of ST9 differed from the flowers of the other genotypes. Flower of ST9 joined together with one another. Therefore, ST9 showing high growth rate at the early stage and unique flowering characteristics was selected to as the paternal line for genetic mapping study. Second, we investigated pollen germination rates for each stage of flower development. Pollen started to germinate at the yellow bud stage and pollen germination rate was highest in the bloomed flower stage. This results show that self-fertilization hardly occurs when the flower is ivory bud stage, and there is no need to use young bud flowers for artificial crossing. This work is intended to serve as the basis for the breeding of new varieties in Senna tora.

Capsinoids, low-pungent compounds, have the same biological effects as capsaicinoids such as anticancer and anti-obesity. A precursor of capsinoids, vanillyl alcohol, is known to be produced by mutations in the putative-aminotransferase (pAMT) gene. In the previous study, ‘SNU11-001’ (Capsicum chinense) containing high levels of capsinoids was identified in germplasm collections of Capsicum. This collection has a unique mutation in the pAMT gene that can cause dysfunction of this gene. In order to develop pepper varieties containing high capsinoids contents, marker-assisted foreground and background selections were performed during backcross breeding. Compared to the conventional backcrossing, marker-assisted backcrossing (MABC) is extremely useful for recovery of a recurrent parent’s genetic background. For foreground selection, plants carrying the pAMT/pamt genotype were selected from a BC1F1 and BC2F1 populations using SCAR markers derived from the unique pAMT mutation of ‘SNU11-001’. To obtain background selection markers, a total of 412 single nucleotide polymorphism (SNP) markers was screened on ‘Shinghong’ parental lines and ‘SNU11-001’ to obtain polymorphic SNP markers. Of the 412 SNP markers, 144 and 204 polymorphic SNP markers evenly distributed in pepper genome were finally selected. BC1F1 and BC2F1 plants carrying the pAMT/pamt genotype were subjected to background selection using the selected marker sets. Multiple genotype analysis was done using a high-throughput genotyping system (EP1TM, Fluidigm®, USA). As a result, one BC1F1 plant 84% similar to the recurrent parent and several BC2F1 plants more than 96% recovery rate of the recurrent parent were selected. Genetic backgrounds of the selected BC2F1 plants were evaluated by the genotype-by-sequencing (GBS) method in order to confirm the background selection results using the SNP marker set. GBS results showed that recovery rate and positions of introgressed segments were well matched between two methods demonstrating MABC can be successfully done with a couple hundred SNP markers.

주요 작물들의 표준유전체, 핵심집단 재분석, 전사체 등의 다양한 NGS 정보가 NCBI와 같은 공개 데이터베이스에 빠르게 축적되고 있다. 현재 NCBI의 SRA(Sequence Read Archive) DB에 등록되어 있는 토마토 유전체(genome) 시퀀싱 데이터만 800건 이상, 파일 크기는 23.5 Tb에 달한다. 그러나 이러한 NGS 데이터로부터 원하는 정보를 추출하기 위해 사용할 수 있는 분석용 대용량 서버 자원 및 빅데이터(big data) 처리 기술이 접목된 생물정보분석 프로그램은 매우 제한적이다. 이에 따라 대용량 서버를 갖추고 있지 않아도 대규모 유전체 데이터를 분석할 수 있도록 Genome Cloud 서버에서 작동하는 웹 기반의 SNP 분석 프로그램을 개발하고, 분석 자동화 컨베이어 QUEUE 시스템을 적용하였다. 이 프로그램은 사용자가 분석하고자 하는 SRA accession을 수집하여 프로그램에 입력하면, 자동으로 NCBI-SRA DB에 접속하여 SRA 파일을 서버로 다운로드하면서 SRA 포맷에서 FASTQ 포맷으로 전환한다. 전환된 FASTQ 파일은 자동으로 SNP 분석 파이프라인에 입력되어 SNP가 추출되고, 결과물은 데이터베이스화 된다. 또한 이 프로그램에는 컨베이어 QUEUE 시스템이 접목되어 IO 버퍼와 같은 시스템 과부하를 막아 효율적으로 분석 파이프라인이 진행된다. 1개 FASTQ 파일이 분석되는 동안, 다음 분석이 진행될 1개 SRA 파일의 다운로드 및 포맷 전환이 자동 진행된다. 위 시스템을 적용하였을 때, 1개 SRA(서열 길이 14Gbp)를 Cloud 서버(16 core CPU, RAM 64Gb 사양)로 다운로드하고 포맷을 전환하는데 약 30분~1시간이 소요되었으며, SNP 분석에는 약 6시간이 소요되었다. Cloud의 장점인 확장성을 적용하여 서버 5대를 병렬로 연결하여 사용할 경우, 500개의 샘플을 한 달 이내에 처리할 수 있을 것으로 예상된다. 현재 약 200여개의 토마토 SRA resequencing 데이터에서 표준유전체 대비 수백만 개의 SNP genotype을 확보하였다. 분석 결과물은 토마토 계통 및 집단 정보를 이용하여 향후 Haplotype, LD 분석 등의 주요 응용 분석을 진행하고, TGsol(http://tgsol.seeders.co.kr)에 데이터베이스로 구축하여 제공하고자 한다.

Powdery mildew disease caused by Leveillula taurica is a serious fungal threat to greenhouse pepper production. In contrast to most epiphytic powdery mildew species, L. taurica is an endophytic fungus which colonizes in the mesophyll tissues of the leaf. In the genus Capsicum, several studies have been conducted to identify resistance sources to L. taurica. In previous studies, five quantitative trait loci (QTLs) for powdery mildew resistance have been identified. An F2 population derived from self-pollination of the commercial cultivar Capsicum annuum ‘PM Singang’ was used for genetic analysis of powdery mildew resistance. Resistance of the F2 plants was tested under the natural environmental conditions. Sporulation intensity on infected leaves was used as a disease scale to assign resistance levels to plants, where 0-5% is Resistant, 6-15% Moderate resistant and 16-100% Susceptible. A total of 83 F2 plants were evaluated for resistance. The results showed that 59 plants were resistant, 10 susceptible and 14 moderately resistant. If we consider MR as S, segregation ratio fitted to a single dominant resistance gene model. In the future study, closely linked molecular marker will be developed and tested to locate this gene. The developed marker will be used to identify the powdery mildew resistance gene.

High yield is the most important trait in various agricultural characteristics. Many approaches to improve yield have been tried in conventional agricultural practice and recently biotechnological tools employed for same goal. Genetic transformation of key genes to increase yield is one way to overcome current limitation in the field. We are producing transgenic soybean plants through high efficient transformation method by introducing all gene member with AT-hook binding domain, hoping to obtain manageable delay of senescence. Many transgenic soybean plants are growing in greenhouse and GMO field, and will be evaluated their senescence and any association with yield increase.

Small RNAs, such as microRNAs (miRNAs) and small interfering RNAs (siRNAs), play crucial roles in post-transcriptional gene silencing (PTGS) in eukaryotes. Small RNAs function cell-autonomously as well as non-cell-autonomously. It has been well characterized that pathogenic fungi secrete some effector molecules facilitating their infection into plants. However, it is unclear whether molecules produced in plant cells are able to move into fungal cells during infection. To test if small RNAs generated from plant cells can move to fungal cells during infection, we generated transgenic Arabidopsis and rice plants expressing siRNAs targeting GFP gene generated from double-stranded RNA interference (dsRNAi) constructs for GFP gene. And then these transgenic plants were inoculated with transgenic rice blast fungus, Magnaporthe oryzae, expressing GFP transgene. Here, we showed that ectopic expression of siRNAs targeting GFP gene in transgenic plants significantly suppressed GFP expression in rice blast fungi inoculated, indicating that small RNA molecules generated in plant cells can move into infected fungal cells and efficiently degrade fungal GFP transcripts. Our results would provide a new small RNA-based strategy for the development of resistant crops against fungal pathogens.

Caffeic acid O-methyltransferase (COMT) methylates N-acetylserotonin into melatonin; that is, it has N-acetylserotonin O-methyltransferase (ASMT) activity. The ASMT activity of COMT was first detected in Arabidopsis thaliana COMT (AtCOMT). To confirm the ASMT activity of COMT in other plant species, we evaluated the ASMT activity of a COMT from rice (Oryza sativa) (OsCOMT). Purified recombinant OsCOMT protein from Escherichia coli was used to validate the high ASMT activity of OsCOMT, similar to that of AtCOMT. The Km and Vmax values for the ASMT activity of OsCOMT were 243 μm and 2,400 pmol/min/mg protein, which were similar to those of AtCOMT. Similar to AtCOMT, OsCOMT was localized in the cytoplasm. In vitro ASMT activity was significantly inhibited by either caffeic acid or quercetin in a dose-dependent manner. Analogously, in vivo production of melatonin was significantly inhibited by quercetin in 4-week-old detached rice leaves, suggestive of a positive role of COMT in melatonin biosynthesis in plants.