Na-Young Ro

Evaluation of Resistance to Ralstonia solanacearum in Tomato Genetic Resources at Seedling Stage

Bacterial wilt of tomatoes caused by Ralstonia solanacearum is a devastating disease that limits the production of tomato in Korea. The best way to control this disease is using genetically resistant tomato plant. The resistance degree to R. solanacearum was evaluated for 285 tomato accessions conserved in the National Agrobiodiversity Center of Rural Development Administration. These accessions of tomato were originated from 23 countries. Disease severity of tomato accessions was investigated from 7 days to 14 days at an interval of 7 days after inoculation of R. solanacearum under greenhouse conditions. A total of 279 accessions of tomato germplasm were susceptible to R. solanacearum, resulting in wilt and death in 70 to 90% of these plants. Two tomato accessions were moderately resistant to R. solanacearum. Only four accessions showed high resistance against R. solanacearum. No distinct symptom of bacterial wilt appeared on the resistant tomato germplasms for up to 14 days after inoculation of R. solanacearum. Microscopy of resistant tomato stems infected with R. solanacearum revealed limited bacterial spread with thickening of pit membrane and gum production. Therefore, these four resistant tomato germplasms could be used in tomato breeding program against bacterial wilt.

Evaluation of Genetic Diversity of Red Pepper Landraces (Capsicum annuum L.) from Bulgaria Using SSR Markers

The amount of genetic variability of a species is essential for its survival and adaptation in different environments, and studies of genetic diversity using molecular markers are necessary to understand the genetic structure of a population and to orientate effective strategies of germplasm conservation. The aim of current study was to determine the SSR markers that can be used rapidly and reliably to evaluated the pepper of Bulgaria landraces, and applied the markers to assessment of introduce genetic diversity of the pepper germplasm. We used 22 polymorphic microsatellite markers to analysis of genetic diversity within 61 pepper collection of Bulgaria landraces germplasm, all SSR primers pairs produced 82 polymorphic and reproducible amplification fragments. Results showed a relatively low level of genetic diversity among pepper accessions from Bulgaria for both molecular and morphological markers. An average value of polymorphic information contents (PIC) were 0.334 with a range of 0.061 to 0.63. The mean values of observed (HO) and gene diversity (GD) were 0.383 and 0.154, respectively, indicating a considerable amount of polymorphism within this collection. A genetic distance-based phylogeny grouped into three distinct groups according to genetic difference among the accessions. An average day of flowering time was 56.9 days with a range of 48 to 65 days. The average of fruit length and width were 6.9cm with a range 2.6 to 13.9cm, and 1.9cm with a range 0.5 to 4.2cm, respectively.

Evaluation of Resistance to Colletotrichum acutatum in Pepper Genetic Resources

Resistance of pepper (Capsicum spp.) to anthracnose (Colletotrichum acutatum) was evaluated during regeneration of Capsicum spp. in National Agrobiodiversity Center. Disease severity of 896 pepper accessions (430 accessions of C. annuum, 219 accessions of C. baccatum, 14 accessions of C. chacoense, 153 accessions of C. chinense, 70 accessions of C. frutescens, 2 accessions of C. pubescens, and unidentified 8 accessions) was investigated at 14 days after inoculation in 28 C humid chamber. Forty nine accessions of pepper germplasm were resistant to C. acutatum. Among them, nine accessions were highly resistant to C. acutatum without wounding spray inoculation. Four accessions belonged to the species C. baccatum, one accession to C. chacoense, and four accessions to C. frutescens. Forty two resistant candidate accessions were inoculated with pin-prick wounding using a syringe needle. Five accessions were resistant as a less than 3% of disease severity to C. acutatum with wounding inoculation 5 days after inoculation. All resistant accessions were C. baccatum. These five pepper germplasm might be used as breeding resources for the anthracnose resistance breeding program.

The Complete Chloroplast Genome of Capsicum frutescens (Solanaceae)

Premise of the study: We report the complete sequence of the chloroplast genome of Capsicum frutescens (Solanaceae), a species of chili pepper. Methods and Results: Using an Illumina platform, we sequenced the chloroplast genome of C. frutescens. The total length of the genome is 156,817 bp, and the overall GC content is 37.7%. A pair of 25,792-bp inverted repeats is separated by small (17,853 bp) and large (87,380 bp) single-copy regions. The C. frutescens chloroplast genome encodes 132 unique genes, including 87 protein-coding genes, 37 transfer RNA (tRNA) genes, and eight ribosomal RNA (rRNA) genes. Of these, seven genes are duplicated in the inverted repeats and 12 genes contain one or two introns. Comparative analysis with the reference chloroplast genome revealed 125 simple sequence repeat motifs and 34 variants, mostly located in the noncoding regions. Conclusions: The complete chloroplast genome sequence of C. frutescens reported here is a valuable genetic resource for Capsicum species.

QTL mapping and GWAS reveal candidate genes controlling capsaicinoid content in Capsicum

Summary Capsaicinoids are unique compounds produced only in peppers (Capsicum spp.). Several studies using classical quantitative trait loci (QTLs) mapping and genomewide association studies (GWAS) have identified QTLs controlling capsaicinoid content in peppers; however, neither the QTLs common to each population nor the candidate genes underlying them have been identified due to the limitations of each approach used. Here, we performed QTL mapping and GWAS for capsaicinoid content in peppers using two recombinant inbred line (RIL) populations and one GWAS population. Whole‐genome resequencing and genotyping by sequencing (GBS) were used to construct high‐density single nucleotide polymorphism (SNP) maps. Five QTL regions on chromosomes 1, 2, 3, 4 and 10 were commonly identified in both RIL populations over multiple locations and years. Furthermore, a total of 109 610 SNPs derived from two GBS libraries were used to analyse the GWAS population consisting of 208 C. annuum‐clade accessions. A total of 69 QTL regions were identified from the GWAS, 10 of which were co‐located with the QTLs identified from the two biparental populations. Within these regions, we were able to identify five candidate genes known to be involved in capsaicinoid biosynthesis. Our results demonstrate that QTL mapping and GBS‐GWAS represent a powerful combined approach for the identification of loci controlling complex traits.

Changes in Carotenoid Contents of Colored Pumpkin (Cucurbita spp.) Germplasms

Changes in Carotenoid