Bacterial wilt (BW) caused by Ralstonia solanacearum is one of the most common soil-borne vascular diseases of many solanaceous crops such as pepper and tomato. This study aimed to develop molecular markers closely linked to bacterial wilt resistance genes using a 150 F8 recombinant inbred line (RIL) population obtained from a cross of ‘YCM334’ x ‘Taean’. For pathogen inoculations, R. solanacearum isolate WR-1 was cultured on NB medium at 28℃ for 48 h and a bacterial suspension was adjusted to 1 x 107 to 1 X 108 CFU/mL (A 600 = 0.3 to 0.4). Each RIL and the parents were sown in a 72-cell plastic tray filled with sterilized soil, and the seedlings were inoculated at the 6 to 8 leaf stage using soil-drenching (3 to 5 ml/ plant) inoculation methods with 3 replications. After 10 days post inoculation (dpi), each line was evaluated visually for occurrence of bacterial wilt ranging from 1 (most resistant) to 5 (most susceptible). Two candidate R-response genes, AT4G14130 and AT3G23730, were selected to find SNPs between YCM334 and Taean. In previous transcriptome analysis, these two genes were reported as significantly differentially expressed in Capsicum annuum L. root inoculated with R. solanacearum, which were up-regulated in a resistant genotype. Once the synteny of the gene locations between Arabidopsis and pepper was documented, the sequences on pepper chromosome 12 were obtained from pepper. v.1.55 (http://solgenomics.net). SNP markers associated with resistance to BW will be mapped using pepper RIL population.

The goal of marker-assisted backcrossing is to reduce the number of generations significantly by using genome-based molecular markers. Among other types of molecular markers, SNP (single nucleotide polymorphism) is mostly used in genetic diversity analysis due to its abundance. To develop high-throughput SNP marker for MAB system, we selected 20 Chinese cabbage lines each represent traits as inner leaf color, disease resistance, head type and maturity etc. Then, we sequenced the transcriptomes of 20 lines by using Illumina Hiseq2000. The average transcriptome size was 1.37 Gbase, and the average of short reads mapping rate was about 62.15% (30xcoverage). We identified 13,976 SSR markers and 380,198 SNPs by aligning contigs of 20 Chinese cabbage lines. To develop SNP marker set, we chose 409 SNPs that covers the whole Brassica rapa transcriptome. The filtering criteria were depth, polymorphism, segregation ratio, lack of adjacent SNP and copy number. We positioned the selected SNP markers to the Chinese cabbage linkage map. Clustering dendrogram was produced using SNP marker and three different clusters were generated. The result showed that the genotyping data is partially linked to the phenotyping data. We assume that the developed SNP marker set can be applied in the Chinese cabbage MAB system soon.

Watermelon (Citrullus lanatus) is one of the most economically important cucurbitaceous crop over the world. Anthracnose disease caused by Colletotrichum orbiculare, result to severe damage to cucurbits worldwide. Anthracnose is a typical plant disease which significantly affecting the yield of cucurbit crop. Pathogeneis-related (PR) proteins are well-known plant defense proteins against pathogens. Therefore, we observed PR genes expression patterns when watermelon got anthracnose disease. We did RT-PCR experiment to evaluate differences of PR genes expression pattern among Au-Producer(R), one of the representative of resistance watermelon varieties against anthracnose, and 920533(S), one of the representative of susceptible watermelon varieties against anthracnose. As a result, there were differences of the expression of several PR genes between the R and S watermelon. Analysis of the function of these genes is expected to perform in the future.

Watermelon (Citrullus lanatus) is one of the most economically important cucurbitaceous crop over the world. Screening of proper reference genes was needed to reverse transcription quantitative real-time PCR (qRT-PCR), and it is bausic step of many researches including gene expression analysis. However, the reference genes on watermelon has not yet been reported systematically. Therefore, eight candidates of reference genes were selected with reference to Arabidopsis or cucumber papers. They are β-Actin, elongation factor 1-α, glyceraldehy-3-phosphate-dehydrogenase, NADP-isocitrate dehydrogenase, leunig, polypyrimidine tract-binding protein1, ubiquitin-conjugating eznyme E2, and 18S ribosomal RNA. The expression levels of genes were evaluated by qRT-PCR under biotic stress (Colletotrichum orbiculare treatment), plant hormone treatment (100 μM ABA), and abiotic stresses such as drought, cold (4℃), salt (250 mM NaCl) stresses. We founded appropriate reference genes which did not induce or reduce gene expression levels under broad spectrum of stresses by qRT-PCR analysis. These results may provide proper information for the use of appropriate reference genes for gene expression studies in watermelon qRT-PCR analysis.

고추의 고유 특성인 매운맛은 태좌 조직에서 주로 발현되는 capsaicinoid라는 화학물질에 의한 것으로 알려져 있고, 이 물질을 생합성하는 유전자와 매운맛의 유무를 판별할 수 있는 분자표지까지 개발되어 있다. 그러나, 아직 매운맛 함량에 대한 유전연구와 분자적 기전은 그 연구가 깊지 못한 상황이고, 본 연구는 고추 매운맛 함량 연구를 위한 F7 RIL mapping집단을 육성하고 매운맛 함량을 비롯한 주요한 원예적 특성들을 평가하기 위해 수행되었다. 자방친인 ‘생력211’의 capsaicinoid 함량은 341.6 mg/100 g으로 ‘청양’ 고추 품종보다 높은 수준인 것으로 확인되었고, 화분친인 ‘생력213’은 무신미인 것으로 HPLC 결과와 분자표지 결과가 일치하였다. 양친을 교배 후 자가수정하여 육성된 F7 RIL 93계통들에 대해서 매운맛 함량을 분석한 결과, 최저 77.8 mg/100 g부터 최고 1046.0 mg/100 g까지로 그 변이 폭이 매우 크며, 매운 계통들 내에서의 함량 분포도는 정규곡선 양상을 보여 본 육성 집단이 향후 매운맛 함량 연구를 위해 매우 유용하게 활용될 수 있을 것으로 기대된다.

본 연구는 고추의 다양한 품질 관련 특성 연구를 위한 분자육종시스템 구축의 기초 연구로서, 고추의 매운맛과 고색소, 다양한 색소, 과형 등이 다양한 고세대(F6) RIL 집단을 육성하여 그 원예적 특성을 조사하였다. 자방친으로 단고추 계통인 “만다린(Capsicum annuum L.)”을 이용하였고, 화분친으로는 “블랙클러스터(Capsicum annuum L.)”를 이용하여 F1 조합을 작성한 후, 자식으로 세대를 유지한 고세대(F6) RIL 집단 129계통들에 대해서 과실특성과 초장, 잎, 꽃 등 13가지 원예적 특성들을 평가했다. 미숙과에서 성숙과로의 색 변화의 경우 그 변화 양상이 매우 다양하여 모두 12가지 양상으로 구분해 볼 수 있었는데, 녹색에서 바로 적색으로 변화하는 양상이 51계통으로 가장 많은 분포를 차지했고, 녹색에서 진보라색으로의 변화가 45계통, 상아색에서 주황색으로 변색하는 양상이8계통 등 숙기에 따른 과색 변화가 대단히 다양한 것을 확인할 수 있었다. 숙과색은 적색과가 99계통으로 가장 많은 분포를 보였고, 주황색이 17계통, 황색이 13계통이었다. 과형은 크게 세가지로 구분되었는데, 삼각형 과실이 64계통으로 가장 많은 분포를 보였고, 타원형이 52계통, 심장형이 13계통이었다. 착과방향은 61.2%가 상향 착과성을 보였고, 38.7%가 하향이었다. 원예적 특성 평가 결과 본 F6 RIL 집단은 그 다양성이 풍부하여 향후 고추 품질 특성 연구에 유용하게 활용될 수 있을 것으로 기대된다.

Clubroot, caused by a soil borne fungus Plasmodiophora brassicae Woronin, is a common disease of cabbages and other plants belonging to the genus Brassica, which is the most extensively cultivated vegetable crops worldwide. This present study was to evaluate the utilization possibility of SNP primers, which we designated as molecular markers linked to disease resistance based on B. rapa genome, it may be possible to apply them to B. oleracea, and to survey SNP marker related to clubroot resistance of cabbages. In total, 425 SNP markers can be applied to B. oleracea were selected from 8,000 SNP markers based on B. rapa genome linked to disease resistance. New 123 SNP markers of them were designed to be analysed to High Resolution Melt (HRM), and tested for clubroot resistance using 6 cabbage varieties, including 3 clubroot resistances (YR Chunrok, YR Dongjanggun, and Grandmart Cabbage) and 3 susceptibilities (Chungam-45, Bogam-1, and Junggam-21). Of them, 118 SNP primers amplified cabbage genomic DNA using HRM analysis, suggesting that it is possible to apply SNP markers based on B. rapa genome to B. oleracea. A total of 4 candidate SNP markers related to clubroot resistance were detected at 80.2℃ of melt temperature in BRS6, 79.2℃ in BRS18, 82.2℃ in BRS79, and at 84.4℃ in BRS114, respectively. These results provide valuable information that can be used for the utilization of the genus Brassica genome study and breeding for clubroot resistance in cabbages.