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.

Fluorescence in situ hybridization (FISH) is a powerful tool for the detection of DNA sequences in the specific region of the chromosomes. As well as for the integrated physical mapping, FISH karyotype analysis has to be preceded. The detailed karyotypes of two onion cultivars, which are resources for onion genome sequencing project (‘Eumginara’ and ‘Sinsunhwang’), were constructed based on triple color fluorescence in situ hybridization (FISH) using 5S rDNA, 45S rDNA, and tandem repeat sequence. All used our materials showed 2n=2x=16 with x=8 as basic chromosome number. 5S rDNAs were located on 4 loci in one pair of interstitial region of short arm chromosome in both onion cultivars. Two pairs of 45S rDNAs were positioned in distal region of short arm chromosome in ‘Eumginara’. Otherwise 5 loci of 45S rDNAs were located in distal region of two pairs of short arm chromosome in ‘Sinsunhwang’. Among them, two signals of 45S rDNAs were co-localized in distal part of short arm and long arm chromosome, respectively. In case of tandem repeat sequence was detected on telomeric region of 8 pairs of chromosomes except on 45S ribosomal DNA sites. These results will provide a valuable background for physical mapping and help to further more understand the genome sequencing project in Allium cepa.

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.