The Asteraceae/Compositae family is one of the biggest families in flowering plants and has more than 23000 species including the economically important lettuce, sunflower, and chicory as well as the agronomic weeds. With its significance and the progress in sequencing technology, its species have been subjected to the genome sequencing project worldwide. Although chrysanthemum is an important plant in the floricultural industry, however, it has been less studied at the level of genomics, compared with other species in the Asteraceae. There were only several reports on comparative analysis of transcriptome for chrysanthemum. Actually, the genome of Chrysanthemum species is known to be gigantic and complex with diverse status ranging from diploid to decaploid. Since the cultivated and commercial chrysanthemum exhibits hexaploid genome, we decided to select the diploid species with smaller genome as a material for reference genome sequencing. Thus, we launched a genome sequencing project with C. boreale which was previously reported to be diploid by cytogenetic analysis. We constructed sequencing libraries with insert size 300bp and 500bp and sequenced them from the paired end in 100bp read length with Illumina’s HiSeq platform. After quality checking, we preprocessed raw reads by removing duplicated reads and trimming reads with low quality value. Kmer frequency analysis with the cleaned reads showed that the genome is heterozygous, highly repetitive and gigantic, ranging from 2.9Gb to 5.8Gb. The cleaned reads were further subjected to error correction and primary assembly with SOAPdenovo2. Here, we’ll report the result of Kmer frequency analysis and genome assembly.

In Brassica as matter of seedling manner, they have the bilocular ovary and 20~28 seeds per silique after fertilization. Rarely some of B. juncea and yellow sarson (Brassica rapa ssp, tricolaris) have multilocular ovary. In this stdudy, the LP8 (YS-033, CGN06835) is shown tetralocular ovary as well as high seed yields. As microscope study for the different size of immature bud sections and we have known the floral meristem with already four locules in immature buds less size than 1mm of LP8. To identify of determining of tetralocular ovary formation, RNA-seq was carried out on the isolated RNA from less than 1mm and from 1mm of bud size respectively. By contrast tetralocular ovay and bilocular ovary, Chiifu is used. A total of 994 differentially expressed genes(DEGs) are detected in only LP8. Among the DEGs, we identify 18 DEGs in only immature buds of less size than 1mm. The expression patterns of 18 DEGs are validated by real time quantitative PCR and these genes are cloned and the sequence analyzed. At present, 12 candidated gene are analyzed by sequencing and there are detected by large fragment insertion as well as SNPs in sequence comparison to Chiifu. We will perform the genetic transformation of these DEG genes in Arabidopsis for relation between genes and tetralocular ovary. Our results will be helpful in understanding for mechanisms of tetraovular ovary in Brassica rapa.

Brassica rapa subspecies show morphological variability, containing vegetable types and oilseed types. The yellow sarson types(Brassica rapa ssp, tricolaris) have distinct morphology, yellow seeded and contain some lines with very unique character of tetralocular ovary. For genetic studies on tetralocular ovary related to high seed yields, we produced genetic segregation population with F2 and double haploid(DH) population. The yellow sarson LP8 (YS-033, CGN06835) with character of tetralocular ovary used as a maternal plant and crossed by LP21 of turnip rape type with bilocular ovary as paternal plant. We took on the microspore cultures on immature bud which is collected on sizing from 2mm to 3.2mm for DH population. The regenerations DH plants are analyzed by ploidy determination using flow cytrometer and selected on diploid plants. These regenerated DH and F2 plants are doing bud pollination and measuring the phenotype traits. Also, these populations will be used for identify of genetic locus relate to tetralocular ovary using genotyping by sequencing.