The immature embryos during seed development were examined to predict the suitable embryos for an efficient regeneration system. Five spring wheat genotypes and five winter wheat genotypes were tested using immature embryos as explants. Spring wheat genotypes showed much higher levels of plant regeneration than those of winter wheat genotypes. The highest frequencies of embryogenesis and regeneration were obtained when embryos at 13-14 days after anthesis (DAA) were used as explant and decreased using embryos at 21-22 DAA during seed development. Significant differences were also found for callus induction and regeneration as affected by immature embryo size. The regeneration efficiency was drastically decreased in spring and winter wheat genotypes when embryos larger than 2.0 mm of length were used. The optimum developmental stage and embryo length for regeneration efficiency were at 13-14 DAA and 1.0-1.5 mm, respectively. The selection of suitable embryos for the high frequencies of embryogenesis and regeneration leads us to efficient genetic improvement of wheat.

We previously reported that reverse transcription-polymerase chain reaction/restriction fragment length polymorphism (RT- PCR/RFLP) was an effective method to identify SMV strains. Using this method a new SMV strain G6H was successfully identified. To introduce resistance locus Rsv4 of V94-5152, we made crosses between two parents, Hwanggumkong and V94-5152, and obtained 6 BC3 F3 progeny lines, which have different size of DNA fragment of Rsv4 locus region. To confirm the virus resistance of progeny lines, artificial inoculation were conducted with 10 SMV strains, G1-G7, G7A, G6H, and G7H. Genomic DNA of tested lines was extracted and used marker genotyping using 9 SSR marker, which covered about 20 cM genetic distance including Rsv4 locus. In the virulence test, only two progeny lines showed resistance to all the SMV strains like a V94-5152. However, the other lines showed necrotic symptoms to G6H strain. It is considered that a minor gene is located near the Rsv4 locus between Satt157 and Sat_254 marker which interacts with G6H. A new strain can be a clue to find a minor gene in the SMV resistance soybean breeding.

Colored soybean for cooking with rice have been used traditionally in Korea which is distinguished from other countries. Although many soybean cultivars have been developed for cooking with rice since the launch of the first cultivar Geomgeongkong1 in 1994, the breeding history of soybeans for cooking with rice is not quite long comparing to that of soybean paste/ bean curd and soy-sprout. In addition to developed cultivar, various landrace soybeans have still used for cooking with rice to Korean. This study was performed to select useful breeding materials and to evaluate the diversity of Korean landrace germplasms, especially black and/or green color seed coat soybeans. About five hundred eighty Korean colored soybean landraces were investigated for agricultural traits in experimental field and for DNA diversity using five SSR markers which showed high polymorphism between Korean soybean cultivars in a previous study. PowerCore (v. 1.0) software (http://genebank.rda.go.kr/PowerCore/) was used to analyze diversity of our landraces and to construct core set. In conclusion, we could obtain core set of forty-five germplasms by PowerCore analysis. Satt002 in analysed five SSR markers had twenty-two alleles and well represented diversity of black and/or green color germplasms.