A total of 41 microsatellite markers were used with 29 genotypes to examine the relationship between SSR polymorphisms and N‐use efficiency related traits with a goal to identify the putative QTLs related to these traits. These primers yielded a total of 183 alleles (average 4.46 alleles per primer), and polymorphism information content (PIC) values of the SSRs ranged from 0.119 to 0.805 with mean value of 0.425. Correlation coefficients were obtained among the four N‐use efficiency traits in the 34 accessions and significant positive correlations of relative ratios between grain yield and harvest index (r=0.3404) and total dry matter (r=0.7976), while N uptake showed a moderate level of correlation with the ratios of the grain yield and total dry matter, respectively. 36.5% (15/41) SSR markers were monomorphic among the 25 japonica accessions out of the 29 accessions. Association between SSR genotypes and phenotypic performances from the total (29) or japonica (25) accessions was tested based on a single point analysis. Three putative QTL regions were detected for the ratio of grain yield. These include the chromosomal region containing the RM283 locus on chromosome 1 and RM25 on chromosome 8 (all and japonica accessions) and the region with the SSR marker, RM206 on chromosome 11 (the japonica accessions). For the total dry matter ratio, two chromosomal regions were identified as the putative QTL region. One is the region with the SSR marker, RM162 on chromosome 6 (all and japonica accessions) and the other was the one with the SSR marker RM25 on chromosome 8 (the japonica accessions). Among these markers, RM25 showed associations with both traits.

"Juan1" is a new japonica rice variety of mid-late maturing, tolerance to lodging and adaptable to direct seeding which was developed by the rice breeding team of National Institute of Crop Science, RDA, in 2005. This variety is derived from a cross between Ilpumbyeo, a variety of good-eating quality and high yield, and SR18392-HB683-104. The Juanl has heading date of August 19 at ordinary planting in the middle plain. It has semi-erect plant type with culm length of about 80cm and tolerance to lodging. This variety shows susceptible to blast, bacterial blight, virus diseases and brown planthopper. The milled rice kernels of Juanl are translucent with non-glutinous endosperm, clear in chalkiness and medium short grain. It has also low amylose content of 18.8%, low gelatinization temperature and good palatability. The average milled rice yield of this variety was 5.68 MT/ha at ordinary planting in local adaptability test for three years from 2003 to 2005. Juan! would be highly adaptable to middle plain and mid-eastern coastal region of Korea.

"Gopumbyeo" is a new japonica rice variety developed and registered by the rice breeding team of National Institute of Crop Science, RDA in 2004, which was derived from a cross between a line SR15225-B-22-1-2 which has good eating-quality and high yield potential and a line SR15140-58-2-2-3 which has lodging and disease resistances. This variety has medium heading date of Aug. 13, medium culm length of 78 cm and tolerance to lodging. It has also relatively semi-erect pubescent leaf blades and slightly tough culm with good canopy architecture. Gopumbyeo has a bit less number of tillers per hill and more spikelets per panicle than Hwaseongbyeo. It shows less sensitivity to premature heading in delayed transplanting of 50-day old seedlings. It showed longer delay of heading date but higher spikelet fertility than Hwaseongbyeo when exposed to cold stress. This variety shows delayed leaf senescence and considerable tolerance to viviparous germination during ripening. It shows moderate resistance to leaf blast, and bacterial blight, but susceptibility to stripe virus and insect pests. The milled rice of Gopumbyeo exhibits translucent, clear non-glutinous endosperm and medium short grains. It shows similar amylose content of 19.6%, and gelatinization temperature, and better palatability of cooked rice compared to Hwaseongbyeo. The milled rice yield of this variety is about 5.48 MT/ha at ordinary culture in local adaptability test for three years. Gopumbyeo would be highly adaptable to the central lowland and mid-southern mountainous areas of Korea.

"Seoanl" is a new japonica rice variety developed from a cross between Namyang9, a line of lodging tolerance and adaptable to reclaimed saline area, and Gyehwa7, a line of good-quality, adaptable to reclaimed saline area and high yield by the rice breeding team of National Institute of Crop Science, RDA, in 2005. This variety has about 131 days of growth duration from transplanting to harvesting in central plain area, and mid-western coastal area in Korea. It is about 73 cm in culm length and tolerance to lodging. It has also semi-erect pubescent leaf blade and slightly tough culm with good canopy architecture. The number of panicles per hill of Seoanl is slightly more than that of Hwaseongbyeo. Seoanl was susceptible to major diseases, blast, bacterial blight and viruses, and insect, brown plant hopper. This variety has lower amylose content of 18.8% and better palatability of cooked rice than those of Hwaseongbyeo. The milled rice yield performance of this variety is about 5.60MT/ha in local adaptability test for three years. Seoanl would be adaptable to central plain area and mid-western coastal area of Korea.

Nitrogen (N) fertilization is essential for alleviating nutrient deficiencies of the world’s population by increasing rice production, one of the most important food crops of our time. Here we established an in vivo hydroponics rice seedling culture system to investigate the physio-biochemical and molecular responses of various rice genotypes to low nitrogen application. Yoshida’s nutrient solution (YS) was used to grow rice seedlings, and at three-week-old the seedlings manifested highly stable and reproducible symptoms, such as reduced shoot growth and length. Out of 12 genetically selected or tested genotypes, almost all (11 genotypes) showed varied degrees of growth reduction response to applied nitrogen (4 and 40 ppm N for treatment and control, respectively), but SR19663-B-B-34-3-3-3-1 showed similar growth as the control though its leaf width was smaller than the control. The leaves of a 11 representative low nitrogen-responsive genotype as BG90-2 were sampled for revealing the protein profiles between low and normal (control) nitrogen application by using two-dimensional gel electrophoresis (2-DGE) followed by staining of separated proteins with silver. Fifty differentially expressed silver stained protein spots were excised from 2-D gels and 41 proteins identified using high-throughput mass spectrometry (MS) using matrix-assisted laser desorption/ionization-time of flight-MS and nano electrospray ionization liquid chromatography tandem MS. These proteins could be assigned as major (energy metabolism, photosynthesis and oxidative stress) and minor functional categories, revealing many novel low N-responsive proteins, including those having energy/photosynthesis, and defense/stress, and iron homeostasis-related functions.

This experiment was conducted to investigate the variation of nitrogen(N) uptake efficiency and their relationships withciency and partitioning parameters as physiological N use efficiency [PNUE], agronomic N use efficiency [ANUE], apparentrecovery [AR],

Soybean seeds contain high amounts of isoflavones that display biological effects and isoflavone content of soybean seed can vary by year, environment, and genotype. Objective of this study was to identify quantitative trait loci that underlie isoflavone content in soybean seeds. The study involved 85 F2 populations derived from Korean soybean cultivar 'Kwangkyo' and wild type soybean 'IT182305' for QTL analysis associated with isoflavone content. Isoflavone content of seeds was determined by HPLC. The genetic map of 33 linkage groups with 207 markers was constructed. The linkage map spanned 2,607.5 cM across all 33 linkage groups. The average linkage distance between pair of markers among all linkage groups was 12.6 cM in Kosambi map units. Isoflavone content in F2 generations varied in a fashion that suggested a continuous, polygenic inheritance. Eleven markers (4 RAPD, 3 SSR, 4 AFLP) were significantly associated with isoflavone content. Only two markers, Satt419 and CTCGAG3 had F-tests that were significant at P<0.01 in F2 generation for isoflavone content. Interval mapping using the F2 data revealed only two putative QTLs for isoflavone content. The peak QTL region on linkage group 3, which was near OPAG03c, explained 14~% variation for isoflavone content. The peak QTL region on linkage group 5, which was located near OPN14 accounted for 35.3~% variation for isoflavone content. Using both Map-Maker-QTL (LOD~geq2.0) and single-factor analysis (P~leq0.05) , one marker, CTCGAG3 in linkage group 3 was associated with QTLs for isoflavone content. This information would then be used in identification of QTLs for isoflavone content with precision

Soybean is a major source of protein meal in the world. Kunitz trypsin inhibitor (KTI) protein is responsible for the inferior nutritional quality of unheated or incompletely heated soybean meal. The objective of this research was to identify RAPD markers linked to KTI protein allele using bulked segregant analysis. Cultivar Jinpumkong2 (TiTi) was crossed with C242 (titi, absence of KTI protein) and F. seeds were planted. The F1 . plants were grown in the greenhouse to produce F2 seeds. Each F2 seed from F1 . plants was analysed electrophoretically to determine the presence of the KTI protein band. The present and absent bulks contained twenty individuals each, which were selected on the basis of the KTI protein electrophoresis, respectively. Total 94 F2 individuals were constructed and 1,000 Operon random primers were used to identify RAPD primers linked to the Ti locus. The presence of KTI protein is dominant to the lack of a KTI protein and Kunitz trypsin inhibit protein band is controlled by a single locus. Four RAPD primers (OPAC12, OPAR15, OPO12, and OPC08) were linked to the Ti locus. RAPD primer OPO12 was linked to Ti locus, controlling kunitz trypsin inhibitor protein at a distance of 16.0 cM. This results may assist in study of developing fine map including Ti locus in soybean.

Genetic linkage maps serve the plant geneticist in a number of ways, from marker assisted selection in plant improvement to map-based cloning in molecular genetic research. Genetic map based upon DNA polymorphism is a powerful tool for the study of qualitative and quantitative traits in crops. The objective of this study was to develop genetic linkage map of soybean using the population derived from the cross of Korean soybean cultivar 'Kwangkyo, and wild accession 'IT182305'. Total 1,000 Operon random primers for RAPD marker, 49 combinations of primer for AFLP marker, and 100 Satt primers for SSR marker were used to screen parental polymorphism. Total 341 markers (242 RAPD, 83 AFLP, and 16 SSR markers) was segregated in 85 ~textrmF2 population. Forty two markers that shown significantly distorted segregation ratio (1:2:1 for codominant or 3:1 for domimant marker) were not used in mapping procedure. A linkage map was constructed by applying the computer program MAPMAKER/EXP 3.0 to the 299 marker data with LOD 4.0 and maximum distance 50 cM. 176 markers were found to be genetically linked and formed 25 linkage groups. Linkage map spanned 2,292.7 cM across all 25 linkage groups. The average linkage distance between pair of markers among all linkage groups was 13.0 cM. The number of markers per linkage group ranged from 2 to 55. The longest linkage group 3 spanned 967.4 cM with 55 makers. This map requires further saturation with more markers and agronomically important traits will be joined over it.