In this review, we discuss the ways in which our understanding of the controls of nitrogen use efficiency applied to crop improvement has been increased through the development of molecular physiology studies using transgenic plants or mutants with modified capacities for nitrogen uptake, assimilation and recycling. More recently, exploiting crop genetic variability through quantitative trait loci and candidate gene detection has opened new perspectives toward the identification of key structural or regulatory elements involved in the control of nitrogen metabolism for improving crop productivity. All together these studies strongly suggest that in the near future nitrogen use efficiency can be improved both by marker-assisted selection and genetic engineering, thus having the most promise for the practical application of increasing the capacity of a wide range of economically important species to take up and utilize nitrogen more efficiently.

Protein characteristics of Korean wheat were evaluated to determine the effects of protein content and quality on processing and textural properties of white salted noodles compared to US wheat flours with various wheat classes and commercial flours for making noodles. Protein quality parameters, which were independent of protein content and included SDS sedimentation volume with constant protein weight, mixograph mixing time and proportion of 50% 1-propanol insoluble protein, of Korean wheat flours with 2.2+12 subunits in high molecular weight glutenin subunit compositions were comparable to those of commercial flours for making noodles. Parameters related to noodle making, including optimum water absorption, thickness and color of noodle dough sheet, correlated with protein content and related parameters, including SDS sedimentation volume with constant flour weight, mixograph water absorption and gluten yield. No significant relationship was found in protein parameters independent of protein content. Hardness of cooked noodles from Korean wheats was lower than that of US wheat flours compared to similar protein content of commercial noodle flours. Adhesiveness, springiness and cohesiveness of cooked noodles from Korean wheats were similar to US wheat flours. Hardness of cooked noodles correlated with protein content and related parameters.

The roots of Aristolochia elegans Mast.(Aristolochiaceae) are widely used in Mexican traditional medicine as a remedy for scorpion venom. Current experimental evidence supports its purported antidote properties. However, collection from the wilderness has lead to local extinction of natural populations. In order to contribute to species preservation, cultivation, and standardization of morphological and pharmacological properties, a micropropagation method was developed. This includes in-vitro germination of seeds to produce aseptic plantlets, induction of multiple budding, and acclimatization. The treatment with benzylamino purine(10 ${\mu}M$) induced the highest number of buds(3.1 on average) in both types of explants. On the other hand, indolebutyric acid(1.5 ${\mu}M$) caused the highest root index(11.8) per explant. One hundred percent of the micropropagated plantlets developed vigorously after the acclimatization process.

Xanthomonas axonopodis pv. glycines(Xag) is a pathogen that causes bacterial leaf pustule(BLP) disease in soybeans grown in Korea and the southern United States. Typical and early symptoms of the disease are small, yellow to brown lesions with raised pustules that develop into large necrotic lesions leading to a substantial loss in yield due to premature defoliation. After Xag infects PI 96188, only pustules without chlorotic haloes were observed, indicating the different response to Xag. To identify differentially expressed genes prior to and 24 hr after Xag inoculation to PI 96188 and BLP-resistant SS2-2, an oligonucleotide macroarray was constructed with 100 genes related to disease resistance and metabolism from soybean and Arabidopsis. After cDNAs from each genotype were applied on the oligonucleotide macroarrays with three replicates and dye swapping, 36 and 81 genes were expressed as significantly different between 0 hr and 24 hr in PI 96188 and SS2-2, respectively. Six UniGenes, such as the leucine-rich repeat protein precursor or 14-3-3-like protein, were selected because they down-regulated in PI 96188 and up-regulated in SS2-2 after Xag infection, simultaneously. Using tubulin and cDNA of Jangyeobkong(BLP-susceptible) as controls, the oligonucleotide macroarray data concurred with quantitative real-time RT-PCR(QRT RT-PCR) results in most cases, supporting the accuracy of the oligonucleotide macroarray experiments. Also, QRT RT-PCR data suggested six candidate genes that might be involved in a necrotic response to Xag in PI 96188.

Soybean Kunitz trypsin inhibitor(SKTI) protein is a small, monomeric and non-glycosylated protein containing 181 amino acid residues and is responsible for the inferior nutritional quality of unheated or incompletely heated soybean meal. The objective of this research is to confirm SSR marker(Satt228) tightly linked to the Ti locus using several germplasm accessions with TiTi or titi genotypes for MAS in soybean breeding programs. TiTi genotypes('Jinpumkong2', 'Clark', and 'William') had allele1 and titi genotypes(PI196168, C242, W60, and PI157440) had allele2 in Satt228 marker analysis. 'Jinpumkong2', 'Clark', and 'William'(TiTi genotype) had a Kunitz trypsin inhibitor protein of 21.5 kDa size, and PI196168, C242, W60, and PI157440(titi genotype) did not have the band in protein gel electrophoresis from the mature seed. Cosegregation between the SKTI protein(21.5 kDa size) and allele of Satt228 marker was observed in seven germplasm accessions with different genetic backgrounds. Any recombination between the SKTI protein and allele of the Satt228 marker was not observed. This result indicates that Satt228 marker may effectively utilized to select the plants with the titi genotype.

Diurnal changes in levels of endogenous gibberellins(GAs) were investigated in three rice cultivars i.e. Sangjubyeo, Shingeumobyeo(photo-neutral) and Chucheongbyeo(photosensitive). The rice cultivars were grown under a 12-hr photoperiod and endogenous GA levels were assayed by gas chromatography-mass spectrometry(GC-MS-SIM) every 3 h for 24 h. The endogenous bioactive $GA_1$ and its immediate precursor $GA_{20}$ contents were significantly different in both photosensitive and photo-neutral rice cultivars, though less pronounced differences were observed for endogenous $GA_{12},\;GA_{53},\;GA_{19}$, and $GA_8$ levels with in the three rice cultivars. The levels of bioactive $GA_1$ and its immediate precursor $GA_{20}$ were significantly higher in Chucheongbyeo than in the other two cultivars. In Chucheongbyeo, the $GA_1$ contents increased significantly from 11.00 to 17.00 o'clock, thus indicating a correlation with light. In Shingeumobyeo, $GA_1$ contents slightly increased during morning hours, while a similar hike in $GA_1$ contents was observed for Sangjubyeo during evening hours. $GA_{19}$ was found to be the most abundant GA form in the three rice cultivars. Our results suggested that GA production in rice depends upon the response potential of rice cultivars and that light positively correlated to GA production in photosensitive rice cultivar.

Spongy Alphonso mangoes were found to be infected with Staphylococcus bacteria. A Gram positive Staphylococcus strain was isolated from spongy pulp and identified from CABI Bioscience, UK, by partial 16S rDNA sequence analysis and by morphological and biochemical characterization through IMTECH, Chandigarh, India. Although identification by both of these methods indicated the organism belonged to same genus, different species names were given. Changes in total phenolics, reducing, and non-reducing sugars, respiration rate, total carotenoids, peroxidase(POX), and catalase activities were monitored during ripening of these fruits. The climacteric rise in spongy fruits was marked by an increase in respiration rate and a decrease in sugar content. Total phenolics content increased in spongy fruits as compared to ripe non-spongy fruits. Development of corky white tissue in spongy fruits was associated with about a 2.5-fold reduction in total carotenoids and a concomitant increase in lipoxygenase-mediated, $\beta$-carotene co-oxidation. A marked decrease in soluble protein content and about a 1.5-fold increase in POX activity was observed. Maximum POX activity was confined to 50-70%$(NH_4)_2SO_4$ fraction. The intense dark bands visible after POX specific substrate staining of the Native gel indicated a high expression of isoenzymes of POX in spongy fruits. Similarly, changes in levels of catalase activity were also observed in spongy fruits. The results suggest that infection of Alphonso mangoes with Staphylococcus bacteria affects the normal ripening processes of the fruit interfering with the carbohydrate and carotenoid metabolism. Also, the studies indicate the expression of POX and catalase enzymes as a plant defense response to microbial invasion.

Two subspecies, japonica and indica, have been reported in rice, which differ in several ecotypic traits. However, reproductive barriers in hybrid progenies between subspecies have been major obstacles in breeding programs using inter-subspecific hybridization. As the first step to elucidate the reproductive barriers, we developed subspecies-specific(SS) STS markers in this study. A total of 765 STS primers were designed through comparing DNA sequences at every $2{\sim}3$cM interval between japonica and indica rices, which are available at Web DBs such as IRGSP, NCBI, TIGR, and GRAMENE, and tested for subspecies-specificity using 15 indica and 15 japonica varieties of diverse origin. Of them, 67 STS markers were identified as SS STS markers and their subspecies-specificity scores were estimated. The SS markers were dispersed throughout the genome along chromosomes. Of them, 64 SS markers were mapped on an RIL population derived from a Dasanbyeo(indica)/TR22183(japonica) cross. Genomic inclination of RILs was evaluated based on the genotyping with different types of markers. Association test between markers and segregation distortion revealed that segregation distortion might not be the cause of generating SS markers. The SS markers will be applicable to estimate the genomic inclination of varieties or lines and to study the differentiation of indica and japonica, and ultimately to breed true hybrid rice varieties in which desirable characters from both subspecies are recombined.

Near-infrared spectroscopy(NIRS) was used to develop a rapid and efficient method to determine lignan glucosides in intact seeds of sesame(Sesamum indicum L.) germplasm accessions in Korea. A total of 93 samples(about 2 g of intact seeds) were scanned in the reflectance mode of a scanning monochromator, and the reference values for lignan glucosides contents were measured by high performance liquid chromatography. Calibration equations for sesaminol triglucoside, sesaminol($1{\rightarrow}2$) diglucoside, sesamolinol diglucoside, sesaminol($1{\rightarrow}6$) diglucoside, and total amount of lignan glucosides were developed using modified partial least square regression with internal cross validation(n=63), which exhibited lower SECV(standard errors of cross-validation), higher $R^2$(coefficient of determination in calibration), and higher 1-VR(ratio of unexplained variance divided by variance) values. Prediction of an external validation set(n=30) showed a significant correlation between reference values and NIRS estimated values based on the SEP(standard error of prediction), $r^2$(coefficient of determination in prediction), and the ratio of standard deviation(SD) of reference data to SEP, as factors used to evaluate the accuracy of equations. The models for each glucoside content had relatively higher values of SD/SEP(C) and $r^2$(more than 2.0 and 0.80, respectively), thereby characterizing those equations as having good quantitative information, while those of sesaminol($1{\rightarrow}2$) diglucoside showing a minor quantity had the lowest SD/SEP(C) and $r^2$ values(1.7 and 0.74, respectively), indicating a poor correlation between reference values and NIRS estimated values. The results indicated that NIRS could be used to rapidly determine lignan glucosides content in sesame seeds in the breeding programs for high quality sesame varieties.

Mungbean plants generally have a relatively close canopy, thus a large amount of self-shading can reduce yield due to poor light penetration. Modification of leaflet type can affect leaf canopy and could alter seed yield. Two multiple leaflet mutants were obtained from gamma-ray irradiation and used to study the mode of inheritance related to leaflet types and to evaluate their agronomic features. The cross between large-heptafoliate leaflet with small-pentafoliate leaflet mutants produce all $F_1$ plants with normal trifoliate leaflets. The $F_2$ plants segregated in leaflet size and leaflet number into a 9:3:3:1 ratio of large-trifoliate: large-heptafoliate: small-pentafoliate: small-heptafoliate plants, suggesting that independent loci control leaflet size and leaflet number. Regarding leaflet number, the $F_2$ population can be classified into normal-trifoliate, small-pentafoliate, large-heptafoliate, and small-heptafoliate at the dihybrid ratio of 9:3:3:1. The gene symbols $N_1,n_1$ and $N_2,n_2$ are proposed to represent leaflet number. Since no plant was found with large-pentafoliate leaflets, we hypothesize that the $N_2$ allele expresses pleiotropic effect on both leaflet number and leaflet size. Another possibility is that an additional locus with S and s alleles controls leaflet size and S is tightly linked with $N_2$. The effect of multifoliate leaflet on yield and yield components was evaluated in four mungbean families each with four leaflet isolines under three environments. Averaging across the families and environments, the normal-trifoliate and large-heptafoliate lines gave higher yield than small pentafoliate and heptafoliate ones. These two large leaflet lines also had higher leaf area per plant than the other multifoliate lines. Therefore, the mungbean lines with a greater leaf area, which were likely to intercept more sunlight, gave greater yield. Three AFLP markers that were found to be linked to number of leaflets per leaf, corresponded to the N1 allele of the smallpentafoliate parent.