Molybdenum (Mo) in rhizosphere influences sulfate assimilation as well as a number of other physiological aspects. In this study, the activity of key enzymes in sulfate assimilatory pathways, such as ATP sulfurylase (ATPs), adenosine 5'-phosphosulphate reductase (APR), as well as the responses of reactive oxygen species (ROS), were analyzed to elucidate the metabolic and physiological effects of external Mo supply to detached leaves of Trifolium repens L. Mo supply with a range from 1 mM to 40 mM depressed the activity of ATPs throughout the entire time course. In the leaves exposed to 1 mM Mo, a continuous decrease in the activity of ATPs was confirmed by Native-PAGE. The APR activity was also declined by Mo treatment. The accumulation of H2O2 and O2 were not significant up to 10 mM Mo, whereas a remarked accumulation was detected under 40 mM Mo supply. The data suggest that an external supply of Mo has an inhibitory effect on sulfate assimilation, and induces oxidative stress only at an extremely high concentration.

Sulphur deficiency has become widespread over the past several decades in most of the agricultural area. Oilseed rape (Brassica napus L.) is a very sensitive to S limitation which is becoming reduction of quality and productivity of forage. Few studies have assessed the sulphur mobilization in the source-sink relationship, very little is known about the regulatory mechanism in interaction between sulphur and nitrogen during the short-term sulphur deficiency. In this study, therefore, amount of sulphur and nitrogen incorporated into amino acids and proteins as affected by different S-supplied level (Control: 1 mM SO4 2 , S-deficiency: 0.1 mM SO4 2 , and S-deprivation: 0 mM SO4 2 ) were examined. The amount of sulphur in sulphate (S-sulphate) was significantly decreased by 25.8% in S-deprivation condition, compare to control, but not nitrogen in nitrate (N-nitrate). The markedly increase of sulphur and nitrogen incorporated amino acids (S-amino acids and N-amino acids) was observed in both S-deficiency and S-deprivation treatments. The amount of nitrogen incorporated proteins (N-protein) was strongly decreased as sulphur availability while the amount of sulphur incorporated into proteins (S-protein) was not affected. A highly significant (p<0.001) relationship between S-sulphate and S-amino acid was observed whereas the increase of N-amino acids is closely associated with decrease of N-proteins. These data indicate that increase of sulphur and nitrogen incorporated into amino acids was from different nitrogen and sulphur metabolites, respectively.

유채 품종에서 황 공급수준이 황산염 흡수 및 동화에 미치는 영향을 구명하고자 어린 잎과 성엽조직에서 ATP sulfurylase (ATPs), SO42－ 흡수, 글루타치온 함량을 분석하였다. 본 실험에서 10가지 유채 품종들 (Mosa, Capitol, Saturnin, Akela, Pollen, Mokpo, Youngsan, Tamra Colosse 그리고 Naehan)은황 공급수준에 따라 몇 가지 황산염 흡수와 동화 능력이 다르게 나타났다. 황 결핍 조건에서 모든 품종의 ATP sulfurylase (ATPs) 활력은 늙은 잎에 비해 어린 잎에서 높게 나타났으며, 글루타치온 함량은황 공급수준이 감소함에 따라 어린 잎에서 많이 증가하였다. 이러한 결과들은 유채 품종별 황 결핍조건에서 황을 이용하는 능력이 다르다는 것을 잘 보여주었다.

To investigate the effect of S-availability on N and S assimilations, Enzymatic activity of nitrate reductase (NR), glutamine synthetase (GS), ATP sulfurylase (ATPS) and O-acetylserine(thiol)lyase (OASTL) was measured, and also followed by their activity staining in forage rape (Brassica napus L.) fed with three different SO₄²? levels (0, 0.1 and 2.0 mM) for 25 hours. NR activity decreased as S-availability decreased, especially in young and middle leaves. S-limited conditions (0 and 0.1 mM sot) resulted in a reduction of GS activity. The activity of ATPS tended to increase with decreasing the exogenous SO₄²? supplying level. The activity of OASTL also increased as S-availability decreased for all leaf tissues, while tended to decrease in root. The results indicated t㏊t N assimilation was restricted by the limited S-nutrition especially in the developing leaf tissues, but S assimilation was stimulated except for OASTL activity in the roots.

Zoysiagrass [Zoysia marella (L.) Merr.]와 creeping bentgrass (Agrostis palustris Huds)에서 고온 스트레스에 대한 탄수화물대사 반응을 규명하기 위해 4월부터 9월까지의 식물체내의 탄수화물 대사산물의 변화를 비교 분석하였다. 각 초종의 샘플은 1998년 조성된 무안 Country Club의 green과 fairway에서 채취하였다. Creeping bentgrass의 지상부 수량은 6월부터

To investigate the physiological responses to naturally occurring winter freezing stress in creeping bentgrass, changes in carbohydrates were monitored during winter period. Turf quality and leaf growth was nearly parallel with temperature fluctuation. Th

Eight-week old perennial ryegrass (Lolium perenne L. cv. Reveille) plants were exposed to different NO3-concentrations or osmotic stress with NaCI. Previously labeled "N was chased during 14 days of non-labeled'NO3 feeding in order to investigate NO3 meta

암모니아 확산 및 암모니아 발색후 자외선 분광광도계에 의한 질소분석방법을 설정하기 위한 실험을 실시하였다. 미세확산용기(Conway microdiffusion cell)을 이용해 켈달소화 후 무기질화된 질소를 NaOH에 의한 알칼리화 및 HCI에 의한 산화반응을 통하여 으로 유도하였다. 암모니움 베이스의 표준용액을 이용하여 확산시간에 따fms 전소함량 및 회수율를 측정한 바 15시간 이상 반응으로 99% 이상의 질소회수율을 보여주었으며, 반복간 높은 재

We used an amplified fragment length polymorphism (AFLP) analysis, a novel PCR-based technique, to differentiate Xanthomonas oryzae pv. oryzae (Xoo) of Korean races. The 6 strains of Xoo K1, K2, K3 races were tested with 81 AFLP primer combinations to identify the best selective primers. The primer combinations were selected according to their reproducibility, number of polymorphic bands and polymorphism detected among Xoo strains. 18 strains of Xoo K1, K2 and K3 races were analyzed with the selected combinations of primer set. Some primer combinations (Eco R I +1 / Mse I+1) could differentiate Xoo of Korean races that were not distinguished by other fingerprinting analysis. Thus AFLP fingerprinting permitted very fine discrimination among different races.

To investigate the changes in the composition and pool size of nitrogen metabolites under drought stress, white clover (Trifolium repens L.) were exposed to -0.04MPa (well-watered, control) or to -0.12MPa (drought-stressed) of soil water potential during 28 days. Dry weight of leaves in drought-stressed plants was remarkably decreased by 45% and 74% within 14 days and 28 days, respectively, compared with control. For nitrate concentration after 28 days of treatment, a significant difference (1.6 times higher in drought-stressed plants) was observed only in stolon. NH3 -NH4 + concentration in all three organs of drought-stressed plants linearly increased to more than 1.6 times higher level at 28 day when compared to the initial level (day 0), while the increasing rate in control was much less than that of drought-stressed plants. Proline concentrations in drought-stressed plants remarkably increased and reached to 7, 13 and 17 times higher level at 28 day compared to control. Protein concentration in leaves of drought-stressed plants tended to decrease, while it slightly increased during the first 14 days and reached a plateau afterward in control. There was not significant difference in the proteins concentration of stolon and roots throughout experimental period. On SDS-PAGE analysis, two major proteins specifically induced by drought stress (16-kD and 18-kD) were detected in stolon.n.

To investigate the changes in the composition and pool size of carbohydrates under drought stress, white clover (Triforium repens L.) were exposed to -0.04 Mpa(well-watered, control) or to -0.12 Mpa (drought-stressed) of soil water potential during 28 days. Dry weight of leaves in drought-stressed plants was remarkably decreased by 45% within 14 days and 74% within 28 days compared to those of the control. Glucose concentration in drought-stressed plants was increased, while that of control was slightly decreased or remained at same level throughout experimental period. Fructose and sucrose concentrations in leaves were not significantly changed for drought-stressed plants, but those of the control were significantly decreased on plant after 14 days. Fructose and sucrose concentrations in stolon of control plants were sharply decreased, while that of drought-stressed plants was less varied. Those concentrations in roots were generally increased in drought-stressed plants. The concentration of total soluble sugars at 28 day was 438.0 and 632.6 mg g-l dwt. in control and drought stressed plants, respectively. Starch concentration of stolon and roots of control plants was significantly increased to 2.0 and 1.4 times of initial level, respectively, whereas those of drought stressed plants was nearly same level or slightly decreased compared to initial level.l.

To investigate the partitioning of newly absorbed N derived from NO3 - and NH4 + , 6 mM K15 NO3 or 3 mM (15 NH4 )2 was fed continuously in Italian ryegrass (Lolium multiflrum L.) for 7 days. Nitrogen metabolites (nitrate, amino acid, soluble- and insoluble protein) were analyzed at the end of 15 N feeding. Dry weight in shoot, stubble and root was not significantly different between NO3 [-10] and NH4 + feeding. Total nitrogen content in all three organs was significantly higher in NH4 + than NO3 [-10] feeding. Sum on N content in reduced N fractions (amino acids + proteins) in shoot, stubble and roots in NH4 + feeding increased by 13.3, 12.5 and 35.4 %, respectively, compared to NO3 [-10] feeding. The Relative Specific Activity (RSA, percentage of newly absorbed 15 N relative to total N in a sample) values of amino acids and insoluble proteins were significantly higher in NH4 + feeding. Total amount of newly absorbed 15 N in NO3 [-10] and NO3 [-10] feeding was 52.3 and 69.5 mg/plant on dry matter basis, respectively. In both NH4 + and NO3 [-10] grown plants, most of the N was allocated to the shoot, 67.5% in NH4 + feeding and 58.8% NO3 [-10] feeding, respectively. The 15 N amount incorporated in the reduced N compounds (amino acids and proteins) in NH4 + grown plants significantly increased by 74.8% compared to NO3 [-10] grown plants. The increase of the 15 N amount assimilated to amino acids in NH4 + grown plants was remarkably higher in roots as more than 7.25 times compared to NO3 [-10] feeding. These results indicated that Italian ryegrass was much efficiently utilized NH4 + -N for the synthesis of reduced N compounds.reduced N compounds.

To investigate of C and N metabolisms in response to phosphorus-deficient stress during regrowth of Italian ryegrass (Lolium multiflorum L.), C and N metabolites were analyzed at 0, 6, 12 and 24 days after defoliation. P-sufficient (control, +P) and P-absent (-P) nutrient solutions were applied from 7 days before defoliation, and continued for one cycle of 24 day-regrowth period. During 24 days of regrowth, dry matter of regrowing shoots and remaining tissues were not significantly different between +P and -P treatment. In remaining stubble, 70% to 91 % decline of the initial level (at day 0) in all C compounds occurred during the first 6 days of regrowth. Initial amounts of nitrate and amino acids in roots were significantly higher in the +P medium. Nitrate contents in stubble in the +P medium significantly decreased for the first 12 days and then rapidly recovered, while that of the -P medium continuously decreased until day 24. Amino acids in stubble in the P medium were continuously increased during the whole regrowth period. Soluble proteins in stubble in the +P medium also largely fell down (46.0% of the initial) for only the first 6 days, however the decline in the -P medium continued until day 12. In regrowing shoots, the accumulation of C compounds was significantly higher, while that of N compounds except amino acids was largely lower in the -P medium. These results showed a stimulation of carbohydrate synthesis and a compensatory utilization of organic reserves occurred to support regrowth under P-deficient condition.