We carried out to better understand calcium behavior in plant growing in media with different calcium levels, deficiency (3), normal (1), and surplus (3). Growth of cucumber plants did not appear significant difference among calcium levels by 7 days after transplanting, but growth rate at 14 days was the highest in normal and followed deficiency and surplus. Increase in calcium concentration treated resulted in not only an excessive Ca uptake of plant but also a proportional decrease in Mg contents. In addition, excessive absorbed Ca was preferentially accumulated in stem and root to avoid leaf damage. Oxalate playing a role as a mediator of excessive Ca through Ca-oxalate crystal formation in cell was analyzed. Oxalate content in leaves was proportionally increased with an increase in calcium level in media, and the correlation coefficient was 0.94(>0.001), while Ca and oxalate in stem and roots did not show significant relation. Ca-oxalate crystal isolated from different Ca-treated leaves and stem was observed using SEM-EDX. Large amount of Ca-oxalate crystal was formed with an increase in Ca concentration. This means that excessive Ca in cell is immobilized through the formation of Ca-oxalate crystal with oxalate bio-synthesized.

Reductions in the ozone column have led to substantial increase in UV-B radiation at the Earth's surface with the amount and intensity dependent on atmospheric and geographic factors. Our objectives were to understand the effect of UV-B radiation on photosynthesis and carbohydrate synthesis of soybean, and to establish an indicator to select resistant soybean cultivar against UV-B radiation. Soybean seeds (cv. Daepungkong) were sown and grown for 4 weeks in an environmentally controlled chamber. UV-B radiation was delivered to plants for four hours, each day, from 10:00 to 14:00 h by five fluorescent UV lamps. A distance of 1 m from lamps to the top of plants was always maintained throughout the experiment. The biologically effective UV-B radiation level was 21.6 kJ m-2 d-1 using the generalized plant responses action spectrum normalized at 300 nm. The damage of soybean leaves was optically observed at the second day of UV-B radiation, and leaf veins were first injured. Photosynthetic rate was reduced after 2 days of UV-B radiation, and, at 5 days, it was a half level (6.3 μmol m-2 s-1) compared with control (12.1 μmol m-2 s-1). UV-B radiation led to the reduction of stomatal conductance around 5 days of treatment. The decrease in stomatal conductance means the reduction of leaf transpiration and the influx of carbon dioxide. Also, the reduction of photosynthetic rate caused an accumulation of the intercellular carbon dioxide. It is suggested that photosynthetic characteristics can be used an indicator to select UV-B-resistant soybean cultivar.

An attempt was made to link rice embryo proteins to DNA sequences and to understand their functions. One hundred of the 700 spots detected on the embryo 2-DE gels were microsequenced. Of these, 28% of the embryo proteins were matched to DNA sequences with known functions, but 72% of the proteins were unknown in functions as previously reported (Woo et al. 2002). In addition, twenty-four protein spots with 100% of homology and nine with over 80% were matched to ESTs (expressed sequence tags) after expanding the amino acid sequences of the protein spots by Database searches using the available rice EST databases at the NCBI (http://www/ncbi.nlm.nih.gov/) and DDBJ (http://www.ddbj.nig.ac.jp/). The chromosomal location of some proteins were also obtained from the rice genetic map provided by Japanese Rice Genome Research Program (http://rgp.dna.affrc.go.jp). The DNA sequence databases including EST have been reported for rice (Oryza sativa L.) now provides whole or partial gene sequence, and recent advances in protein characterization allow the linking proteins to DNA sequences in the functional analysis. This work shows that proteome analysis could be a useful tool strategy to link sequence information and to functional genomics.

The present study describes carbohydrate metabolism, macro-element utilization and antioxidant defenses in response to an ozone dose (100 ppb, 8d) in two rice varieties. Tolerant (cv. Jinpumbyeo) and sensitive (cv. Chucheongbyeo) varieties of rice were grown in growth chamber for 30 days after sowing. Concentrations of chloroplast pigments and non-structural carbohydrates as well as activity of antioxidant enzymes were determined to evaluate the resistance against ozone stress. Ozone caused the decrease in chlorophyll a and carotenoid contents, and also resulted in faster decomposition of non-structural carbohydrate in leaf blade and leaf sheath. The contents of nitrogen and potassium in leaves were visibly decreased in cv. Chucheongbyeo with an increase in ozone exposure, but not in cv. Jinpumbyeo. Enzymatic antioxidants against ROS in both varieties responded in the order of POD, SOD and CAT, and their capacity was stronger in cv. Jinpumbyeo.

Germination characteristics and alterations in soluble sugar-starch transition and phytic acid during germination were studied in rice seeds under saline conditions. NaCl significantly reduced the speed of germination. Also, the radicle growth out of seeds was severely inhibited by the exposure to NaCl solution, thus, seeds were almost impossible to grow to seedlings. Soluble sugar was remarkably accumulated, whereas starch was decomposed stepwise during seed germination. The metabolism of soluble sugar and starch in germinating seeds showed a distinct difference. The level of phytic acid in seeds decreased in all NaCl treatments during germination, but the level was affected differently by NaCl concentration in the two varieties. Overall, our results suggest that salt stress retard the radicle growth of rice seeds, and affect the starch-to-sugar conversion and the decomposition of phytic acid differently in two varieties.

The effects of UV-B radiation on the seedling growth, carbohydrate metabolism and antioxidants activities of rice (Oryza sativa L.) were investigated under environmentally controlled chamber. Supplementary UV­B radiation reduced dry matter as well as leaf area, there­fore, relative growth rates (RGR) of seedlings were decreased by up to half compared to control. Photosynthetic products such as soluble sugars and starch were rapidly and significantly reduced by within 1 day of enhanced UV-B radiation due to the inhibition and degradation of photosynthetic processes and thylakoid membrane integrity. In our study, nonstructural carbohydrate levels were proved to be a main indicator on UV-B­induced stress. The behavior of SOD, CAT, APX and POD activities was monitored in the leaves of rice seedlings subjected to UV-B radiation. Under UV-B treatments, SOD activity was initially increased, whereas CAT and POD activities were slowly and slightly increased. However, APX activity showed no presumable results with an increase of UV-B dose. In leaves of rice seedlings, supplementary UV-B radiation caused an increase in free putrescine and spermidine, however spermine remained unaltered, although 24-hrs UV-B treatment slightly increased. This result presumes that an excess UV-B dose may induce ethylene biosynthesis (senescence) rather than polyamine biosynthesis (defense).

This study was conducted to examine the physiological and biochemical responses against UV-B radiation in the seedling of 15 different rice cultivars, having the different physiological sensitivities. Out of 15 rice cultivars tested, moderate and susceptible groups showed significant decreases in biomass and RGR (relative growth rate). Contents of total chlorophyll were reduced remarkedly by irradiation of UV-B. In all rice cultivars tested, the content of chlorophyll a was strongly decreased, while the contents of chlorophyll b were slightly reduced without showing clear different among three groups and 15 cultivars. Carotenoid content was largely reduced by UV-B radiation, whereas polyamine content was moderately increased. The contents of MDA (malondialdehyde) that reflect the level of lipid peroxidation of cell membranes were clearly increased by UV-B stress, showing higher content in susceptible cultivars than moderate and torelant cultivars. The physiological important parameters highly related to visible injury were leaf color, chlorophyll, carotenoid, and lipid peroxidation, whereas biomass and polyamines were not closely correlated. Based on this results, it was concluded that changes of visible injury and the contents of chlorophyll and MDA could be adequately applied and utilized as physiological indicators to UV-B radiation

In plants, nitrogen is the major component for growth and development. Leaf growth is based on the division, elongation and maturation of cells, which are used for making of epidermis, mesophyll, bundle sheath, xylem, phloem and so on. Dynamics of these tissues with respect to nitrogen are required for better understanding. This experiment was conducted to evaluate effect of nitrogen on the elongation of epidermal and guard cell of two rice (Oryza sativa L.) varieties, Seoanbyeo and Dasanbyeo on May 2000 at Chungbuk national university in Cheongju. After transplaning the 20-day-old seedlings into a/5000 pots, the main characteristics related with cell elongation were investigated and evaluated. A maximum. leaf length reached at 7 or 8 days after emerging from the collar, and also the leaf elongation rates were greatly affected by the increase of N application rate. The initial and final cell length were about 17~mu~textrmm and 130~mu~textrmm , respectively. Cell divisions occurred within 1.0mm from leaf base. With die higher nitrogen application rate of 22 kg-N 10~textrma-1 , cell division per hour was greater 1.5 to 1.9 and 1.2 to 1.3 fold as compared to the N application rate of 0 and 11 kg-N 10~textrma-1 , respectively. Cell enlargement of epidermal and guard cell under higher N application rate (22kg-N 10~textrma-1 ) was finished within about 20 (Seoanbyeo) and 15 hours (Dasanbyeo), while it took much time, about 30 hours.

In order to investigate low molecular antioxidants synthesized by enhanced UV-B radiation, we used the seedlings of two rice varieties. Woonjangbyeo, UV-tolerant, and Hwajoongbyeo, UV-susceptible, were subjected under supplemental UV-B irradiation. When rice seedlings were irradiated with UV light for short period, biosynthesis of total phenolic compound, ascorbate and glutathione were momently reduced. With an increase of UV-B radiation, however, those were slightly synthesized. The content of lipid peroxides in UV-challenged rice leaves was considerably increased after 12 hrs of UV-B treatment. Lipoxygenase activity under supplemental UV-B radiation was differently responded on rice varieties.