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.

The effect of salicylic acid(SA) on antioxidant system and protective mechanisms against UV-B induced oxidative stress was investigated in cucumber(Cucumis sativus L.) leaves. UV-B radiation and SA were applied separately or in combination to first leaves of cucumber seedlings, and dry matter accumulation, lipid peroxidation and activities of antioxidant enzymes were measured in both dose and time-dependant manner. UV-B exposure showed reduced levels of fresh weight and dry matter production, whereas SA treatment significantly increased them. SA noticeably recovered the UV-B induced inhibition of biomass production. UV-B stress also affected lipid peroxidation and antioxidant enzyme defense system. Malondialdehyde(MDA), a product of lipid peroxidation, was greatly increased under UV-B stress, showing a significant enhancement of a secondary metabolites, which may have antioxidative properties in cucumber leaves exposed to UV-B radiation. Combined application of UV-B and SA caused a moderate increase in lipid peroxidation. These results suggest that SA may mediate protection against oxidative stress. UV-B exposure significantly increased SOD, APX, and GR activity compared with untreated control plants. Those plants treated with 1.0 mM SA showed a similar pattern of changes in activities of antioxidant enzymes. SA-mediated induction of antioxidant enzyme activity may involve a protective accumulation of H2O2 against UV-B stress. Moreover, their activities were stimulated with a greater increase by UV-B+SA treatment. The UV-B+SA plants always presented higher values than UV-B and SA plants, considering the adverse effects of UV-B on the antioxidant cell system. ABA and JA, second messengers in signaling in response to stresses, showed similar mode of action in UV-B stress, supporting that they may be important in acquired stress tolerance. Based on these results, it can be suggested that SA may participates in the induction of protective mechanisms involved in tolerance to UV-B induced oxidative stress.

Tocopherol belongs to the Vitamin E class of lipid soluble antioxidants that are essential for human nutrition. Tocopherols consist of a chromanol ring and a 15-carbon tail derived from homogentisate (HGA) and phytyl diphosphate, respectively. Condensation of HGA and phytyl diphosphate, the committed step in tocopherol biosynthesis, is catalyzed by HGA phytyltransferase (HPT). To increase tocopherol level in cucumber fruit, we performed Agrobacterium-mediated transformation with mdhpt gene, encoding HPT, isolated from apple (Malus domestica). We obtained two independent T0 cucumber plants from transforming 2,142 explants. Southern blot analysis of T0 showed that mdhpt was inserted in the genome. In order to test the tocopherol level, T1 cucumber fruits were screened by GC analysis. From 39 T1 fruits tested, some fruits showed 1.5-2 fold in α- and β-tocopherol content comparing to control. However, most of fruits contained lower levels of γ- and δ- tocopherol indicating a partition of metabolites in tocopherol biosynthesis pathway. We selected these T1 line and made a self-cross to obtain T2 seeds.

Root colonization by a rhizobacterium, Pseudomonas chlororaphis O6, elicited induced systemic resistance (ISR) in the leaves of cucumber plants against fungal and bacterial pathogens. To understand the role of unique genes during strain O6-mediated ISR, a suppressive subtractive hybridization method was undertaken and led to isolation of twenty-five distinct genes. The transcriptional levels of all the genes showed an increase much earlier under O6 treatment than in water control plants only after challenge with pathogen, while no difference detected on the plants without pathogen challenge. This suggests that O6-mediated ISR is associated with the priming phenomenon, an enhanced capacity for the rapid and effective activation of cellular defense responses after challenge inoculation.

In the present study we studied the growth, photosynthetic traits and protective mechanisms against oxidative stress in the primary loaves of cucumber (Cucumis sativus L.) seedlings with or without UV-B treatment. Cucumber seedings were irradiated with UV-B for 10 days in environment-controlled growth chambers. The primary leaves irradiated with UV-B showed reduction in leaf length and decreased biomass production. The reduced biomass production seemed to be due to a negative effect of UV-B radiation on the photosynthetic process. Changes in chemical properties of leaf, such as chi a/b ratio affected photosynthesis. UV-B significantly affected chl b content compared with chi a in the light harvesting complex resulting reduced photosynthetic activity Fv/Fm decreased with an UV-B stress, suggesting that the photosynthetic apparatus, and particularly, PS II was damaged under UV-B stress. Malondialdehyde(MDA) concentration which represents the state of membrane lipid peroxidation Increased significantly under UV-B stress confirming an oxidative stress. UV-B exposure with SA solution(0.1-1.0 mM) can partially ameliorated some of the detrimental effects of UV-B stress. Leaf injuries including loss of chlorophyll and decreased ratio of Fv/Fm were reduced with combined application of UV-B and SA. ABA and JA showed similar mode of action in physiological effects on photosynthetic activities though the levels were lower than those from SA treated plants. Chloroplast ultrastructure was also affected by UV-B exposure. The thickness of leaf tissue components decreased and the number of grana and thylakoids was reduced in chloroplast applied UV-B or SA alone. At combined stress granal and stromal thylakoids were less affected. The leaves under combined stress acquired a significant tolerance to oxidative stress. From these results, it can be suggested that SA may have involved a protective role against UV-B induced oxidative damage.

본 연구는 2종류의 하우스, 즉 1-2W 형 하우스와 무기둥하우스에, 시설억제재배, 촉성계배, 반측성재배 그리고 여름재배의 4 재배시기에 8개의 오이 품종을 재식하여, 재배시기에 따른 품종들의 암수꽃의 발생, 개체 당 과실수에 따른 퇴화 과실수, 그리고 수량을 조사 비교하여 각 작형에 알맞은 품종들을 추천하기 위해 수행하였다. 시설억제재배에서는 낙합계나 흑진주계 또는 입추백다다기오이가 생육 및 수량이 양호하였고, 촉성재배에서는 겨우살이청장오이, 입추백다다기오이 그리고 가을낙합오이가 추천된다. 반측성재배에서는 청장계 오이나 낙합계 오이가 비교적 양호한 수량을 보였으며 여름재배에서는 남부청장오이나 가을낙합오이가 양호하였다.

본 연구는 여러 오이 품종들의 억제작형에서의 생장과 수량을 조사하여 이 작형에서 적합한 품종을 선발하기 위해 수행하였다. 엽수에 있어서 청장계 오이가 가장 많았고 흑진주계 오이에서 가장 적어 영양생장으로는 청장계 오이가 가장 좋았다. 암꽃수에 있어서 흑진주계 오이가 가장 많았고 청장계 오이가 가장 적었다. 암꽃비율에서도 흑진주계 오이가 가장 높았으며 청장계 오이가 가장 낮았다. 퇴화 암꽃비율에서는 흑진주계 오이가 가장 높았으며 청장계 오이는 0%로 거의 퇴화를 보이지 않았다. 측지제거처리와 측지무제거 처리간 수량은 유이한 차이가 없었다. 수량에 있어서 흑진주계 오이가 가장 높았고 청장계 오이가 가장 낮아 억제작형재배에서 가장 적합한 품종은 흑진주계 오이인 것으로 나타났다.