한국형 잔디에 있어 병원성 (라지 팻치) 감염이 산화적 스트레스의 발현에 미치는 영향을 규명하기 위하여 라지 팻치에 감염된 잔디의 항산화 효소의 활성을 조사하였다. 처리 후 6일 동안 이틀간격으로 잎과 뿌리 시료에 대해 각각 분석하였다. 초기 2일 동안 SOD효소 활성은 처리 간 아무런 차이가 나타나지 않았으나 처리 후 6일차에는 대조구에 비해 라지 팻치에 감염된 잎에서 48% 뿌리에서 49% 각각 높게 나타났다. CAT 효소활성은 처리 후 2일간 잎에

한국형 잔디에 있어 병원성 (라지 팻치) 감염이 산화적 스트레스의 발현에 미치는 영향을 규명하기 위해 라지 팻치에 감염된 잔디의 생육, 뿌리 건사율, 과산화수소 농도 및 지질과산화 정도를 감염이되지 않은 대조구와 비교하였다. 처리 후 6일 동안 이틀간격으로 잎과 뿌리 시료에 대해 각각 분석하였다. 라지 팻치에 감염된 잔디 뿌리의 건사율은 대조구에 비해 약 30% 증가하였다. 건물 함량은 4일째까지는 유의적인 차이가 없었으며 6일차에서만 라지 팻치 감염에

The present study was conducted to determine the effect of hexaconazole (HEX), a triazole fungicide, on the growth, yield, photosynthetic response and antioxidant potential in cucumber (Cucumis sativus L.) plants subjected to UV-B stress. UV-B radiation and HEX were applied separately or in combination to cucumber seedlings. The growth parameters were significantly reduced under UV-B treatment, however, this growth inhibition was less in HEX treated plants. HEX caused noticeable changes in plant morphology such as reduced shoot length and leaf area, and increased leaf thickness. HEX was quite persistent in inhibiting shoot growth by causing a reduction in shoot fresh and dry weight. HEX noticeably recovered the UV-B induced inhibition of biomass production. Significant accumutation in anthocyanin and flavonoid pigments in the leaves occurred as a result of HEX or UV-B treatments. HEX permitted the survival of more green leaf tissue preventing chlorophyll content reduction and higher quantum yield for photosystemⅡ under UV-B exposure. HEX treatment induced a transient rise in ABA levels in the leaves, and combined application of HEX and UV-B showed a significant enhancement of ABA content which activates H2O2 generation. UV-B exposure induced accumulation of H2O2 in the leaves, while HEX prevented UV-B induced increase in H2O2, indicating that HEX serves as an antioxidant agent able to scavenge H2O to protect cells from oxidative damage. An increase in the ascorbic acid was observed in the HEX treated cucumber leaves affecting many enzyme activities by removing H2O2 during photosynthetic processes. The activities of antioxidant enzymes including catalase(CAT), ascorbate peroxidase(APX), superoxide dismutase(SOD) and peroxidase(POD) in the leaves in the presence of HEX under UV-B stress were higher than those under UV-B stress alone. These findings suggest that HEX may participate in the enhanced tolerance to oxidative stress. From these results it can be concluded that HEX moderately ameliolate the effect of UV-B stress in cucumber by improving the components of antioxidant defense system.

상시담수 하에서 발아 및 안정적인 입모를 확보하는 것은 담수직파에서 매우 중요한 일이다. 일반적으로 담수 조건에 서는 유묘생장이 억제되지만, 담수 처리 시 초기생육이 우수한 익산429와 담수 처리 시 생육이 저조하며 생존율이 낮은 Woodrose 2품종에 대해 발아 및 초기생육기간 담수 처리하여 혐기대사와 관련된 ADH활성과 항산화효소들의 변화를 관찰하였다. 1. 담수 처리 시 벼는 유아만 신장하며 뿌리는 신장하지 못했고, 익산429가 Woodrose보다 담수상태에서 생존기간이 길었고 생장도 빨랐다. 그러나 무 처리에서는 Woodrose의 생육이 빨랐다. 2. ADH활성은 담수 처리 시 무 담수에 비해 급격히 증가하였고, 익산429가 Woodrose보다 활성이 오래 유지되었는데, 처리 7일째는 익산429가 무처리에 비해 약 7배, Woodrose는 약 2.5배 증가하였다. 4. SOD, POX, CAT 활성 모두 담수 처리에서 무 담수보다 낮았다. 그러나 SOD는 담수시 무 담수에 비해 크게 활성이 낮지는 않았으며 품종 간에는 익산429의 활성이 무 담수 및 담수 처리 모두 Woodrose보다 높았고 담수 시에도 익산429가 Woodrose보다 높게 유지되었다. POX 활성변화는 담수시 익산429가 지속적으로 증가한 반면 Woodrose는 큰 변화가 없었다. CAT활성은 담수 처리 초기부터 아주 낮은 활성을 보여 처리기간 동안 거의 증가하지 않았으나 무 담수시에는 3일까지 활성이 크게 증가하였다. 따라서 담수 처리 시 발아 및 초기생육기간 동안 담수내성이 약한 품종에서 SOD와 POX의 역할이 크고 ADH활성이 높게 유지되어 에너지를 공급할 수 있는 품종이 담수 시 초기생육에 유리할 것으로 사료된다.

인삼재배지 180지점으로부터 토양을 채취하여 토양산도, 유기물함량 및 유효인산함량을 측정한 결과 재배년수별 유의한 차이는 나타나지 않았다. 채취한 토양의 메탄올추출액으로 상추종자 발아실험을 실시한 결과 5~6년 재배지의 토양에서 종자발아나 유묘생장을 강하게 억제하는 토양추출액을 선발하였다. 선발된 토양 추출액중 발아와 유묘생장을 억제하였던 추출액은 인삼배양세포의 활력을 최대 90%까지 억제하였으나 전해물질의 누출은 증가하지 않았다. 토양추출액으로 세가지 종류의 항산화 효소 활성을 측정한 결과 superoxide dismutase는 거의 영향을 받지 않았으나, 상추유묘의 생체중억제형 토양추출액을 처리한 인삼배양세포의 peroxidase의 활성이 현저하게 억제되었고, catalase의 활성은 발아억제형 및 생체중억제형 토양추출액 모두에서 유의한 억제를 보였다.

In order to examine the cross-tolerance of two chilling-tolerant cultivars (Donganbyeo and Heukhyangbyeo) and two chilling-susceptible cultivars (Hyangmibyeo and Taekbaekbyeo) to salt, paraquat, and drought, changes of physiological response and antioxidant enzymes were investigated. The seedlings were grown in a growth chamber until the 4-leaf stage. The seedlings were exposed to chilling at 5~circC for 3 days. For drought treatment, the seedlings were subjected to drought by withholding water from plants for 5 days. For paraquat study, plants were sprayed with 300~muM paraquat. For the salt stress, the seedlings were transferred to the Hoagland's nutrient solution containing 0.6% (w/v) NaCl for 4 days. Chilling-tolerant cultivars showed cross-tolerant to other stresses, salt, paraquat, and drought in physiological parameters, such as leaf injury, chlorophyll a fluorescence, and lipid peroxidation. The baseline levels of antioxidative enzyme activities, catalase (CAT) and peroxidase (POX) activities in chilling-tolerant cultivars were higher than in the chilling-susceptible cultivars. However, there were no differences in ascorbate peroxidase (APX) and glutathione reductase (GR) activities between chilling-tolerant and -susceptible cultivars in untreated control. CAT activity in chilling-tolerant cultivars was higher than that in chilling-susceptible cultivars during chilling, salt, and drought treatments, but not during paraquat treatment. However, other antioxidative enzymes, APX, POX, and GR activities showed no significant differences between chilling-tolerant and -susceptible cultivars during chilling, salt, paraquat, and drought treatments. Thus, it was assumed that CAT contribute to cross-tolerance mechanism of chilling, salt, and drought in rice plants.

This study was carried out to investigate the antioxidative enzymes and isozymes between chilling-tolerant and -susceptible varieties at the booting stage under cold water stress (13~circC) in japonica rice. Total SOD, CAT, POX, and GR activities on the basis of protein were found to be important factors to defend cold water stress. Especially, SOD and CAT activities showed distinctive differences between chilling-tolerant and -susceptible varieties. Chilling-tolerant varieties were higher than chilling-susceptible varieties for SOD and CAT activities. One of eight isozyme bands for SOD was a inducible isoform. Three isozymes for CAT and one isozyme for POX were closely correlated with defense to cold water stress. Total GR activities except Stejaree 45 on the basis fresh weight and POX were increased by cold water stress, but there was no difference between chilling-tolerant and -sus­ceptible varieties.

In order to examine the mechanistic basis for differential sensitivities to chilling and subsequent recovery between two rice (Oryza sativa L.) cutivars, a chilling-tolerant japonica type (Ilpumbyeo) and a chilling-susceptible indica type (Taebaekbyeo), changes of physiological responses and antioxidant enzymes were investigated. Both cultivars at 3 leaf stage were exposed at a low temperature of 5~circC for 3 days and subsequently recovered in a growth chamber at a 25~circC for 5 days with 250 mmol m-2 s-1 . Physiological parameters such as leaf fresh weight, relative water content, cellular leakage, lipid peroxidation, and chlorophyll a fluorescence showed that the chilling tolerant cultivar had a high tolerance during chilling. However, the chilling-susceptible cultivar revealed severe chilling damages. The chilling-tolerant cultivar was also faster in recovery than the chilling-susceptible cultivar in all parameters examined. We analyzed the activity and isozyme profiles of four antioxidant enzymes which are: superoxide dismutase (SOD), caltalase (CAT), ascorbate peroxidase (APX), and glutation reductase (GR). We observed that chilling-tolerance was due to a result of the induced or higher antioxidant enzyme system, CAT and APX in leaves and SOD, CAT, APX, and GR in roots. Especially, we observed the most significant differences between the chilling-tolerant cultivar and -susceptible cultivar in CAT and APX activity. Also in isozyme profiles, CAT and APX band intensity in the chilling-tolerant cultivar was distinctively higher than in the chilling-susceptible cultivars during chilling and recovery. Thus, the cold stability of CAT and APX are expected to contribute to a tolerance mechanism of chilling in rice plants. In addition, the antioxidative enzymes activity in roots may be more important than in that of leaves to protect chilling damage on rice plants.

Ozone (O3 )-induced changes in chlorophyll content and specific activities of antioxidant enzymes, such as superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) were investigated in two rice cultivars (Oryza sativa L.) grown under variable nutrient treatments. For this study, two rice cultivars of Ilpumbyeo (IL) and Keumobyeo#l (KM), which were known as resistant and susceptible to O3 , respectively, were exposed to O3 at 0.15ppm for 30 days and investigated with 10 days interval. The available nutrient regimes were varied by doubling the supply of nitrogen (N), phosphorus (P) and potassium (K) Within a basic fertilizer status (N, P, K; 15, 12, 12kg/l0a-1 ). In both cultivars and at all nutrient status, chlorophyll content in O3 -treated plants decreased with prolonged treatment period, although higher N, P and K supply with O3 treatment alleviated the decrease in chlorophyll content. The activities of almost all enzymes investigated for this study were decreased during initial stages of O3 - exposure except GPX which maintained higher activity throughout the exposure period than the non-treated plant. However, the antioxidant enzymes in O3 -treated plants showed almost the same or higher activities on 30 days after O3 - exposure. The most significant changes in activities were observed in GR of the O3 -treated leaves. With the prolonged treatment period, the activity of GR at 30 days was increased by 3-8 times compared to those in 10 days. Most of the investigated enzymes showed very similar tendency to O3 treatment in all fertilizer status. There was no observed evidence for enhanced detoxification of O3 -derived activated oxygen species in plants grown under higher fertilizer status compared with that in plants grown under basic fertilizer status. The increase in the activities of SOD, APX and GR in rice leaves by relatively long-term treatment with O3 at low concentration is considered to indicate that the plant became adapted to the O3 stress and the protection system increased its capacity to scavenge toxic oxygen species. Our results in two rice cultivars indicated that there was little difference in the activities of antioxidant enzymes between IL and KM, which were known as resistant and susceptible cultivar to O3