본 연구는 식용화 팬지의 UV-B 주·야간 처리에 따른 항산화물질 변화와 생장반응을 알아보고자 수행되었다. 식용화 팬지(Viola comuta ‘Purple’, ‘Blue’)를 대상으로 인공 재배기에서 광원을 LED(백색) 120μmol·m-2s-1로 16시간으로 하였으며, 자외선 UV-B(310~320nm)처리는 기존연구에서 UV-B처리 효과가 좋았던 20분을 주간(11:50~12:10)과 야간(23:50~00:10)으로 처리하였다. 처리 결과, 두 품종 모두 대조구와 UV-B 주·야간 처리간의 꽃과 잎의 생체중 및 건물중은 유의한 차 이가 없었으며, ‘Blue’의 야간 UV-B 처리를 제외한 모든 처리구에서 꽃수도 유의차가 없었다. 처리 후 1, 3, 5주차에 분석한 결과, 잎의 엽록소함량은 ‘Purple’의 3주차를 제외한 모든 처리구에서 유의차가 없었으며, 두 품종 모두 Fv/Fm과 NPQ(Non Photochemical Quenching)값이 처리 간 유의차가 없었다. 또한 UV-B 처리 5주차에 활성산소(superoxide, O2 -)의 Nitrotetrazolium blue chloride(NBT) 염색 후 현미경으로 관찰한 결과, 처리 간 차이가 없었다. 항산화물질인 총 플라보노이드 함량을 분석한 결과, ‘Purple’은 3주차까지 대조구보다 주간 UV-B 처리구가 많은 것을 알 수 있었고, ‘Blue’의 경우 5주차까지 유의차는 없었지만 주·야간 UV-B 처리구가 대조구에 비해 높은 것을 알 수 있었다. 안토시아닌 함량은 ‘Purple’의 경우 3주차만 제외하고 야간 UV-B 처리구가 가장 높은 것을 알 수 있었으나, ‘Blue’의 경우 처리 간 유의차가 없었다. 결론적으로, 주·야간 UV-B 20분처리는 팬지 ‘Purple’과 ‘Blue’의 생장에 거의 영향을 주지 않았으며, ‘Purple’의 총 플라보노이드 함량은 처리 3주까지 증가하였다.

This study was conducted to investigate the effect of ultraviolet light (UV-B) on plant growth and petal antioxidants of edible flower pansy (Viola × wittrochiana ‘Rose’ and ‘Yellow’, V. cornuta ‘Purple’). The plants were grown under white LED of 100 μmol·m-2·s-1 PPFD and treated by UV-B of 10, 20 and 30 minutes per day: UVB-10, UVB-20, and UVB-30 respectively. The plant growth was significantly inhibited as longer UV-B radiation exposure, even ‘Rose’ could not f lower under UVB-30. NPQ increase was observed in all cultivars with longer UV-B irradiation exposure. Also, anthocyanin in ‘purple’ and ‘Rose’ or carotenoid in ‘Yellow’ increased in the petals as longer UV-B radiation exposure. Unexpectedly the contents of total phenol and DPPH did not show the significance in UV-B treatments. In conclusion, the applicable UVB exposure to edible pansy in order to more accumulate antioxidants in petals would be in 20 minutes per day.

The UV-B sensitivity was tested for the intertidal species Chondrus ocellatus from Korea, by measuring photosynthesis estimated as effective quantum yield (ΦPSII) of photosystem II (PS II), growth and content and composition of photosynthetic pigm

남극에 생육하는 5종의 홍조류(Curdiea racouitzae, Gigartina skottsbergii, Mazzaella obovata, Myriogramme manginii, Palmaria decipiens)를 대상으로 인공 중파 자외선과 태양광선에 대한 종별 생리적 반응을 광합성이라는 파라미터를 사용하여 조사 연구하였다. 실험실연구 결과, 종간에 중파 자외선에 대한 내성 차이가 확인되었으며 이러한 차이는 각 종들이 채집되기 전에 서식하고 있었

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.

The effect of nitric oxide (NO) on antioxidant system and protective mechanism against oxidative stress under UV-B radiation was investigated in leaves of maize (Zea mays L.) seedlings during 3 days growth period. UV-B irradiation caused a decrease of leaf biomass including leaf length, width and weight during growth. Application of NO donor, sodium nitroprusside (SNP), significantly alleviated UV-B stress induced growth suppression. NO donor permitted the survival of more green leaf tissue preventing chlorophyll content reduction and of higher quantum yield for photosystem Ⅱ than in non-treated controls under UV-B stress, suggesting that NO has protective effect on chloroplast membrane in maize leaves. Flavonoids and anthocyanin, UV-B absorbing compounds, were significantly accumulated in the maize leaves upon UV-B exposure. Moreover, the increase of these compounds was intensified in the NO treated seedlings. UV-B treatment resulted in lipid peroxidation and induced accumulation of hydrogen peroxide (H2O2) in maize leaves, while NO donor prevented UV-B induced increase in the contents of malondialdehyde (MDA) and H2O2. These results demonstrate that NO serves as antioxidant agent able to scavenge H2O2 to protect plant cells from oxidative damage. The activities of two antioxidant enzymes that scavenge reactive oxygen species, catalase (CAT) and ascorbate peroxidase (APX) in maize leaves in the presence of NO donor under UV-B stress were higher than those under UV-B stress alone. Application of 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3- oxide (PTIO), a specific NO scavenger, to the maize leaves arrested NO donor mediated protective effect on leaf growth, photosynthetic pigment and free radical scavenging activity. However, PTIO had little effect on maize leaves under UV-B stress compared with that of UV-B stress alone. Nω -nitro-L-arginine (LNNA), an inhibitor of nitric oxide synthase (NOS), significantly increased H2O2 and MDA accumulation and decreased antioxidant enzyme activities in maize leaves under UV-B stress. This demonstrates that NOS inhibitor LNNA has opposite effects on oxidative resistance. From these results it is suggested that NO might act as a signal in activating active oxygen scavenging system that protects plants from oxidative stress induced by UV-B radiation and thus confer UV-B tolerance.

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 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.