Heading time is important element for yield and quality in crops. Among day length and temperature which influence on heading, temperature effect has not been investigated well. To investigate temperature effect on heading, heading date and plant growth characters were checked under the low and high temperature conditions in short day length. Analyzing heading date of six Korean varieties under the high and low temperature condition, heading date of varieties were delayed under low temperature. In the low temperature condition, dry weight and area of leaf were reduced. Varieties showing more delay of heading under low temperature also showed more reduction in leaf area. After selecting three varieties showing significant difference in leaf growth and heading date under different temperature conditions, nutrient contents of plant were analyzed. Nitrogen content was reduced in leaf and shoot under the low temperature condition. OsNRT2.3, nitrate transporter, was significantly down regulated in varieties showing more heading delay. Available phosphate content was decreased in leaf, but increased in shoot due to reduction of phosphate mobility. OsPT1, phosphate transporter regulating phosphate uptake, was more down regulated in varieties showing more heading delay. OsPT6, phosphate transporter regulating phosphate transport in plant, was also significantly down regulated in those varieties. With these data, we expected that active nitrogen and available phosphate uptake and transport in plant would increase leaf growth then might reduce heading delay under the low temperature condition.Keywords : heading date, leaf area, nutrient, rice, temperature Cultivation season and yield in crops are changed by flowering date. Day length and temperature are reported as the main elements which effect on flowering time. According to effect of day length on flowering, plants can be classified as three types; longer day length, short day length and neutral plant. Longer and shorter day length stimulate flowering in long-day plant and short day plant, respectively. Day length is not effect on flowering in neutral plant. Rice is a typical short day length plant. In short day length, endogenous genes related with flowering are expressed then protein complex of florigen is translated, finally young panicle is developed in shoot. The growth period of rice is divided as two parts, vegetative growth phase and reproductive stage. After vegetative growth, panicle initiation is started during reproductive stage. Vegetative growth phase is showed difference according to varieties and also greatly effect on growth duration in rice cultivars (Vergara et al., 1985). The vegetative growth phase is also divided as two phases, the basic vegetative phase (BVP) and the photoperiod sensitive phase (PSP). BVP is not affected by light length. However day length is greatly influence on flowering during PSP.Day length is not changed according to the environment condition. It is just different according to the latitude. However temperature can be...
In the present study, the effects of paprika extract and its components including vitamin C, lycopene and beta-carotene on cell death in ultraviolet B (UVB)-exposed HaCaT cells were investigated. The cell viability upon treatment for 24 hr with either paprika extract or vitamin C alone was similar to or greater than that of the untreated control. However, the viability of the cells treated with lycopene or beta-carotene decreased to about 20% of that in the untreated control. When UVB-exposed cells were post-incubated for 24 hr in medium containing paprika extract or vitamin C, cell viability increased in a concentration dependent manner as compared to those post-incubated in a normal growth medium. In contrast, post-incubation of UVB-exposed cells with lycopene or beta-carotene decreased cell viability in a concentration dependent manner as compared to those post-incubated in a normal growth medium. The nuclear fragmentation analysis showed that paprika extract or vitamin C decreases UVB-induced apoptosis. The apoptotic nuclear fragmentation resulting from UVB exposure was also protected by the paprika extract or vitamin C post-incubation. However, the UVB-induced apoptotic nuclear fragmentation of the cells treated with lycopene or beta-carotene increased in a concentration dependent manner. Western blot analysis showed that either paprika extract or vitamin C treatment alone did not significantly change the level of p53 and GADD45 protein.Interestingly, post-incubation of UVB-exposed cells with paprika extract or vitamin C decreased the p53 and GADD45 protein level as compared to those post-incubated in a normal growth medium. In contrast, incubation of UVB-exposed or non-irradiated cells with lycopene or beta-carotene increased the p53 and GADD45 protein levels in a concentration dependent manner as compared to those incubated in a normal growth medium. All these results suggest that paprika extract and vitamin C help the survival of the UVB-exposed cells, while lycopene and beta-carotene potentiate the apoptotic death of UVB-exposed cells, in accordance with the respective changes in p53 and GADD45 protein levels.
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