請用此 Handle URI 來引用此文件: http://hdl.handle.net/11455/21693
標題: 低溫/相對強光逆境下Chlorella光合作用與超氧歧化酶活性之變化
The change in Chlorella photosynthesis and superoxide dismutase activity under low temperature/relatively high irradiation stress
作者: 林文豪
Lin, Wen-Hao
關鍵字: Chlorella
小球藻
superoxide dismutase
low temperature
high irradiation
stress
超氧歧化酶
低溫
高光
逆境
出版社: 生命科學系
摘要: 光合作用是植物生長發育所需能量之來源,但其效率與環境因素有相當密切之關係。低溫環境下植物的光合作用效能變差,與強光環境下植物吸收過多的光能,都容易讓多餘的能量造成活性氧化物,進而破壞光系統影響整體光合作用。更有研究指出低溫環境容易導致細胞受到強光的傷害。因此,我們利用單細胞綠藻Chlorella為材料,在不同低溫和光度下,測量其葉綠素螢光之增減,亦即光合作用效率之變化,以了解低溫與強光對於光系統之傷害。另外,我們也探討植物抗氧化系統的第一道防線,超氧歧化酶(SOD)之活性與植物在逆境環境下生長之關聯性。本實驗之材料Chlorella DT與8b,兩者生理表現極為相似,其中DT具有較佳的抗乾旱性。由實驗結果得知,在適當光度(120 ■mol m-2s-1)處理下,低溫對DT與8b的生長速率、光合作用效率的影響都很相似,且15℃以下的環境兩者都無法適應。同時發現,在相同蛋白質含量的粗萃取液中,DT之SOD活性略比8b強,且活性增加較快。在相對強光(240 ■mol m-2s-1)的實驗中,發現DT初期的光合作用效率比8b易受影響,但後期兩者又相當接近。而SOD活性表現方面,在15℃實驗中,發現DT的SOD活性比8b大且異構酶多。本研究證實低溫確實易導致光抑制的現象,而DT較8b能藉由SOD活性來減少光抑制產生的傷害。
Photosynthesis is energy source for plant growth and development. And the efficiency of photosynthesis has a closely relationship with environmental conditions. Low temperature results in a net decrease in photosynthetic efficiency. In high light environment plants absorb energy that exceeds the consumed by photosynthetic processes. Too much energy can lead to increased production of reactive oxygen species (ROS). Then ROS damage the photosynthetic apparatus and decrease photosynthetic efficiency. We would like to understand how low temperature and high light damage photosynthesis. So we study green alga Chlorella which has a chloroplast structure comparable to that of higher plants. In addition, we want to clarify the relationship between the growth and the activity of superoxide dismutase (SOD) which is the first line of cellular defense against oxidative stress. Chlorella DT and 8b are almost alike in their physiology, but DT strain is a desiccation tolerance strain. With optimal illumination of 120 ■mol m-2s-1, the cell growth rate and chlorophyll fluorescence Fv/Fm value were nearly the same between DT and 8b at various temperature. When temperature was below 15oC, DT and 8b could not survive. The SOD activity of DT was higher than that of 8b at low temperature. With higher illumination of 240 ■mol m-2s-1, Fv/Fm rations of DT decreased more greatly than those of 8b in the early period of low temperature acclimation. As for SOD activity, we found that DT had higher SOD activity and more induced isoenzymes than 8b at 15oC. In our study, we approve that a combination of high light and low temperature greatly increases the photoinhibition process. DT uses SOD more efficiently than 8b to decrease the damage of photoinhibition under the stress of low temperature.
URI: http://hdl.handle.net/11455/21693
顯示於類別:生命科學系所

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