Studies on oxidative stress in rice seedlings under low temperature

在台灣，一期作水稻 (Oryza sativa L.) 於早期生長階段易受低溫影響而降低其存活率、阻礙光合作用進行、抑制生長、能量和脂質代謝及蛋白質的合成，進而導致後期產量減少。本論文擬探討8個水稻品種幼苗於低溫環境下地上部與根部之生理反應現象，以目前台灣8個水稻領先品種，分別為台東30號 (Taitung 30, TT30)、台南11號 (Tainan 11, TN11)、台農71號 (Tainung 71, TNG71)、高雄139 (Kaohsiung 139, KH139)、台稉9號 (Taikeng 9, TK9)、台稉14號 (Taikeng 14, TK14)、台稉16號 (Taikeng 16, TK16) 及台中秈10號 (Taichung sen 10, TCS10) 為試驗材料。以15℃低溫處理不同品種水稻幼苗4天，發現8個品種之地上部與根部生長明顯受抑制，鮮重、乾重與長度皆顯著降低，且根部MDA 含量有提高之趨勢，但TNG 71與TK14與控制組相比則無顯著差異；測量根部過氧化氫 H2O2含量也與MDA趨勢相同，並由相關分析也發現H2O2及MDA含量與水稻幼苗根部之鮮重、乾重和長度呈現負相關性，表示水稻於低溫逆境下會受氧化逆境影響，使得水稻生長受到抑制，而TNG 71與TK14則反之，說明應較能抵禦逆境之發生。結果也發現TNG 71、TK14與TCS10的ASC及GSH含量變動不明顯，且SOD、APX和GR活性上升幅度也較少，其他品種則為因應氧化逆境使抗氧化系統皆有顯著改變，此現象可能與TNG 71及TK14累積ROS較少有關，然而TCS10雖有氧化逆境發生，但其清除ROS能力較差，因此受低溫影響更為嚴重。由上述結果得知稉稻中TNG 71與TK14應為對低溫較具耐性之品種，而TCS10可能因屬於秈稻系統，所以相較其他品種而言對低溫抵抗能力更為不佳。In Taiwan, low temperature will inhibit rice growth, photosynthesis, protein synthsis, energy and lipid metabolism, and cause lower survival rate at early stage. Because of these reasons, low temperature may reduce production in Taiwan rice. We use rice (Oryza sative L.) seedlings including Taitung 30, Tainan 11, Tainung 71, Kaohsiung 139, Taikeng 9, Taikeng 14, Taikeng 16 and Taichung sen 10 to investigate how affects of different cultivars rice under low temperature. After treated 15℃ for 4 days, shoot and root fresh weight, dry weight, shoot height and root length are all reduced in eight cultivars of rice seedlings. The MDA and H2O2 content are also increased in roots after cold treatment, but TNG 71 and TK14 are not affected significantly. And MDA and H2O2 content are negative correlation between root fresh weight, dry weight and length by correlation analysis. This indicates low temperature will induce oxidative stress among all cultivars except TNG 71 and TK14. The results also reveal that the ASC and GSH content are not influenced onTNG 71, TK14 and TCS10 seedling roots, and SOD, APX, GR activities are only increased slightly. But the antioxidantive system of other cultivars of rice have strong reponse to oxidative stress. This possibly related to less accumulation of ROS in TNG 71 and TK14. However, severe oxidative stress was observed in TCS10 due to its poor ROS scavenging ability. The study suggests that TCS10 will be damaged the most among these eight rice cultivars . According to this finding, we know japonica rice TNG71 and TK14 have better tolerance of chilling. And because of TCS10 may belongs to indica rice system, so its ability to resistance chilling is worse than other rice varietis.目錄 中文摘要----------------------------------------------------------------------------i 英文摘要------------------------------------------------------------------------- iii 目錄------------------------------------------------------------------------------v 圖表目錄-------------------------------------------------------------------------vii 縮寫字對照-------------------------------------------------------------------- ix 壹、前言-----------------------------------------------------------------------------1 貳、前人研究-----------------------------------------------------------------------3 一、 低溫對台灣糧食作物造成之經濟損失------------------------3 二、 低溫對作物生長之影響------------------------------------------4 (一) 低溫對水稻生長之影響------------------------------5 (二) 低溫對水稻光合作用之影響----------------------------6 (三) 低溫對水稻養分吸收之影響----------------------------7 (四) 低溫對水稻花穗及產量之影響-------------------------8 三、 低溫伴隨氧化逆境的發生---------------------------------------9 (一) 植物產生ROS的來源------------------------------------9 (二) 植物清除ROS之機制-----------------------------------10 (三) 低溫對水稻氧化逆境之影響---------------------------15 四、 低溫耐受性與低溫逆境訊號之關聯-------------------------17 (一) 低溫耐受性對水稻蛋白質體與基因表現之影響--17 (二) 冷馴化提升水稻幼苗之低溫耐受性----------------19 (三) ROS為提高低溫耐受性之因子----------------------19 (四) ROS調節低溫逆境訊號-------------------------------21 參、論文之研究目的與試驗架構---------------------------------------------23 肆、材料與方法------------------------------------------------------------------24 伍、結果---------------------------------------------------------------------------35 一、 低溫對水稻幼苗生長之影響---------------------------------------35 二、 低溫伴隨氧化逆境之發生------------------------------------------43 三、 低溫下水稻幼苗抗氧化系統之變化------------------------------50 四、TNG71、TK14、KH139及TCS10幼苗於低溫經回溫後H2O2 與MDA含量之改變-------------------------------------------------70 陸、討論---------------------------------------------------------------------------74 柒、參考文獻---------------------------------------------------------------------9