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標題: 鹽分處理對水稻醣類代謝之影響
Effects of Salt Stress on Carbohydrate Metabolism of the Rices(Oryza sativa L.)
作者: 黃瑞彰
Huang, Rui-Zhang
關鍵字: Rice
Carbohydrate Metabolism

出版社: 植物學系
摘要: 分別以 150mM 及 250mM 氯化鈉,處理水耕及組織培養之供試水稻。結果 發現鹽分處理導致生長明顯減緩,鮮重及乾重亦下降。供試株地上部葉片 組織之光合成速率、呼吸速率及固碳作用相關的核酮糖雙磷酸羧化/加氧 酵素 ( ribulose-1, 5-bisphosphate carboxylase / oxygenase)活性 ,亦均受鹽分抑制。上述之抑制情形,以鹽敏感之供試水稻品種 (IR34、 台農72) 較嚴重。鹽分逆境下,供試水稻之呼吸率降低,主要歸因於細胞 色素途徑活性受抑制,交替途徑活性則增加;葉片中可溶糖及脯胺酸含量 ,亦隨鹽處理而明顯增加,此兩種物質累積,可當作相容物質或滲透保護 劑。利用高效液相層析法(HPLC)分析可溶糖組成,發現果糖、葡萄糖、蔗 糖等三糖含量皆增加,其中以蔗糖最多。可溶糖累積,有助於供應植株呼 吸所需之基質。而與蔗糖代謝相關酵素中,蔗糖磷酸合成酵素 (sucrose phosphatesynthase)及蔗糖合成酵素(sucrose synthase) 活性增加,酸 性轉化酵素(acid invertase)活性受抑制,中性轉化酵素 (neutral invertase)活性則無明顯變化。由這些結果,可知蔗糖累積,取決於蔗糖 磷酸合成酵素及酸性轉化酵素間之平衡。鹽處理株,光合成速率受抑制, 而體內蔗糖含量增加 ,澱粉含量則降低,導致蔗糖/澱粉比上升,其中以 耐鹽之供試水稻(IR44 、台農秈19) 最明顯。這些改變歸因於鹽誘導光合 成產物碳分配改變所致,且蔗糖之增加,是水稻適應鹽分逆境之一種表現 。
Rices (Oryza sativa L.) were grown in media supplemented with 150mM NaCl using hydroponic culture system or with 256mM NaCl using tissue culture system. In both cases, the plant growth were arrested, the fresh weight and dry weight were decreased as well. Further analysis of photosynthesis and dark respiration rate indicated that both processes were inhibited by salt stress. A higher degree of inhibition by salt were found in salt-sensitive varieties, including IR34 and TNG72. In all varieties, the decreased respiration rate was due to decreased activity of cytochrome pathway, whereas the activity of alternative pathway was increased. Total soluble sugar and proline contents of rice leaves under salt stress were increased. Both sugar and proline have been shown to serve as compatible solutes which have been known involved in the mechanism of salt-stress tolerance. Analysis of constitutes of total soluble sugars with HPLC indicated fructose, glucose, sucrose contents were increased under salt stress. Among them, sucrose content was the highest. Along with the increased sucrose content under salt stress, the enzymes in the pathway for sucrose synthesis ,e.g. SPS and SS activity were also increase. Acid invertase activity was decreased under salt stress while the activity of neutral invertase remained relatively unchanged. These results indicated that both SPS and acid invertase are con- tributed to the sucrose accumulation in response to salinity in rice leaves. Photosynthesic rate of rice leaves under salt stress were decreased and the ratios of sucrose to starch were increased. The increased ratio of sucrose to starch in salt-tolerance varieties were more significant, such as IR44 and TNS19. These changes were in part due to more in partitioning of photosynthates into sucrose synthesis pathway. These results suggest a role of sucrose accumulation in adaptation
Appears in Collections:生命科學系所



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