Title page for etd-0714111-151313


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URN etd-0714111-151313
Author MUFIDAH AFIYANTI
Author's Email Address No Public.
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Department Biological Sciences
Year 2010
Semester 2
Degree Master
Type of Document
Language English
Title Characterization of a leaf-type catalase and its enzymatic regulation in sweet potato (Ipomoea batatas (L.))
Date of Defense 2011-07-11
Page Count 57
Keyword
  • calmodulin
  • calcium
  • Sweet potato
  • Leaf senescence
  • Ethephon
  • Catalase
  • 3-Amino-1,2,4-triazole
  • Abstract A major sweet potato leaf-type catalase was detected and identified from fullyexpandedmature leaves using in-gel activity staining assay with native- andSDS-PAGEs. The putative catalase activity band was inhibited by a catalaseinhibitor 3-amino-1,2,4-triazole. The major leaf-type catalase activity wasoptimal over 8, and was significantly repressed by β-mercaptoethanol. However,its activity was much less affected by temperature within the range of 5 to 450C.Temporal and spatial expression showed that it was specifically detected inleaves, but not in roots and stems. Its activity increased from the immature L2leaves, and reached the maximal at the fully-expanded mature L3 leaves, thenslightly decreased in partial yellowing senescent L4 leaves, and was almost notdetected in completely yellowing L5 leaves similar to folding unopenedimmature L1 leaves. The catalase level showed approximately inversecorrelation with the H2O2 amounts in leaves of different developmental stages.Dark and ethephon, an ethylene-releasing compound, also temporarily enhancedthe catalase activities from 6 h to 24 h, however, the enhanced activitydecreased from 24 h to 48 h in detached leaves after treatment. The catalaselevel also showed approximately negative correlation with the H2O2 amounts intreated leaves. The major leaf-type catalase activity was repressed by EGTA,and the repression can be reversed by exogenous CaCl2. The major leaf-typecatalase activity was also repressed by calmodulin inhibitor chlorpromazine,and the repression can be reversed by exogenous purified SPCAM calmodulinfusion protein. Chlorpromazine-treated leaves also elevated H2O2 amount.Based on these data we conclude that a major leaf-type catalase with maximalactivity in L3 leaf was identified in sweet potato. Its activity was temporarilyenhanced by dark and ethephon, and was modulated by external calcium ion(Ca2+) and calmodulin. A possible physiological role and function in associationwith cellular H2O2 homeostasis in cope with developmental and environmentalcues in sweet potato leaves is suggested.
    Advisory Committee
  • Chung-Lung Cho - chair
  • Ching-Nen Nathan Chen - co-chair
  • Hsien-Jung Chen - advisor
  • Files
  • etd-0714111-151313.pdf
  • indicate in-campus access in a year and off_campus not accessible
    Date of Submission 2011-07-14

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