Ascorbate peroxidase SPAPX and reduced ascorbate alleviate NaCl-mediated leaf senescence in sweet potato
| Autor: | Rui-qi Xu, 徐瑞琪 |
|---|---|
| Rok vydání: | 2016 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 104 Ascorbate peroxidase ( APX ) is one of the key enzymes of the glutathione-ascorbate cycle. It utilizes the reduced ascorbate to scavenge the reactive oxygen species and maintains the cellular H2O2 homeostasis. Therefore, it plays an important role in association with developmental response and stress adaptation. In our laboratory, an ethephon-inducible ascorbate peroxidase SPAPX has been cloned. Exogenous application of the SPAPX fusion protein and reduced ascorbate alleviate NaCl-promoted leaf senescence. In this research the main issue focuses on whether the cloned sweet potato SPAPX and reduced ascorbate can modulate NaCl-promoted leaf senescence. Western blot hybridization with the anti-SPAPX antibody showed that the level of ascorbate peroxidase SPAPX in natural, ethephon and NaCl-mediated senescent leaves was slightly reduced and negatively correlated with the level of leaf senescence. NaCl stress promoted leaf senescence demonstrated with senescence-associated markers, including leaf yellowing, reduced chlorophyll content and Fv/Fm level, elevated H2O2 and MDA amounts. Exogenous SPAPX fusion protein mitigated NaCl-promoted leaf senescence dose-dependently, which could be abolished and reversed by inactivation of the SPAPX fusion proteins using 95℃ and anti-SPAPX antibody pre-treatment. Exogenous SPAPX fusion protein did not significantly affect leaf senescence under the dark. Exogenous reduced ascorbate, however, also attenuated NaCl-promoted leaf senescence dose-dependently. Based on these results, sweet potato ascorbate peroxidase SPAPX and reduced ascorbate attenuate NaCl-promoted leaf senescence. It also suggests that ascorbate peroxidase SPAPX requires NaCl but not dark inducible interacting components for efficient attenuation of NaCl-mediated leaf senescence. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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