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Reduced glutathione and NADPH oxidase inhibitor DPI alleviates ethephon-mediated leaf senescence, H2O2 elevation and senescence-associated gene expression in sweet potato

Ethylene has long been considered as the main plant growth regulator that plays a key role in the regulation of leaf senescence. In sweet potato, ethephon, an ethylene releasing compound, promoted leaf senescence and H2O2 elevation. These ethephon-mediated effects were alleviated or attenuated by exogenous reduced glutathione and ascorbic acid. Ethephon treatment gradually increased endogenous total and reduced glutathione and ascorbic acid levels in sweet potato detached leaves 3 days after treatment. The H2O2 amount, however, was also increased at 72 h after treatment. Sweet potato detached leaves pretreated with reduced glutathione did significantly increased endogenous total and reduced glutathione levels at 24 h and remarkably decreased H2O2 amount at 72 h after ethephon application compared to that of ethephon alone control. Ethephon caused quick elevation of a small H2O2 peak at about 4 h after application, and the enhancement was eliminated by reduced glutathione pretreatment in treated sweet potato leaves. Pretreatment of diphenylene iodonium (DPI), an NADPH oxidase inhibitor, also repressed leaf senescence and H2O2 elevation at day 3 after ethephon treatment in sweet potato detached leaves, and the attenuation was effective within the first 4 h after ethephon treatment. For senescence-associated gene expression, ethephon and L-buthionine sulfoximine (BSO), an endogenous glutathione synthase inhibitor, did induced asparaginyl endopeptidase (SPAE) and cysteine proteases (SPCP1, SPCP2 and SPCP3) gene expression and the activation was repressed by reduced glutathione pretreatment. Based on these data we conclude that ethephon treatment may cause quick elevation of a small H2O2 peak likely via the NADPH oxidase, which may function as a signal component leading to leaf senescence, H2O2 elevation and senescence-associated gene expression in sweet potato detached leaves. The rate of endogenous antioxidant such as reduced glutathione elevation is also important and affects leaf senescence, H2O2 elevation and senescence-associated gene expression in sweet potato leaves.

Identiferoai:union.ndltd.org:NSYSU/oai:NSYSU:etd-1123111-115045
Date23 November 2011
CreatorsHuang, Chin-shu
ContributorsChung-lung Cho, Hsien-jung Chen, Guan-jhong Huang
PublisherNSYSU
Source SetsNSYSU Electronic Thesis and Dissertation Archive
LanguageCholon
Detected LanguageEnglish
Typetext
Formatapplication/pdf
Sourcehttp://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-1123111-115045
Rightsuser_define, Copyright information available at source archive

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