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Studies On Relationship Of Signals SA, NO And H2O2 In The Responses Of Arabidopsis To Toxin Of Verticillium Dahliae

Posted on:2005-11-25Degree:MasterType:Thesis
Country:ChinaCandidate:S S LiFull Text:PDF
GTID:2120360122989234Subject:Botany
Abstract/Summary:PDF Full Text Request
In this experiment, seedlings of Arabidopsis thaliana (Col) were observed after being treated by Verlicillium dahliae (VD-toxin), exogenous salicylic acid (SA), nitric oxide donor (SNP) and nitric oxide synthase inhibitor (NNA), then we investigated the changes of endogenous H2O2 content, the activity of the antioxidant enzymes catalase (CAT,EC: 1.11.1.6) and ascorbate peroxidase (APX,EC:1.11.1.11) and mRNA levels of CAT3 in different stress conditions,we also identified the localizations of H2O2 and NO accumulated in the leaves of Arabidopsis.The accumulation of hydrogen peroxide (H2O2) in Arabidopsis was induced by the treatment of SA and SNP. The effect of SNP was the most intense. H2O2 level was not increased in Arabidopsis treated with NNA. It was identified with the results of DAB staining of H2O2 accumulates in the leaves of Arabidopsis. H2O2 was cytochemically detected in the cells of epidermal hair and the cell wall of vascular parenchyma cell. CAT and APX were the two major H2O2-scavenging enzymes in plants. When seedlings of Arabidopsis thaliana were treated by VD-toxin, the activity of CAT and CAT3 mRNA level were decreased after SA treatment. The activity of APX was also decresed after SA and VD-toxin treatment.The activity of CAT was decreasded more obviously. In the VD-toxin infected Arabidopsis, NO also restrained the activity of CAT and decreased the level of CAT3 mRNA . The results suggested that H2O2 acted as a signal to involve the defense reactions which is induced by SA and NO in Arabidopsis.The dual effects of NO were validated in this research. NO was either oxidative or antioxidative which depends on the circumstances. Generally NO took part in the antioxidant cellular system by elevating the activities of CAT and APX .While in the VD-toxin infected Arabidopsis, NO supressed the activity of CAT and may participate in redox signaling during the activation of defense responses which follows the pathognen attack.We use a specific NO probe diaminofluorescein diacetate (DAF-2DA) to visualize the changes of NO content with different treatments and its localization . The NO burst in Arabidopsis was induced by VD-toxin, SA and H2O2. NO accumulated in the guard cells and the epidermal cells of the lowerepidermal layer of Arabidopsis.These results revealed that there may be a complicated interaction among the three signal moleculars NO,SA and H2O2 in the Responses of Arabidopsis to Toxin of Verticillium dahliae. The interaction played important function in the defence reactions of Arabidopsis.
Keywords/Search Tags:Arabidopsis, hydrogen peroxide, nitric oxide, salicylic acid, Verlicillium dahliae
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