The redox state of glutathione links to flowering induction via ascorbate - glutathione cycle in Oncidium Gower Ramsey
Date Issued
2013
Date
2013
Author(s)
Hsieh, Chia-Chi
Abstract
The mechanism of how the phase transition from vegetative to bolting stage in Oncidium is still not distinctive. Previous studies have shown that high temperature-induced flowering is regulated by Oncidium cytosolic ascorbate peroxidase 1 (OgcytAPX1) through mediating the redox state of ascorbate (AsA). However, there were no reports on the regulating proteins interacting with AsA in the flowering process.
Here, we demonstrate that the effect of AsA redox state underlying flowering induction of Oncidium was correlated with glutathione (GSH) redox state, and this signal transduction is transduced via AsA-GSH cycle. By analyzing over-expression of OgcytAPX1 in Arabidopsis, and Arabidopsis mutant lines, apx1-1, to realize the relationship in redox homeostasis between AsA and GSH under high-temperature. This result indicate that the redox changes in GSH is closely related with AsA redox state, and further to induce flowering. Biochemical assays of the GSH levels, and GSH redox ratio, revealing that the decrease of GSH redox ratio was associated with bolting stage and high-temperature induced flowering. Analysis of transcripts level and enzymatic activity revealed that the GSH biosynthesis enzyme (γ-glutamylcysteine synthetase, GSH1 ; glutathione synthetase, GSH2) and glutathione reductase (GR1), the GSH-redox related enzyme, were decrease during bolting stage and after the high-temperature stress condition. To reconfirm the influence of GSH redox ratio in bolting, we applied glutathione biosynthesis inhibitor, buthionine sulphoximine (BSO), and GSSG (the oxidized form of GSH) in Oncidium. The results demonstrate that GSH redox ratio could strongly influence bolting. Moreover, analysis on the expression profiling of floral genes also demonstrating that GIGANTEA (GI), FLOWERING LOCUS T (FT), LEAFY (LFY), and APETALA 1 (AP1) are highly induced in these treatment, suggesting that GSH redox ratio plays the crucial role on flowering induction in Oncidium.
Subjects
維他命Ｃ-穀胱甘肽循環
穀胱甘肽氧化還原比例
開花
高溫
文心蘭
Type
thesis
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