1. Recovery of heat shock-triggered released apoplastic Ca2+ accompanied by pectin methylesterase activity is required for thermotolerance in soybean seedlings
- Author
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Wen-Dar Huang, Hui-Chen Wu, Shih-Feng Hsu, Dan-Li Luo, Tsung-Luo Jinn, Shiang-Jiuun Chen, and Huu-Sheng Lur
- Subjects
food.ingredient ,Pectin ,Physiology ,Plant Science ,pectin methylesterase ,Models, Biological ,thermotolerance ,Cell wall ,chemistry.chemical_compound ,food ,Heat shock protein ,Heat shock ,Pectinase ,Egtazic Acid ,Organelles ,pectin ,Esterification ,Staining and Labeling ,biology ,Protein Stability ,Spectrophotometry, Atomic ,Temperature ,Adaptation, Physiological ,Research Papers ,heat shock ,Apoplast ,Enzyme assay ,Protein Transport ,Ca2+ ,EGTA ,Polygalacturonase ,Solubility ,chemistry ,Biochemistry ,Seedlings ,Biophysics ,biology.protein ,Pectins ,Calcium ,Soybeans ,Carboxylic Ester Hydrolases ,Heat-Shock Response - Abstract
Synthesis of heat shock proteins (HSPs) in response to heat shock (HS) is essential for thermotolerance. The effect of a Ca(2+) chelator, EGTA, was investigated before a lethal HS treatment in soybean (Glycine max) seedlings with acquired thermotolerance induced by preheating. Such seedlings became non-thermotolerant with EGTA treatment. The addition of Ca(2+), Sr(2+) or Ba(2+) to the EGTA-treated samples rescued the seedlings from death by preventing the increased cellular leakage of electrolytes, amino acids, and sugars caused by EGTA. It was confirmed that EGTA did not affect HSP accumulation and physiological functions but interfered with the recovery of HS-released Ca(2+) concentration which was required for thermotolerance. Pectin methylesterase (PME, EC 3.1.1.11), a cell wall remodelling enzyme, was activated in response to HS, and its elevated activity caused an increased level of demethylesterified pectin which was related to the recovery of the HS-released Ca(2+) concentration. Thus, the recovery of HS-released Ca(2+) in Ca(2+)-pectate reconstitution through PME activity is required for cell wall remodelling during HS in soybean which, in turn, retains plasma membrane integrity and co-ordinates with HSPs to confer thermotolerance.
- Published
- 2010
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