Molecular Bases of the Heat Shock Response in Plants- Identification of Elements Involved in Heat Shock Transduction Pathway and in the Cross Talk between Heat Shock and Oxidative Stress
Date Issued
2010
Date
2010
Author(s)
Wu, Hui-Chen
Abstract
While being unable to escape their lands, plants are continuously submitted to the modifications of their environment, and need to adjust proper physiological processes in response to various stimuli. During this work, I devoted my studies on two major stresses affecting plant development, heat shock (HS) and oxidative stresses (OS), focusing on key elements in these pathways (HS chaperons and HS-related thioredoxins) in order to bring news elements of knowledge and interconnexion of these pathways.
Using rice and soybean as mono- and dicotyledonous plant systems, I show how HS leads to calcium release from plant cell apoplast to the cytosol in a typical “calcium signature”, conferring cell wall rigidity and enhancing HS signaling pathway. I also identify pectin methylesterase (PME) as required in this pathway for cell wall remodeling and plasma membrane integrity. I further investigate how plant sense temperature increases and how they transmit the HS signal to downstream elements. Using systematic analyses of calmodulin (CaM) and small heat shock protein (sHSP) gene expression, I identify one CaM as a coordinator of HS response, which I characterize as involving specific cytosolic/nuclear isoforms of the sHSP family.
I latter perform the molecular analysis of TDX, a thioredoxin suspected to be involved in heat shock response. I show that TDX interacts with nucleo-cytoplasmic members of the HSP70 family in a redox dependent manner, both HS and OS inducing its nuclear relocation, and that TDX is required for both acquired thermotolerance and OS signaling.
I finally discuss the data brought by this work and propose models with cross-talks between HS and OS signaling.
Subjects
Calcium
Chaperone
Calmodium
Heat shock proteins
Oxidative stress
Pectin methylesterase
Tetratricoredoxin
Type
thesis
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