Structural and Functional Heat Stress Responses of Chloroplasts of Arabidopsis thaliana.

Puneet Paul,Maik Böhmer,Enrico Schleiff,Wolfram Weckwerth,Palak Chaturvedi,Arindam Ghatak,Anida Mesihovic

doi:10.3390/genes11060650

Abstract

Temperature elevations constitute a major threat to plant performance. In recent years, much was learned about the general molecular mode of heat stress reaction of plants. The current research focuses on the integration of the knowledge into more global networks, including the reactions of cellular compartments. For instance, chloroplast function is central for plant growth and survival, and the performance of chloroplasts is tightly linked to the general status of the cell and vice versa. We examined the changes in photosynthesis, chloroplast morphology and proteomic composition posed in Arabidopsis thaliana chloroplasts after a single or repetitive heat stress treatment over a period of two weeks. We observed that the acclimation is potent in the case of repetitive application of heat stress, while a single stress results in lasting alterations. Moreover, the physiological capacity and its adjustment are dependent on the efficiency of the protein translocation process as judged from the analysis of mutants of the two receptor units of the chloroplast translocon, TOC64, and TOC33. In response to repetitive heat stress, plants without TOC33 accumulate Hsp70 proteins and plants without TOC64 have a higher content of proteins involved in thylakoid structure determination when compared to wild-type plants.

Highlights

The maintenance of cellular homeostasis depends on a multitude of cellular processes, which ensures cellular and organismic survival [1]
Previous studies inspecting the impact of heat stress (HS) on the performance of chloroplasts have focused either on a single or repetitive HS treatment [19,26,37,67]
HS either once (HS-I) application yielded no significant change of the chlorophyll content in ppi1 or toc64-1 when compared to control conditions (Figure 1b)

Summary

Introduction

The maintenance of cellular homeostasis depends on a multitude of cellular processes, which ensures cellular and organismic survival [1]. Important is the proper distribution of proteins within cells and their insertion into the destined compartments [5,6,7,8], which is either mediated by specialized translocon components within membranes or by vesicle transport [9,10]. Protein homeostasis and distribution in plant cells is sensitive to environmental changes [16,17,18]. Temperature changes are known to affect multiple aspects of cellular homeostasis, including the regulation and distribution of proteins in cellular sub-compartments [19,20]. First insights were obtained into the organellar proteins in response to the HS of chloroplasts [19,26]

Methods

Results

Conclusion