Cold acclimation is accompanied by complex responses of glycosylphosphatidylinositol (GPI)-anchored proteins in Arabidopsis.

Daisuke Takahashi,Matsuo Uemura,Yukio Kawamura

doi:10.1093/jxb/erw279

Abstract

Cold acclimation results in changes of the plasma membrane (PM) composition. The PM is considered to contain specific lipid/protein-enriched microdomains which can be extracted as detergent-resistant plasma membrane (DRM). Previous studies in animal cells have demonstrated that glycosylphosphatidylinositol-anchored proteins (GPI-APs) can be targeted to microdomains and/or the apoplast. However, the functional significance of GPI-APs during cold acclimation in plants is not yet fully understood. In this study, we aimed to investigate the responsiveness of GPI-APs to cold acclimation treatment in Arabidopsis We isolated the PM, DRM, and apoplast fractions separately and, in addition, GPI-AP-enriched fractions were prepared from the PM preparation. Label-free quantitative shotgun proteomics identified a number of GPI-APs (163 proteins). Among them, some GPI-APs such as fasciclin-like arabinogalactan proteins and glycerophosphoryldiester phosphodiesterase-like proteins predominantly increased in PM- and GPI-AP-enriched fractions while the changes of GPI-APs in the DRM and apoplast fractions during cold acclimation were considerably different from those of other fractions. These proteins are thought to be associated with cell wall structure and properties. Therefore, this study demonstrated that each GPI-AP responded to cold acclimation in a different manner, suggesting that these changes during cold acclimation are involved in rearrangement of the extracellular matrix including the cell wall towards acquisition of freezing tolerance.

Highlights

Plants are often exposed to severe external stresses, such as extreme temperatures, drought, flooding, high salinity, nonpreferred nutrition, high or low light, and high UV
The plasma membrane (PM) fractions obtained were used for isolation of microdomain-enriched detergent-resistant plasma membrane (DRM) and glycoslphosphatidylinositol-anchored protein (GPI-AP) fractions
GPI-AP fractions after or before the phosphatidylinositol-specific phospholipase C (PI-PLC) treatment were subjected to one-dimensional SDS–PAGE to check the efficiency of PI-PLC treatment for the enrichment of GPI-APs

Summary

Introduction

Plants are often exposed to severe external stresses, such as extreme temperatures, drought, flooding, high salinity, nonpreferred nutrition, high or low light, and high UV. Freezing stress consists of cold, mechanical, drought, and osmotic stresses—all of which are caused by a combination of low temperature and extracellular ice formation (Steponkus, 1984). When recognizing a decline in temperature and shortening of the light period, plants can increase their freezing tolerance by changing their cellular metabolism in the cold acclimation process. An example of the representative changes during cold acclimation is the increase of cellular osmolality by accumulation of compatible solutes, such as sugars and amino acids (Koster and Lynch, 1992), and specific proteins (mostly with hydrophilic properties) to prevent membranes and proteins from freeze-induced disruption and/or denaturation (Koster and Lynch, 1992; Wanner and Junttila, 1999)

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