Detergent Resistant Membrane Domains in Broccoli Plasma Membrane Associated to the Response to Salinity Stress

Lucía Yepes-Molina,Maria Carmen Martínez-Ballesta,Micaela Carvajal

doi:10.3390/ijms21207694

Abstract

Detergent-resistant membranes (DRMs) microdomains, or “raft lipids”, are key components of the plasma membrane (PM), being involved in membrane trafficking, signal transduction, cell wall metabolism or endocytosis. Proteins imbibed in these domains play important roles in these cellular functions, but there are few studies concerning DRMs under abiotic stress. In this work, we determine DRMs from the PM of broccoli roots, the lipid and protein content, the vesicles structure, their water osmotic permeability and a proteomic characterization focused mainly in aquaporin isoforms under salinity (80 mM NaCl). Based on biochemical lipid composition, higher fatty acid saturation and enriched sterol content under stress resulted in membranes, which decreased osmotic water permeability with regard to other PM vesicles, but this permeability was maintained under control and saline conditions; this maintenance may be related to a lower amount of total PIP1 and PIP2. Selective aquaporin isoforms related to the stress response such as PIP1;2 and PIP2;7 were found in DRMs and this protein partitioning may act as a mechanism to regulate aquaporins involved in the response to salt stress. Other proteins related to protein synthesis, metabolism and energy were identified in DRMs independently of the treatment, indicating their preference to organize in DMRs.

Highlights

Plant plasma membrane (PM) is a selective barrier between cells and the environment, playing a crucial role in the reception and transduction of environmental signals and the regulation of cell-environment communication [1]
Based on biochemical lipid composition, higher fatty acid saturation and enriched sterol content under stress resulted in membranes, which decreased osmotic water permeability with regard to other PM vesicles, but this permeability was maintained under control and saline conditions; this maintenance may be related to a lower amount of total PIP1 and PIP2
Based on the idea that sterols are required for the formation of a liquid-ordered lipid phase in plants and that this fact will condition protein membrane location [35], in the present study we determined the detergent resistant membranes (DRMs) isolated from the root PM of broccoli plants, describing the changes induced by salinity

Summary

Introduction

Plant plasma membrane (PM) is a selective barrier between cells and the environment, playing a crucial role in the reception and transduction of environmental signals and the regulation of cell-environment communication [1]. PM is important in essential functions such as cellular nutrition, endocytosis and response to environment stresses [2]. Membrane lipids and transport proteins have an important function in regulating the permeability of PM, which triggers responses to salinity [3]. Since the control of water and nutrient distribution in the whole plant is an important factor in the acclimation of plants to a saline environment, the role of membrane proteins, such as aquaporins, is crucial, which has been widely reported in different species, such as Arabidopsis [4], maize [5] and broccoli [6]. Aquaporins work out mainly as channels to facilitate and regulate the permeability of water across cell membranes [7] and are representative markers of water uptake and whole plant water status [8]. Salinity modifies aquaporin expression and protein abundance, which indicates that these proteins must be involved in the tolerance response to salt stress [9]

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