Detergent-resistant microdomains (lipid rafts) in endomembranes of the wild halophytes

Abstract

In the present work, we studied detergent-resistant membrane microdomains (DRM) of chloroplasts and mitochondria – organelles that provide photosynthesis and respiration in a plant cell. The objects of the study were euhalophyte Salicorniaperennans Willd., which relates to salt-accumulating plants and glycohalophyte Artemisia santonica L., which relates to salt-excluder plants. To get DRM, the chloroplast and mitochondria fractions were solubilised with a solution containing Triton X-100. The resulting material was introduced in sucrose gradient of 35–25–15–5% and centrifuged at 200000 g, 2 h. The presence of an opalescent detergent-resistant zone of membranes in 15% sucrose layer and a specific lipid composition of this zone were the signs of successful rafts obtaining of. The isolated DRM are sterol- and cerebroside-enriched (27–89% of the sum of membrane lipids) domains with a high degree of saturation of fatty acids composition (more than 50% of the sum). The main DRM-specific lipids of chloroplast of A. santonica glycohalophyte are cerebrosides, whereas those of S. perennans euhalophyte are sterols. The revealed differences in the composition of raft-forming lipids in chloroplast and mitochondria halophyte membranes, differing in the salt-resistance strategy, suggest the participation of rafts in salt-resistance mechanisms.

Lipids of Halophyte Species Growing in Lake Elton Region (South East of the European Part of Russia)

“…The content of sphingolipids in the chloroplast membranes of eu-and glycohalophytes is only 2-3%, and it does not depend on the strategy of salt accumulation (Nesterov et al 2017). In halophyte mitochondria, on the other handthe organelles supplying the cell with energythe content of sphingolipids reaches 11% of total membrane lipids (Rozentsvet et al 2019). The relative content of sphingolipids in euhalophytes is three-fold of that in glycohalophytes.…”

“…In A. santonica, the predominant PL of mitochondrial DRM is PC; in S. perennans, it is DPG. The content of each of these components, however, does not exceed 5% of total membrane lipids (Rozentsvet et al 2019).…”

“…In DRM, the content of the main unsaturated FA (C18:3n3) is reduced to trace amounts (Rozentsvet et al 2019). The relative content of С18:2 in the lipids of chloroplast and mitochondrial DRM is also low and does not exceed 7%.…”

“…In the plant cell, rafts were found in plasmalemma, vacuole membranes, and membranes of the Golgi apparatus (Laloi et al 2007;Ozolina et al 2013). In the euhalophyte S. perennans and glycohalophyte A. santonica, raft structures were also found in the membranes of chloroplasts and mitochondria (Nesterov et al 2017;Rozentsvet et al 2019). An observation supporting the existence of rafts in plant membranes is the appearance of an opalescence zone in the sucrose gradient after high-speed centrifugation of detergent-treated plant material.…”

Changes in the lipid profile of detergent resistant microdomains (lipid rafts) of cell organelles of euhalophyte plants under salinization conditions

“…Например, изменения состава липидов в рафтах при холодовой акклиматизации в экспериментальных условиях приводило к изменениям термодинамических свойств и физиологических функций микродоменов, что, в свою очередь, влияло на устойчивость растений к низким температурам [7]. В отношении дикорастущих солеустойчивых растений были обнаружены различия в относительном содержании рафтоспецифичных липидов в микродоменах эндомембран галофитов с разными механизмами регуляции солевого обмена -эугалофитах и гликогалофитах [8]. Понятие…”