Studies of the physicochemical properties of membranes from Barley roots exposed to cold stress and recovery periods

VILCHEZ. AC; ANA LAURA VILLASUSO; N. WILKE

virtual

Congreso; XLIX XLIX Reunión Anual SAB (virtual).; 2021

Sociedad Argentina de Biofísica

arley tissues can respond to cold stress by modifying the fatty acid composition of themembrane. What remains unknown is whether the modifications in membranecomposition are maintained or rapidly adapted during stress relief. The present studyattempted to compare the lipid profile and physicochemical properties of membrane frombarley roots both under chilling stress treatment and in the subsequent recovery to stress.Lipids were obtained through a single-extraction method with a polar solvent mixture,directly from seedlings which had been exposed at 4°C for 36h (stress condition) and25°C for 2h or 24h (recovery conditions). Mass spectrometry analysis indicate that lipidmetabolism was significantly affected by chilling. Most of the glycerolipids analyzedreturned to control values during short- and long-term recovery, whereas severalrepresentative phosphatidic acid (PA) molecular species were edited during long-termrecovery. The natural extracts were studied using monolayers at the air/liquid interfaceand large unilamellar vesicles (LUVs). Surface pressure and surface potential compressionisotherms, as well as monolayer observation with Brewster-angle microscopy (BAM) wereperformed at 25°C and 4°C. All isotherms showed a similar shape, with a kink at about 25mN/m indicating a structure rearrangement of the monolayer, also detected by thecompressional modulus. At 4°C the collapse pressure decreases from 45 (at 25°C) to 35mN/m. BAM images of monolayers during compression showed the apparition of light graydots (thick regions) upon compression, with no significant differences betweenconditions. LUVs were studied with zeta potential determinations as well as Laurdanfluorescence data. Regarding to zeta potential, significant differences were foundbetween each condition and also between measurements at 25°C and 4°C during control,stress and short recovery, but in long recovery the values at both temperatures weresimilar. The generalized polarization (GP) value determinate by Laurdan fluorescenceintensity decreased during stress condition and restored to control values during longrecovery. All these results highlight the impact of the phospholipid remodeling on thephysicochemical properties of membranes that may be responsible for plant membraneadaptation and tolerance.