EDITING AND REMODELING OF PHOSPHATIDIC ACID DURING TEMPERATURE STRESS RECOVERY IN BARLEY ROOTS

VILCHEZ, A C; PEPPINO MARGUTTI, M; REYNA, M; VILLASUSO, A L

Congreso; IV Reunión Conjunta de Sociedades de Biología de la República Argentina y XXIII Reunión Anual de la Sociedad de Biología de Córdoba; 2020

Low temperature exposure affects the composition and biophysical properties of plant membranes, interfering with their proper functions and triggering signaling pathways. Plants respond to temperature stress by altering lipid class composition and lipid unsaturation to maintain membrane integrity. Cold tolerance acquisition involves activation of several stress cellular mechanisms while adverse condition is persisting. However, the correct timing and rate of recovery resulting in loss of cold tolerance, repairing structural damage and redirecting the energy resources to resume growth and development is equally relevant for plant fitness and survival. Despite the critical role of the membrane when conditions are restored, limited lipidomic studies have been reported during stress recovery. The objective of this study was to describe lipid rearrangements of barley roots (Hordeum vulgare) during chilling and short and long stress recovery.  Glycerolipidome was perform in roots of barley seedlings exposed to suboptimal temperatures 4°C (36h), and recovered at 25°C during short (2h) and long (24h) periods. Lipids were obtained by a modified version of multi- extraction method based in a single-extraction method with a polar solvent mixture and were identified by mass spectrometry (ESI-MS / MS). Then, unsaturation index was determinate. The data showed a significant increase in total lipid composition in response to cold stress as a consequence of an increase in phospholipids, with no significant differences in galactolipids and lysophospholipids. Total lipid content decreased to control values during recovery ​​as a result of the reduction of the following lipid classes: phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylserine (PS) and phosphatidylinositol (PI). Contrasting, phosphatidic acid (PA) showed an opposite behavior and it increased significantly after 24 h of recovery. Analyses at the molecular species level revealed the main contribution of PA 34:2 and 36:4. Similarly, PA species that increase were the same PC species that decrease in recovery and showed a negative correlation according to the correlation analysis (based on Pearson´s coefficient). These results suggest that PA recovery-formed is derived primarily from PC. Post-stress PA edition might establish a new membrane configuration modifying membrane curvature, lipids-binding to proteins and consequently, signaling functions. Further analyses on model membranes are required to unravel how polyunsaturated species of PA modify its biophysical properties during recovery. Moreover, biochemical analyses of PA formation will describe recovery signaling pathways as a key determinant in the acquisition of tolerance to low temperatures.