Choline priming-induced plasma membrane lipid alterations contributed to improved wheat salt tolerance

Abstract

Salt stress is a major environmental threat influencing crop growth and yield. The plasma membrane (PM) is believed to be one facet of the cellular mechanisms of salt adaptation. Choline priming has been reported to enhance salt tolerance of the sensitive wheat cultivar used in this work. The study was, therefore, undertaken to examine whether changes in the PM lipids will participate in choline-improved salt tolerance. The caryopses were primed in choline chloride (0, 5 and 10 mM) for 24 h. They were then germinated in sand for 10 days, watered with 1/4-strength modified Hoagland solution (MHS). The seedlings were grown in the sand, watered with MHS containing 150 mM NaCl for 3 weeks. Root PM was isolated by two-phase partitioning method and its lipid classes were determined. Choline maintained the PM total lipids, sterol and phospholipids, which were altered by NaCl. The PM sterols/phospholipids ratio was decreased by NaCl, whereas choline retained this ratio. Salt stress reduced the PM unsaturated fatty acids while increased its saturated fatty acids. Choline alleviated PM unsaturated/saturated ratio reduction. NaCl declined the PM phosphatidylcholine (PC), phosphatidylglycerol (PG) and diphosphatidylglycerol (DPG) whereas increased phosphatidylserine (PS), phosphatidylinositol (PI) and phosphatidylethanolamine (PE). Choline decreased PS and PE, while increased PC level. The PM cholesterol, campesterol and β-sitosterol were increased while stigmasterol was declined under NaCl. Choline increased stigmasterol whereas decreased cholesterol and campesterol. The alterations in the PM lipids were discussed in relation to choline-enhanced salt tolerance.