The membrane lipid bilayer as a regulated barrier to cope with detrimental ionic conditions: making new tolerant plant lines with altered membrane lipid bilayer

Abstract

ABSTRACTSeveral detrimental ionic conditions can occur in crop fields: soil acidity, salinity, heavy metal toxicity, and/or nutrient deficiency. Crop plants tolerant to these detrimental ionic conditions have excellent strategies that are related to external and/or internal mechanisms. Recently, we proposed a new concept of aluminum (Al) tolerance in plants; specifically, a plasma membrane (PM) lipid bilayer mechanism. This mechanism is defined as the retardation of Al permeation through the PM lipid bilayer based on the specific composition of the lipid molecules in the PM. The molecular basis of a less negatively charged PM lipid bilayer is smaller proportions of phospholipids and greater proportions of galactolipids and sterols. This leads to reduced adsorbability of detrimental ions onto the PM lipid bilayer, resulting in less permeabilization. Phenolics and carotenoids have two moieties; a hydrophilic moiety and a hydrophobic moiety. The hydrophobic moieties of these compounds can occlude the permeabilized spaces in the PM lipid bilayer, thereby reinforcing it. Another strategy to retard the permeability of the PM to detrimental ions is to decrease the proportion of stigmasterol, which has been shown to have no ability to reduce water permeability. The beneficial or harmful effects of various organic materials (organic fertilizers, soil organic matter, agrochemicals, or organic pollutants) on the productivity or quality of crop plants in relation to changes in the PM lipid bilayer are discussed. Modulation of the PM lipid bilayer is a promising strategy to produce new crop lines tolerant to detrimental ionic conditions.