Differences in membrane lipid homeostasis confer contrast tolerance to low phosphorus in two wheat (Triticum aestivum L.) cultivars

Although lipids are involved in plant adaptation to phosphorus (P) deficiency, the underlying relationships are not fully understood, especially in wheat. Thus, a comparative study of changes in leaf lipid content, composition and implicated gene expression during low-P was conducted hydroponically using two wheat cultivars differing in low-P tolerance. Low-P reduced phospholipid content but increased digalactosyldoacylglycerol (DGDG) and sulfoquinovosyldiacylglycerol (SQDG) content in older fully unfolded leaves (OL), with ND2419 (tolerant) showing greater changes than ZM366 (sensitive), suggesting a greater capacity to recycle internal P in ND2419. Interestingly, a novel lipid remodeling pattern was detected in the youngest unfolded leaf (YL) of ND2419, which reduced less in phospholipid content but accumulated more DGDG and SQDG with higher unsaturation levels than ZM366. These changes favored better chloroplast development, functionality and membrane integrity of ND2419, which together improved low-P tolerance. The expression of genes encoding glycolipid synthases and enzymes involved in phospholipid biosynthesis and degradation explained the lipid changes. Furthermore, our findings indicate that phospholipid loss in OL is primarily caused by enhanced degradation, whereas that in YL is driven by decreased biosynthesis and increased degradation. The detailed description of the changes in lipid profiles and gene expression under low P provides a basis for improving wheat low-P tolerance.