Abstract:

In this study, the causes of the changes in lipid composition induced by different phosphate nutrient levels were investigated. Wheat plants were grown in phosphate-deficient and phosphate-sufficient conditions, respectively, and lipid composition in the leaves of 9-day-old and 16-day-old plants was analyzed. We found that phosphate deficiency induced a dramatic change in the lipid levels in photosynthetic membranes of wheat leaves and the extent of changes in lipid composition depended on the leaf ages. Phosphate deficiency induced a gradual decrease in PG and MGDG and a concomitant increase in DGDG and SQDG from the first leaf to the second and the third leaf on 16-day-old plants. In addition, as compared to leaves grown under phosphate sufficient solution, PG content in the first leaf of 16-day-old plants was significantly lower than that of 9-day-old leaf with 2.5 mol% versus 5.5 mol% when these plants were grown under phosphate deficient condition. From these results, it is suggested that the alternation in lipid composition in wheat leaves induced by phosphate deficiency is related to both lipid biosynthesis and PG degradation. PG decrease in younger leaves is mainly due to insufficient phosphate supply for PG biosynthesis, while PG degradation mainly resulted in the PG decrease in older leaves.

Key words: phosphate transport, phosphate deficiency, phosphatidylglycerol, thylakoid membrane lipids, wheat leaf