磷缺失引起小麦叶片中脂含量的变化与脂的合成和磷脂酰甘油的降解有关

对生长在不同磷营养水平条件下小麦(Triticum aestivum var.Zhongyou 9507)叶片中光合膜脂含量变化的原因进行了研究.通过对生长在不同磷营养水平条件下9 d龄和16 d龄小麦叶片中光合膜脂含量的分析,发现在磷缺失培养条件下,小麦光合膜脂的相对含量发生了很大变化,这种变化与小麦叶龄密切相关.在16d龄小麦植株中,第一片叶为老叶,第二片叶为较老叶,而第三片叶为新叶,PG和MGDG在叶片中的相对含量从新叶到老叶逐渐下降,而DGDG和SQDG含量逐渐上升;在磷缺失条件下,16 d龄小麦第一叶片中PG的含量(2.5%)远远低于其在9 d龄第一叶片中的含量(5.5%).以上结果说明,磷缺失引起小麦叶片中脂含量的变化不仅与脂合成有关,而且与PG的降解有关;新生叶片中PG含量减少的主要原因是由于磷供应不足,从而影响了PG的合成;而PG的降解则是老叶中PG含量下降的主要原因.

Alternation in Lipid Composition of Wheat Leaves Induced by Phosphate Deficiency Is Related to Both Lipid Biosynthesis and Phosphatidylglycerol Degradation

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.