บทคัดย่องานวิจัย

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Metabolism of polar lipids during senescence of watercress leaves.

Meir, S.; Philosoph-Hadas, S.;

Plant Physiology and Biochemistry (Paris) Year: 1995 Vol: 33 Issue: 2 Pages: 241-249 Ref: 32 ref.

1995

บทคัดย่อ

Metabolism of polar lipids during senescence of watercress leaves.

 

The metabolism of polar lipids in senescent leaves of watercress was monitored following the incorporation of [1-14C]acetate prior to induction of senescence. Leaves were kept either in permanent darkness or under a photoperiod of 14 h. During senescence under these conditions, the leaves showed concomitant changes in the contents of chlorophyll (Chl), and of phospholipids (PL) and galactolipids (GL) and their constituents (digalactosyldiglyceride (DGDG) and monogalactosyldiglyceride (MGDG)), phosphatidylcholine (PC), phosphatidyl-ethanolamine (PE), phosphatidylglycerol (PG), and phosphatidyl-inositol (PI). The decrease in GL content (MGDG and DGDG) was more pronounced than that of PL. The first PL to decrease during dark senescence was PC, followed by PE and PG, whereas PI concentration did not change significantly. Thus, the changes in total PL and in their main constituents, PC and PE, during dark senescence resulted from both increased degradation and reduced rate of synthesis. On the other

hand, the increase in PI concentration and the constant PG concentrations observed during senescence under photoperiodic conditions resulted from reduced degradation and continuation of biosynthesis. Hence, the senescence-retarding effect of light was exhibited through the retardation of Chl loss and the catabolic processes of all polar lipids, as well as through increased biosynthesis of PG and PI.