Affordable Access

Publisher Website

Senescence of oat leaves: changes in the free sterol composition and enzyme activities of the plasma membrane

Authors
Journal
Plant Science
0168-9452
Publisher
Elsevier
Publication Date
Volume
79
Issue
1
Identifiers
DOI: 10.1016/0168-9452(91)90062-d
Keywords
  • Avena Sativa
  • Plasma Membrane
  • Senescence
  • Sterols
  • Atpase
Disciplines
  • Biology

Abstract

Abstract Plasma membrane fractions were prepared from young (10-day-old), mature (17-day-old) and senescent (10 + 7-day-old) oat leaves ( Avena sativa L.) through aqueous two-phase partitioning and analyzed for their free sterol composition. Continued leaf growth resulted in a strong increase in overall sterol content from 40 nmol · mg −1 lipid to about 120 nmol · mg −1 lipid (1.5% and 5% by wt. of total lipids respectively). This increase could be completely ascribed to increased cholesterol and stigmasterol concentrations. Kinetic parameters of vanadate-sensitive ATPase and NADH-FeCN reductase activities did not change significantly with leaf maturation. The sterol concentration increased to a lesser extent (4.2% and 4.4% by weight) in the plasma membrane of 10-day-old leaf segments that were cut and kept in light or dark for 7 more days. However, the increase in this case was completely due to a raise in Δ 7-avenasterol and 28-isofucosterol concentrations. The K m and V max values for the ATPase activity decreased significantly in these membranes. The characteristics of the FeCN 2 reductase and of glucan synthetase II activity were apparently not affected. The effect of senescence on sterol biosynthesis and on plasma membrane enzyme activities is discussed.

There are no comments yet on this publication. Be the first to share your thoughts.