Sterol Interconversions

Publisher Summary This chapter discusses the sterol derivatives in higher plants. It discusses the subjects of function and changes related to physiological phenomena of sterol. The measurement of sterol derivatives in the intact plant, either by analysis of endogenous sterols or by the use of isotope labeling techniques, provides valuable evidence of the action of synthetic and degradative enzymes. The lipids of the potato tuber are particularly rich in sterol derivatives. Aging potato tuber discs have been useful subjects for the study of cyanide-insensitive respiration and fatty acid synthesis. Apart from the stabilizing effect of free sterols on phospholipid-containing membranes, other functions indicate that the sterol derivatives are transport forms, that the sterols are precursors of hormones, and that sterol derivatives are auxin synergists. The effects of sterol derivatives on membrane permeability need further study as the effects of cholesterol have been and changes in permeability need to be correlated with changes in the composition of sterol derivatives.