Function of sterols

Abstract

In plants, neither sterol synthesis nor sterol balance is static. While all plant tissues have the ability to synthesize sterols, generally the younger tissue has a higher rate of synthesis. Additionally, the synthesis of the various individual sterols changes with tissue age and environmental factors. For example, the plant apex has a higher level of sitosterol than stigmasterol and as the tissue becomes older the ratio of sitosterol changes in favour of stigmasterol. The level of campesterol is also quite high in the plant apex, especially in the region of cell division. The change in sterols of the various tissues is apparently not due to intercellular sterol transport. With regard to light, both its intensity and photoperiod are important factors in controlling sterol synthesis, especially the sitosterol to stigmasterol balance. The change in sterol metabolism induced by light does not appear to be due to activation of the 22,23-dehydrogenase enzyme. The change in sterols and their possible relation to the development and physiology of the plant are discussed.