Biosynthesis of phytosterols and latex triterpenes in Hoya australis R.Br. ex Traill and Hoya carnosa R. Br.

Young plant parts of Hoya species incorporate exogenously supplied acetic acid and mevalonic acid mainly into phytosterols; triterpenes are synthesized mainly in older plant tissues. Sugars are the only efficient substrates in biosynthesis of latex triterpenes. This synthesis occurs in all laticifer containing parts of the plant and is not related to sterol and triterpene biosynthesis of laticifer surrounding tissue.