Quantitative aspects of triterpene synthesis in the laticifers of Hoya diversifolia Bl

Abstract

The esterified triterpenes extracted from the stem of Hoya diversifolia were found to represent the latex triterpenes. The triterpene content of the five apical internodes was fairly constant, ranging from 0.4-0.5 mg cm⁻¹ stem in growing plants and values of 0.52-0.60 mg cm⁻¹ were obtained from slowly or non-growing plants. When [¹⁴C]sugars were absorbed by node-containing stem segments, a [¹⁴C]latex triterpene synthesis could be observed for several weeks. After 4 weeks up to 9% of the supplied [¹⁴C]sugars had been involved in latex lipid metabolism. In this period the stem segments had synthesized the amount of the latex lipids which was lost at excision (about 50%). No remarkable quantitative differences in latex triterpene synthesis were observed in the five apical internodes.