Isopentenoid polycycles

With certain Oomycetes, "sterol-like molecules, eg. tetracyclic and pentacyclic triterpenoids (Fig. 2), may produce the same physiological end response as sterols (2). The growth response to these polycyclic isopentenoids is intimately associated with their 3-dimen-sional geometry, molecular features and subcellular quantity. In order to discuss sterol function for What we assume is an evolutionary determinant of developmental change, a brief overview of sterol occurrence and biosynthesis is given first. 

Moench in various stages of development. Evidence for the developmental regulation of the amounts and biosynthesis of these polycyclic isopentenoids and its correlation with floral initiation have been obtained in this and our previous studies.Sterol and FT composition of individual fully mature leaf blades was determined at various stages in the life cycle of S. bicolor (L.) Moench cv. G499 GBR (Figure 1). 

R.C. Heupel, Varietal similarities and differences in the polycyclic isopentenoid composition of sorghum. Phytochemistry 24 2929 (1985). 

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