Diversity of sterol biosynthetic capacity in the caryophyllidae

The order Caryophyllales, along with its two associated orders, the Polygonales and Plumbaginales, comprise the angiosperm subclass Caryophyllidae. We have now characterized the sterol compositon of 231 members of this subclass. This includes 210 species and 21 cultivars in 108 genera within the 14 families of these three orders. From these data, clear differences in biosynthetic capability and putative relationships between taxa have been established. Members of the two monofamilial orders (Polygonales and Plumbaginales) contain Δ⁵-sterols in ratios typical of “main line” angiosperms. Members of families in the Caryophyllales contain Δ⁵-sterols, or Δ⁷-sterols or mixtures of Δ⁵- and Δ⁷-sterols. In the majority of species where Δ⁷-sterols are the dominant sterols produced, trace amounts to almost equal amounts of Δ⁵-sterols are also present. Replicate samples of many of these species have shown that the ratio of Δ⁵-sterols to Δ⁷-sterols in these species is stable over time and/or location. From these data, it appears that the conversion of Δ⁷-sterols to Δ⁵-sterols is highly regulated in the majority of species within this order. In these families, similarities in sterol composition correlate well with taxonomic relatedness. Relationships between these taxa with respect to biosynthetic capability can now be postulated. Based on a paper presented at the Symposium on Plant and Fungal Sterols: Biosynthesis, Metabolism and Function, held at the AOCS Annual Meeting, Baltimore, Maryland, April 1990.