Embodiments of the disclosure encompass systems, methods, and compositions related to selective advantages to somatic cells that harbor one or more particular genetic modifications. In particular embodiments, there is selective expansion of gene-targeted cells wherein the strategy involves deletion of an essential gene product that is replaced with targeted integration that also includes integration of a therapeutic transgene. The cells that harbor the replaced essential gene product, and thereby the therapeutic transgene, are selected for using pharmaceutical or nutritional agents that are linked to the function of the essential gene product.

The disclosure relates to a method of making at least one serrulatane comprising contacting a terpene or a terpenoid substrate with at least one of a cis-prenyl transferase, a terpene synthase, and a cytochrome P45Q. The disclosure also relates to an expression system comprising one or more expression cassettes, each expression cassette comprising a promoter operably linked to a nucleic acid segment encoding at least one of: a cis-prenyl transferase, a terpene synthase, and a cytochrome P450. The disclosure also relates to a host cell comprising an expression system comprising one or more expression cassettes, each expression cassette comprising a promoter operably linked to a nucleic acid segment encoding at least one of: a cis-prenyl transferase, a terpene synthase, and a cytochrome P450.

The disclosure relates to a method of making at least one serrulatane comprising contacting a terpene or a terpenoid substrate with at least one of a cis-prenyl transferase, a terpene synthase, and a cytochrome P45Q. The disclosure also relates to an expression system comprising one or more expression cassettes, each expression cassette comprising a promoter operably linked to a nucleic acid segment encoding at least one of: a cis-prenyl transferase, a terpene synthase, and a cytochrome P450. The disclosure also relates to a host cell comprising an expression system comprising one or more expression cassettes, each expression cassette comprising a promoter operably linked to a nucleic acid segment encoding at least one of: a cis-prenyl transferase, a terpene synthase, and a cytochrome P450.

The disclosure relates to a method of making at least one serrulatane comprising contacting a terpene or a terpenoid substrate with at least one of a cis-prenyl transferase, a terpene synthase, and a cytochrome P450. The disclosure also relates to an expression system comprising one or more expression cassettes, each expression cassette comprising a promoter operably linked to a nucleic acid segment encoding at least one of: a cis-prenyl transferase, a terpene synthase, and a cytochrome P450. The disclosure also relates to a host cell comprising an expression system comprising one or more expression cassettes, each expression cassette comprising a promoter operably linked to a nucleic acid segment encoding at least one of: a cis-prenyl transferase, a terpene synthase, and a cytochrome P450.