Sterol profile determind by GC-MS of <i>erg7</i> expressing a tobacco cycloartenol synthase CAS1.

A, TIC of a total unsaponifiable extract of erg7 transformed with a void vector. B, TIC of a total unsaponifiable extract of erg7::NtCAS1. C, 9β,19-cyclopropylsterol biosynthetic pathway in yeast. Compounds are: 1, 2,3-oxidosqualene; 2, ergosterol; 3, cycloartenol; 4, 31-norcycloartenol; 5, 24-dehydropollinastanol; 6, cycloeucalenol; 7, 24-methylene pollinastanol. Compounds are identified according to their mass spectra and to those of authentic standards for 3, 6, and 7 purified from plant material as previously described [25], [26], [44]. Peaks that are not numbered are not sterols.