Multiple metabolic innovations and losses are associated with major transitions in land plant evolution by Cannell, N, Emms, DM, Hetherington, AJ, MacKay, J, Kelly, S, Dolan, L, Sweetlove, LJ

“…Our results revealed that genes encoding the complete biosynthetic pathway for brassinosteroid phytohormones and enzymes for brassinosteroid inactivation are present only in spermatophytes. Genes encoding only part of the biosynthesis pathway are present in ferns and lycophytes, indicating a stepwise evolutionary acquisition of this pathway. …”