Figure 1.

Simplified scheme of sterol and BR biosynthesis. In sterol biosynthesis, squalene is converted in a series of reactions to 24-methylenelophenol, where the pathway splits into the C29-branch leading to β-sitosterol and stigmasterol as end products and into the C28-branch with campesterol, the precursor of BR biosynthesis, as a final product. In A. thaliana, the early C-22 oxidation pathway seems to be the predominant route of BR biosynthesis, which is, however, interconnected with late C-6 oxidation at multiple steps. The sterol synthesis pathway was adapted from [40] and the BR biosynthesis pathway from [59,62,63].