Figure 2.

Model of the functions of SMO2s in Arabidopsis embryo patterning and postembryonic development. 4α-methylsterol (24-ethylidene lophenol and 24-ethyl lophenol) are catalyzed by SMO2-1 and SMO2-2 enzymes to 4α-caboxysterols, which are further transformed into membrane sterols biosynthesis. Correct localization of PIN1 protein, acting as auxin efflux carrier, which is needed for PAT, requires normal membrane sterol composition and this is required for embryo patterning and postembryonic development. 4α-caboxysterols, SMO2 products, may regulate PAT, embryo patterning, and postembryonic development.