Methylation increases tissue-permeability. A. thaliana seedlings were incubated in 50 μM solutions of compounds 10 and 15 in ½ MS medium. Samples were taken after the indicated time and the in situ levels of compound 15 were analysed by HPLC. The solid line represents the results for plants incubated with compound 10 and the dashed line shows the results for compound 15. The averages and standard deviations were calculated from 3 independent assays.