MST2 is essential for mycorrhizal colonization. Top panels: Mycorrhizal colonization of control and MST2 RNA interference roots 25 d after inoculation with Glomus intraradices shown by ink staining. Bottom left: Estimations of mycorrhization in MST2 RNA interference hairy roots in comparison to control roots (EV); parameters are frequency (F%) and intensity (M%) of mycorrhiza and arbuscule abundance (A%). Transcript accumulation of MST2 (bottom middle) and Mt-PT4 (bottom right) in MST2 RNA interference and control roots measured by quantitative real-time PCR. (Figure reprinted from Figure 6 of Helber et al. [2011].)