Figure 6

PtJAZ6-interacting proteins in Populus ectomycorrhizal root tips. (a) PtJAZ6 physically interacts with the transcription factors PtMYC2s and PtJAM1s, as well as with PtTPR4.1, NINJA1 and NINJA3. It also forms homodimers and heterodimers with PtJAZ5, PtJAZ10.2 and PtJAZ12. PtJAZ6 probably suppresses the transcriptional activity of PtMYC2s and PtJAM1s by recruiting the general repressor PtTPR4.1 to the promoter of MYC2-responsive genes. (b) The fungal symbiotic effector MiSSP7 interacts with PtJAZ6¹² inhibiting homo- and heterodimerization of PtJAZ6. Such inhibition may alter the stability of PtJAZ6. The presence of MiSSP7 does not impair the interaction between PtJAZ6 and PtNINJA1 or PtNINJA3 However, MiSSP7 loosens the interaction between PtJAZ6 and PtMYC2.2, while strengthening the interaction between PtJAZ6 and PtMYC2.1. MiSSP7-mediated enhancement of the PtJAZ6-PtMYC2.1 interaction probably dampens the transcriptional activity of PtMYC2.1. On the other hand, the release of PtMYC2.2 from PtJAZ6-mediated repression may activate gene expression depending on this transcription factor.