Figure 7
Proposed model of reciprocal small secreted proteins (SSP) feedback between ectomycorrhizal fungi and their host plants. During colonization of receptive plant hosts, fungal hyphae (brown cell) produce effector-like SSPs (black stars) that are secreted from the hyphal cell (#1). A portion of these proteins cross the symbiotic interface (grey shaded area) and enter the plant cell (green cell; #2) where they localize to different sub-cellular compartments (#3). These effectors may induce a change in the transcription of host genes (#4; adapted from Plett et al. 35). Plant cells, in turn, produce small effector-like SSPs (red stars) that are secreted, cross the symbiotic interface (#5) where some may enter the hyphal cell and localize to different sub-cellular compartments. Some effectors may induce a change in the transcription of host genes (#6). GB = Golgi bodies; N = nucleus; S.I. = symbiotic interface. Note: we do not currently know the priority of this signaling network (i.e. if the fungus signals and the plant responds or vice-versa). Rather, numbering here is used to enable description of the different steps in a feedback system that is likely reciprocal in nature.
