Interspecific secondary plasmodesmata at the parasitic interface

Obligate parasitic plants often establish symplastic connections with their hosts. This symplastic continuity is mediated by plasma membrane-lined channels referred to as interspecific secondary plasmodesmata, which develop at the interface between the parasite and its host. However, the molecular mechanisms underlying the formation of these interspecific secondary plasmodesmata remain unclear. In this mini review, we summarize current knowledge of plasmodesmata biogenesis at diverse cellular boundaries with distinct developmental origins, including those at graft junctions and between mesophyll and bundle sheath cells. Based on the literature review, we hypothesize that the formation of interspecific secondary plasmodesmata involves three key events: cell wall thinning, membrane rearrangement, and metabolic regulation. Finally, we discuss future research directions to elucidate the molecular basis of interspecific secondary plasmodesmata formation.