Fig. 4.
Transient plasmodesmal closure mediated by callose accumulation/degradation during lateral root development and fibre cell growth. (A) Lateral root primordia (LRPs) are symplastically isolated during mid-stage growth, a process correlated with a high level of callose deposition specifically within the LRP area (red). This could allow turgor pressure and LRP-specific differentiation signals to drive emergence. Upon the development of new phloem within the lateral root, symplastic connectivity (blue) is restored. Epi, epidermal layer; Cor, cortical layer; Endo, endodermal layer; Peri, pericycle layer. (B) Turgor-driven elongation of cotton fibre cells is dependent upon their spatiotemporal cytoplasmic isolation through callose deposition (red), allowing the transporter-driven influx of solute (green) and water to enter the fibre without leaking out through plasmodesmata. Upon completion of elongation, plasmodesmal connectivity is restored (blue), owing in part to the callose-degrading activity of fibre-specific glucanase GhGlu1. DAA, days after anthesis.