Figure 1.

Model describing sugar dynamics in source and sink tissues and translocation of sucrose through the phloem tube. (A) In a source leaf, the circadian clock and carbon metabolism are reciprocally regulated. (B) Translocated sucrose is used for growth and respiration in the sink. Each structural component is expressed by a cylinder of radius r_X and height l_X, where X is either G (source), T (tube), or Y (sink). (C) Tubal structure of the model. p_i represents hydrostatic pressure at the apex of component i (i ϵ {0,…, 5}). Xylem adjacent to the phloem tube is also schematized. SAM, shoot apical meristem; RAM, root apical meristem. (D) Fluxes in the model. Red arrows (J_i) indicate phloem sap flow. Light blue arrows (w_i) indicate pure water flow due to osmosis, which occurs at the region represented by light blue circles.