Glucose is manufactured in the chloroplasts by photosynthesis.This is converted to sucrose in the cytoplasm of the mesophyll cells.1. Hydrogen ions are actively transported from the companion cells into the surrounding cell walls (apoplast) using ATP.2. The hydrogen ions then diffuse into the companion cells with sucrose through a co-transport protein. The sucrose moves against its concentration gradient.3. This increases the concentration of sucrose in the companion cells.4. Sucrose then moves into the sieve elements through the plasmodesmata down a concentration gradient.