The root as a sink for chloride under chloride-salinity

Maize has to avoid excess tissue accumulation of Cl- to withstand conditions of Cl--salinity. Restriction of loading of Cl- into the root xylem is one mechanism to keep shoot Cl--concentrations low. The proportion of Cl(- )that reaches the shoot has to be stored away from the primary site of photosynthesis and growth. We tested whether or not maize is able to re-translocate significant amounts of Cl- from shoot back to root and out into the rooting media. Ion analysis revealed that maize cannot re-translocate Cl-; however, it is stored in sheaths of the old leaves and, surprisingly, in roots. Sequestration of Cl- in the roots might be a strategy to keep concentrations low in young growing shoot tissues and in leaf blades where photosynthesis is running.