The root as a sink for chloride under chloride-salinity

Abstract

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.

Keywords: Chloride; Maize; Salt resistance; Sequestration; Split-root; Translocation.