Effect of aluminum on growth and distribution of aluminum in tolerant and sensitive cultivars of triticum aestivum L.

Abstract

An Al‐tolerant cultivar (Atlas‐66) and an Al‐sensitive cultivar (scout‐66) of Triticum aestivum L. (wheat) were grown in culture solution with different levels of aluminum (Al) to investigate plant growth response and Al uptake and distribution. With 50 uM Al in solution, root and leaf growth of Scout‐66 decreased to 41±1% and 65±5% of the control, however, both root and leaf growth of Atlas‐66 were not affected. At 200 UM Al, root and leaf growth of Scout‐66 were reduced to 28±1% and 49±2% of control, while root growth of Atlas‐66 was not affected and the leaf growth was reduced to 57±5% of the control. With an increase of Al in solution from 50 to 1000 uM, concentrations of Al in the roots of Atlas‐66 increased from 2500+450 to 4000±110 ug g^‐1, and for Scout‐66 from 1980±60 to 3830+20 ug g^‐1. In both cultivars, concentrations of Al in the leaves were undetectable below 200 uM Al in solution. Between 200 and 1000 uM Al in solution, concentrations of Al in the leaves were higher in Atlas‐66 (50±2 to 180±40 ug g"¹) than in Scout‐66 (40+8 to 130+20 ug g^‐1). Of the total absorbed Al, a higher percentage was accumulated in roots of Atlas‐66 (91±1% to 97±1%) than Scout‐66 (83±1% to 92±2%). These results suggest that greater accumulation of Al in roots is one of the characteristics of Al‐tolerant plants, but that Al‐tolerance in wheat is not achieved by exclusion of Al from the symplasm. Ihis conclusion, however, must await separation of absorbed Al into apoplasm and symplasm compartments.