Localization of absorbed aluminium in pea root and its binding to nucleic acids

Abstract

Aluminium (Al3+) considerably inhibited the root elongation of Alaska pea at concentrations higher than 10−4 M and pH 4.5. The absorbed Al3+ in roots was localized in the epidermis and regions where cells actively divided, such as root tip and differentiating lateral root. In cells, Al3+ accumulated mainly in the nuclei and walls. Al3+ in nucleic acids increased up to 24 hr after treatment with 10−3M AlCl3, and did not decrease markedly after transfer of 10-hr treated plants to water. Molecular sieving chromatography showed that Al3+ in nucleic acids associated preferentially with DNA. However, in vitro association of Al3+ with DNA and RNA was nearly the same. When Al3+ and nucleic acid were mixed in vitro, the molecules of Al3+ being adjusted to be equal to those of phosphorus in nucleic acid, only 25% of the Al3+ associated with nucleic acid. The presence of NaCl up to 0.4 M and MgCl2 up to 0.05 M increased the association of Al3+ with DNA. When the phosphorus in DNA was masked by histone, the association of Al3+ with DNA was considerably reduced.