Acquisition of selenium tolerance by a selenium non‐accumulating Astragalus species via selection

Article type: Research Article

Authors: Wang, Y. | Böck, A. | Neuhierl, B.^;

Affiliations: Lehrstuhl für Mikrobiologie der Universität München, Maria‐Ward‐Straße 1a, D‐80638 München, Germany

Note: [] Address for correspondence: B. Neuhierl, Lehrstuhl für Mikrobiologie der LMU München, Maria‐Ward‐Straße 1a, D‐80638 München, Germany. Tel.: +89 17919854; Fax: +89 17919862.

Abstract: Selection of cultured cells of the selenium sensitive and non‐accumulating Astragalus cicer for tolerance to stepwise increasing concentrations of selenite in the medium lead to a variant able to grow at 75 \curmu M selenite. The Se‐tolerant culture synthesized a selenocysteine methyltransferase immunologically related but not identical to that of the accumulating A. bisulcatus species and produced Se‐methyl‐selenocysteine in vivo. Re‐cultivation in selenium‐free medium lead to breakdown of tolerance and the disappearance of the methyltransferase from cellular proteins. The results prove that the non‐accumulating species A. cicer has the cryptic capacity for synthesis of a selenocysteine methyltransferase and also demonstrate that synthesis of the organoselenium compounds in Se‐accumulating plants are contributing to selenium tolerance.

Keywords: Selenium tolerance, selenocysteine methyltransferase, selenium accumulation

Journal: Biofactors, vol. 9, no. 1, pp. 3-10, 1999