Effects of metal ions and heat shock on the expression of a metallothionein-like gene htMT2 in Helia

The expression of htMT2 in tissues of Helianthus tuberosus treated with metal ions and heat shock is studied by Northern blot hybridization. The results indicate that htMT2 is not expressed in roots. The expression in leaves and stems can be reduced by Cu2+ and induced by low concentration of Zn2+. However, the expression of htMT2 can be suppressed by Zn2+ when its concentrations are above 500 μmol/L. The effects of Ca2+ on the expression of htMT2 in leaves are similar to that of Zn2+. But Ca2+ induces the expression of htMT2 in stems. The expression levels of htMT2 in various tissues are not significantly affected by heat shock. The results above demonstrate that the expression of htMT2 can be regulated by metal ions and confirm that htMT2 is a new metallothionein-like gene.