Manganese and iron both influence the shoot transcriptome of Typha angustifolia despite distinct preference towards manganese accumulation

Typha angustifolia is a metal hypertolerant grass that predominates the wetlands of uranium tailings in Jaduguda, India, contaminated with extreme levels of iron (Fe) and manganese (Mn). In the paper investigations were carried out to understand the molecular mechanism of metal tolerance in this tolerant macrophyte. Metal analysis was coupled with fluorescent differential display (FDD) and reverse northern to compare the metal profile and transcriptome between Typha plants growing in the tailings versus a control wetland. The expressions of the validated transcripts in Mn and Fe stress were confirmed using reverse northern and semiquantitaive RT-PCR. Typha selectively accumulated and stored Mn in shoots but excluded/restricted Fe both in the field and in vitro. Differential expressions of 23 ESTs were validated among 118 FDD genes. Although Typha behaved as a Mn accumulator, these transcripts were found to be regulated in a complex fashion not only by Mn accumulated in the shoots but also by Fe excluded from the shoots. Our results provide the first report in the molecular understanding of metal tolerance in Typha angustifolia and indicate a complex regulation of genes in response to metals in a contaminated habitat.