Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 3.09

ANALYSES OF EXPRESSION OF A TYPE-II METALLOTHIONEIN-ENCODING GENE IN THE SEAGRASS POSIDONIA OCEANICA

R. COZZA*, T. PANGARO*, P. MAESTRINI**, A. CAVALLINI**

*) Università degli Studi della Calabria, Dip.to di Ecologia Ponte P. Bucci, cubo 6B, 87030 Arcavacata di Rende (Cosenza)

**) Università degli Studi di Pisa, Dip.to di Biologia delle Piante Agrarie, Sezione di Genetica-Pisa

Posidonia oceanica, metallothioneins, in situ hybridization, heavy metals

The phanerogam Posidonia oceanica is endemic to the Mediterranean basin, growing as extended meadows in the infralittoral bottom and playing a pivotal role for the maintenance of the coastal ecological equilibrium. It has been established that Posidonia is able to absorb and accumulate trace metals from marine environment thus controlling metal bioavailability in the marine ecosystem. All these findings highlight that this plant is a potential “biological indicator” of metal contamination. Concerning the response of marine angiosperms to metals, so far studies have been mainly focused on their accumulation into plants tissues, whereas a few studies have been reported on the physiological and molecular processes triggered in these plants by metal exposure. As far as Posidonia is concerned, it has been shown that Cd++ exposure induces the synthesis of mRNAs encoding putative metallothioneins (Mts), small peptides, Cys-rich proteins that bind heavy metals. In this work we have isolated a number of DNA sequences putatively encoding metallothioneins. Southern and sequences similarity analyses indicate that such DNA sequences belong to a multigene family of at least five members.

We have also determined, by in situ tecnique, the expression domain of one type-II metallothionein gene in Posidonia plants in vivo. This gene shows a tissue specific expression being localized along the vascular bundle of the leaves; moreover the transcript show differences in expression in relation to the leaf axes, the leaf development and in the shoot. Our results suggest that, at least some plant metallothioneins may have specialized functions confined to a few plant cell types.