Cadmium affects root formation and development by altering auxin transport and accumulation

Cadmium (Cd) is a very toxic element for plants and animals, easily absorbed through the root system and accumulated in plant tissues. This pollutant causes serious damages to the root apparatus of numerous plants, by altering the quiescent center (QC) and the surrounding apical meristem of the primary root (PR) and the differentiation of its tissues. The QC controls apical meristem definition and activities in the PR, and post-embryonic roots (lateral roots, LRs, and adventitious roots, ARs). The QC identity and maintenance are controlled by auxin levels. In this work we investigated Cd effects on Arabidopsis thaliana root apparatus investigating QC maintenance and functioning, and analyzing auxin levels and distribution in LRs and ARs, in particular. To the aim, seeds of the wild type and QC25::GUS, DR5::GUS, PIN1::GUS, LAX3::GUS transgenic lines were sown in the presence and absence of different Cd concentrations. The results show that Cd significantly inhibited the PR and hypocotyl growth, but significantly increased LR and AR formation. Moreover, Cd compromised the regular QC definition and functioning in LRs and ARs, and disturbed the expression patterns of auxin transport genes, and auxin accumulation.