Keywords: Scorpiurum circinatum, moss bags, heavy metals, OASTL, O-acetylserine(thio)lyase, TEM, transmission electron microscopy, cysteine synthesis, biomarkers, biomonitoring, air pollution, pollution monitoring, environmental pollution
Cysteine synthesis in Scorpiurum circinatum as a suitable biomarker in air pollution monitoring
Heavy metals enter ecosystems by both natural and anthropogenic processes. An excess of metals in the environment damages plant metabolism, leading to oxidative stress in the cell. Most metal ions present in the cell are bound to low molecular mass ligands. The major types of S-containing ligands involved in metal binding are derived from cysteine. The authors show, for the first time in Scorpiurum circinatum, a Mediterranean epiphytic moss, that cysteine synthesis is linked to environmental heavy metal pollution. In moss bag exposed in strongly heavy metals polluted sites, O-acetylserine(thio)lyase (OASTL) activity seems strongly related to heavy metal exposure. In addition, heavy metal exposure in S. circinatum caused ultrastructural alterations of vacuolar system and thylakoid organisation, as shown through Transmission Electron Microscopy (TEM) observations. Because S. circinatum is able to tolerate and accumulate various heavy metals, the authors suggest the OASTL enzymatic assay in S. circinatum as biomarker of heavy metals.