Mercury's Paths In Rice

Toxic mercury species tend to accumulate in living things, and researchers would like to better understand the process in an effort to prevent it. Recent research suggests that methylmercury in rice grains is more abundant than would be expected from ratios of mercury species in soil. Inspired by that work, Eva M. Krupp, Jörg Feldmann, and colleagues at the University of Aberdeen, in Scotland, combined electrospray and inductively coupled plasma-mass spectrometry to look for mercury species in the roots and shoots of rice plants (Chem. Commun., DOI: 10.1039/b823121d). Their MS technique allowed them to identify previously unknown Hg-phytochelatin complexes in the roots. Moreover, they found that these phytochelatins, small peptides that detoxify heavy metals in plants, can sequester Hg²⁺, but not methylmercury. This finding points to a different uptake and transport mechanism for methylmercury in rice, compared with Hg²⁺, and might explain why it's disproportionately able to reach rice grains, Krupp says. "This study advances our understanding of how plants respond to mercury contamination in soil and water," says mercury pollution researcher Dan Cristol of the College of William & Mary.