Root-secreted nicotianamine from Arabidopsis halleri facilitates zinc hypertolerance by regulating zinc bioavailability
Heavy metal hyperaccumulators grow endemically on metal-rich soils and exhibit extraordinarily high metal tolerance. Arabidopsis halleri, one of 500 found heavy metal hyperaccumulators in the world, is recognized as a zinc hyperaccumulator. In this study, we first discover that nicotianamine is secreted from the root of A. halleri and functions as a zinc chelator to regulate zinc availability in the rhizosphere for uptake. The secretion is zinc regulated and directly related to excess zinc tolerance.