Phytochelatins are involved in differential arsenate tolerance in Holcus lanatus

Arsenate tolerance is conferred by suppression of the high-affinity phospha te/arsenate uptake system, which greatly reduces arsenate influx in a numbe r of higher plant species. Despite this suppressed uptake, arsenate-toleran t plants can still accumulate high levels of As over their lifetime, sugges ting that constitutive detoxification mechanisms may be required. Phytochel atins are thiol-rich peptides, whose production is induced by a range of me tals and metalloids including arsenate. This study provides evidence for th e role of phytochelatins in the detoxification of arsenate in arsenate-tole rant Holcus lanatus. Elevated levels of phytochelatin were measured in plan ts with a range of tolerance to arsenate at equivalent levels of arsenate s tress, measured as inhibition of root growth. The results suggest that arse nate tolerance in H. lanatus requires both adaptive suppression of: the hig h-affinity phosphate uptake system and constitutive phytochelatin productio n.