Integrative response of arsenic uptake, speciation and detoxification by Salix atrocinerea

Abstract

Despite arsenic (As) being very toxic with deleterious effects on metabolism, it can be tolerated and accumulatedby some plants. General genetic mechanisms responsible for As tolerance in plants, includingSalixspecies, havebeen described in transcriptomic analysis, but further experimental verification of the significance of particulartranscripts is needed. In this study, aSalix atrocinereaclone, able to thrive in an As-contaminated brownfield,was grown hydroponically in controlled conditions under an As concentration similar to the bioavailable fractionof the contaminated area (18 mg kg−1) for 30 days. At different time points,i.e.short-term and long-term expo-sure, biometric data, As accumulation, phytochelatin synthesis, non-protein thiol production and expression oftarget genes related to these processes were studied. Results showed thatS. atrocinereapresents a great toleranceto As and accumulates up to 2400 mg As kg−1dry weight in roots and 25 mg As kg−1dry weight in leaves. Rootsreduce As V to As III rapidly, with As III being the predominant form of As accumulated in root tissues, whereas inthe leaves it is As V. After 1 d of As exposure, roots and leaves showde novosynthesis and an increase in non-protein thiols as compared to the control. Integrating these data on As accumulation in the plant and its specia-tion, non-protein thiol production and the kinetic gene expression of related target genes, a fundamental role ishighlighted for these processes in As accumulation and tolerance inS. atrocinerea. As such, this study offers newinsights in the plant tolerance mechanisms to As, which provides important knowledge for future application ofhigh-biomass willow plants in phytoremediation of As-polluted soils