The effects of arsenic and induced-phytoextraction methods on photosynthesis in Pteris species with different arsenic-accumulating abilities

Arsenic (As) accumulation and photosynthesis occur simultaneously in plants under As exposure. We investigated the effects of As and induced-phytoextraction methods on photosynthesis in two As hyperaccumulators (Pteris vittata and Pteris cretica var. nervosa) and two non-hyperaccumulators (Pteris semipinnata and Pteris ensiformis) under soil culture conditions. Chlorophyll fluorescence parameters (the maximum [Fv/Fm] and actual quantum efficiency [FPSII]) and the activities of three photosynthetic enzymes (ATPase, ribulose-1, 5-bisphosphate carboxylase [RuBPC] and glyceraldehyde-3-phosphate dehydrogenase [GAPDH]) were measured. Arsenic accumulation and photosynthetic behaviours in response to enhanced-phytoextraction methods (trans-1, 2-cyclobexylenedinitrilotetraacetic acid [CDTA] and phosphorous [P] addition and soil pH adjustment) of P. cretica and P. semipinnata were monitored and compared under conditions of 100 mg As kg−1. Significant decreases in the Fv/Fm (19.9%) and FPSII (36.1%) were observed in P. vittata when exposed to 100 mg As kg−1 in comparison to the control (0 mg As kg−1). Compared to the control (0 mg As kg−1), the activities of GAPDH increased by 0.5% in P. cretica var. nervosa and decreased by only 8.3% in P. vittata even when both of them were treated with 200 mg As kg−1, whereas a significant decrease, 56.1% and 51.7%, of this enzyme was observed in P. semipinnata and P. ensiformis, respectively, when exposed to 50 mg As kg−1. Compared to the control (0 mg CDTA kg−1 or 0 mg P kg−1), the activities of ATPase increased by 53.7% and 82.7% in P. cretica when exposed to 0.5 g CDTA kg−1 and 50 mg P kg−1, respectively, and an increase of up to 175% was also observed in P. semipinnata when exposed to 600 mg P kg−1. The activities of GAPDH increased by 68.9% and 90.7% in P. cretica when exposed to 2 g CDTA kg−1 and 600 mg P kg−1, respectively, but a decrease of up to 60% was observed in P. semipinnata when exposed to 2 g CDTA kg−1. The uptake of As in P. semipinnata increased by 80.9% and 73.3% when 1 g CDTA kg−1 and 600 mg P kg−1 were added, respectively, compared to the control (0 g CDTA kg−1 or 0 mg P kg−1). It was concluded that GAPDH played an important role in the photosynthesis of As hyperaccumulators under As treatments.

► We examine the photosynthetic process in four ferns belonging to the Pteris genus.
► The photosynthesis of ferns under induced-phytoextraction conditions is also tested.
► High activities of GAPDH are maintained in As hyperaccumulators under As stress.
► Arsenic uptake in Pteris semipinnata is improved by 1 g CDTA kg−1 or 600 mg P kg−1.
► GAPDH plays an important role in the photosynthesis of As hyperaccumulators.