Abstract
Background
Arsenic (As) toxicity induces a range of metabolic responses in plants, including DNA methylation. The focus of this paper was on the relationship between As-induced long-term stress and plant senescence in the hyperaccumulator Pteris cretica var. Albo-lineata ( Pc -Al).Results
We showed that Pc -Al grown in pots of haplic chernozem contaminated with 100 mg As kg -1 (As 100 ) for 122 days could accumulate more than 2000 and 2800 mg As kg -1 dry matter in old and young fronds, respectively. Analysis of 5-methylcytosine (5mC) in Pc -Al confirmed that the overall DNA methylation status in fronds of As 100 ferns was reduced in contrast to control treatment. Compared with controls, the overall DNA methylation status in fronds of As 100 ferns was reduced (by 6% in young and 10% in old fronds); however, the decrease was significant only in old fronds. The significant correlations for 5mC, in contrast to direct As toxicity, showed that decreases of chlorophylls, fluorescence and photosynthetic rate could be affected by epigenetic changes. Photosynthetic processes were determined in As 100 treatment and showed a reduction of gas-exchange parameters, and a decrease in carotenoids and chlorophylls (by 5% and 26%, respectively). Hyperaccumulation of As resulted in a significant elevation of all analysed nutrients (Cu, Mn, Zn, Mg, S) in old fronds, but not in young fronds.Conclusions
The results of this paper point to complex changes in the metabolism of the hyperaccumulator plant Pc -Al, upon exposure to As contamination. The most significant impact was found in young fronds. The physiological parameters correlated more significantly with a decrease of DNA methylation than with direct As toxicity. Our analysis of the very low water potential values and lignification of cell walls in roots showed that transports of assimilated metabolites and water between roots and fronds were reduced.
A comparison of the photosynthesis response to arsenic stress in two Pteris cretica ferns
