Abstract

Experiments were conducted with arsenic-hyperaccumulator, Pteris vittata, and non-hyperaccumulator, Pteris ensiformis, subjected to various arsenic toxicity levels (0 to 1500 mg As kg-1) in peat-moss or soil for up to 14 weeks, to evaluate phenotypic responses and total lipid with fatty acid profiles, and P. vittata influence on rhizosphere enzyme activities. P. ensiformis exhibited significant phenotypic toxicity response compared to P. vittata. P. vittata sequestered significantly (p<0.5) higher arsenic (5,160.6 mg As kg-1) than P. ensiformis (313.4 mg As kg-1). Cellular damage and physiological death occurred in P. ensiformis with alteration in fatty acids and lipid compositions but no significant changes in P. vittata. Both showed no detectable C16:3 but a decrease in C18:3, which was more pronounced in P. ensiformis (51.2%); hence, are reported as C18:3 plants for the first time. Acid phosphatase, β-glucosidase, alrysulphatase, and N-acetyl-β-D-glucosaminidase activities were inhibited by As and significantly (p<0.5) negatively correlated to As concentration. Enzyme inhibition range from 6% in β-glucosidase to 67% in N-acetyl-β-D-glucosaminidase. These results revealed P. vittata phenotypic tolerance to As stress was mediated through metabolic-readjustment, especially its fatty acid and lipid compositions. Additionally, P. vittata rhizospheric events modulate soil enzyme activities in the As-contaminated soil.

Key words: Fern, heavy metal, phenotypic response, fatty acids, acid phosphatase, β-glucosidase, alrysulphatase, N-acetyl-β-D-glucosaminidase, rhizosphere.

Abbreviation

BF, Bioaccumulation factor; DBI, Double bond index; FAMEs, Fatty acids methyl  esters;  GLU,  β-glucosidase; NAG, N-acetyl-β-D-glucosaminidase; PHOS6, Acid phosphatase; ROS, Reactive oxygen species; RZS, Rhizosphere soil; SUL, Arylsulfatase; TF, Translocation factor; THAM, Tris-hydroxymethyl aminomethane.