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| Effect of indoleacetic acid on photosynthesis of arsenic-stressed plants with different arsenic-accumulating ability |
| Received:January 17, 2017 |
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| KeyWord:indoleacetic acid;arsenic;hyperaccumulator;photosynthesis;ultrastructure |
| Author Name | Affiliation | E-mail | | ZHAO Shu-han | Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China | | | WANG Hai-juan | Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China | | | WANG Hong-bin | Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China | whb1974@126.com |
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| Abstract: |
| A hydroponic experiment was conducted to investigate the stress effect of arsenic(As) on Pteris cretica var. nervosa and Pteris ensiformis in the presence of indoleacetic acid(IAA). The growth, arsenic(As) accumulation, photosynthetic pigment content, chlorophyll fluorescence parameters, activities of two dark-reaction enzymes, and chloroplast ultrastructure of the two plants were evaluated to identify the stress effect at different IAA concentrations. The results showed that biomass and frond As concentration of the two plants were significantly increased in the presence of 20 mg·L-1 IAA compared to those in the respective control. The concentration of As in P. cretica var. nervosa fronds was much higher than that in P. ensiformis fronds. The photosynthetic pigment content in P. cretica var. nervosa fronds was similar to that of the control samples, but was significantly decreased in P. ensiformis. Increasing IAA concentrations did not affect the chlorophyll a/b value of P. cretica var. nervosa, compared to the control samples. However, the chlorophyll a/b value of P. ensiformis was significantly reduced in the presence of 40 mg·L-1 IAA. The maximal photochemical efficiency of photosystem Ⅱ(Fv/Fm), actual quantum yield(ΦPSII), and non-photochemical quenching coefficient(qN) remained unchanged in P. cretica var. nervosa fronds with increasing IAA concentrations, but decreased profoundly in P. ensiformis, especially in the presence of 20 mg·L-1 IAA. The photochemical quenching coefficient(qP) increased significantly in P. cretica var. nervosa but diminished significantly in P. ensiformis at 10 or 40 mg·L-1 IAA. The activity of ribulose-1,5-bisphosphate carboxylase(RuBPC) reduced significantly in P. ensiformis fronds with increasing IAA concentration. The RuBPC activity of P. cretica var. nervosa increased significantly at 20 mg·L-1 IAA but decreased at 10 mg·L-1 IAA, compared to the control. IAA addition severely damaged the ultrastructure of chloroplasts in P. ensiformis at all levels of IAA treatment but no visible damage was detected in P. cretica var. nervosa at 20 mg·L-1 IAA treatment. Therefore, 20 mg·L-1 IAA could protect the phytosynthesis of P. cretica var. nervosa under As stress, resulting in normal growth and hyperaccumulation of As. |
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