Journal Article

Effects of zinc and influence of <i>Acremonium lolii</i> on growth parameters, chlorophyll <i>a</i> fluorescence and antioxidant enzyme activities of ryegrass (<i>Lolium perenne</i> L. cv Apollo)

Muriel Bonnet, Olivier Camares and Philippe Veisseire

in Journal of Experimental Botany

Volume 51, issue 346, pages 945-953
Published in print May 2000 | ISSN: 0022-0957
Published online May 2000 | e-ISSN: 1460-2431 | DOI: https://dx.doi.org/10.1093/jexbot/51.346.945
Effects of zinc and influence of Acremonium lolii on growth parameters, chlorophyll a fluorescence and antioxidant enzyme activities of ryegrass (Lolium perenne L. cv Apollo)

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The effects of zinc on growth, mineral content, chlorophyll a fluorescence, and detoxifying enzyme activity (ascorbate peroxidase (APX), EC 1.11.1.11; superoxide dismutase (SOD), EC 1.15.1.1) of ryegrass infected or not by Acremonium lolii, and treated with nutrient solution containing 0–50 mM ZnSO4 were studied. The introduction of zinc induces stress with a decrease in growth at 1, 5 and 10 mM ZnSO4 and a cessation of growth at 50 mM ZnSO4, in ryegrass plants infected by A. lolii or not. This decrease in growth may be due to an accumulation of zinc in leaves. Nevertheless, symbiotic plants showed higher values in tiller number, an advantage conferred by the fungus. After 24 d of Zn exposure, leaf fresh weights and leaf water content were lower in plants growing with Zn in the culture medium and no advantage was conferred by the fungus to its host. An increase in Zn supply resulted in a decrease of the Ca, K, Mg, and Cu content of the leaves, a reduction in the quantum yield of electron flow throughout photosystem II (ΔF/[math]and a lowering of the efficiency of photosynthetic energy conversion (Fv/Fm), compared to control plants. To counter this zinc stress, detoxifying enzymes APX and SOD increased (100%) when Zn reached the value of 50 mM in the nutrient solution. At 10 mM ZnSO4, the presence of the fungus in the plant led to an increase in the threshold toxicity of plants to zinc by a diminution of APX activity.

Keywords: Zinc toxicity; Lolium perenne; Acremonium lolii; antioxidant enzymes; chlorophyll a fluorescence.; APX, ascorbate peroxidase; DW, dry weight; DTT, dithiothreitol; EDTA, ethylenediaminetetraacetic acid; FW, fresh weight; Fv/Fm, variable fluorescence to maximal fluorescence ratio; ΔF/F′m, quantum yield of electron flow throughout photosystem II; NBT, nitro‐blue tetrazolium; PSII, photosystem II; s.e., standard error; SOD, superoxide dismutase.

Journal Article.  5940 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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