Avaliação do potencial de <i>Pistia stratiotes</i> L. (alface d'água) para a bioindicação e fitorremediação de ambientes aquáticos contaminados com arsênio

Espécimes de Pistia stratiotes foram submetidos a cinco concentrações de arsênio (As), durante sete dias. Crescimento, absorção de As, concentração de malondialdeído (MDA), pigmentos fotossintéticos, atividades enzimáticas, concentração de aminoácidos e alterações anatômicas foram avaliadas. O acúmulo de As pelas plantas aumentou com o incremento do metaloide na solução, enquanto que a taxa de crescimento e o teor de pigmentos fotossintéticos diminuiu. O conteúdo MDA aumentou, indicando estresse oxidativo. A atividade de enzimas antioxidantes e os teores de aminoácidos aumentaram nas doses mais baixas de As, declinando nas concentrações mais elevadas. Nas folhas foram observados clorose e necrose. As folhas apresentaram acumulação de amido e aumento da espessura do mesofilo. No sistema radicular houve perda e escurecimento das raízes. Camadas de células formadas nos pontos de inserção da raiz podem ter sido responsáveis pela queda das raízes. Estes resultados indicam que a alface da água apresenta potencial para bioindicação e fitorremediação de ambientes aquáticos contaminados com As.

enzimas antioxidantes; contaminação da água; análise estrutural; pigmentos fotossintéticos

Autoria

FS Farnese

Departamento de Biologia Vegetal, Universidade Federal de Viçosa – UFV, Av. Peter Henry Rolfs, s/n, Campus Universitário, CEP 36570-000, Viçosa, MG, BrazilUniversidade Federal de Viçosa – UFVBrazilViçosa, MG, BrazilDepartamento de Biologia Vegetal, Universidade Federal de Viçosa – UFV, Av. Peter Henry Rolfs, s/n, Campus Universitário, CEP 36570-000, Viçosa, MG, Brazil

JA Oliveira ^**e-mail: jalves@ufv.br

Departamento de Biologia Geral, Universidade Federal de Viçosa – UFV, Av. Peter Henry Rolfs, s/n, Campus Universitário, CEP 36570-000, Viçosa, MG, BrazilUniversidade Federal de Viçosa – UFVBrazilViçosa, MG, BrazilDepartamento de Biologia Geral, Universidade Federal de Viçosa – UFV, Av. Peter Henry Rolfs, s/n, Campus Universitário, CEP 36570-000, Viçosa, MG, Brazil

FS Lima

Departamento de Ciências Biológicas, Universidade Federal do Triângulo Mineiro – UFTM, Av. Getúlio Guaritá, 159, Abadia, CP 136, CEP 38025-440, Uberaba, MG, BrazilUniversidade Federal do Triângulo Mineiro – UFTMBrazilUberaba, MG, BrazilDepartamento de Ciências Biológicas, Universidade Federal do Triângulo Mineiro – UFTM, Av. Getúlio Guaritá, 159, Abadia, CP 136, CEP 38025-440, Uberaba, MG, Brazil

GA Leão

GS Gusman

LC Silva

*e-mail: jalves@ufv.br

SCIMAGO INSTITUTIONS RANKINGS

Figuras

Figuras (8)

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Figure 1.
Relative growth rate ( ) and As concentration in the aerial parts ( ) and roots ( ) of P. stratiotes exposed to arsenate.

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Figure 2.
Content of MDA in the aerial parts ( ) and roots ( ) of P. stratiotes exposed to arsenate. Bars represent standard deviation. Means followed by the same upper-case letter, between treatments for the same organ, and by the same lower-case letter, between organs for the same treatment, were not significantly different according to Tukey's test at 5% probability.

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Figure 3.
Concentration of chla (chlorophyll a), chb (chlorophyll b), total chlorophyll and carotenoids in P. stratiotes under As stress.

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Figure 4.
Enzimatic activity of SOD (superoxide dismutase; A), POX (peroxidases; B) and CAT (catalases; C) in the aerial parts ( ) and roots ( ) of P. stratiotes under As stress. Bars represent standard deviation. Means followed by the same uppercase letter, between treatments for the same organ, and by the same lower-case letter, between organs for the same treatment, were not significantly different according to Tukey's test at 5% probability.

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Figure 5.
Amino acid content in the aerial parts ( ) and roots ( ) of P. stratiotes exposed to arsenate. Bars represent standard deviation. Means followed by the same uppercase letter, between treatments for the same organ, and by the same lower-case letter, between organs for the same treatment, were not significantly different according to Tukey's test at 5% probability.

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Figure 6.
Effect of different As concentrations on P. stratiotes growth (A). Visible symptoms of toxicity: Control (B) and 20 µM As (C). Observed chlorosis and necrosis (arrows).

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Figure 7.
General appearance of the leaf in the control plant (A) and at As concentration of 20 µM (B), in which increased numbers of trichomes may be seen. Detail of the palisade parenchyma in the control plant (C) and treated specimen (D), showing increased numbers of layers. Accumulation of starch (arrow) in the bundle sheaths of plants treated with As (F) as compared to the control (E). Differential accumulation of starch (arrow) in the control (G) and treated specimen (H), visualized with polarized light. (Bar =100µm).

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Figure 8.
General appearance of the root (A) and detail of the vascular cylinder (B), where casparian ridges can be observed (arrow). Longitudinal section at the root insertion point on the stem in the control (C) at As concentration of 15 µM (D). Observe the formation of the abscission zone in D (arrow). (Bar=50µm).

Figure 1. Relative growth rate ( ) and As concentration in the aerial parts ( ) and roots ( ) of P. stratiotes exposed to arsenate.

Figure 2. Content of MDA in the aerial parts ( ) and roots ( ) of P. stratiotes exposed to arsenate. Bars represent standard deviation. Means followed by the same upper-case letter, between treatments for the same organ, and by the same lower-case letter, between organs for the same treatment, were not significantly different according to Tukey's test at 5% probability.

Figure 3. Concentration of chla (chlorophyll a), chb (chlorophyll b), total chlorophyll and carotenoids in P. stratiotes under As stress.

Figure 4. Enzimatic activity of SOD (superoxide dismutase; A), POX (peroxidases; B) and CAT (catalases; C) in the aerial parts ( ) and roots ( ) of P. stratiotes under As stress. Bars represent standard deviation. Means followed by the same uppercase letter, between treatments for the same organ, and by the same lower-case letter, between organs for the same treatment, were not significantly different according to Tukey's test at 5% probability.

Figure 5. Amino acid content in the aerial parts ( ) and roots ( ) of P. stratiotes exposed to arsenate. Bars represent standard deviation. Means followed by the same uppercase letter, between treatments for the same organ, and by the same lower-case letter, between organs for the same treatment, were not significantly different according to Tukey's test at 5% probability.

Figure 6. Effect of different As concentrations on P. stratiotes growth (A). Visible symptoms of toxicity: Control (B) and 20 µM As (C). Observed chlorosis and necrosis (arrows).

Figure 7. General appearance of the leaf in the control plant (A) and at As concentration of 20 µM (B), in which increased numbers of trichomes may be seen. Detail of the palisade parenchyma in the control plant (C) and treated specimen (D), showing increased numbers of layers. Accumulation of starch (arrow) in the bundle sheaths of plants treated with As (F) as compared to the control (E). Differential accumulation of starch (arrow) in the control (G) and treated specimen (H), visualized with polarized light. (Bar =100µm).

Figure 8. General appearance of the root (A) and detail of the vascular cylinder (B), where casparian ridges can be observed (arrow). Longitudinal section at the root insertion point on the stem in the control (C) at As concentration of 15 µM (D). Observe the formation of the abscission zone in D (arrow). (Bar=50µm).

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