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Molecular, Biochemical and Ultrastructural Changes Induced by Pb Toxicity in Seedlings of Theobroma cacao L.

Reis GS, de Almeida AA, de Almeida NM, de Castro AV, Mangabeira PA, Pirovani CP - PLoS ONE (2015)

Bottom Line: The activity of guaiacol peroxidases and the expression of genes associated to synthetase of phytochelatin, SODcyt and PER increased in response to Pb.The progeny of CCN-10 x SCA-6 was more tolerant to Pb stress when compared to Catongo, since: (i) it accumulated more Pb in the roots, preventing its translocation to the shoot; (ii) it presented higher activity of peroxidases in the roots, which are enzymes involved in the elimination of excess of reactive oxygen species; and (iii) increased expression of the gene in the phytochelatin biosynthesis route.The results of the proteomic analysis were of paramount importance to differentiate the defense mechanisms used by both progenies of T. cacao.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, State University of Santa Cruz, Campus Soane Nazaré de Andrade, Rodovia Jorge Amado, km 16, 45662-900, Ilhéus, BA, Brazil.

ABSTRACT
Pb is a metal which is highly toxic to plants and animals, including humans. High concentrations of Pb have been observed in beans of T. cacao, as well as in its products. In this work, we evaluated the molecular, biochemical, and ultrastructural alterations in mature leaves and primary roots of seedlings of two progenies of T. cacao, obtained from seed germination in different concentrations of Pb (0, 0.05, 0.1, 0.2, 0.4, 0.8 g L(-1)), in the form of Pb(NO3)2. The progenies resulted from self-fertilization of Catongo and a cross of CCN-10 x SCA-6. The Pb, supplied via seminal, caused alterations in the ultrastructures of the mesophyll cells and in the amount of starch grains in the chloroplasts. The dosage of substances reactive to thiobarbituric acid showed that Pb induced lipid peroxidation. The activity of guaiacol peroxidases and the expression of genes associated to synthetase of phytochelatin, SODcyt and PER increased in response to Pb. In addition, there was alteration in the expression of stress-related proteins. The progeny of CCN-10 x SCA-6 was more tolerant to Pb stress when compared to Catongo, since: (i) it accumulated more Pb in the roots, preventing its translocation to the shoot; (ii) it presented higher activity of peroxidases in the roots, which are enzymes involved in the elimination of excess of reactive oxygen species; and (iii) increased expression of the gene in the phytochelatin biosynthesis route. The results of the proteomic analysis were of paramount importance to differentiate the defense mechanisms used by both progenies of T. cacao.

No MeSH data available.


Related in: MedlinePlus

Deposition of electro-dense material in the cell wall detected by ultrastructural micrographs of leaf mesophyll cells.CCN-10 x SCA-6 Control (A) and (C), and submitted to dose of 0.8 g Pb L-1(B) and (D). st—starch; ch—chloroplast; p—plastoglobule; t—thylakoid; Arrow-deposition of electro-dense material. Bars: 1.0 mm.
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pone.0129696.g002: Deposition of electro-dense material in the cell wall detected by ultrastructural micrographs of leaf mesophyll cells.CCN-10 x SCA-6 Control (A) and (C), and submitted to dose of 0.8 g Pb L-1(B) and (D). st—starch; ch—chloroplast; p—plastoglobule; t—thylakoid; Arrow-deposition of electro-dense material. Bars: 1.0 mm.

Mentions: Pb caused changes in the cell ultrastructure of the foliar mesophyll in the susceptible progeny (Catongo), when subjected to the dose of 0.8 g Pb L-1 via seminal. Disorganization in tilacoidal membranes, poorly developed chloroplasts (Fig 1E), and rupture of the nuclear membrane (Fig 1F), were verified in this progeny. In both progenies, electrodense deposits were observed between the cell walls of the foliar mesophyll (Figs 1D and 2D). Catongo and CCN-10 x SCA-6, in the absence of Pb, presented cells of the foliar and radicular mesophyll with normal aspect (Figs 1A–1C; 2A and 2C; 3A and 3C, and 4A and 4C).


Molecular, Biochemical and Ultrastructural Changes Induced by Pb Toxicity in Seedlings of Theobroma cacao L.

Reis GS, de Almeida AA, de Almeida NM, de Castro AV, Mangabeira PA, Pirovani CP - PLoS ONE (2015)

Deposition of electro-dense material in the cell wall detected by ultrastructural micrographs of leaf mesophyll cells.CCN-10 x SCA-6 Control (A) and (C), and submitted to dose of 0.8 g Pb L-1(B) and (D). st—starch; ch—chloroplast; p—plastoglobule; t—thylakoid; Arrow-deposition of electro-dense material. Bars: 1.0 mm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493102&req=5

pone.0129696.g002: Deposition of electro-dense material in the cell wall detected by ultrastructural micrographs of leaf mesophyll cells.CCN-10 x SCA-6 Control (A) and (C), and submitted to dose of 0.8 g Pb L-1(B) and (D). st—starch; ch—chloroplast; p—plastoglobule; t—thylakoid; Arrow-deposition of electro-dense material. Bars: 1.0 mm.
Mentions: Pb caused changes in the cell ultrastructure of the foliar mesophyll in the susceptible progeny (Catongo), when subjected to the dose of 0.8 g Pb L-1 via seminal. Disorganization in tilacoidal membranes, poorly developed chloroplasts (Fig 1E), and rupture of the nuclear membrane (Fig 1F), were verified in this progeny. In both progenies, electrodense deposits were observed between the cell walls of the foliar mesophyll (Figs 1D and 2D). Catongo and CCN-10 x SCA-6, in the absence of Pb, presented cells of the foliar and radicular mesophyll with normal aspect (Figs 1A–1C; 2A and 2C; 3A and 3C, and 4A and 4C).

Bottom Line: The activity of guaiacol peroxidases and the expression of genes associated to synthetase of phytochelatin, SODcyt and PER increased in response to Pb.The progeny of CCN-10 x SCA-6 was more tolerant to Pb stress when compared to Catongo, since: (i) it accumulated more Pb in the roots, preventing its translocation to the shoot; (ii) it presented higher activity of peroxidases in the roots, which are enzymes involved in the elimination of excess of reactive oxygen species; and (iii) increased expression of the gene in the phytochelatin biosynthesis route.The results of the proteomic analysis were of paramount importance to differentiate the defense mechanisms used by both progenies of T. cacao.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, State University of Santa Cruz, Campus Soane Nazaré de Andrade, Rodovia Jorge Amado, km 16, 45662-900, Ilhéus, BA, Brazil.

ABSTRACT
Pb is a metal which is highly toxic to plants and animals, including humans. High concentrations of Pb have been observed in beans of T. cacao, as well as in its products. In this work, we evaluated the molecular, biochemical, and ultrastructural alterations in mature leaves and primary roots of seedlings of two progenies of T. cacao, obtained from seed germination in different concentrations of Pb (0, 0.05, 0.1, 0.2, 0.4, 0.8 g L(-1)), in the form of Pb(NO3)2. The progenies resulted from self-fertilization of Catongo and a cross of CCN-10 x SCA-6. The Pb, supplied via seminal, caused alterations in the ultrastructures of the mesophyll cells and in the amount of starch grains in the chloroplasts. The dosage of substances reactive to thiobarbituric acid showed that Pb induced lipid peroxidation. The activity of guaiacol peroxidases and the expression of genes associated to synthetase of phytochelatin, SODcyt and PER increased in response to Pb. In addition, there was alteration in the expression of stress-related proteins. The progeny of CCN-10 x SCA-6 was more tolerant to Pb stress when compared to Catongo, since: (i) it accumulated more Pb in the roots, preventing its translocation to the shoot; (ii) it presented higher activity of peroxidases in the roots, which are enzymes involved in the elimination of excess of reactive oxygen species; and (iii) increased expression of the gene in the phytochelatin biosynthesis route. The results of the proteomic analysis were of paramount importance to differentiate the defense mechanisms used by both progenies of T. cacao.

No MeSH data available.


Related in: MedlinePlus