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Phytoplasma infection in tomato is associated with re-organization of plasma membrane, ER stacks, and actin filaments in sieve elements.

Buxa SV, Degola F, Polizzotto R, De Marco F, Loschi A, Kogel KH, di Toppi LS, van Bel AJ, Musetti R - Front Plant Sci (2015)

Bottom Line: We investigated modifications of the sieve-element ultrastructure induced in tomato plants by 'Candidatus Phytoplasma solani,' the pathogen associated with the stolbur disease.Western blot analysis revealed a decrease of actin and an increase of ER-resident chaperone luminal binding protein (BiP) in midribs of phytoplasma-infected plants.Collectively, the studies provided novel insights into ultrastructural responses of host sieve elements to phloem-restricted prokaryotes.

View Article: PubMed Central - PubMed

Affiliation: Department of Phytopathology and Applied Zoology, Justus Liebig University Giessen, Germany.

ABSTRACT
Phytoplasmas, biotrophic wall-less prokaryotes, only reside in sieve elements of their host plants. The essentials of the intimate interaction between phytoplasmas and their hosts are poorly understood, which calls for research on potential ultrastructural modifications. We investigated modifications of the sieve-element ultrastructure induced in tomato plants by 'Candidatus Phytoplasma solani,' the pathogen associated with the stolbur disease. Phytoplasma infection induces a drastic re-organization of sieve-element substructures including changes in plasma membrane surface and distortion of the sieve-element reticulum. Observations of healthy and stolbur-diseased plants provided evidence for the emergence of structural links between sieve-element plasma membrane and phytoplasmas. One-sided actin aggregates on the phytoplasma surface also inferred a connection between phytoplasma and sieve-element cytoskeleton. Actin filaments displaced from the sieve-element mictoplasm to the surface of the phytoplasmas in infected sieve elements. Western blot analysis revealed a decrease of actin and an increase of ER-resident chaperone luminal binding protein (BiP) in midribs of phytoplasma-infected plants. Collectively, the studies provided novel insights into ultrastructural responses of host sieve elements to phloem-restricted prokaryotes.

No MeSH data available.


Related in: MedlinePlus

(A–D) TEM micrographs of main-vein cross-sections of healthy tomato leaves. Gold labeling of SE actin was clustered at the plasma membrane (A,D, squares) and the near cytoplasm area (mictoplasm) of sieve elements (B,C, squares). Labeling also occurs on the proximity of cell walls (A, arrow), in the lumen of the SEs (B, arrow) and in the cytoplasm of the adjacent companion cells (A). In insets, areas of interest of (A–D), are magnified. CC, companion cell; CW, cell wall; SE, sieve element; Scale bars = 200 nm.
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Figure 3: (A–D) TEM micrographs of main-vein cross-sections of healthy tomato leaves. Gold labeling of SE actin was clustered at the plasma membrane (A,D, squares) and the near cytoplasm area (mictoplasm) of sieve elements (B,C, squares). Labeling also occurs on the proximity of cell walls (A, arrow), in the lumen of the SEs (B, arrow) and in the cytoplasm of the adjacent companion cells (A). In insets, areas of interest of (A–D), are magnified. CC, companion cell; CW, cell wall; SE, sieve element; Scale bars = 200 nm.

Mentions: Control sections (from both healthy and infected samples), incubated with buffer alone, did not show labeling (not shown). In agreement with labeling with α-actin-gold-conjugated antibodies, actin occurred along the sieve-element membrane (Figure 3A), in the sieve-element mictoplasm and lumen (Figures 3B–D), and also in companion cell cytoplasm. The existence of an actin network in sieve elements has recently been demonstrated by Hafke et al. (2013).


Phytoplasma infection in tomato is associated with re-organization of plasma membrane, ER stacks, and actin filaments in sieve elements.

Buxa SV, Degola F, Polizzotto R, De Marco F, Loschi A, Kogel KH, di Toppi LS, van Bel AJ, Musetti R - Front Plant Sci (2015)

(A–D) TEM micrographs of main-vein cross-sections of healthy tomato leaves. Gold labeling of SE actin was clustered at the plasma membrane (A,D, squares) and the near cytoplasm area (mictoplasm) of sieve elements (B,C, squares). Labeling also occurs on the proximity of cell walls (A, arrow), in the lumen of the SEs (B, arrow) and in the cytoplasm of the adjacent companion cells (A). In insets, areas of interest of (A–D), are magnified. CC, companion cell; CW, cell wall; SE, sieve element; Scale bars = 200 nm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541602&req=5

Figure 3: (A–D) TEM micrographs of main-vein cross-sections of healthy tomato leaves. Gold labeling of SE actin was clustered at the plasma membrane (A,D, squares) and the near cytoplasm area (mictoplasm) of sieve elements (B,C, squares). Labeling also occurs on the proximity of cell walls (A, arrow), in the lumen of the SEs (B, arrow) and in the cytoplasm of the adjacent companion cells (A). In insets, areas of interest of (A–D), are magnified. CC, companion cell; CW, cell wall; SE, sieve element; Scale bars = 200 nm.
Mentions: Control sections (from both healthy and infected samples), incubated with buffer alone, did not show labeling (not shown). In agreement with labeling with α-actin-gold-conjugated antibodies, actin occurred along the sieve-element membrane (Figure 3A), in the sieve-element mictoplasm and lumen (Figures 3B–D), and also in companion cell cytoplasm. The existence of an actin network in sieve elements has recently been demonstrated by Hafke et al. (2013).

Bottom Line: We investigated modifications of the sieve-element ultrastructure induced in tomato plants by 'Candidatus Phytoplasma solani,' the pathogen associated with the stolbur disease.Western blot analysis revealed a decrease of actin and an increase of ER-resident chaperone luminal binding protein (BiP) in midribs of phytoplasma-infected plants.Collectively, the studies provided novel insights into ultrastructural responses of host sieve elements to phloem-restricted prokaryotes.

View Article: PubMed Central - PubMed

Affiliation: Department of Phytopathology and Applied Zoology, Justus Liebig University Giessen, Germany.

ABSTRACT
Phytoplasmas, biotrophic wall-less prokaryotes, only reside in sieve elements of their host plants. The essentials of the intimate interaction between phytoplasmas and their hosts are poorly understood, which calls for research on potential ultrastructural modifications. We investigated modifications of the sieve-element ultrastructure induced in tomato plants by 'Candidatus Phytoplasma solani,' the pathogen associated with the stolbur disease. Phytoplasma infection induces a drastic re-organization of sieve-element substructures including changes in plasma membrane surface and distortion of the sieve-element reticulum. Observations of healthy and stolbur-diseased plants provided evidence for the emergence of structural links between sieve-element plasma membrane and phytoplasmas. One-sided actin aggregates on the phytoplasma surface also inferred a connection between phytoplasma and sieve-element cytoskeleton. Actin filaments displaced from the sieve-element mictoplasm to the surface of the phytoplasmas in infected sieve elements. Western blot analysis revealed a decrease of actin and an increase of ER-resident chaperone luminal binding protein (BiP) in midribs of phytoplasma-infected plants. Collectively, the studies provided novel insights into ultrastructural responses of host sieve elements to phloem-restricted prokaryotes.

No MeSH data available.


Related in: MedlinePlus