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Maize EMBRYO SAC family peptides interact differentially with pollen tubes and fungal cells.

Woriedh M, Merkl R, Dresselhaus T - J. Exp. Bot. (2015)

Bottom Line: Furthermore, peptide fragments were found to bind differently to fungal cells.Mapping of peptide interaction sites identified amino acids differing in pollen tube burst and fungal response reactions.In summary, these findings indicate that residues targeting pollen tube burst in maize are specific to the ES family, while residues targeting fungal growth are conserved within defensins and defensin-like peptides.

View Article: PubMed Central - PubMed

Affiliation: Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, 93053 Regensburg, Germany.

No MeSH data available.


Related in: MedlinePlus

ES-d induces maize pollen tube burst. (A) Maize pollen grains were germinated in PGM at various pHs. Percentages of maize pollen tube germination and burst were measured after 1h at pH indicated. At pH 5 there was 100% germination with no burst. Error bars represent the standard error of 10 independent experiments. (B) Percentage of maize pollen tube burst was measured 5min after application of the indicated concentrations of peptides in PGM (pH 5). Acetonitrile was used as a negative control. (C) Percentage of maize pollen tube burst in PGM was measured 5min after application of ES-c and 15 mutated versions at the indicated concentrations. In each mutant version, the indicated amino acid was modified to Ala. Ala4 was modified to Val. Amino acids showing a strong increase in pollen tube burst are indicated by arrows. (D) Same experiment as shown in (C) but using ES-d and its variants. Amino acids reducing pollen tube burst below 10% are indicated by arrows. Error bars represent the standard error of eight independent experiments.
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Figure 2: ES-d induces maize pollen tube burst. (A) Maize pollen grains were germinated in PGM at various pHs. Percentages of maize pollen tube germination and burst were measured after 1h at pH indicated. At pH 5 there was 100% germination with no burst. Error bars represent the standard error of 10 independent experiments. (B) Percentage of maize pollen tube burst was measured 5min after application of the indicated concentrations of peptides in PGM (pH 5). Acetonitrile was used as a negative control. (C) Percentage of maize pollen tube burst in PGM was measured 5min after application of ES-c and 15 mutated versions at the indicated concentrations. In each mutant version, the indicated amino acid was modified to Ala. Ala4 was modified to Val. Amino acids showing a strong increase in pollen tube burst are indicated by arrows. (D) Same experiment as shown in (C) but using ES-d and its variants. Amino acids reducing pollen tube burst below 10% are indicated by arrows. Error bars represent the standard error of eight independent experiments.

Mentions: Previous studies have shown that the female gametophyte of maize likely secretes large amounts of ES1–4 required to induce pollen tube burst prior to fertilization (Cordts et al., 2001; Amien et al., 2010). ES1, ES4, mES4 (each 61 amino acid long); smaller peptide fragments ES-a, ES-b, ES-c, ES-d, and ES-e; and mutated versions mES-d1 and mES-d2 (13–16 amino acid long) were applied to growing pollen tubes in order to study their effects on pollen tube growth behaviour. First, the pH optimum of maize PGM was determined. Fig. 2A shows the germination and growth of maize pollen tubes for 1h at different pH values (pH 3.5 to pH 8). The maize pollen tubes germinated well, with between 92% and 99% germinating with no burst between pH 5 and 5.5. As a result, PGM at pH 5 was used for all further maize pollen tube assays. Different concentrations (100nM, 250nM, and 500nM) of peptides were applied to germinated maize pollen and showed that ES1 and ES4 induces maize pollen tube burst of 60.8±3.3% at 500nM (P < 0.001). Furthermore, a small peptide of 15 amino acids (ES-d) was even more active than full-length ES peptides and showed induction of pollen tube burst of 82.5±5.2% at 500nM. Peptides covering other ES domains showed no burst at all or a maximum burst efficiency of 39.3±2.4%. Mutants of ES-d (mES-d1 and mES-d2) and mutants of ES4 (mES4) showed significant reduction of pollen tube burst to about 29.2±7.0 to 41.2±4.4% (P < 0.001) (Fig. 2B). Moreover, after application of ES-d, maize pollen tubes started to burst within a few seconds, which is significantly faster than the response to mature peptides and other small peptides, in which the tubes started to burst after 1–2min. A series of concentrations was applied to obtain the optimal concentrations for the burst assay. Additionally, the time until burst was correlated with the concentration of the applied peptides. As a result, quantification of pollen tube burst was measured in the following experiments after 5min.


Maize EMBRYO SAC family peptides interact differentially with pollen tubes and fungal cells.

Woriedh M, Merkl R, Dresselhaus T - J. Exp. Bot. (2015)

ES-d induces maize pollen tube burst. (A) Maize pollen grains were germinated in PGM at various pHs. Percentages of maize pollen tube germination and burst were measured after 1h at pH indicated. At pH 5 there was 100% germination with no burst. Error bars represent the standard error of 10 independent experiments. (B) Percentage of maize pollen tube burst was measured 5min after application of the indicated concentrations of peptides in PGM (pH 5). Acetonitrile was used as a negative control. (C) Percentage of maize pollen tube burst in PGM was measured 5min after application of ES-c and 15 mutated versions at the indicated concentrations. In each mutant version, the indicated amino acid was modified to Ala. Ala4 was modified to Val. Amino acids showing a strong increase in pollen tube burst are indicated by arrows. (D) Same experiment as shown in (C) but using ES-d and its variants. Amino acids reducing pollen tube burst below 10% are indicated by arrows. Error bars represent the standard error of eight independent experiments.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4526917&req=5

Figure 2: ES-d induces maize pollen tube burst. (A) Maize pollen grains were germinated in PGM at various pHs. Percentages of maize pollen tube germination and burst were measured after 1h at pH indicated. At pH 5 there was 100% germination with no burst. Error bars represent the standard error of 10 independent experiments. (B) Percentage of maize pollen tube burst was measured 5min after application of the indicated concentrations of peptides in PGM (pH 5). Acetonitrile was used as a negative control. (C) Percentage of maize pollen tube burst in PGM was measured 5min after application of ES-c and 15 mutated versions at the indicated concentrations. In each mutant version, the indicated amino acid was modified to Ala. Ala4 was modified to Val. Amino acids showing a strong increase in pollen tube burst are indicated by arrows. (D) Same experiment as shown in (C) but using ES-d and its variants. Amino acids reducing pollen tube burst below 10% are indicated by arrows. Error bars represent the standard error of eight independent experiments.
Mentions: Previous studies have shown that the female gametophyte of maize likely secretes large amounts of ES1–4 required to induce pollen tube burst prior to fertilization (Cordts et al., 2001; Amien et al., 2010). ES1, ES4, mES4 (each 61 amino acid long); smaller peptide fragments ES-a, ES-b, ES-c, ES-d, and ES-e; and mutated versions mES-d1 and mES-d2 (13–16 amino acid long) were applied to growing pollen tubes in order to study their effects on pollen tube growth behaviour. First, the pH optimum of maize PGM was determined. Fig. 2A shows the germination and growth of maize pollen tubes for 1h at different pH values (pH 3.5 to pH 8). The maize pollen tubes germinated well, with between 92% and 99% germinating with no burst between pH 5 and 5.5. As a result, PGM at pH 5 was used for all further maize pollen tube assays. Different concentrations (100nM, 250nM, and 500nM) of peptides were applied to germinated maize pollen and showed that ES1 and ES4 induces maize pollen tube burst of 60.8±3.3% at 500nM (P < 0.001). Furthermore, a small peptide of 15 amino acids (ES-d) was even more active than full-length ES peptides and showed induction of pollen tube burst of 82.5±5.2% at 500nM. Peptides covering other ES domains showed no burst at all or a maximum burst efficiency of 39.3±2.4%. Mutants of ES-d (mES-d1 and mES-d2) and mutants of ES4 (mES4) showed significant reduction of pollen tube burst to about 29.2±7.0 to 41.2±4.4% (P < 0.001) (Fig. 2B). Moreover, after application of ES-d, maize pollen tubes started to burst within a few seconds, which is significantly faster than the response to mature peptides and other small peptides, in which the tubes started to burst after 1–2min. A series of concentrations was applied to obtain the optimal concentrations for the burst assay. Additionally, the time until burst was correlated with the concentration of the applied peptides. As a result, quantification of pollen tube burst was measured in the following experiments after 5min.

Bottom Line: Furthermore, peptide fragments were found to bind differently to fungal cells.Mapping of peptide interaction sites identified amino acids differing in pollen tube burst and fungal response reactions.In summary, these findings indicate that residues targeting pollen tube burst in maize are specific to the ES family, while residues targeting fungal growth are conserved within defensins and defensin-like peptides.

View Article: PubMed Central - PubMed

Affiliation: Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, 93053 Regensburg, Germany.

No MeSH data available.


Related in: MedlinePlus