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The dynamics of apoplast phenolics in tobacco leaves following inoculation with bacteria.

Baker CJ, Mock NM, Smith JM, Aver'yanov AA - Front Plant Sci (2015)

Bottom Line: The patterns of phenolic change in the apoplast were compared for tobacco inoculated with P. syringae pathovars, pv. syringae, which causes a resistant HR reaction within 15 h, and pv. tabaci, which causes a susceptible reaction with delayed visible symptoms.Both pathogens elicited lower increased levels of acetosyringone compared to the saprophyte, P. fluorescens but had greatly increased levels of the chlorogenic acid derivatives.This unexpected aspect will require further study of intracellular phenolics.

View Article: PubMed Central - PubMed

Affiliation: Molecular Plant Pathology Lab., U.S. Department of Agriculture Beltsville, MD, USA.

ABSTRACT
This study demonstrates that the accumulation of apoplastic phenolics is stimulated in planta in response to bacterial inoculation. Past studies have shown that levels of extracellular phenolics are elicited in plant cell suspensions in response to bacteria, and that tomato plants infected with viroids showed changes in apoplastic phenolics. The method described here monitored changes in apoplastic phenolics in tobacco leaves following bacterial inoculation of the same tissue. Inoculation with a saprophyte, Pseudomonas fluorescens, which does not cause visible symptoms or physical damage, was used to elicit phenolics and examine the effects of variable parameters on phenolic composition. Location of the inoculation on the leaf, position, or developmental age of the leaf on the plant, and inoculum concentration were standardized for further experiments. The patterns of phenolic change in the apoplast were compared for tobacco inoculated with P. syringae pathovars, pv. syringae, which causes a resistant HR reaction within 15 h, and pv. tabaci, which causes a susceptible reaction with delayed visible symptoms. Both pathogens elicited lower increased levels of acetosyringone compared to the saprophyte, P. fluorescens but had greatly increased levels of the chlorogenic acid derivatives. The latter metabolites appear to have come from the intracellular stores, which could indicate a weakening of the apoplast/symplast barrier. This unexpected aspect will require further study of intracellular phenolics.

No MeSH data available.


Related in: MedlinePlus

Effect of inoculum concentration on the induction of apoplastic phenolics. Tobacco leaf segments were inoculated with varying concentrations of P. fluorescens, 105–108 CFU ml−1, as indicated on the figure. The relative concentrations of two phenolics are shown over a 9 h period, (A) Acetovanillone and (B) Acetosyringone. (C) The peak concentrations of these metabolites vs. the log of inoculum concentration is shown. See Materials and Methods for further details.
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Figure 3: Effect of inoculum concentration on the induction of apoplastic phenolics. Tobacco leaf segments were inoculated with varying concentrations of P. fluorescens, 105–108 CFU ml−1, as indicated on the figure. The relative concentrations of two phenolics are shown over a 9 h period, (A) Acetovanillone and (B) Acetosyringone. (C) The peak concentrations of these metabolites vs. the log of inoculum concentration is shown. See Materials and Methods for further details.

Mentions: Studies with cell suspensions indicated that the concentration of induced phenolics increased with inoculum concentration (Baker et al., 2005b). To examine this in leaves we varied the inoculum concentration from 105 to 108 CFU ml−1 and followed the induced phenolics over a 9 h period. The concentration of induced acetovanillone and acetosyringone are shown in (Figures 3A,B). The rate of induction of the phenolics increased with inoculum concentration (Figure 3C). Acetovanillone induction peaked at about 5 h for 106–108 CFU ml−1 suggesting the induction period was independent of inoculum concentration (Figure 3A), while acetosyringone continues to increase over this time period (Figure 3B). The experiment was repeated twice with similar results. For further experiments 108 CFU ml−1 was routinely used for all bacteria.


The dynamics of apoplast phenolics in tobacco leaves following inoculation with bacteria.

Baker CJ, Mock NM, Smith JM, Aver'yanov AA - Front Plant Sci (2015)

Effect of inoculum concentration on the induction of apoplastic phenolics. Tobacco leaf segments were inoculated with varying concentrations of P. fluorescens, 105–108 CFU ml−1, as indicated on the figure. The relative concentrations of two phenolics are shown over a 9 h period, (A) Acetovanillone and (B) Acetosyringone. (C) The peak concentrations of these metabolites vs. the log of inoculum concentration is shown. See Materials and Methods for further details.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4542506&req=5

Figure 3: Effect of inoculum concentration on the induction of apoplastic phenolics. Tobacco leaf segments were inoculated with varying concentrations of P. fluorescens, 105–108 CFU ml−1, as indicated on the figure. The relative concentrations of two phenolics are shown over a 9 h period, (A) Acetovanillone and (B) Acetosyringone. (C) The peak concentrations of these metabolites vs. the log of inoculum concentration is shown. See Materials and Methods for further details.
Mentions: Studies with cell suspensions indicated that the concentration of induced phenolics increased with inoculum concentration (Baker et al., 2005b). To examine this in leaves we varied the inoculum concentration from 105 to 108 CFU ml−1 and followed the induced phenolics over a 9 h period. The concentration of induced acetovanillone and acetosyringone are shown in (Figures 3A,B). The rate of induction of the phenolics increased with inoculum concentration (Figure 3C). Acetovanillone induction peaked at about 5 h for 106–108 CFU ml−1 suggesting the induction period was independent of inoculum concentration (Figure 3A), while acetosyringone continues to increase over this time period (Figure 3B). The experiment was repeated twice with similar results. For further experiments 108 CFU ml−1 was routinely used for all bacteria.

Bottom Line: The patterns of phenolic change in the apoplast were compared for tobacco inoculated with P. syringae pathovars, pv. syringae, which causes a resistant HR reaction within 15 h, and pv. tabaci, which causes a susceptible reaction with delayed visible symptoms.Both pathogens elicited lower increased levels of acetosyringone compared to the saprophyte, P. fluorescens but had greatly increased levels of the chlorogenic acid derivatives.This unexpected aspect will require further study of intracellular phenolics.

View Article: PubMed Central - PubMed

Affiliation: Molecular Plant Pathology Lab., U.S. Department of Agriculture Beltsville, MD, USA.

ABSTRACT
This study demonstrates that the accumulation of apoplastic phenolics is stimulated in planta in response to bacterial inoculation. Past studies have shown that levels of extracellular phenolics are elicited in plant cell suspensions in response to bacteria, and that tomato plants infected with viroids showed changes in apoplastic phenolics. The method described here monitored changes in apoplastic phenolics in tobacco leaves following bacterial inoculation of the same tissue. Inoculation with a saprophyte, Pseudomonas fluorescens, which does not cause visible symptoms or physical damage, was used to elicit phenolics and examine the effects of variable parameters on phenolic composition. Location of the inoculation on the leaf, position, or developmental age of the leaf on the plant, and inoculum concentration were standardized for further experiments. The patterns of phenolic change in the apoplast were compared for tobacco inoculated with P. syringae pathovars, pv. syringae, which causes a resistant HR reaction within 15 h, and pv. tabaci, which causes a susceptible reaction with delayed visible symptoms. Both pathogens elicited lower increased levels of acetosyringone compared to the saprophyte, P. fluorescens but had greatly increased levels of the chlorogenic acid derivatives. The latter metabolites appear to have come from the intracellular stores, which could indicate a weakening of the apoplast/symplast barrier. This unexpected aspect will require further study of intracellular phenolics.

No MeSH data available.


Related in: MedlinePlus