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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

Time course monitoring apoplast phenolics in tobacco inoculated with P. fluorescens (A,B), P.s. tabaci (C,D), and P.s. syringae (E,F). The leaf segments were inoculated with 108 CFU ml−1 and the apoplast fluid extracted periodically and analyzed for phenolic content using UPLC/UV/MS. Hydroxycinnamic acids (A,C,E) and chlorogenic acid isomers (B,D,F). See Materials and Methods for further details; AV (acetovanillone); ACE (acetosyringone); CGA (chlorogenic acid isomers).
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Figure 4: Time course monitoring apoplast phenolics in tobacco inoculated with P. fluorescens (A,B), P.s. tabaci (C,D), and P.s. syringae (E,F). The leaf segments were inoculated with 108 CFU ml−1 and the apoplast fluid extracted periodically and analyzed for phenolic content using UPLC/UV/MS. Hydroxycinnamic acids (A,C,E) and chlorogenic acid isomers (B,D,F). See Materials and Methods for further details; AV (acetovanillone); ACE (acetosyringone); CGA (chlorogenic acid isomers).

Mentions: Leaves were inoculated with 108 CFU ml−1 and the apoplastic fluid was monitored every 3 h for a 24 h period. The experiment was repeated two times. No visible symptoms developed over a 6-day observation period. The level of the two major acetophenones, AV, and ACE, increased after 3 h and peaked by 6–9 h (Figure 4A). The AV level then decreased and remained at baseline by 15 h. The ACE level decreased but after 15 h it peaked again at 24 h. The chlorogenic acid isomers, CGA-A, CGA-B, and CGA-C, remained relatively low during the 24 h period (Figure 4B).


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)

Time course monitoring apoplast phenolics in tobacco inoculated with P. fluorescens (A,B), P.s. tabaci (C,D), and P.s. syringae (E,F). The leaf segments were inoculated with 108 CFU ml−1 and the apoplast fluid extracted periodically and analyzed for phenolic content using UPLC/UV/MS. Hydroxycinnamic acids (A,C,E) and chlorogenic acid isomers (B,D,F). See Materials and Methods for further details; AV (acetovanillone); ACE (acetosyringone); CGA (chlorogenic acid isomers).
© Copyright Policy
Related In: Results  -  Collection

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

Figure 4: Time course monitoring apoplast phenolics in tobacco inoculated with P. fluorescens (A,B), P.s. tabaci (C,D), and P.s. syringae (E,F). The leaf segments were inoculated with 108 CFU ml−1 and the apoplast fluid extracted periodically and analyzed for phenolic content using UPLC/UV/MS. Hydroxycinnamic acids (A,C,E) and chlorogenic acid isomers (B,D,F). See Materials and Methods for further details; AV (acetovanillone); ACE (acetosyringone); CGA (chlorogenic acid isomers).
Mentions: Leaves were inoculated with 108 CFU ml−1 and the apoplastic fluid was monitored every 3 h for a 24 h period. The experiment was repeated two times. No visible symptoms developed over a 6-day observation period. The level of the two major acetophenones, AV, and ACE, increased after 3 h and peaked by 6–9 h (Figure 4A). The AV level then decreased and remained at baseline by 15 h. The ACE level decreased but after 15 h it peaked again at 24 h. The chlorogenic acid isomers, CGA-A, CGA-B, and CGA-C, remained relatively low during the 24 h period (Figure 4B).

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