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The bacterial pathogen Xylella fastidiosa affects the leaf ionome of plant hosts during infection.

De La Fuente L, Parker JK, Oliver JE, Granger S, Brannen PM, van Santen E, Cobine PA - PLoS ONE (2013)

Bottom Line: The elemental composition of leaves was used as an indicator of the physiological changes in the host at a specific time and relative position during plant development.Bacterial infection was found to cause significant increases in concentrations of calcium prior to the appearance of symptoms and decreases in concentrations of phosphorous after symptoms appeared.This descriptive ionomics approach characterizes the existence of a mineral element-based response to X. fastidiosa using a model system suitable for further manipulation to uncover additional details of the role of mineral elements during plant-pathogen interactions.

View Article: PubMed Central - PubMed

Affiliation: Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, United States of America. lzd0005@auburn.edu

ABSTRACT
Xylella fastidiosa is a plant pathogenic bacterium that lives inside the host xylem vessels, where it forms biofilm believed to be responsible for disrupting the passage of water and nutrients. Here, Nicotiana tabacum was infected with X. fastidiosa, and the spatial and temporal changes in the whole-leaf ionome (i.e. the mineral and trace element composition) were measured as the host plant transitioned from healthy to diseased physiological status. The elemental composition of leaves was used as an indicator of the physiological changes in the host at a specific time and relative position during plant development. Bacterial infection was found to cause significant increases in concentrations of calcium prior to the appearance of symptoms and decreases in concentrations of phosphorous after symptoms appeared. Field-collected leaves from multiple varieties of grape, blueberry, and pecan plants grown in different locations over a four-year period in the Southeastern US showed the same alterations in Ca and P. This descriptive ionomics approach characterizes the existence of a mineral element-based response to X. fastidiosa using a model system suitable for further manipulation to uncover additional details of the role of mineral elements during plant-pathogen interactions. This is the first report on the dynamics of changes in the ionome of the host plant throughout the process of infection by a pathogen.

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Changes in total ionome of tobacco leaves infected with Xylella fastidiosa.Tobacco plants (Nicotiana tabacum ‘Petite Havana SR1’) growing in the greenhouse were inoculated with X. fastidiosa or buffer (control) and the ionome of each leaf was characterized by inductively coupled plasma optical emission spectroscopy (ICP-OES). Mean values of element concentrations (in mg/g of plant tissue) were obtained from leaves in positions ≥ #4. Mean relative percentage of change with corresponding standard errors (represented only towards 0 value) were calculated by comparing mean leaf concentrations across five time points and three experimental sets between leaves where X. fastidiosa was detected (‘infected’) against those were the bacterium was not detected (‘non-infected’) (n∼375/treatment). P values for main treatment effects are included for each element; those highlighted in bold with red bars are considered significant (p<0.05).
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pone-0062945-g003: Changes in total ionome of tobacco leaves infected with Xylella fastidiosa.Tobacco plants (Nicotiana tabacum ‘Petite Havana SR1’) growing in the greenhouse were inoculated with X. fastidiosa or buffer (control) and the ionome of each leaf was characterized by inductively coupled plasma optical emission spectroscopy (ICP-OES). Mean values of element concentrations (in mg/g of plant tissue) were obtained from leaves in positions ≥ #4. Mean relative percentage of change with corresponding standard errors (represented only towards 0 value) were calculated by comparing mean leaf concentrations across five time points and three experimental sets between leaves where X. fastidiosa was detected (‘infected’) against those were the bacterium was not detected (‘non-infected’) (n∼375/treatment). P values for main treatment effects are included for each element; those highlighted in bold with red bars are considered significant (p<0.05).

Mentions: For an overall assessment of the effect of infection on the ionome of tobacco leaves when X. fastidiosa is present, all leaves in positions ≥ #4 collected during five sampling time points in three experimental sets were considered (Fig. 3). The overall treatment*time*position (p≥0.60) and treatment*position (p≥0.32) interactions were not significant sources of variation in these experiments. Based on this, further analysis focused on the effect of the treatment (infected vs. non-infected leaves) on the concentrations of elements analyzed. Significant treatment effects were observed for Ca (p = 0.04, DF = 118) and P (p = 0.03, DF = 122) when a p = 0.05 threshold was considered. Considering overall means from all leaves collected over five time points during three experimental sets, Ca concentration increased by 13% (Fig. 3) in leaves with X. fastidiosa compared to leaves without the bacterium (18.8 to 21.3 mg/g tissue). P was reduced by 11% in leaves with X. fastidiosa (3.7 to 3.3 mg/g tissue) (Fig. 3). Changes in the concentration of other elements between infected and non-infected leaves were non-significant (p>0.05). This analysis served to identify elements of interest (Ca and P) but do not reflect changes in element concentrations at a specific time or leaf location, which are considered below and provide a better representation of the dynamics of disease progression.


The bacterial pathogen Xylella fastidiosa affects the leaf ionome of plant hosts during infection.

De La Fuente L, Parker JK, Oliver JE, Granger S, Brannen PM, van Santen E, Cobine PA - PLoS ONE (2013)

Changes in total ionome of tobacco leaves infected with Xylella fastidiosa.Tobacco plants (Nicotiana tabacum ‘Petite Havana SR1’) growing in the greenhouse were inoculated with X. fastidiosa or buffer (control) and the ionome of each leaf was characterized by inductively coupled plasma optical emission spectroscopy (ICP-OES). Mean values of element concentrations (in mg/g of plant tissue) were obtained from leaves in positions ≥ #4. Mean relative percentage of change with corresponding standard errors (represented only towards 0 value) were calculated by comparing mean leaf concentrations across five time points and three experimental sets between leaves where X. fastidiosa was detected (‘infected’) against those were the bacterium was not detected (‘non-infected’) (n∼375/treatment). P values for main treatment effects are included for each element; those highlighted in bold with red bars are considered significant (p<0.05).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3646994&req=5

pone-0062945-g003: Changes in total ionome of tobacco leaves infected with Xylella fastidiosa.Tobacco plants (Nicotiana tabacum ‘Petite Havana SR1’) growing in the greenhouse were inoculated with X. fastidiosa or buffer (control) and the ionome of each leaf was characterized by inductively coupled plasma optical emission spectroscopy (ICP-OES). Mean values of element concentrations (in mg/g of plant tissue) were obtained from leaves in positions ≥ #4. Mean relative percentage of change with corresponding standard errors (represented only towards 0 value) were calculated by comparing mean leaf concentrations across five time points and three experimental sets between leaves where X. fastidiosa was detected (‘infected’) against those were the bacterium was not detected (‘non-infected’) (n∼375/treatment). P values for main treatment effects are included for each element; those highlighted in bold with red bars are considered significant (p<0.05).
Mentions: For an overall assessment of the effect of infection on the ionome of tobacco leaves when X. fastidiosa is present, all leaves in positions ≥ #4 collected during five sampling time points in three experimental sets were considered (Fig. 3). The overall treatment*time*position (p≥0.60) and treatment*position (p≥0.32) interactions were not significant sources of variation in these experiments. Based on this, further analysis focused on the effect of the treatment (infected vs. non-infected leaves) on the concentrations of elements analyzed. Significant treatment effects were observed for Ca (p = 0.04, DF = 118) and P (p = 0.03, DF = 122) when a p = 0.05 threshold was considered. Considering overall means from all leaves collected over five time points during three experimental sets, Ca concentration increased by 13% (Fig. 3) in leaves with X. fastidiosa compared to leaves without the bacterium (18.8 to 21.3 mg/g tissue). P was reduced by 11% in leaves with X. fastidiosa (3.7 to 3.3 mg/g tissue) (Fig. 3). Changes in the concentration of other elements between infected and non-infected leaves were non-significant (p>0.05). This analysis served to identify elements of interest (Ca and P) but do not reflect changes in element concentrations at a specific time or leaf location, which are considered below and provide a better representation of the dynamics of disease progression.

Bottom Line: The elemental composition of leaves was used as an indicator of the physiological changes in the host at a specific time and relative position during plant development.Bacterial infection was found to cause significant increases in concentrations of calcium prior to the appearance of symptoms and decreases in concentrations of phosphorous after symptoms appeared.This descriptive ionomics approach characterizes the existence of a mineral element-based response to X. fastidiosa using a model system suitable for further manipulation to uncover additional details of the role of mineral elements during plant-pathogen interactions.

View Article: PubMed Central - PubMed

Affiliation: Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, United States of America. lzd0005@auburn.edu

ABSTRACT
Xylella fastidiosa is a plant pathogenic bacterium that lives inside the host xylem vessels, where it forms biofilm believed to be responsible for disrupting the passage of water and nutrients. Here, Nicotiana tabacum was infected with X. fastidiosa, and the spatial and temporal changes in the whole-leaf ionome (i.e. the mineral and trace element composition) were measured as the host plant transitioned from healthy to diseased physiological status. The elemental composition of leaves was used as an indicator of the physiological changes in the host at a specific time and relative position during plant development. Bacterial infection was found to cause significant increases in concentrations of calcium prior to the appearance of symptoms and decreases in concentrations of phosphorous after symptoms appeared. Field-collected leaves from multiple varieties of grape, blueberry, and pecan plants grown in different locations over a four-year period in the Southeastern US showed the same alterations in Ca and P. This descriptive ionomics approach characterizes the existence of a mineral element-based response to X. fastidiosa using a model system suitable for further manipulation to uncover additional details of the role of mineral elements during plant-pathogen interactions. This is the first report on the dynamics of changes in the ionome of the host plant throughout the process of infection by a pathogen.

Show MeSH
Related in: MedlinePlus