Limits...
Synchrotron based phase contrast X-ray imaging combined with FTIR spectroscopy reveals structural and biomolecular differences in spikelets play a significant role in resistance to Fusarium in wheat.

Lahlali R, Karunakaran C, Wang L, Willick I, Schmidt M, Liu X, Borondics F, Forseille L, Fobert PR, Tanino K, Peng G, Hallin E - BMC Plant Biol. (2015)

Bottom Line: The FTIR spectra showed significant variability between infected and non-infected floret and rachis of the wheat cultivars.In the rachis of the wheat cultivars, PCA underlines significant changes in pectin, cellulose, and hemicellulose characteristic absorption spectra.The combined technique is a powerful new tool for internal visualisation and biomolecular monitoring before and during plant-microbe interactions to understand both the differences between cultivars and their different responses to disease stress.

View Article: PubMed Central - PubMed

Affiliation: Canadian Light Source Inc., 44 Innovation Boulevard, Saskatoon, SK, S7N 2V3, Canada. Rachid.Lahlali@lightsource.ca.

ABSTRACT

Background: Fusarium head blight (FHB), a scab principally caused by Fusarium graminearum Schw., is a serious disease of wheat. The purpose of this study is to evaluate the potential of combining synchrotron based phase contrast X-ray imaging (PCI) with Fourier Transform mid infrared (FTIR) spectroscopy to understand the mechanisms of resistance to FHB by resistant wheat cultivars. Our hypothesis is that structural and biochemical differences between resistant and susceptible cultivars play a significant role in developing resistance to FHB.

Results: Synchrotron based PCI images and FTIR absorption spectra (4000-800 cm(-1)) of the floret and rachis from Fusarium-damaged and undamaged spikes of the resistant cultivar 'Sumai3', tolerant cultivar 'FL62R1', and susceptible cultivar 'Muchmore' were collected and analyzed. The PCI images show significant differences between infected and non-infected florets and rachises of different wheat cultivars. However, no pronounced difference between non-inoculated resistant and susceptible cultivar in terms of floret structures could be determined due to the complexity of the internal structures. The FTIR spectra showed significant variability between infected and non-infected floret and rachis of the wheat cultivars. The changes in absorption wavenumbers following pathogenic infection were mostly in the spectral range from 1800-800 cm(-1). The Principal Component Analysis (PCA) was also used to determine the significant chemical changes inside floret and rachis when exposed to the FHB disease stress to understand the plant response mechanism. In the floret and rachis samples, PCA of FTIR spectra revealed differences in cell wall related polysaccharides. In the florets, absorption peaks for Amide I, cellulose, hemicellulose and pectin were affected by the pathogenic fungus. In the rachis of the wheat cultivars, PCA underlines significant changes in pectin, cellulose, and hemicellulose characteristic absorption spectra. Amide II and lignin absorption peaks, persistent in the rachis of Sumai3, together with increased peak shift at 1245 cm(-1) after infection with FHB may be a marker for stress response in which the cell wall compounds related to pathways for lignification are increased.

Conclusions: Synchrotron based PCI combined with FTIR spectroscopy show promising results related to FHB in wheat. The combined technique is a powerful new tool for internal visualisation and biomolecular monitoring before and during plant-microbe interactions to understand both the differences between cultivars and their different responses to disease stress.

No MeSH data available.


Related in: MedlinePlus

Images of diseased and healthy florets in the spikelets of wheat cultivars using phase contrast X-ray imaging at 4 days after inoculation with FHB. The spikelets were kept inside a 18 mm diameter falcon tube and X-ray images were recorded at 18 keV using a 8.75 μm resolution detector. Brackets indicate the imaged part of the wheat spike. Scale bars indicate 1 mm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4340487&req=5

Fig3: Images of diseased and healthy florets in the spikelets of wheat cultivars using phase contrast X-ray imaging at 4 days after inoculation with FHB. The spikelets were kept inside a 18 mm diameter falcon tube and X-ray images were recorded at 18 keV using a 8.75 μm resolution detector. Brackets indicate the imaged part of the wheat spike. Scale bars indicate 1 mm.

Mentions: Synchrotron PCI has the potential to revolutionize the study of physiology and internal biomechanical structures in different plant samples. This non-destructive technique has the spatial and temporal resolution, penetrating power and sensitivity to soft tissue that is required to visualize the internal structure of living plants or animals on the scale from millimeters to microns [43]. In the current study, we have used this technique to compare the structural differences among resistant cultivar Sumai3, tolerant or Canadian resistant germplasm FL62R1, and moderately susceptible cultivar Muchmore. Scanned wheat heads of three cultivars that contain artificially infected and non-infected florets in the same spikelets with FHB at 4 DAI are shown in Figures 2 and 3. Differences in mass densities and phase contrast signals between healthy and infected spikelets were observed. Healthy florets appear in white colors filled with internal structures while infected ones are largely empty and transparent, perhaps due to loss of water and floret tissues. The high X-ray energy (18 keV) and the low resolution detector (8.75 μm) used here are not able to reveal any visible fungal structures such as mycelia of Fusarium graminearum. A total loss of cell viability in infected floret structures such as external and internal epidermis of glumes, and external and internal epidermis of anthers is revealed by the X-ray images (Figure 4). This phenomenon was more pronounced in Muchmore cultivar compared to the other two cultivars. The ovary in an infected Muchmore floret appears to be in a stressed state with the absence of anthers which may be destroyed by the fungus itself, indicating a loss of fertility in the infected spikelets of that cultivar.Figure 2


Synchrotron based phase contrast X-ray imaging combined with FTIR spectroscopy reveals structural and biomolecular differences in spikelets play a significant role in resistance to Fusarium in wheat.

Lahlali R, Karunakaran C, Wang L, Willick I, Schmidt M, Liu X, Borondics F, Forseille L, Fobert PR, Tanino K, Peng G, Hallin E - BMC Plant Biol. (2015)

Images of diseased and healthy florets in the spikelets of wheat cultivars using phase contrast X-ray imaging at 4 days after inoculation with FHB. The spikelets were kept inside a 18 mm diameter falcon tube and X-ray images were recorded at 18 keV using a 8.75 μm resolution detector. Brackets indicate the imaged part of the wheat spike. Scale bars indicate 1 mm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4340487&req=5

Fig3: Images of diseased and healthy florets in the spikelets of wheat cultivars using phase contrast X-ray imaging at 4 days after inoculation with FHB. The spikelets were kept inside a 18 mm diameter falcon tube and X-ray images were recorded at 18 keV using a 8.75 μm resolution detector. Brackets indicate the imaged part of the wheat spike. Scale bars indicate 1 mm.
Mentions: Synchrotron PCI has the potential to revolutionize the study of physiology and internal biomechanical structures in different plant samples. This non-destructive technique has the spatial and temporal resolution, penetrating power and sensitivity to soft tissue that is required to visualize the internal structure of living plants or animals on the scale from millimeters to microns [43]. In the current study, we have used this technique to compare the structural differences among resistant cultivar Sumai3, tolerant or Canadian resistant germplasm FL62R1, and moderately susceptible cultivar Muchmore. Scanned wheat heads of three cultivars that contain artificially infected and non-infected florets in the same spikelets with FHB at 4 DAI are shown in Figures 2 and 3. Differences in mass densities and phase contrast signals between healthy and infected spikelets were observed. Healthy florets appear in white colors filled with internal structures while infected ones are largely empty and transparent, perhaps due to loss of water and floret tissues. The high X-ray energy (18 keV) and the low resolution detector (8.75 μm) used here are not able to reveal any visible fungal structures such as mycelia of Fusarium graminearum. A total loss of cell viability in infected floret structures such as external and internal epidermis of glumes, and external and internal epidermis of anthers is revealed by the X-ray images (Figure 4). This phenomenon was more pronounced in Muchmore cultivar compared to the other two cultivars. The ovary in an infected Muchmore floret appears to be in a stressed state with the absence of anthers which may be destroyed by the fungus itself, indicating a loss of fertility in the infected spikelets of that cultivar.Figure 2

Bottom Line: The FTIR spectra showed significant variability between infected and non-infected floret and rachis of the wheat cultivars.In the rachis of the wheat cultivars, PCA underlines significant changes in pectin, cellulose, and hemicellulose characteristic absorption spectra.The combined technique is a powerful new tool for internal visualisation and biomolecular monitoring before and during plant-microbe interactions to understand both the differences between cultivars and their different responses to disease stress.

View Article: PubMed Central - PubMed

Affiliation: Canadian Light Source Inc., 44 Innovation Boulevard, Saskatoon, SK, S7N 2V3, Canada. Rachid.Lahlali@lightsource.ca.

ABSTRACT

Background: Fusarium head blight (FHB), a scab principally caused by Fusarium graminearum Schw., is a serious disease of wheat. The purpose of this study is to evaluate the potential of combining synchrotron based phase contrast X-ray imaging (PCI) with Fourier Transform mid infrared (FTIR) spectroscopy to understand the mechanisms of resistance to FHB by resistant wheat cultivars. Our hypothesis is that structural and biochemical differences between resistant and susceptible cultivars play a significant role in developing resistance to FHB.

Results: Synchrotron based PCI images and FTIR absorption spectra (4000-800 cm(-1)) of the floret and rachis from Fusarium-damaged and undamaged spikes of the resistant cultivar 'Sumai3', tolerant cultivar 'FL62R1', and susceptible cultivar 'Muchmore' were collected and analyzed. The PCI images show significant differences between infected and non-infected florets and rachises of different wheat cultivars. However, no pronounced difference between non-inoculated resistant and susceptible cultivar in terms of floret structures could be determined due to the complexity of the internal structures. The FTIR spectra showed significant variability between infected and non-infected floret and rachis of the wheat cultivars. The changes in absorption wavenumbers following pathogenic infection were mostly in the spectral range from 1800-800 cm(-1). The Principal Component Analysis (PCA) was also used to determine the significant chemical changes inside floret and rachis when exposed to the FHB disease stress to understand the plant response mechanism. In the floret and rachis samples, PCA of FTIR spectra revealed differences in cell wall related polysaccharides. In the florets, absorption peaks for Amide I, cellulose, hemicellulose and pectin were affected by the pathogenic fungus. In the rachis of the wheat cultivars, PCA underlines significant changes in pectin, cellulose, and hemicellulose characteristic absorption spectra. Amide II and lignin absorption peaks, persistent in the rachis of Sumai3, together with increased peak shift at 1245 cm(-1) after infection with FHB may be a marker for stress response in which the cell wall compounds related to pathways for lignification are increased.

Conclusions: Synchrotron based PCI combined with FTIR spectroscopy show promising results related to FHB in wheat. The combined technique is a powerful new tool for internal visualisation and biomolecular monitoring before and during plant-microbe interactions to understand both the differences between cultivars and their different responses to disease stress.

No MeSH data available.


Related in: MedlinePlus