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Relative crystallinity of plant biomass: studies on assembly, adaptation and acclimation.

Harris D, DeBolt S - PLoS ONE (2008)

Bottom Line: Within this study, RCI correlated positively with leaf geometric constraints and with mass per unit area, suggestive of allometry.Further, in etiolated pea hypocotyls, RCI values also decreased compared to plants that were grown in light, consistent with alterations in FTIR cellulose fingerprint peaks and live cell imaging experiments revealing rapid orientation of the YFP::cellulose synthase-6 array in response to light.Herein, results and technical challenges associated with the structure of the cell wall that gives rise to sample crystallinity are presented and examined with respect to adaptation, acclimation and assembly in ecosystem-level processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Horticulture, University of Kentucky, Lexington, Kentucky, United States of America.

ABSTRACT
Plant biomechanical design is central to cell shape, morphogenesis, reproductive performance and protection against environmental and mechanical stress. The cell wall forms the central load bearing support structure for plant design, yet a mechanistic understanding of its synthesis is incomplete. A key tool for studying the structure of cellulose polymorphs has been x-ray diffraction and fourier transform infrared spectroscopy (FTIR). Relative crystallinity index (RCI) is based on the x-ray diffraction characteristics of two signature peaks and we used this technique to probe plant assembly, adaptation and acclimation. Confocal microscopy was used to visualize the dynamics of cellulose synthase in transgenic Arabidopsis plants expressing a homozygous YFP::CESA6. Assembly: RCI values for stems and roots were indistinguishable but leaves had 23.4 and 21.6% lower RCI than stems and roots respectively. Adaptation: over 3-fold variability in RCI was apparent in leaves from 35 plant species spanning Ordovician to Cretaceous periods. Within this study, RCI correlated positively with leaf geometric constraints and with mass per unit area, suggestive of allometry. Acclimation: biomass crystallinity was found to decrease under conditions of thigmomorphogenesis in Arabidopsis. Further, in etiolated pea hypocotyls, RCI values also decreased compared to plants that were grown in light, consistent with alterations in FTIR cellulose fingerprint peaks and live cell imaging experiments revealing rapid orientation of the YFP::cellulose synthase-6 array in response to light. Herein, results and technical challenges associated with the structure of the cell wall that gives rise to sample crystallinity are presented and examined with respect to adaptation, acclimation and assembly in ecosystem-level processes.

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Hypocotyls lengths and RCI of etiolated pea (Pistum sativum) seedlings compared with light grown seedlings were significantly different.(A) Histogram of hypocotyl length for light grown and (B) dark grown. Dark grown hypocotyls had a significantly lower RCI that light grown (C) (*P<0.001 ANOVA). (D) Arabidopsis plants expressing YFP::CESA6 displayed a transverse orientation under dark conditions and longitudinal array under light conditions, images are time averages of 61 frames taken 10 sec apart for 10 min. Maximal linear trajectories particles was 14.66 mm for dark and 26.8 mm for light grown. Scale bar = 10 mm (E) FTIR spectral variance plot of light versus dark grown pea plant samples.
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pone-0002897-g003: Hypocotyls lengths and RCI of etiolated pea (Pistum sativum) seedlings compared with light grown seedlings were significantly different.(A) Histogram of hypocotyl length for light grown and (B) dark grown. Dark grown hypocotyls had a significantly lower RCI that light grown (C) (*P<0.001 ANOVA). (D) Arabidopsis plants expressing YFP::CESA6 displayed a transverse orientation under dark conditions and longitudinal array under light conditions, images are time averages of 61 frames taken 10 sec apart for 10 min. Maximal linear trajectories particles was 14.66 mm for dark and 26.8 mm for light grown. Scale bar = 10 mm (E) FTIR spectral variance plot of light versus dark grown pea plant samples.

Mentions: Dark-grown versus light grown seedlings invest a greater proportion of cellular energy into seeking light (elongation) and maximizing, capturing and transmitting light [31]. Shade conditions have also been shown to increase Young's modulus in petioles resulting in greater tensile strength [32]. Because the plant modified its body plan under dark growing conditions, this provided an opportunity to test whether RCI changed. Seven day old, dark-grown etiolated pea (Pisum sativum) seedlings displayed no pigmentation of hypocotyls and the tissue geometry and morphology were perpendicular to the growth media horizontal surface. Seedling heights were variable as demonstrated by the average height frequency graph (Figure 3A and 3B). The average height of dark-grown seedlings (9.5±2.8 cm) was significantly greater than light-grown seedlings (3.7±1.2 cm P<0.001, Wilcoxan Ranked Signed Test). Leaf and root tissue was separated and discarded and light and dark-grown hypocotyls were then oven dried, pressed and packed into boric acid for analysis by XRD. The corresponding RCI measurement of dark grown hypocotyls was 23.07±1.54% (n = 3) with an estimated experimental accuracy of 2.07 (total was 3.61 or 15.64%). Based on sample replicates, this value was significantly lower (P<0.05 ANOVA) than measurements made in light grown hypocotyls 26.86±1.17%, however considering the level of experimental accuracy measured using a scan of the sample (Figure 1B), the determination of significance was not substantiated (Figure 1C and D, Figure 3C, Table 1).


Relative crystallinity of plant biomass: studies on assembly, adaptation and acclimation.

Harris D, DeBolt S - PLoS ONE (2008)

Hypocotyls lengths and RCI of etiolated pea (Pistum sativum) seedlings compared with light grown seedlings were significantly different.(A) Histogram of hypocotyl length for light grown and (B) dark grown. Dark grown hypocotyls had a significantly lower RCI that light grown (C) (*P<0.001 ANOVA). (D) Arabidopsis plants expressing YFP::CESA6 displayed a transverse orientation under dark conditions and longitudinal array under light conditions, images are time averages of 61 frames taken 10 sec apart for 10 min. Maximal linear trajectories particles was 14.66 mm for dark and 26.8 mm for light grown. Scale bar = 10 mm (E) FTIR spectral variance plot of light versus dark grown pea plant samples.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2483349&req=5

pone-0002897-g003: Hypocotyls lengths and RCI of etiolated pea (Pistum sativum) seedlings compared with light grown seedlings were significantly different.(A) Histogram of hypocotyl length for light grown and (B) dark grown. Dark grown hypocotyls had a significantly lower RCI that light grown (C) (*P<0.001 ANOVA). (D) Arabidopsis plants expressing YFP::CESA6 displayed a transverse orientation under dark conditions and longitudinal array under light conditions, images are time averages of 61 frames taken 10 sec apart for 10 min. Maximal linear trajectories particles was 14.66 mm for dark and 26.8 mm for light grown. Scale bar = 10 mm (E) FTIR spectral variance plot of light versus dark grown pea plant samples.
Mentions: Dark-grown versus light grown seedlings invest a greater proportion of cellular energy into seeking light (elongation) and maximizing, capturing and transmitting light [31]. Shade conditions have also been shown to increase Young's modulus in petioles resulting in greater tensile strength [32]. Because the plant modified its body plan under dark growing conditions, this provided an opportunity to test whether RCI changed. Seven day old, dark-grown etiolated pea (Pisum sativum) seedlings displayed no pigmentation of hypocotyls and the tissue geometry and morphology were perpendicular to the growth media horizontal surface. Seedling heights were variable as demonstrated by the average height frequency graph (Figure 3A and 3B). The average height of dark-grown seedlings (9.5±2.8 cm) was significantly greater than light-grown seedlings (3.7±1.2 cm P<0.001, Wilcoxan Ranked Signed Test). Leaf and root tissue was separated and discarded and light and dark-grown hypocotyls were then oven dried, pressed and packed into boric acid for analysis by XRD. The corresponding RCI measurement of dark grown hypocotyls was 23.07±1.54% (n = 3) with an estimated experimental accuracy of 2.07 (total was 3.61 or 15.64%). Based on sample replicates, this value was significantly lower (P<0.05 ANOVA) than measurements made in light grown hypocotyls 26.86±1.17%, however considering the level of experimental accuracy measured using a scan of the sample (Figure 1B), the determination of significance was not substantiated (Figure 1C and D, Figure 3C, Table 1).

Bottom Line: Within this study, RCI correlated positively with leaf geometric constraints and with mass per unit area, suggestive of allometry.Further, in etiolated pea hypocotyls, RCI values also decreased compared to plants that were grown in light, consistent with alterations in FTIR cellulose fingerprint peaks and live cell imaging experiments revealing rapid orientation of the YFP::cellulose synthase-6 array in response to light.Herein, results and technical challenges associated with the structure of the cell wall that gives rise to sample crystallinity are presented and examined with respect to adaptation, acclimation and assembly in ecosystem-level processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Horticulture, University of Kentucky, Lexington, Kentucky, United States of America.

ABSTRACT
Plant biomechanical design is central to cell shape, morphogenesis, reproductive performance and protection against environmental and mechanical stress. The cell wall forms the central load bearing support structure for plant design, yet a mechanistic understanding of its synthesis is incomplete. A key tool for studying the structure of cellulose polymorphs has been x-ray diffraction and fourier transform infrared spectroscopy (FTIR). Relative crystallinity index (RCI) is based on the x-ray diffraction characteristics of two signature peaks and we used this technique to probe plant assembly, adaptation and acclimation. Confocal microscopy was used to visualize the dynamics of cellulose synthase in transgenic Arabidopsis plants expressing a homozygous YFP::CESA6. Assembly: RCI values for stems and roots were indistinguishable but leaves had 23.4 and 21.6% lower RCI than stems and roots respectively. Adaptation: over 3-fold variability in RCI was apparent in leaves from 35 plant species spanning Ordovician to Cretaceous periods. Within this study, RCI correlated positively with leaf geometric constraints and with mass per unit area, suggestive of allometry. Acclimation: biomass crystallinity was found to decrease under conditions of thigmomorphogenesis in Arabidopsis. Further, in etiolated pea hypocotyls, RCI values also decreased compared to plants that were grown in light, consistent with alterations in FTIR cellulose fingerprint peaks and live cell imaging experiments revealing rapid orientation of the YFP::cellulose synthase-6 array in response to light. Herein, results and technical challenges associated with the structure of the cell wall that gives rise to sample crystallinity are presented and examined with respect to adaptation, acclimation and assembly in ecosystem-level processes.

Show MeSH
Related in: MedlinePlus