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Sorghum mutant RG displays antithetic leaf shoot lignin accumulation resulting in improved stem saccharification properties.

Petti C, Harman-Ware AE, Tateno M, Kushwaha R, Shearer A, Downie AB, Crocker M, Debolt S - Biotechnol Biofuels (2013)

Bottom Line: Reduced lignin was linked to improved saccharification in RG stems, but a chemical shift to greater S:G ratios in RG stem lignin was also observed.Antithetic lignin accumulation was observed in the RG mutant leaf-and stem-tissue, which resulted in greater saccharification efficiency in the RG stem and differential thermochemical product yield in high lignin leaves.Thus, the red leaf coloration of the RG mutant represents a potential marker for improved conversion of stem cellulose to fermentable sugars in the C4 grass Sorghum.

View Article: PubMed Central - HTML - PubMed

Affiliation: Plant Physiology, Department of Horticulture, Agricultural Science Center North, University of Kentucky, Lexington, KY 40546, USA. sdebo2@uky.edu.

ABSTRACT

Background: Improving saccharification efficiency in bioenergy crop species remains an important challenge. Here, we report the characterization of a Sorghum (Sorghum bicolor L.) mutant, named REDforGREEN (RG), as a bioenergy feedstock.

Results: It was found that RG displayed increased accumulation of lignin in leaves and depletion in the stems, antithetic to the trend observed in wild type. Consistent with these measurements, the RG leaf tissue displayed reduced saccharification efficiency whereas the stem saccharification efficiency increased relative to wild type. Reduced lignin was linked to improved saccharification in RG stems, but a chemical shift to greater S:G ratios in RG stem lignin was also observed. Similarities in cellulose content and structure by XRD-analysis support the correlation between increased saccharification properties and reduced lignin instead of changes in the cellulose composition and/or structure.

Conclusion: Antithetic lignin accumulation was observed in the RG mutant leaf-and stem-tissue, which resulted in greater saccharification efficiency in the RG stem and differential thermochemical product yield in high lignin leaves. Thus, the red leaf coloration of the RG mutant represents a potential marker for improved conversion of stem cellulose to fermentable sugars in the C4 grass Sorghum.

No MeSH data available.


Related in: MedlinePlus

Internode and node assessment. The length of the internode was compared between RG and wild type (n = 25) (A). Histograms display the distribution of internode lengths for each genotype (B, RG; C, WT). The average number of nodes per stems (D). Error bars in all figures are standard error from the mean. Significance (P < 0.05) is indicated by a star (★). Visually, the node and internodes are depicted in (E). Scale bar = 3.5 cm.
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Figure 2: Internode and node assessment. The length of the internode was compared between RG and wild type (n = 25) (A). Histograms display the distribution of internode lengths for each genotype (B, RG; C, WT). The average number of nodes per stems (D). Error bars in all figures are standard error from the mean. Significance (P < 0.05) is indicated by a star (★). Visually, the node and internodes are depicted in (E). Scale bar = 3.5 cm.

Mentions: The RG mutant was phenotypically identified by a marked accumulation of red/purple pigments in the leaf blades (Figure 1A). This trait was characterized as leaf-specific and it evolved in a basipetal manner, from the tip of the leaf to the base and further to the leaf sheath (Figure 1A). The initial evaluation was completed in a temperature-controlled glasshouse and all leaves, in a progressive manner, manifested the phenotype thus resulting in a notable red/purple plant (Figure 1). To explore the mature RG plant phenotype outside the greenhouse, a field performance trial was established over two growing seasons. RG displayed a reduction in maximum height, compared with wild type. Results showed an average decrement of 37% (P < 0.0001, Mann–Whitney) during the first year and 40% (P < 0.0001, Mann–Whitney) for the second year (Figure 1B, C, D). Reduction in height could arise in association with three phenotypes: 1) reduced internodal length, 2) fewer nodes initiated during the life cycle or 3) both fewer internodes of a shorter length. A large internodal length decrease was calculated for the RG mutant as compared to the wild type (Figure 2A and E, P < 0.0001). Notably, the number of nodes was significantly greater in RG versus wild type (Figure 2D, E; P < 0.0001) but this could not compensate for the shorter internode length for RG, resulting in shorter plants. Additionally, the frequency distributions of internode lengths between the two genotypes indicated that the RG mutant is skewed toward shorter internodes relative to a more normal distribution of overall longer lengths in WT (Figure 2B and C). Leaf length and width was also estimated but was not significantly different (Data not shown). Further, it was found that the average seed weight (1000 seeds weight, with replication) was not different between RG and the wild type (RG, 1.80 ± 0.04; WT, 1.85 ± 0.03), which was consistent with no visible change in the RG inflorescence. Moreover, no changes in the nature and the extent of bran pigmentation, brown for Della variety, were observed.


Sorghum mutant RG displays antithetic leaf shoot lignin accumulation resulting in improved stem saccharification properties.

Petti C, Harman-Ware AE, Tateno M, Kushwaha R, Shearer A, Downie AB, Crocker M, Debolt S - Biotechnol Biofuels (2013)

Internode and node assessment. The length of the internode was compared between RG and wild type (n = 25) (A). Histograms display the distribution of internode lengths for each genotype (B, RG; C, WT). The average number of nodes per stems (D). Error bars in all figures are standard error from the mean. Significance (P < 0.05) is indicated by a star (★). Visually, the node and internodes are depicted in (E). Scale bar = 3.5 cm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3852544&req=5

Figure 2: Internode and node assessment. The length of the internode was compared between RG and wild type (n = 25) (A). Histograms display the distribution of internode lengths for each genotype (B, RG; C, WT). The average number of nodes per stems (D). Error bars in all figures are standard error from the mean. Significance (P < 0.05) is indicated by a star (★). Visually, the node and internodes are depicted in (E). Scale bar = 3.5 cm.
Mentions: The RG mutant was phenotypically identified by a marked accumulation of red/purple pigments in the leaf blades (Figure 1A). This trait was characterized as leaf-specific and it evolved in a basipetal manner, from the tip of the leaf to the base and further to the leaf sheath (Figure 1A). The initial evaluation was completed in a temperature-controlled glasshouse and all leaves, in a progressive manner, manifested the phenotype thus resulting in a notable red/purple plant (Figure 1). To explore the mature RG plant phenotype outside the greenhouse, a field performance trial was established over two growing seasons. RG displayed a reduction in maximum height, compared with wild type. Results showed an average decrement of 37% (P < 0.0001, Mann–Whitney) during the first year and 40% (P < 0.0001, Mann–Whitney) for the second year (Figure 1B, C, D). Reduction in height could arise in association with three phenotypes: 1) reduced internodal length, 2) fewer nodes initiated during the life cycle or 3) both fewer internodes of a shorter length. A large internodal length decrease was calculated for the RG mutant as compared to the wild type (Figure 2A and E, P < 0.0001). Notably, the number of nodes was significantly greater in RG versus wild type (Figure 2D, E; P < 0.0001) but this could not compensate for the shorter internode length for RG, resulting in shorter plants. Additionally, the frequency distributions of internode lengths between the two genotypes indicated that the RG mutant is skewed toward shorter internodes relative to a more normal distribution of overall longer lengths in WT (Figure 2B and C). Leaf length and width was also estimated but was not significantly different (Data not shown). Further, it was found that the average seed weight (1000 seeds weight, with replication) was not different between RG and the wild type (RG, 1.80 ± 0.04; WT, 1.85 ± 0.03), which was consistent with no visible change in the RG inflorescence. Moreover, no changes in the nature and the extent of bran pigmentation, brown for Della variety, were observed.

Bottom Line: Reduced lignin was linked to improved saccharification in RG stems, but a chemical shift to greater S:G ratios in RG stem lignin was also observed.Antithetic lignin accumulation was observed in the RG mutant leaf-and stem-tissue, which resulted in greater saccharification efficiency in the RG stem and differential thermochemical product yield in high lignin leaves.Thus, the red leaf coloration of the RG mutant represents a potential marker for improved conversion of stem cellulose to fermentable sugars in the C4 grass Sorghum.

View Article: PubMed Central - HTML - PubMed

Affiliation: Plant Physiology, Department of Horticulture, Agricultural Science Center North, University of Kentucky, Lexington, KY 40546, USA. sdebo2@uky.edu.

ABSTRACT

Background: Improving saccharification efficiency in bioenergy crop species remains an important challenge. Here, we report the characterization of a Sorghum (Sorghum bicolor L.) mutant, named REDforGREEN (RG), as a bioenergy feedstock.

Results: It was found that RG displayed increased accumulation of lignin in leaves and depletion in the stems, antithetic to the trend observed in wild type. Consistent with these measurements, the RG leaf tissue displayed reduced saccharification efficiency whereas the stem saccharification efficiency increased relative to wild type. Reduced lignin was linked to improved saccharification in RG stems, but a chemical shift to greater S:G ratios in RG stem lignin was also observed. Similarities in cellulose content and structure by XRD-analysis support the correlation between increased saccharification properties and reduced lignin instead of changes in the cellulose composition and/or structure.

Conclusion: Antithetic lignin accumulation was observed in the RG mutant leaf-and stem-tissue, which resulted in greater saccharification efficiency in the RG stem and differential thermochemical product yield in high lignin leaves. Thus, the red leaf coloration of the RG mutant represents a potential marker for improved conversion of stem cellulose to fermentable sugars in the C4 grass Sorghum.

No MeSH data available.


Related in: MedlinePlus