Cellulose, xylan, uronic acid, acetyl groups, cellulose/xylan and cellulose/lignin in RB867515 (RB) and <i>S</i>. <i>spontaneum</i> (AG) internodes.

<p>Means followed by different letters differ significantly between internodes (Tukey test, p<0.05). Asterisks indicate a significant difference between the genotypes for the same internode (t-test, p<0.05), (n = 3).</p><p>Cellulose, xylan, uronic acid, acetyl groups, cellulose/xylan and cellulose/lignin in RB867515 (RB) and <i>S</i>. <i>spontaneum</i> (AG) internodes.</p

Interactions between cell wall compounds and ethanol production.

<p>Scatterplot representing all internodes analyzed of <i>S</i>. <i>spontaneum</i> (AG) and RB867515 (RB). Ethanol is shown as a function of (A) S/G, (B) acid insoluble lignin, (C) xylans, (D) acetyl groups, (E) total lignin, (F) ester ferulate, (G) ester caffeate, (H) ester <i>p</i>-coumarate, (I) ether ferulate, (J) ether caffeate, (K) cellulose. The Pearson correlation coefficient and its corresponding <i>p</i> value are shown at the top of each graph.</p

2D NMR spectra revealing lignin unit composition.

<p><b>Partial short-range</b>^<b>1</b><b>H–</b>^<b>13</b><b>C(HSQC) correlation spectra (aromatic regions).</b> A) RB867515 (RB) internode 2, B) RB internode 5, C) RB internode 9, D) <i>S</i>. <i>spontaneum</i> (AG) internode 2, E) AG internode 5, F) AG internode 9. S = syringyl, G = guaiacyl, H = <i>p</i>-hydroxyphenyl, <i>P</i>CA = <i>p-</i>coumarate, FA = ferulate.</p

Lignin content of dry cell wall from RB867515 (RB) and <i>S</i>. <i>Spontaneum</i> (AG) internodes throughout development.

<p>(A) total lignin (%) in internodes (IN2, IN4, IN5, IN9) from RB867515 (grey bars) and <i>S</i>. <i>spontaneum</i> (white bars). (B) acid insoluble lignin (%) in internodes (IN2, IN4, IN5, IN9) from RB867515 (grey bars) and <i>S</i>. <i>spontaneum</i> (white bars). Bars with common letters were not significantly different (Tukey test, p<0.05). Asterisks indicate a significant difference (t-test, p<0.05) between same internode. Error bars indicate SE of technical replicates of a pool of biological samples (n = 3).</p

Micromorphometric analysis of internode 5 from cultivar RB867515 (RB) and <i>S</i>. <i>spontaneum</i> (AG).

<p>Values are mean and standard error (n = 5). Asterisks indicate a significant difference between the genotypes (t-test, p<0.05).</p><p>Micromorphometric analysis of internode 5 from cultivar RB867515 (RB) and <i>S</i>. <i>spontaneum</i> (AG).</p

Maüle staining of internode transverse sections observed by light microscopy using cross-polarizing optics.

<p>Transverse sections of cultivar RB867515 and <i>S</i>. <i>spontaneum</i> Second internode (A, B and C, D), 4^th internode (E, F and G, H), 5^th internode (I, J and K, L) and 9^th internode (M, N and O, P). Red staining indicates the presence of syringyl residues in the plant secondary cell wall. Detail of the vascular bundle of the central region of the second internode (B, D), 4^th internode (F, H), 5^th internode (J,L), 9^th internode (N, P). Photographs are representative of at least six samples. Rind and pith indicate their positions in the sections. E: epidermal cells, Fi: fiber, Ph: phloem, CP: cortical parenchyma, Pp: pith parenchyma, Mx: metaxylem, Px: protoxylem. Scale bar = 50 μm.</p

Abundance of total, esterified and etherified phenols in <i>S</i>. <i>spontaneum</i> (AG) and RB867515 (RB) through culm development.

<p>Data are means of relative quantification of total, ester-bound and ether-bound phenolic from CWD material. Values are given relative to the abundance in IN2 of RB. Means followed by different letters differ significantly between internodes (Tukey test, p<0.05). Asterisks indicate a significant difference between genotypes for the same internode (t-test, p<0.05), (n = 3). IN2: internode 2, IN4: internode 4, IN5: internode 5 and IN9: internode 9.</p><p>Abundance of total, esterified and etherified phenols in <i>S</i>. <i>spontaneum</i> (AG) and RB867515 (RB) through culm development.</p

Wiesner staining (phloroglucinol-HCl) of transverse sections of internodes in distantly related sugarcane genotypes.

<p>Transverse sections of-cultivar RB867515 and <i>S</i>. <i>spontaneum</i>. Second internode (A, B and C, D), 4^th internode (E, F and G, H), 5^th internode (I, J and K, L) and 9^th internode (M, N and O, P). Detail of the vascular bundle of the central region of the second internode(B, D), 4^th internode (F, H), 5^th internode (J,L), 9^th internode (N, P). Photographs are representative of at least six samples. The labels “Rind” and “pith” indicate their positions in the sections. E: epidermal cells, Fi: fiber, Ph: phloem, CP: cortical parenchyma, Pp: pith parenchyma, Mx: metaxylem, Px: protoxylem. Scale bar = 50 μm.</p

Enzymatic hydrolysis and fermentation.

<p>A) Sugar release efficiency (%) in RB867517 and <i>S</i>. <i>spontaneum</i> in different stages of culm development B) conversion of cellulose to ethanol (%) in RB867517 and <i>S</i>. <i>spontaneum</i> in different stages of culm development C) g ethanol/ g glucose ratio in RB867517 and <i>S</i>. <i>spontaneum</i> in different stages of culm development. Values are mean and standard error (n = 3). Black bars–<i>S</i>. <i>spontaneum</i> (AG), grey bars–RB867515 (RB). Bars with common letters were not significantly different (Tukey test, p<0.05). Asterisks indicate a significant difference (t-test, p<0.05) between the same internodes of the two plants studied. Error bars indicate SE of three biological replicates (n = 3). IN2: internode 2, IN4: internode 4, IN5: internode 5, IN9: internode 9.</p

Interactions between cell wall compounds and sugar release efficiency.

<p>Scatterplots representing all internodes analyzed of <i>S</i>. <i>spontaneum</i> (AG) and RB867515 (RB). Sugar release efficiency is shown as a function of (A) S/G ratio, (B) acid insoluble lignin, (C) xylans, (D) acetyl groups, (E) total lignin, (F) ester ferulate, (G) ester caffeate, (H) ester <i>p</i>-coumarate, (I) ether ferulate, (J) ether caffeate, (K) cellulose. The Pearson correlation coefficient and its corresponding <i>p</i> value are shown at the top of each graph.</p