Fig 1.
Variation in sorghum stem dry biomass composition in a representative survey of energy and sweet sorghums.
(A) Ratio of dry biomass to fresh biomass of a diverse selection of sorghum internodes at 150 DAE (experiments 1, 2, and 3, see Materials and Methods). (B) NIRS prediction of the percentage of the sorghum stem dry biomass that is composed of soluble and structural molecules of the ESAP in 2012 at 150 DAE (experiment 1). Accessions with (*) were at or past anthesis developmentally. Each bar represents data obtained from five bulked internode segments from ESAP accessions. Soluble and structural compositional data was obtained from the NIRS prediction model. Della and TX08001 stem segments from 150 DAE (experiments 2 and 3), which are the average of nine plants, are included in the figure for comparison.
Fig 2.
Nonstructural carbohydrate profiles of sorghum stems from a selection of representative energy and sweet sorghums as a percentage of the dry biomass of the stem.
Data were obtained from plant material from experiments 1, 2, and 3. ESAP samples were obtained from bulked internode samples of five plants that were harvested at 150 DAE (experiment 1). Data from TX08001 (experiment 2) and Della (experiment 3) were obtained from plants harvested at 150 DAE and 80 DAE respectively and are from 9 biological replicates bulked into three samples. Accessions with (*) were at or past anthesis developmentally. Measurement of sucrose, glucose, fructose and starch was performed in duplicate and MLG assays were performed in triplicate. Error bars represent standard error of the mean.
Fig 3.
Biomass and composition of TX08001 stems and leaves at 120 DAE.
(A) The dry biomass of stems, leaves, and shoots and their components of TX08001 at 120 DAE in 2009 (experiment 2). (B) The percentage of total stem biomass represented by each component as determined by NIRS. (C) Composition differences between TX08001 stem and leaf tissues at 120 DAE. Values indicate the proportion in stem tissue relative to leaf tissue. (*) indicates statistically significant difference (* = α < 0.05, ** = α < 0.01, and *** = α < 0.001) between stems and leaves at 120 DAE. The analysis consisted of 9 biological replicates. Statistics calculated using a t-test. Ex; extractives.
Table 1.
Relative levels, determined from 2D-NMR volume-integrals, of various units in the whole-cell-walls of sweet sorghum Della and the energy sorghum TX08001.
Fig 4.
Monolignol and monolignol hydroxycinnamate conjugate concentrations released from TX08001 and Della stems by DFRC.
Error bars represent standard error of mean. H; 4-hydroxycinnamyl alcohol, G; coniferyl alcohol, S; sinapyl alcohol, G-DHpCA; coniferyl dihydro-p-coumarate, G-DHFA; coniferyl dihydroferulate, S-DHpCA; sinapyl dihydro-p-coumarate, S-DHFA; sinapyl dihydroferulate, all as their diacetates. Data were obtained from two technical replicates of two biological replicates for both TX08001 and Della (experiments 2 and 3).
Fig 5.
Variation in stem biomass and composition of TX08001 during vegetative development.
(A) TX08001 stem biomass components as a percentage of total biomass of TX08001 in 2009 (experiment 2). (B) Composition changes in stem tissue from 90 to 180 DAE of TX08001. Positive values indicate a higher relative percentage in stems at 180 DAE vs. 90 DAE. (*) indicates statistically significant difference (* = α < 0.05, ** = α < 0.01, and *** = α < 0.001) calculated using a t-test, between 90 DAE and 180 DAE component percentages. The analysis consisted of 9 biological replicates. Statistics calculated using a t-test. Ex; extractives.
Fig 6.
Impact of limited irrigation on the biomass and composition of TX08001 stem tissue at 150 DAE.
(A) The difference in dry biomass of irrigated (IRR) and limited irrigation (L-IRR) stems of TX08001 at 150 DAE in 2009 (experiment 2). (B) TX08001 stem biomass components as a percentage of the total composition of irrigated and non-irrigated plants at 150 DAE. (C) Stem composition changes between irrigated and non-irrigated TX08001 at 150 DAE. (*) indicates statistically significant difference (* = α < 0.05, ** = α < 0.01, and *** = α < 0.001) calculated using a t-test, between L-IRR and IRR component percentages. The analysis consisted of 9 biological replicates. Statistics calculated using a t-test. Ex; extractives.