Cell wall composition throughout development for the model grass Brachypodium distachyon

Abstract

Temperate perennial grasses are important worldwide as a livestock nutritive energy source and a potential feedstock for lignocellulosic biofuel production. The annual temperate grass Brachypodium distachyon has been championed as a useful model system to facilitate biological research in agriculturally important temperate forage grasses based on phylogenetic relationships. To physically corroborate genetic predictions, we determined the chemical composition profiles of organ-specific cell walls throughout the development of two common diploid accessions of Brachypodium distachyon, Bd21-3 and Bd21. Chemical analysis was performed on cell walls isolated from distinct organs (i.e., leaves, sheaths, stems, and roots) at three developmental stages of (1) 12-day seedling, (2) vegetative-to-reproductive transition, and (3) mature seed fill. In addition, we have included cell wall analysis of embryonic callus used for genetic transformations. Composition of cell walls based on components lignin, hydroxycinnamates, uronosyls, neutral sugars, and protein suggests that Brachypodium distachyon is similar chemically to agriculturally important forage grasses. There were modest compositional differences in hydroxycinnamate profiles between accessions Bd21-3 and Bd21. In addition, when compared to agronomical important C3 grasses, more mature Brachypodium stem cell walls have a relative increase in glucose of 48% and a decrease in lignin of 36%. Though differences exist between Brachypodium and agronomical important C3 grasses, Brachypodium distachyon should be still a useful model system for genetic manipulation of cell wall composition to determine the impact upon functional characteristics such as rumen digestibility or energy conversion efficiency for bioenergy production.

Standardization of Switchgrass Sample Collection for Cell Wall and Biomass Trait Analysis

“…Histochemical staining of internodes at various developmental stages (data not shown) indicated that lignin deposition increased with progressive maturity, consistent with the biochemical data. The maturation effect on cell wall composition observed in this study is consistent with reports on other grass species [26,27]. Collectively, the data indicate that these biochemical properties vary among stems at different developmental stages (Fig.…”

Brachypodium: A Monocot Grass Model Genus for Plant Biology

“…In B. distachyon, variations in cell wall components (cellulose, hemi-cellulose, and 376 lignin) have been studied in different organs at the seedling, elongating stem and mature stages. For 377 instance, lignin levels are lowest in the leaf and sheath and higher in the stem, with levels increasing as 378 the plant ages (Rancour et al, 2012;Matos et al, 2013). 379…”

Difference of saccharification yields between organs and growth stages in rice

“…Cell wall composition was also examined in Brachypodium distachyon (Rancour et al 2012). Differing from rice, this grass showed more lignin in stem than in leaf blades.…”

“…However, saccharification yields of each of these three organs in straws have yet to be extensively analyzed. In addition, the composition of cell walls was also reported to be different between plant developmental stages in Brachypodium (Rancour et al 2012). This suggests that a harvesting stage also affects saccharification yields.…”

“…It was reported that cell wall compositions were different between organs in wheat, switchgrass and Brachypodium (Bhandari et al 2013;Rancour et al 2012;Zhang et al 2014). Because cell wall compositions affect saccharification yields, this suggests that saccharification yields are different between organs.…”