Arabinoxylan is enriched in those grass cell walls (Sampedro et al. 2015).
Our understanding of the grass cell wall has significantly improved in the past two decades through studies carried out primarily in maize (Zea mays).
Additionally, putative α-rhamnosidases (GH78) were enriched in the SAC and rumen communities relative to the drywood-eating termite hindgut microbiome, although the main rhamnose-containing heteropolysaccharide, pectin, is more prevalent in dicot cell walls than grass cell walls [10].
We obtained 225 Mbp of 454-titanium pyrosequence data from the SAC community and conservatively identified 800 genes encoding glycoside hydrolase domains that were biased toward depolymerizing grass cell wall components.
The group-1 allergens from maize pollen, collectively known as Zea m 1, are highly abundant glycoproteins, constituting ∼4% of the protein extracted from pollen; they are rapidly secreted upon pollen hydration and have wall-loosening activity specific for grass cell walls [12], [19].
Grass cell walls typically contain less pectin than their dicot counterparts (Caffall and Mohnen, 2009; Vogel, 2008).
Both of these grass cell wall components are potential targets of β-expansins in their wall-loosening activity [ 82].
The clear separation between eudicot and grass sequences likely reflects the differing architectures of eudicot and grass cell walls, underscoring the need for a grass model.
This was attributed to both the higher glucan content of grass cell walls and the greater enzymatic conversion efficiency of grass biomass.
Clearly, further work is warranted to reveal the exact structural nature of the rapidly and slowly degraded pools in grass cell walls.
