Comparison of cell wall composition across 15 ecotypes of Brachypodium distachyon originating from the eastern and western Mediterranean

Lignocellulose composition (lignin, ester and ether bound ferulic and p-coumaric acids, hemicellulose and crystalline cellulose) was characterised in ground cell wall preparations from samples of leaf and stem taken from 15 interbred ecotypes of Brachypodium distachyon of Spanish (S) or Turkish (T) origin that were grown in glass house conditions in Aberystwyth in July and August 2012. Significant differences were detected between geographic region for mean lignin concentration in stem (means of 11.35 and 13.75% DW CW (cell wall); s.e.d. 0.69; P=0.004) and leaf (means of 8.12 and 9.09% DW CW ; s.e.d. 0.22; P<0.001) for S and T ecotypes respectively. Significant differences were also detected between geographic regions for the mean cellulose concentration in leaf (means of 17.84 and 11.47 % DW CW) and stem (means of 22.13 and 15.16 % DW CW; s.e.d 1.79; P<0.001) for S and T ecotypes respectively. Analysis of cell wall bound p-coumaric acid and ferulic acid, or hemicellulose did not detect differences between geographic region of origin. These data suggest important differences in cell wall composition between ecotypes from opposite ends of the Mediterranean that may relate to selection by differential environmental conditions or genetic drift between the two regions. Perhaps more importantly, from the perspective of using Brachypodium distachyon as a genetic grass model, it appears that quite distinct cell wall parameters may be selected e.g. high or low lignin or cellulose, that suit particular studies with the aim of manipulating cell wall composition.