Table 1.
Levels of (1,3;1,4)-β-glucans in grains of various grass species.
| Species | (1,3;1,4)-β-glucan | DP3:DP4 | Solubility | Starch |
|---|---|---|---|---|
| (% w/w) | ratio | in water (%) | (% w/w) | |
| Oats | 6–8 | 1.5–2.3:1 | ~80 | ~60 |
| Barley | 4–10 | 2.6:1 | ~20 | ~57 |
| Wheat | 1 | 3.2:1 | 0 | ~57 |
| Brachypodium | 40 | 5.9:1 | Insoluble | <10 |
| Rice | <0.06 | 1:1.4 | ? | 80 |
| Maize | Trace | 2.5:1 | ? | 70–80 |
| Sorghum | 0.07–0.2 | 2.8:1 | ? | 70–80 |
| Transgenic barley | 7.8 | 2.1 | ? | 44 |
| (AsGlo:CslF6) | ||||
| Transgenic barley | 6.0 | 2.8:1 | ? | ? |
| (AsGlo:CslF4) |
Only trace amounts can be detected in rice, maize, and sorghum grain, but in Brachypodium (1,3;1,4)-β-glucans constitute up to 40% (w/w) of the grain. The link between DP3:DP4 ratios and polysaccharide solubility can also be seen. At the relatively low ratios observed in the oat grain (1,3;1,4)-β-glucans, the polysaccharide is more soluble than it is in the other grains, where higher DP3:DP4 ratios are observed. The values shown for the barley AsGlo:CslF lines were obtained from grain of transgenic barley transformed with the CslF genes as described by Burton et al. (2011).