By about the third day after the start of imbibition, the sugars in the
endosperm of a germinated barley grain can reach concentrations as high as
400-500 mOsm so the same effect as that shown in Fig. 8.11 A might well
operate. The action of the sugars appears to be osmotic since osmotically active
agents that are not products of starch hydrolysis, e.g., polyethylene glycol and
mannitol, have the same inhibitory action. In wheat embryos, this appears to be
through the inhibition of the high-pi group of isoenzymes (Fig. 8.1 IB) the
mRNA for which is also suppressed. It should be mentioned, however, that in