Storage product synthesis and accumulation in developing grains of wheat

The time course of synthesis and accumulation of the major storage components in developing grain of wheat cv Hereward has been determined. Gluten proteins were first detected at 10 dpa and accumulated most rapidly between 12 and 35 dpa, with little change after 42 dpa. Differences in the accumulation patterns of two different types of ω-gliadins were observed while the synthesis of the HMW subunits was initiated about 2 days later than that of the other gluten proteins. Although protein accumulation had essentially ceased by 42 dpa, grain desiccation was associated with a dramatic increase in the proportion of large glutenin polymers. The accumulation of starch essentially paralleled that of gluten proteins, reaching 55% of the grain dry weight at maturity. This was associated with an increase in the amylose content, from about 20 to 26% of the total starch. The expression patterns of transcripts encoding enzymes of the synthesis (ADP glucose pyrophosphorylase, starch synthases), branching and modification of starch were consistent with the pattern of starch accumulation and with the expression patterns reported for orthologous genes in developing rice grain, showing high conservation between species