Regulation of Storage Protein Synthesis by Sulphur and Nitrogen Nutrition in Cultured Immature Caryopses of Barley

Techniques are described for the culture of developing barley(Hordeum vulgare L.) caryopses. Over a 7 d period in culturethe dry weights and the amounts of starch and protein increasedby at least twofold. Growth was sustained for at least 20 d.The effects of glutamine and cysteine on the amount and compositionof the hordein storage proteins were also studied. Glutaminestimulated total hordein accumulation but caused a disproportionateincrease in the amount of the S-poor ‘C’ hordeinswhen supplied at 100 mol m^–3. Addition of cysteine at1·0 mol m^–3 did not increase the amount of Srich‘B’ hordeins. The results suggest that althoughisolated caryopses are able to take up sucrose and glutamineand convert them to starch and protein there is some limitationin their ability to convert externally supplied cysteine intoproteins. Key words: Hordeum vulgare L., Caryopses, Glutamine, Cysteine, Storage proteins