Abstract:

The conversion from sucrose to starch in grains is a key process during yield formation of wheat. In a field study, diurnal changes in ATP content and activities of enzymes catalyzing starch synthesis in grains of two winter wheat (Triticum aestivum L.) cv. Lumai 22 and Lumai 14 were investigated. The enzymes included sucrose synthase (SS; EC 2.4.1.13), ADP-glucose pyrophosphorylase (ADPGPPase; EC 2.7.7.27), soluble starch synthase (SSS), and starch granule-bound synthase (GBSS; EC 2.4.1.21). Activities of these enzymes and ATP content showed obvious diurnal patterns. The enzyme activities were generally higher during the nighttime than the daytime, but ATP content showed an opposite pattern. It was found that the super-optimum air temperature could be partly responsible for the low enzyme activities during the daytime. The possible factors influenced the diurnal changes in activities of the enzymes for starch synthesis in wheat grain were discussed.

Key words: winter wheat (Triticum aestivum), diurnal change, starch synthesis, enzyme activity