Effect of different temperature on starch synthase activity in excised grains of wheat cultivars

227-230Excised grains of wheat (Triticum aestivum) varieties HD 2285 (relatively lolerant) and HD 2329 (susceptible type) were incubated for 1 hr at 15°, 25°, 35° and 45°C. In an another treatment, excised grains were incubated for 1 hr at increasing temperature (15°, 25°, 35° and 45°C) continuously, thus exposing the grains to gradual rise in temperature. The above treated grains were then analysed for the activity of soluble starch synthase (SSS) and granule bound starch synthase (GBSS) assayed at 20°C. SSS activity decreased as the pre-exposure temperature was higher, though the tolerant variety showed lesser decrease. Decrease in SSS activity was lesser when excised grains were exposed to gradual rise in temperature from 15° to 45°C as compared to direct exposure to 45°C. Pre-exposure of excised grains to different temperatures however, had no significant effect on GBSS activity