Effects of elevated temperature and reduced water uptake on enzymes of starch synthesis in developing wheat grains
1990
Caley, C.Y. | Duffus, C.M. (School of Agriculture, Edinburgh, Scotland (United Kingdom). Dept. of Agricultural Biochemistry) | Jeffcoat, B. (Shell Research Ltd, Sittingbourne (United Kingdom))
Experiments were conducted in pots in growth rooms and under glasshouse conditions. That starch synthase may be a rate-limiting enzyme for accumulation of starch, and hence dry weight, was suggested by: (1) rates are proportionately less in the cultivar with the lower final endosperm dry weight; (2) at elevated temperatures when starch content and dry weight are reduced, starch synthase activity falls; (3) the rate of starch depostion calculated to be possible from measured rates of starch synthase activity is close to the observed rate of starch deposition. On the other hand, it was concluded that it is not lack of starch synthase activity that causes termination of starch deposition, since activity is maintained well after starch deposition has ceased. Using the same 2 wheat cultivars, grown as detached ears in liquid culture, the effects of reduced endosperm water content, induced by the presence of polyethylene glycol in the culture medium, were investigated. Endosperm starch activity was unaffected but ADPglucose pyrophosphorylase activity was greatly reduced, suggesting a possible role in the termination of starch synthesis.
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