Most of the ethylene produced by seeds is a product of the embryonic axis and not the cotyledons (COR89105). Moist dormant seeds produce low levels of ethylene. In some cases, such as peanut, dormancy has been thought to be due to a low rate of ethylene production (KET72382). Nondormant cocklebur seeds produced four times as much ethylene as dormant ones, though both tissues had similar amounts of ACC. The difference in the rate of ethylene production was due to reduced levels of EFE in dormant seeds. Dormant axial tissue produced less ethylene from ACC than nondormant tissue and higher levels of ACC accumulated in the dormant tissue (SAT83883). The rate of ethylene production increases during germination and seedling growth (COR89105, DUN77561). This makes it difficult to tell if a germination stimulator acts by increasing embryonic ethylene production, or alternatively, if increasing ethylene production is the result of stimulated germination. One way to resolve the question is to show that high levels of externally supplied ethylene mask the effect of the promoter.
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