Coadaptation of seed dormancy and hormonal dependence of α-amylase production in endosperm segments of Avena fatua

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Abstract
Autonomous (independent of the germinating embryo) α-amylase production was compared in the endosperm segments of some genetically pure lines of Avena fatua L. (wild oats) differing in the duration of their seed dormancy. Endosperm segments from six randomly taken dormant lines showed no α-amylase production unless gibberellic acid (GA3) was supplied. In contrast, endosperm segments from four out of six nondormant lines produced and released substantial amounts of α -amylase and reducing sugars. Thus, natural selection has resulted in coadaptation of seed dormancy and a rigorous dependence of endosperm hydrolysis on gibberellins produced by the germinating embryo. The variability in the degree of autonomy amongst nondormant lines indicates that the observed coupling of these two traits in dormant lines is not due to simple pleiotropy, but probably reflects the action of multiple genetic loci or multiple alleles. These results also indicate that long-term endosperm stability confers little advantage in wild oat seeds predisposed to brief periods of residence in soil.