Constitutive α-amylase activity in dry grass seeds
α -Amylase in grass caryopses (seeds) is usually expressed upon commencement of germination and is rarely seen in dry, mature seeds. However, Goggin and Powles show that selection for low dormancy in Lolium rigidum results in constitutive expression of an aluerone-localized α-amylase activity that is, unexpectedly, responsive to both gibberellin and glucose. This activity appears late during seed development and its presence in dry seeds confers resistance to the germination-inhibiting allelochemical benzoxazolinonenone. The incidental selection for expression of a constitutive, sugar- and hormone-responsive α-amylase activity during selection for low seed dormancy may therefore help to enhance seedling establishment under competitive conditions.
