Gibberellic Acid-induced Structural Alterations in the Endosperm of Germinating Lactuca sativa L. Achenes

Summary Exogenously applied gibberellic acid induces structural alterations in the micropylar region of the endosperm in Grand Rapids lettuce ( Lactuca sativa L.) achenes prior to radicle protrusion. Besides the pattern of storage material degradation and vacuole formation, both timing and localization of endosperm alterations are similar to the previously reported phytochrome-mediated ones. These data favor the concept that gibberellic acid and phytochrome promote lettuce achene germination, at least in the later stages, through a similar channel.