Restoration of Juvenility in Maize Shoots by Meristem Culture

Abstract

Shoot-apex culture in maize (Zea mays L.), which results in the formation of an entire new shoot by the cultured meristem, was used to examine phase change. In phase change, patterns of differentiation of leaves, axillary buds, and nodes change in a coordinated manner as the plant matures from a juvenile to an adult. The culturing of meristems from adult-phase plants restored the ability of the plant to form leaves with juvenile traits, including having epicuticular wax, a thin cuticle, violet staining with toluidine blue, and round epidermal cells. Although shoots from cultured apices had a few extra nodes compared to seed-derived plants, the upper, adult-like portion of the culture-derived shoots were identical to the adult region of normal maize plants in such traits as position of ear shoot, size and shape of leaves, and the presence of trichomes on leaves. These results support the conclusion that phase-specific patterns of differentiation in the shoot are the result of signaling throughout the plant and not the age of the meristem.