GREEN-ALGAE TO LAND PLANTS - AN EVOLUTIONARY TRANSITION

Studies focused upon the evolutionary transition from ancestral green algae to the earliest land plants are important from a range of ecolog ical, molecular and evolutionary perspectives. A substantial suite of ultrastructural, biochemical and molecular data supports the concept t hat land plants (embryophytes) are monophyletically derived from an an cestral charophycean alga. However, the details of phylogenetic branch ing patterns linking extant charophytes and seedless embryophytes are currently unclear. Moreover, the fossil record has so far been mute re garding the algae-land plant transition. Nevertheless, an accurate ref lection of major evolutionary events in the history of the earliest la nd plants can be obtained by comparative paleontological-neontological studies, and comparative molecular, cellular and developmental invest igations of extant charophytes and bryophytes. This review focuses upo n research progress toward understanding three clade-specific adaptati ons that were important in the successful colonization of land by plan ts: the histogenetic apical meristem, the matrotrophic embryo, and dec ay-resistant cell wall polymers.