Phytohormones and signal transduction pathways in plants

Abstract

Since the divergence of plants and animals about 1.5 billion yr ago, the signal transduction pathways in both kingdoms have been subjected to very different selection pressures. These fundamental differences have influenced the evolution of both the signaling molecules themselves and the mechanisms by which signals are relayed. Among these differences, a plant's ability to continuously form new organs during its postembryonic development, the increased frequency of high degrees of both ploidy and gene duplication in many higher plants, and the multicellular haploid gametophytes of more primitive plants could be particularly significant. Particular developmental processes, such as totipotency (the ability of a plant to regenerate itself from vegetative tissue), have enabled plants to increase their reproductive potential and are consequences of the idiosyncrasies of a plant's cellular signaling mechanisms. © 2005 Humana Press Inc.