ABSTRACT
Plants are a separate kingdom: they have evolved their multicellular organization independently of animals. For their development too, a unified account can be given, but it is different from that for animals. The four essential processes by which a multicellular organism is made: cell proliferation, cell specialization, cell interaction, and cell movement. Comparison of animal genomes with that of budding yeast, a unicellular eukaryote suggests that two classes of proteins are especially important for multicellular organization. The first class is that of the transmembrane molecules used for cell adhesion and cell signaling. The second class is that of gene regulatory proteins: these DNA-binding proteins are much more numerous in the C. elegans genome than in yeast. Plants and animals are separated by about 1.5 billion years of evolutionary history. They have evolved their multicellular organization independently but using the same initial tool kitthe set of genes inherited from their common unicellular eucaryotic ancestor.
