PHYTOCHROME GENE DIVERSITY

The structures and functions of the phytochrome apoprotein genes (the PHY genes), their diversity across the plant kingdom, and their evolut ion are central concerns in the study of red-light sensing in plants, We summarize here recent advances in two areas relating to these topic s: (1) the characteristics of the PHY gene family in Arabinopsis thali ana, the higher plant species for which the most extensive information on these genes is available, and (2) the similarity relationships, ph ylogeny, and evolutionary implications of PHY gene sequences and parti al sequences which have been described from various plants, Together, these two areas of study, one directed at understanding in detail the phytochromes present in a single species and the other directed at a m uch broader understanding of PHY gene relatedness and distribution, ar e producing an increasingly clear picture of the diversity and evoluti on of plant red-light photoreceptors, Moreover, they suggest that the complexity of the phytochrome family has increased as land plants have evolved novel morphologies.