Revisiting tree maturation and floral initiation in the poplar functional genomics era

The recent release of the Populus trichocarpa genome sequence will dramatically enhance the efficiency of functional and comparative genomics research in trees. This provides researchers studying various developmental processes related to the perennial and tree life strategies with a completely new set of tools. Intimately associated with the life strategy of trees are their abilities to maintain juvenile or nonflowering phases for years to decades, and once reproductively competent, to alternate between the production of vegetative and reproductive shoots. Most of what we know about the regulation of the floral transition comes from research on Arabidopsis thaliana, a small, herbaceous, rapid-cycling, annual plant. In this review, we discuss the similarities and differences between Arabidopsis and tree flowering, and how recent findings in Arabidopsis, coupled to comparative and functional genomics in poplars, will help answer the question of how tree maturation and floral initiation is regulated.