Flowering and flowering genes: from model plants to orchids

Abstract

Floral transition in model plants including Arabidopsis and rice has been studied extensively through molecular genetic approaches. Many genetic factors in different flowering pathways, which depend mainly on photoperiod, vernalization, autonomous and ambient temperature are regulated coordinately to control floral induction. However, for the ornamental plants orchids, the molecular mechanisms underlying the floral transition are still unclear. Recently, genes with potential flowering-related functions have been identified in different orchid species and their functional roles have also been characterized/examined using homologous or heterologous systems. In this review, we summarize the molecular networks of flowering genes and their regulation as revealed in model plants such as Arabidopsis and rice, and also describe the recent discoveries/studies on flowering genes in several commercially representative orchid species providing a perspective on orchid flowering research. In addition, our recent results through transgenic approaches with ectopic expression of Hd3a, a rice florigen gene for the induction of precocious flowering in Phalaenopsis orchids are also discussed.