ABSTRACT
I. INTRODUCTION Orchids are a globally important flower crop. It has been estimated that in the year 2000 there was a worldwide demand of 1600 million units of planting material, and the majority of this was produced by the tissue culture method and used for mass cultivation in Southeast Asian countries [1]. To date, clonal propagation of orchids has been extended to more than 43 genera [2]. Moreover, the physiology of some orchid species in Cymbidium, Dendrobium, Phalaenopsis, and Oncidium has been studied intensively over the past decades, and this has led to the establishment of recommendations for flower induction and storage [2]. Despite the advances made in these areas, numerous questions related to flower production remain to be investigated. Examples are how to increase harvestable flower yield, how to control flowering to meet market demand, how to prolong the vase life of cut flowers, and how to enhance their aesthetic properties such as color and architecture. Such questions can be addressed with a better understanding of the genetic factors affecting such physiological processes including flower production and development, flowering time, senescence, and pigmentation. Careful examination of the orchid literature published over the past decade, particularly from a survey of the molecular database, indicates that researchers are beginning to reveal genes closely associated with these processes (Table 1) and are poised to make further progress in the next few years. In this chapter, we describe what is known to date about these orchid genes in relation to our current knowledge of their counterparts in other plant systems. It is hoped that this chapter will stimulate interest in further investigation of these and other genes associated with the biology of the orchid flower.
