Reproductive Biology of

Editors K.G. Ramawat Former Professor & Head Botany Department, M.L. Sukhadia University Udaipur, Jean-Michel Mérillon Université de Bordeaux Institut des Sciences de la Vigne et du Vin Villenave d’Ornon, France K.R. Shivanna Former Professor & Head Botany Department, University of Delhi Delhi, India

p, A SCIENCE PUBLISHERS BOOK

GL--Prelims with new title page.indd ii 4/25/2012 9:52:40 AM 1100 Reproductive Biological Characteristics of Species Xianyu Shen, Chenggang Liu and Kaiwen Pan*

ABSTRACT Dendrobium, as the second largest genera of , is wildly distributed all over the world and has higher ornamental and medicinal values. Currently, research about the reproductive biological characteristics of the Dendrobium species are still limited. Therefore, only vegetative propagation (tissue culture) and sexual reproduction (fl owering character, visitors, pollination and seed set) are reviewed in this article. Finally, the subjects of further research including fl ower morphology, pseudopollen, anther cap and lower fruiting rate are put forward. Keywords: Dendrobium, vegetative propagation, sexual propagation, pseudopollen, pollinators

PO Box 416, No. 9, Section 4, Renmin South Road, Chengdu 610041, Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, The People’s Republic of . * Corresponding author: [email protected] 196 Reproductive Biology of Plants

Introduction

Dendrobium, which has about 1000–1400 original species with higher ornamental and medicinal values (Kuehnle 2006; Wang et al. 2007; He et al. 2008), is the second largest genera after Bulbophyllum of Orchidaceae. It is extensively distributed between Asia north of the equator and the Oceania regions (Ji et al. 1999; Wang et al. 2007). Seed and vegetative propagation are the major modes of reproduction of the Dendrobium species under natural conditions. However, Dendrobium species often have lower seed setting, and mycorrhizal symbiosis limits seed germination in seed propagation, resulting in the poor ability of natural reproduction (He et al. 2008; Li et al. 2009b). Dendrobium orchids are popular fl owering potted and cut fl owers around the world due to their fl owering fl oriferousness, wide range in fl ower color, size, and shape, year-round availability, and lengthy post- harvest life (Kuehnle 2006). The earliest record about Dendrobium species can be traced back to “Shen Nong’s Classic of Materia Medica” (also named as Shennong’s Herbal), a classic work on plants and their utilization, written in the Han Dynasty (206 B.C.–220 A.D.) in China (Wang et al. 2007). Previous studies have focused on the many chemical ingredients, such as alkaloid, polysaccharide, sesquiterpenoids, phenanthrenes and bibenzyls in the Dendrobium species (Zhang et al. 2003; Ma and Wang 2008; Li et al. 2010), which could be used to effectively treat eosinophilic gastroenteritis, cataract, arthritis, thromboangiitis obliterans and chronic pharyngitis (Wei 2005). Chemical ingredients contained in Dendrobium species are effective in promoting digestion, extending life span, regulating the immune system, dilating blood vessels, lowering or normalizing blood pressure, and treating against tumor (Cheng and Guo 2001; Zhang 2003; Ma and Wang 2008; Zou and Liu 2010; Ng et al. 2012). Although lots of knowledge has been displayed in tissue culture and rapid propagation of Dendrobium species, reproductive biological characteristics of the are still limited. In this present chapter, reproductive biological characteristics of Dendrobium species including vegetative propagation and sexual reproduction are reviewed. Besides, a perspective on unknown reproductive biological characteristics of Dendrobium species w