Early in vitro flowering and seed production in culture in Dendrobium Chao Praya Smile (Orchidaceae)

• Published in: Plant cell reports 2007-12, Vol.26 (12), p.2055-2062
• Main Authors: Hee, Kim Hor, Loh, Chiang Shiong, Yeoh, Hock Hin
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biotechnology; Breeding; Cells, Cultured; Dendrobium Chao Praya Smile; Flowers; Flowers & plants; Flowers - growth & development; Flowers - physiology; Fundamental and applied biological sciences. Psychology; Germination - physiology; In vitro flowering; Orchidaceae; Orchidaceae - cytology; Orchidaceae - growth & development; Orchidaceae - physiology; Plant physiology and development; Pollen; Pollen - growth & development; Pollen - physiology; pollen germination; Pollination - physiology; Praya; Seed production in culture; Seedlings; Seeds; Seeds - growth & development; Seeds - physiology; Sporad analysis
• ISSN: 0721-7714; 1432-203X
• DOI: 10.1007/s00299-007-0421-9

Plantlets of Dendrobium Chao Praya Smile maintained in vitro were induced to flower, which produced viable seeds within about 11 months. A two-layer (Gelrite-solidified layer topped with a layer of liquid medium of the same volume and composition) culture system containing benzyladenine (BA) at 11.1 μM induced the highest percent of flowering (45%) in plantlets within 6 months from germination. The percentage of inflorescence induction was increased to 72% by pre-selecting morphologically normal seedlings prior to two-layer culture. Plantlets in culture produced both complete (developmentally normal but smaller than flowers of field grown plants) and incomplete flowers. Pollen and female reproductive organs of in vitro-developed complete flowers were morphologically and anatomically similar to flowers of field grown plants. In addition, 65% of the pollen grains derived from in vitro-developed flower were tetrad suggesting that regular meiosis occurred during microsporogenesis. The percentage of germination of pollen grains derived from in vitro-developed flowers and flowers of field grown plants, incubated on modified Knops' medium for 8 days, were 18.2 and 52.8%, respectively. Despite a lower percentage of germination of the pollen grains derived from in vitro-developed flowers, flowers induced in culture could be self-pollinated and developed seedpods with viable seeds. Nearly 90% of these seeds developed into protocorms on germination in vitro. These seedlings were grown in culture and induced to flower in vitro again using the same procedure.