Somatic Embryogenesis and Efficient Plant Regeneration in Japanese Cypresses

There are six species in the genus Chamaecyparis worldwide, of which two, namely the Hinoki cypress (Chamaecyparis obtusa Sieb. et Zucc.) and Sawara cypress (Chamaecyparis pisifera Sieb. et Zucc.) are distributed in Japan (Maruyama et al., 2002). The Hinoki cypress is one of the most important commercial timber trees in Japan, representing about 25% of the plantation area in the country. However, the plantation areas are subject to various pests and diseases. In addition, Hinoki cypress pollinosis is reportedly one of the most serious allergic diseases in Japan (Maruyama et al., 2005). The wood quality of Sawara cypress is considered inferior to Hinoki cypress, but grows faster (Fukuhara, 1978), is highly adaptable to humid and poor soils, and is considered more resistant to termite injury (Maeta, 1982) and far more tolerant to cold than the Hinoki cypress (Fukuhara, 1978). Fukuhara (1989) and Yamamoto and Fukuhara (1980) reported the possibility of obtaining natural hybrids between C. obtusa and C. pisifera.