Somatic Embryogenesis of Pine Species: From Functional Genomics to Plantation Forestry

Several economically important tree species belong to the genus Pinus and many of them form the ecological base of forest ecosystems. Pine wood is an important raw material for the forest industry and many of the pine species have been involved in conventional tree improvement programmes. A lot of effort has been made in the development of vegetative propagation methods, especially somatic embryogenesis, in order to rapidly gain the benefits of traditional breeding to be utilized in reforestation. The economically relevant clonal plantation forestry presumes effective mass-propagation systems with high-quality somatic embryo plants. Today this is feasible only for Pinus banksiana Lamb., P. taeda L. and P. radiata D. Don. The recent progress in somatic embryo production and the challenges in functional genomics have increased the understanding of pine zygotic embryo development, leading to improved protocols for somatic embryogenesis. Therefore, clonal plantation forestry might become a reality for more pine species in the coming years. This chapter highlights the recent challenges in the functional genomics of pine embryogenesis. Possibilities for molecular breeding or utilization of somatic embryo plants in conventional breeding and in clonal plantations in line for sustainable forestry are also covered. The importance of cryopreservation for elite genotype preservation and as a storage method during progeny testing is discussed, as well as the use of ectomycorrhizal fungi during somatic embryo conversion in vitro and acclimatization ex vitro.