Propagation of Ornamental Plants Vol. 12, № 1, 2012: 25-51 Invited paper IN VITRO PROPAGATION OF TROPICAL HARDWOOD TREE SPECIES – A REVIEW (2001-2011) Paula M. Pijut1*, Rochelle R. Beasley2, Shaneka S. Lawson2, Kaitlin J. Palla2, Micah E. Stevens2, and Ying Wang2 1USDA Forest Service, Northern Research Station, Hardwood Tree Improvement and Regeneration Center (HTIRC), 715 West State Street, West Lafayette, Indiana, USA 47907 *Fax: + 1-765-494-9461, *E-mail:
[email protected] 2Purdue University, Department of Forestry and Natural Resources, HTIRC, 715 West State Street, West Lafayette, Indiana, USA 47907 Abstract Tropical hardwood tree species are important economically and ecologically, and play a significant role in the biodiversity of plant and animal species within an ecosystem. There are over 600 species of tropical timbers in the world, many of which are commercially valuable in the international trade of plywood, roundwood, sawnwood, and veneer. Many of these tree species are being threatened and are endangered because of logging practices, conversion to agricultural lands, non-optimal management strategies, and overall deforestation rates that cannot keep up with natural regeneration of native forests. Tropical tree species provide timber for com- mercial uses because of the beauty of the wood-grain, -color, or -pattern, strength, durability, and versatility of finishing applications for a vast array of markets. Because of the high value of tropical tree species,in vitro (adventitious shoot regeneration, cryopreservation, genetic transformation, micrografting, protoplast culture, shoot tip and nodal culture, and somatic embryogenesis) propagation technologies are an integral component in tree improvement and conservation programs, in order to complement seed banking and ex situ measures for long-term conservation and clonal propagation of germplasm.