The Role of Synthetic Seeds in Germplasm Conservation of Forest Tree Species

Forests constitute one of the most prominent bioresources on earth, having economic and ecological roles of unparalleled significance. Forests provide abundant natural resources and are major players in maintaining the environmental balance, providing numerous ecological services, and preserving biodiversity. Despite their great importance, the area under forests is constantly shrinking at an alarming rate due to both environmental conditions and anthropogenic activities. To add to the factors detrimental to forest health, climate change has emerged as a phenomenon perilous to the diversity of forest genetic resources. These contributing factors altogether call for immediate attention to the cause of forest germplasm collection and the implementation of conservation measures for the long-term storage of these precious forest resources. Many conservation strategies have been designed for the purpose of preserving germplasm from plant species. Among these, the manufacture and storage of synthetic seeds represent a promising approach. Synthetic seeds or synseeds are developed by encapsulation of explants (meristems or embryos) in a nutritive alginate matrix that serves to help in regrowth when required. Synthetic seed technology has several potential applications in forest tree species. It can be utilized for the rapid reproduction of elite genotypes, conservation of threatened species, generation of disease-free planting stock, and germplasm storage for longer periods of time, and at the same time, it can potentially reduce labor, monetary expenses, and space requirements for propagation. To date, this technique has been used for a wide number of tree species of the forests, including conifers such as pine, spruce, and fir, and broad-leaved species, such as eucalypts, acacias, oak, willow, and Shisham. The present chapter attempts to collate available knowledge on the synthetic seed technology and how they are produced and the propagules used therein, with an emphasis on its application in the forestry sector. The future of synthetic seed technology seems bright as it may be utilized as an effective method for mass propagation and the preservation of forest tree biodiversity, especially rare species, for short- and long-term.