Cryopreservation of Germplasm of Forest Genetic Resources as a Viable Pathway for Sustainable Growth

The forest, home to 80% of amphibians, 75% of birds, and 68% of mammals, is experiencing rampant destruction. Germplasm management prevents the extinction of wild plants as well as the conservation of wild species for future use. Innovative biotechnological techniques act as catalysts for forest germplasm conservation. Conventionally, germplasm conservation occurs through in situ and ex situ methods through biosphere reserves, seed banks, gene banks, cryopreservation, tissue culture banks, etc. Out of the various conservation strategies, ex situ conservation has come up with a backup to the world’s floral and faunal diversity. Cryopreservation can be considered as an imperative long-term preservation method of plant genetic resources among various ex situ conservation methods. Cryopreservation is a long-term conservation method in which plant genetic resources can be stored without any deterioration. A temperature of −196 °C halts biochemical and most physical processes in plants, making cryopreservation ideal for the conservation of meristematic cells, seeds, pollen, hardwood, softwood, endangered plants, vegetatively and biotechnologically propagated crops, including those with recalcitrant seeds and even embryos without any alterations. Various cryopreservation methods include vitrification, encapsulation-vitrification, droplet vitrification, and encapsulation-dehydration. Meristematic tissues can be stored and preserved using the droplet vitrification protocol. Cryopreservation employs agents like dimethyl sulfoxide (DMSO), ethylene glycol, glycerol, and proline as cryoprotectants. Cryoprotectants are chemicals that alter the freezing characteristics of residual water by osmotically removing water from cells. Numerous tropical crops and forest tree materials are successfully cryopreserved. Occasionally, ice crystal formation occurring during cryopreservation may be inimical to anatomical structures. Hence, species-specific optimisation protocols are required. In addition, physical and chemical aspects of freeze drying, cold adaptation, post-thawing regrowth, and problems associated with storage in liquid nitrogen are to be investigated soon.