An Introduction to the Cryopreservation of Clonally Propagated Plants
An Introduction to the Cryopreservation of Clonally Propagated Plants
Jean Carlos Bettoni, Independent Researcher, 35 Brasil Correia Street, Videira, SC 89560510, Brazil<EMAIL_ADDRESS>Katheryn Chen, Department of Soil and Crop Sciences, Colorado State University, 307 University Ave., Fort Collins, Colorado 80523.
Gayle M. Volk, USDA-ARS National Laboratory for Genetic Resources Preservation, 1111 S. Mason St., Fort Collins, Colorado 80521<EMAIL_ADDRESS>The purpose of this chapter is to introduce the concept of cryopreserving plant genetic resources for crops that are clonally/vegetatively propagated.
Outline
1. Introduction
Cryopreservation is the secure storage of biological materials at ultra-low temperatures. Cryopreservation in liquid nitrogen (LN) or in its vapor phase (LNV) is a safe and cost-effective strategy for the long-term storage of plant genetic resources that cannot be stored as orthodox seeds. Once cryopreserved, materials remain safe and available at a low annual cost. In LN or LNV, plant tissues or organs are preserved in a state where cellular division and metabolic processes cease, preserving the structure and function of the biological system and minimizing the risk of contamination.
Cryopreservation is routinely implemented to preserve the diverse genetic resources of many plant species. Effective procedures have been identified for cryopreserving seeds, pollen, cell cultures, dormant buds, and shoot tips. Because each of these plant forms fulfills different roles in ex situ plant genetic resources collections, the most appropriate propagule to cryopreserve depends on the plant species and program targets, as well as the available infrastructure and technical skills. In plant species that produce few to no seeds, intermediate or recalcitrant seeds, or in plants that are vegetatively propagated to maintain a specific gene combination, vegetative propagules such as shoot tips and dormant buds are the most suitable source for preservation (Video 1).
Video 1. A video introducing clonal cryopreservation narrated by Jennifer Kendall.
2. Dormant bud cryopreservation
For clonal cryopreservation of winter-hardy woody species, dormant buds might be the best choice. Dormant bud cryopreservation capitalizes on the natural state of dormancy that enables propagules to survive low temperatures. Unlike traditional shoot tip cryopreservation methods, this approach does not rely on tissue culture introduction and multiplication to provide propagules. Although it is generally a much faster approach, its applicability is much more limited; it completely depends on seasonal availability of dormant buds and it is only successful for some cold-hardy temperate crops such as apple (Tanner et al., 2021).
Video 2. A video summarizing dormant bud cryopreservation narrated by Katheryn Chen.
3. Shoot tip cryopreservation
Unlike dormant buds, shoot tip cryopreservation can effectively preserve a wide range of vegetatively-propagated plants from both tempe