Strawberry Shoot Tip Cryopreservation (Droplet Vitrification)
Strawberry Shoot Tip Cryopreservation (Droplet Vitrification)
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>Kim Hummer, USDA-ARS National Clonal Germplasm Repository, 33447 Peoria Road, Corvallis, Oregon 97333.
Outline
- Introduction
- In vitro cultures and cold acclimation
- Shoot tip excision
- Shoot tip processing and storage
- Shoot tip recovery
- Viability assessment
- References
- Additional information
- Acknowledgments
The strawberry shoot tip cryopreservation procedure is available to download here.
The strawberry shoot tip recovery procedure is available to download here.
1. Introduction
Figure 1. Strawberry fruit at various stages of ripening. Photo credit: USDA Image Gallery.
Strawberry (Fragaria; Fig. 1) is an economically important crop in many countries, with high levels of production in China, the United States, and Mexico. In the United States, the National Plant Germplasm System’s (NPGS) primary collection of strawberry is housed at the National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon (Video 1). Strawberry germplasm is conserved as plants in the field or in screen houses, as in vitro cultures in refrigerated conditions, and may be cryopreserved for long-term storage (Reed and Hummer, 1995).
Strawberry shoot tips may be cryopreserved through a variety of approaches including encapsulation vitrification (Hirai and Sakai, 2001), vitrification (Niino et al., 2003), droplet vitrification (Pinker et al., 2009), and cryo-plate vitrification (Yamamoto et al., 2012). Although the NCGR and the National Laboratory for Genetic Resources Preservation (NLGRP) have applied both vitrification and droplet vitrification to preserve strawberry germplasm, this chapter describes the latter as it tends to produce greater viability.
Video 1. Dr. Kim Hummer, Research Leader at the National Clonal Germplasm Repository, provides an introduction to the National Plant Germplasm System strawberry collection.
2. In vitro cultures and cold acclimation
Figure 2. Potted strawberry plants in National Clonal Germplasm Repository strawberry collection. Photo credit: Gayle Volk.
Healthy potted strawberry plants (Fig. 2) provide a starting point to establish in vitro cultures at NCGR (see “Introduction of clean plant into tissue culture“). These cultures may serve directly for shoot tip cryopreservation at the NCGR, or can be transferred to gas-permeable bags for reduced temperature storage (see “Reduced-temperature storage of temperate crops in tissue culture“). Strawberry kept in reduced temperature storage may later be rewarmed and grown to provide material for shoot tip cryopreservation at NCGR or NLGRP.
Figure 3. In vitro strawberry cultures. Photo credit: Katheryn Chen.
Cultures are maintained on Fragaria Shoot Maintenanc