Cryopreservation and Cryotherapy of Tropical Crops
Plant Germplasm Preservation Research Unit
2013 Annual Report
1a.Objectives (from AD-416):
The objective of this cooperative research is identify methods for increasing tolerance to liquid nitrogen temperatures in avocado and Citrus crops and to determine if pathogens are eliminated during the cryopreservation process.
1b.Approach (from AD-416):
Avocado and Citrus genetic resources will be obtained from the National Plant Germplasm System Repositories in Miami, FL and Riverside, CA, respectively. In vitro cultures will be established and propagated to serve as rootstocks for cryopreserved shoot tips. Cryoprotectant and liquid nitrogen exposure tests will be performed using shoot tips excised from field-grown budwood. Cryopreservation experiments will be performed using disease infected and clean plant materials to determine if liquid nitrogen exposure eradicates diseases from infected tissues.
We have worked to develop cryopreservation protocols for Citrus and sugarcane. The Citrus research has been highly productive, resulting in a publication and increased industry interest. Shoot tip survival rates after liquid nitrogen exposure are high, especially since we have increased the freezing rate and have determined optimal times of year for budwood harvests. We have been cryopreserving key lines of Citrus that are critical to both the USDA National Plant Germplasm System and the California Citrus Industry using the methods that have been developed. We are now performing cryotherapy research, in collaboration with USDA-ARS-Riverside, to determine if viruses and viroids can be removed from contaminated materials as a result of the cryopreservation process (cryotherapy). We have also performed a thorough investigation of in vitro propagation of sugarcane genetic resources. We have performed cryoprotectant exposure trials and have had some successes.