Antimicrobial forcing solution improves recovery of cryopreserved temperate fruit tree dormant buds

Authors: TANNER, JUSTIN - Colorado State University; MINAS, IONNAS - Colorad0 State University; CHEN, KATHRYN - Colorado State University; Jenderek, Maria; WALLNER, STEPHEN - Colorado State University

Submitted to: Journal of Cryobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2020
Publication Date: 2/1/2020
Citation: Tanner, J.D., Minas, I.S., Chen, K.Y., Jenderek, M.M., Wallner, S.J. 2020. Antimicrobial forcing solution improves recovery of cryopreserved temperate fruit tree dormant buds. Journal of Cryobiology. 92:241-247. https://doi.org/10.1016/j.cryobiol.2020.01.019.
DOI: https://doi.org/10.1016/j.cryobiol.2020.01.019

Interpretive Summary: Plant material storage in ultra-low temperature (called cryopreservation, -186o C) safely preserves the material for future use. Using dormant winter buds for this type of storage is cheaper and easier to handle than processing shoot tips of tissue culture. However, regrowth of plants from dormant winter buds after cryopreservation is often connected with bacteria development that inhibits shoot and leaf growth. In our study, using a bacteriostatic chemical (8-hydroxyquinoline citrate with sucrose) that prolongs life of cut flowers, improved bud sprouting of apple, apricot, sweet cherry, peach, pear and three species of walnut from the cryostored dormant buds making this type of plant material more feasible in preservation of the tree species. Potentially, this discovery might be applicable in recovery of dormant buds of other cryopreserved plant species.

Technical Abstract: Dormant bud cryogenic preservation is cost- and labor efficient method of genetic resources backup compared to in vitro derived meristem shoots cryopreservation. While protocols have been developed for cryopreserving apple dormant buds, effective and reproducible protocols are yet to be developed for several temperate fruit and nut species. Dormant bud cryopreservation typically requires material to be grafted to evaluate viability and recover a plant. Forced bud development has been used on a very limited scale for cryostored dormant budwood recovery, however, it provides a labor-efficient alternative viability assessment. To increase the utility of this approach, regrowth must be optimized to allow complete plant recovery. We hypothesized that bacterial attacks are limiting regrowth, thus, an antimicrobial forcing solution can maximize regrowth potential. This study examined the effect of an antimicrobial forcing solution (8-hydroxyquinoline citrate and sucrose, 8-HCQ) on the cyosurvival and recovery of dormant buds of fruit (Malus x domestica, Prunus armeniaca, Prunus avium, Prunus persica, Pyrus communis), and nut species (Juglans regia, Juglans nigra, Juglans microcarpa). Recovery and shoot development were significantly improved for all the fruit and one nut species (J. microcarpa) treated with the 8-HQC, compared to standard recovery under high humidity alone (P<0.001). Additionally, this post cryo recovery approach led to successful in vitro shoot tip establishment across all surviving fruit species, 8-HQC embedded forced bud development method increased viability and efficient for existing cryostored material and can be used as a benchmark to develop protocols for different crops that could potentially lead to plant recovery.