Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 8, 2004
Publication Date: July 17, 2004
Citation: Towill, L.E. 2004. Cryopreservation of apple: results with non-desiccated winter scions. American Society for Horticultural Science, July 16-20, 2004.Austin, Texas. 39(4):752-753. Interpretive Summary: Storage in liquid nitrogen is valuable for long-term conservation of germplasm. Apple is usually processed for storage using desiccation prior to cooling, but this procedure is lengthy. Survival in a number of hardy lines, tested mainly in Malus x domestica, was obtained by substituting slower cooling rates for the desiccation step.
Technical Abstract: Apple cryopreservation at USDA-ARS NCGRP uses a winter vegetative bud method that incorporates desiccation prior to cooling. Although this method is valuable, desiccation is time consuming, requiring cutting nodal sections to exact lengths, moisture content estimates, and 1-4 weeks of desiccation. Processing sections without desiccation is being examined to improve the efficiency of handling Malus accessions. Viability was estimated using an oxidative browning assay or a sprouting test. Sections from mid-winter collected scions were cooled at different rates to -30 degrees C or -35 degrees C and transferred to the vapor phase over liquid nitrogen. Sections were warmed at +4 degrees C and held for 24 hrs before testing viability. Some lines were processed after several months of storage at -3.5 degrees C. In tests with a limited number of lines, cooling rates greater than or equal to 10 degrees C/hr to -30 degrees C caused injury to buds and cambium. Although viability after cryopreservation occurred with a cooling rate of 1 degrees C/hr, slower cooling (5 degrees C/day) was beneficial for many accessions. Scions stored for up to 8 months could survive cryoexposure. Scions from three lines tested survived three cycles of cooling from +4 degrees C to LN. Extent of acclimation affected results. With non-desiccated sections cryogenic survival of cv Golden Delicious differed over years. It is not expected that this method is generally applicable to more tender species of Malus or other fruit genera, but the method has been successful with many lines of M. x domestica, a fairly cold hardy taxa, and with some other cold hardy Malus species. Grafting tests are needed to confirm the usefulness of the method.