Search

Cryopreservation allows the long-term storage of plant germplasm, but can cause damage to plant tissues, which must be repaired for survival to occur. This repair process is fuelled by the metabolic function of mitochondria; however, little is known about how metabolic function is affected by the cryopreservation process in plants. We compared metabolic rates of shoot tips of two Australian native species, Androcalva perlaria and Anigozanthos viridis. Overall, cryopreservation resulted in a significant reduction in the metabolic rates of shoot tips from both species, even in tissues that regenerated after cryopreservation. Metabolic rate did not increase within 48 h after of thawing, even in shoot tips which later regenerated. When examined in isolation, both pre-treatment on desiccation medium and exposure to cryoprotective agents significantly decreased metabolic rates in regenerating shoot tips of A. viridis, however both caused a significant increase in shoot tips of A. perlaria, suggesting diversity of response to cryopreservation stresses across species. Measurements of shoot tip metabolic rate during cryopreservation will inform investigations into cellular energy production and provide critical information on the state of shoot health after exposure to different cryoprotective treatments, which could play a useful role in guiding protocol optimisation for threatened species to maximise post-cryopreservation regeneration., Competing Interests: Declaration of competing interest None., (Copyright © 2022 Elsevier Inc. All rights reserved.)

We report the development of a cryopreservation protocol for the endemic Western Australian plant species Loxocarya cinerea (Restionaceae). Shoot tips from two genotypes, SXH404 and SXH804, were cryopreserved using the droplet-vitrification technique. Control explants, which were cryoprotected, but not cooled, showed regeneration for both genotypes (SXH404, 22.1 +/- 5.9%; SXH804, 67.7 +/- 9.6%). Extension of incubation in PVS2 from 30 to 60 min did not lead to survival after cryopreservation. Thermal analysis using differential scanning calorimetry confirmed the beneficial effect of a loading phase but also revealed no or very little ice formation after cryoprotection of shoot tips in other treatments. Regeneration following cryopreservation was obtained for genotype SXH804 (4.3 +/- 2.1%) but not for SXH404. Regenerated explants of L. cinerea SXH804 were morphologically identical to tissue-cultured plants. As an alternative to shoot tips, callus tissues of clone SXH404 were successfully cryopreserved (> 66.7% post LN survival) using the same protocol.