Influence of abiotic stress preconditioning on antioxidant enzymes in shoot tips of Lomandra sonderi (Asparagaceae) prior to cryostorage

Abstract

Lomandra sonderi (F.Muell.) Ewart (Asparagaceae) is endemic to the south-west Western Australian jarrah (Eucalyptus marginata Donn ex Sm.) forest region, and is a difficult to propagate species important to post-mining restoration. Micropropagation is the only way to currently produce plants of this species for restoration. This study describes investigations into optimising cryopreservation for efficient long-term germplasm storage. In order to investigate the effect of preconditioning on post-cryogenic survival of shoot tips, in vitro grown plants were exposed to a range of light-, temperature- and osmotic-induced preconditioning treatments under culture room conditions for 3 weeks. Room temperature (24°C) preconditioning resulted in the greatest post-cryogenic survival, followed by low light (17 µmol m-2 s-1) preconditioning. Alternating temperature (25/5°C), high temperature (35°C), high sucrose (180mM) and high light (93 µmol m-2 s-1) preconditioning treatments all led to significantly and progressively lower post-cryogenic shoot tip survival than room temperature preconditioning. Antioxidant activity of superoxide dismutase in preconditioned shoot tips showed a positive correlation to post-cryogenic survival overall, whereas the activities of glutathione reductase, glutathione peroxidase and catalase showed little correlation. Analysis throughout the cryopreservation protocol showed that the activity of glutathione reductase decreased significantly after cryopreservation, whilst the activity of glutathione peroxidase and catalase did not change.