ROS-induced oxidative stress and apoptosis-like event directly affect the cell viability of cryopreserved embryogenic callus in Agapanthus praecox

Abstract

Oxidative stress and apoptosis-like programmed cell death, induced in part by H 2 O 2 , are two key factors that damage cells during plant cryopreservation. Their inhibition can improve cell viability. We hypothesized that oxidative stress and apoptosis-like event induced by ROS seriously impact plant cell viability during cryopreservation. This study documented changes in cell morphology and ultrastructure, and detected dynamic changes in ROS components (O 2 (·-) , H2O2 and OH·), antioxidant systems, and programmed cell death (PCD) events during embryonic callus cryopreservation of Agapanthus praecox. Plasmolysis, organelle ultrastructure changes, and increases in malondialdehyde (a membrane lipid peroxidation product) suggested that oxidative damage and PCD events occurred at several early cryopreservation steps. PCD events including autophagy, apoptosis-like, and necrosis also occurred at later stages of cryopreservation, and most were apoptosis. H2O2 is the most important ROS molecule mediating oxidative damage and affecting cell viability, and catalase and AsA-GSH cycle are involved in scavenging the intracellular H2O2 and protecting the cells against stress damage in the whole process. Gene expression studies verified changes of antioxidant system and PCD-related genes at the main steps of the cryopreservation process that correlated with improved cell viability. Reducing oxidative stress or inhibition of apoptosis-like event by deactivating proteases improved cryopreserved cell viability from 49.14 to 86.85 % and 89.91 %, respectively. These results verify our model of ROS-induced oxidative stress and apoptosis-like event in plant cryopreservation. This study provided a novel insight into cell stress response mechanisms in cryopreservation.

Melatonin Increases the Chilling Tolerance of Chloroplast in Cucumber Seedlings by Regulating Photosynthetic Electron Flux and the Ascorbate-Glutathione Cycle

“…Photoinhibition not only decreases the photosynthetic ratio but also induces production of reactive oxygen species (ROS), and these lead to oxygen stress. Membranes can be damaged by excessive ROS, resulting in cell dysfunction such as the depression of membrane transport function and the membrane-associated enzyme activity (Zhan et al, 2014; Zhang et al, 2015a). To enhance plant tolerance to chilling and thus improve crop productivity, application of exogenous substances has been used widely (Shuming et al, 2012; Yang et al, 2015; Han et al, 2016).…”

Adding Ascorbic Acid to Reduce Oxidative Stress During Cryopreservation of Somatic Embryos of <i>Paphiopedilum niveum</i> (Rchb.f.) Stein, an Endangered Orchid Species

“…Chua and Normah (2011) also reported that applying 0.28 mM AsA in the LS step could slightly enhance the survival percentage (3.3%) of pulasan shoot tips (Nephelium rumboutanake). The oxidative stress during callus cryopreservation of Agapanthus praecox was determined by Zhang et al (2015). It was found that the ROS-induced oxida- preconditioned on PGR-free MVW containing 0.1 M sucrose (six days) and then transferred to PGR-free MVW containing 0.1 M sucrose and 0.1 mM ascorbic acid (one day).…”

Stress responses of the oil-producing green microalgaBotryococcus brauniiRace B

“…This hypothesis has some support from other studies. It has been reported that the DAD1 gene was up-regulated in callus cells of Agapanthus praecox during the recovery stage following inoculation into fresh medium after cryopreservation (Zhang et al, 2015). It was important to know the expression change of these genes (Fig.…”