Induction of tolerance to cryogenic protocols in Solanum tuberosum by salicylic acid is mediated by enzymatic antioxidant activity and hydrogen peroxide

Abstract

ABSTRACT Two applications of cryogenic protocols are cryotherapy and cryopreservation for virus cleaning and germplasm storage. They are based on exposing explants to ultra-low temperature (−196°C) in liquid nitrogen. Ultra-low temperature in cryogenics implies abiotic stress, leading to the production of reactive oxygen species (ROS), which are the main reason for the low survival and death of explants. Hydrogen peroxide (H2O2) is an important ROS produced by stress. Enzymatic antioxidants like catalase (CAT) and peroxidase (POX) are essential for avoiding damage due to H2O2, which is a primary signal against stress. Salicylic acid (SA) is involved in tolerance to stress-like cryogeny. Information about the relationship between SA-cryogeny-antioxidant enzymatic activity is scarce. The objective was to evaluate the induction of cryogeny tolerance by SA associated with antioxidant activities like CAT, POX, and H2O2 and proline accumulation in tissue, during cryogenic protocols in two clones of potato (Solanum tuberosum L.). SA-induced cryogenic tolerance in both clones, mediated by reducing CAT enzymatic activity, higher H2O2 content, proline accumulation and higher water potential before cryogeny. Enhanced CAT and POX activities after cryogeny were related to decreased H2O2 content and higher survival. Results suggest the signalling role of H2O2 in the induction of tolerance to cryogenic stress.