Freezing tolerance and antioxidant activity in potato microplants induced by abscisic acid treatment

Abstract

A model based on the in vitro-to-glasshouse system used in potato seed production programs was implemented to investigate the effects of abscisic acid (ABA) on the induction of freezing tolerance in microplants of two potato cultivars with different sensitivity. Microplants 28 days old, cultured in the presence of ABA, were transferred to soil and exposed to -6 C for 4 h. ABA enhanced survival two-fold but inhibited stem growth by 91%. Recovery from the ABA effect was evaluated under in vitro and glasshouse conditions. Plants recovered from the ABA stress had increased growth rate. When microplants incubated in ABA were subcultured to ABA-free medium for 28 days, growth increased 10.4 and 6.9-fold, whereas the growth in controls was 0.36 and 0.6-fold for 'Atlantic' and 'Alpha', respectively. Enzymatic activities of peroxidase and ascorbate peroxidase, along with H2O2 content, significantly increased in microplants incubated in ABA. When the microplants were transferred to ABA-free medium, these parameters declined to control levels. No significant differences were obtained for any of the parameters evaluated in microplants transferred for 120 days to a glasshouse for recovery. ABA did not induce long-term effects on tuber production. These results demonstrate the potential of ABA in the induction of freezing tolerance in microplants transferred to soil. Responses to ABA were associated with the antioxidant system and H2O2 content in the induction of freezing tolerance in potato.