The protective role of exogenous proline in pepper callus exposed to long– term cold stress

Abstract

Cold stress is one of the main abiotic stress factors which restricts pepper growth and development. Thus, identifying alternative strategies is critical to reduce cold damage in peppers. This study evaluated the effect of exogenous proline in reducing cold stress damage in pepper callus. For this purpose, callus was obtained from the hypocotyl explants of germinated seedlings under in vitro conditions. 0,12 and 24 mM proline were applied to the callus and developed under the same photoperiodic settings at 4°C, 8°C, 16°C and 24°C. Low temperatures increased H 2 O 2 and MDA production with the highest H 2 O 2 and MDA amounts determined at 4°C. Proline applications decreased the content of H 2 O 2 at low temperatures, whereby 24 mM proline caused a significant decrease in the amount of H 2 O 2 at 4°C. The lowest MDA accumulation was determined in the 12 mM proline application. The data indicated that the total phenolic content of pepper callus decreased with decreasing temperatures. However, the application of proline increased the total phenolic amounts with the increase in its concentration. DPPH radical scavenging activity, FRAC and total protein content decreased with decreasing the temperature to 4°C and 8°C. However, both exogenous proline applications increased DPPH radical scavenging activity, FRAC and total protein at 4°C and 8°C. The results indicated that the metabolic pathways are triggered by the application of exogenous proline.

Keywords

• capsicum annum
• free radical
• lipid peroxidation
• oxidative stress
• tissue culture
• tolerance