Salicylic acid improves cold and freezing tolerance in pea

Abstract

The most significant crop losses worldwide occur due to unfavorable temperatures such as heat, drought, cold, and freezing. Bioregulator substances like salicylic acid can play important roles in the growth, development, and stress responses of plants. In this study, changes in stem/root length and relative water content of peas under cold and freezing stress, as well as antioxidant system indicators such as proline, malondialdehyde, hydrogen peroxide, chlorophyll and ion leakage levels were investigated. The expressions of genes coding for the TOP2 and PDH47 enzymes, which play important roles in the replication, transcription, and repair of DNA molecules, were also examined in root and stem tissues in the presence of two different concentrations of salicylic acid under cold and freezing stress. The results have shown that the application of salicylic acid, when added to the growth medium, can have positive effects on the cold resistance of pea plants. Salicylic acid likely achieves some of its effects by increasing the activity of superoxide dismutase, one of the most important enzymes taking a role in combating reactive oxygen species. The data obtained indicate that salicylic acid also increased the expressions of TOP2 and PDH47 genes, which can both change the topology of DNA, possibly facilitating the transcription of genes taking a role in antioxidative defense. Salicylic acid also reduced the levels of reactive oxygen species hydrogen peroxide and maintained cell membrane integrity, which leads to a decrease in ion leakage and an increase in water-holding capacity. With this study, the mechanisms of action of salicylic acid in cold stress tolerance have been further elucidated, and its potential use in agricultural cultivation has been evaluated.