Phenylurea-type Cytokinin ameliorates the performance of young pea plants under salt stress

Cytokinins are known to enhance stress tolerance in plants. The present study aimed to assess the possible protective effect of exogenous phenylurea-type cytokinin (4PU-30) on alleviating salt (NaCl) stress. Young pea (Pisum sativum L.) plants were sprayed with cytokinin 4PU-30 and were subsequently subjected to NaCl treatment. The effect of 4PU-30 on cell membrane stability was assessed based on electrolyte leakage from leaves of control and NaCl stressed plants. A previously established model system employing the kinetics of ion leakage served to evaluate the effect of the 4PU-30 application on plants response to salinity. Salt treatment caused a moderate decrease in leaf water content. Accumulation of proline, malondialdehyde (MDA), and hydrogen peroxide (H2O2) in the leaves of NaCl treated plants indicated the development of oxidative stress, which was significantly alleviated by pretreatment with phenylurea-type cytokinin 4PU-30. Foliar application of 4PU-30 reduced the damaging effect of NaCl, as evidenced by decreased electrolyte leakage. Distinct roles of cell walls and plasmalemma in the processes of ion efflux due to salt stress are discussed.