Determination of effects 24-epibrassinolide in tomato (Solanum lycopersicum L.) shoot tip cultures under NaCl stress

Abstract

The negative effects of salt stress on plants and their environment are increasing dramatically day by day, and it is very crucial for plants to develop salt tolerance with various applications. To this end, in recent years, there is a need for studies to increase salt tolerance with in vitro cultures in which controlled conditions are provided as an alternative approach to greenhouse and pot experiments, which are affected by environmental external conditions. In this study, 24-epibrassinolide (24-epiBL) was used for increasing salt tolerance via in vitro shoot tip cultures of tomato M-28 hybrid cultivar. Shoot tips of 10-day sterile seedlings were placed in MS medium supplemented with 2 mg L-1 K + 0.4 mg L-1 NAA in 12-day culture period, and 12-day old plantlets soaked in 24-epiBL solutions (0, 1, 2 µM) were transferred to MS medium containing different concentrations of NaCl (0, 20, 40, 60, 80, 100 mM). After 20 days, it was determined that morphological parameters (lenght, fresh and dry weight of plantlets) and biochemical parameters (pigment, MDA, proline, total soluble protein contents, POX and SOD enzyme activities). All developmental parameters and various biochemical parameters such as pigment and total soluble protein contents negatively affected by NaCl stress, whereas MDA, proline content, SOD and POX enzyme activities increased. It was found that increase in fresh weight, pigment content, SOD and POX enzyme activity with 24-epiBL pretreatment agaist NaCl stress were found statistically significant difference. Hovewer MDA content decreased with 24-epiBL pretreatment under NaCl. As a result, NaCl responses in plant varies between different NaCl and 24-epiBL concentrations, and the various deffence strategies combine multiple tolerance mechanisms. It was determined that 24-epiBL may play a crucial role increasing salt tolerance using in vitro shoot tip cultures of tomato M-28 hybrid cultivar.