Investigation of the effects of dehydroabietic acid on the defense responses and signal transduction in soybean under salt stress

Dehydroabietic acid R=COOH (DHA), natural occuring diterpene resin acid is an activator of systemic acquired resistance (SAR) under biotic stress. However, there is no report how it works under salinity. In the present study, we determined the effects of DHA on salinity and it's possible role as a signal transmitter on soybean (Glycine max L.) leaves under salt treatment (200 mM NaCl) Furthermore physiological parameters, chlorophyll content, proline content, lipid peroxidation product malondialdehyde (MDA), hydrogen peroxide (H2O2) content, superoxide radical (O2●‾) and hydroxyl radical (OH●) scavenge capacity, antioxidant enzymes (SOD, POX, APX and GST) and GmWRKY-71 gene expressions were investigated in treated plants at 6 h,12 h and 24 h. The results obtained that pretreatment of DHA caused a reduction in salt induced damage, improvement in biomass yield, water status, chlorophyll and leaf area, regulation proline level and relative electrolyte leakage, an increased reactive oxygen species scavenging capacity and thus alleviation in oxidative damage. In addition to this, the changes in GmWRKY-71 gene expressions were remarkable in soybean plants under salinity. Collectively, this results showed that DHA can behaviour as a ROS inhibitor or a signal molecule in increasing salt tolerance in soybean leaves under salinity.