Paclobutrazol Dependent Salt Tolerance Is Related to Clc1 and Nhx1 Gene Expression in Soybean Plants

Abstract

Paclobutrazol (PBZ) enhances plant resistance to salt stress in two ways: directly, by straight clearance of reactive oxygen species; and indirectly by enhancing antioxidant enzyme activity, photosynthetic efficiency, and metabolite content, and by regulating transcription factors associated with stress. However, the regulatory effects of PBZ under salt stress in soybean are still not well explained and need further investigation. With this aim, the combination effect of salinity (250 mM NaCl) and three different doses of PBZ (5, 10 and 20 ppm) on physiological, biochemical and molecular traits of soybean (Glycine max L.) leaves were studied in soil experiments. Furthermore, physiological parameters (relative growth rate, relative water content), chlorophyll, malondialdehyde (MDA), hydrogen peroxide (H2O2) content and as well as enzymatic antioxidants (SOD, POX, APX, CAT and GST), ion content (Na, Cl) and soybean Na+/H+ antiporter GmNHX1 and chloride channel GmCLC1 gene expressions were investigated. The results showed that PBZ caused a reduction in salt-induced damages and an increase in biomass yield, water status, and chlorophyll. Moreover, PBZ regulated enzymatic antioxidants and alleviated the oxidative damages under salinity. In this study, for a first time it was determined that PBZ increased both GmNHX1 (ABA dependent or independent) and GmCLC1 (ABA independent) gene expressions and reduced Na and Cl concentrations in soybean under salinity. In conclusion, PBZ plays a role as a regulator and stimulant in salt stress response by mostly regulating ion balance in soybean leaves.

Treatment with auxin and paclobutrazol mediates ROS regulation, antioxidant defence system and cell wall response in salt treated soybean

“…This may be associated with the capability of PBZ to induce a non-enzymatic antioxidant pathway (Seckin Dinler et al, 2021) to restore salt damage. Overall, our previous ndings showed that PBZ is also related to the sequestering of Na + and Cl-ions in the vacuole (NHX and ClC1) in soybean leaves (Seckin Dinler et al 2022). Besides this, the combination of IAA and PBZ performed best to reduce MDA content in soybean leaves under salinity, and this reduction was 44.33% at 200 mM and 48.95% at 300 mM.…”

“…PBZ increases the tolerance of plants to salt stress by reducing the oxidative damage caused by ROS production (Agha et al 2021). Lastly, PBZ application causes a reduction in salt-induced damages and an increase in biomass yield, water status, chlorophyll content, and antioxidant enzymes under salinity in soybean (Seckin Dinler et al 2022).…”