Biochemical and molecular tolerance of Carpobrotus acinaciformis L. halophyte plants exposed to high level of NaCl stress

OpenAlex İngilizce

Carpobrotus acinaciformis L. plant is a kind of halophyte that is able to survive in high salt conditions. It is important to determine its physiological, biochemical and molecular limit of NaCl stress if one aims to use it for phytoremediation purpose. In this study, the alkaline protocol of the modified plant comet assay were used for rapid detection of DNA damage in C. acinaciformis L. plants exposed to a series of NaCl stress concentrations (0-, 50-, 100-, 200-, 300-, 400 and 500 mmol L-1) in hydroponic conditions for 2 weeks. DNA damage was measured as the values of percentage of DNA in tails and tail length. The halophyte C. acinaciformis L. did not show any dose response up to 400 mmol L-1 NaCl level in terms of DNA damages. DNA integrity measured via comet assay showed that DNA preserved its original shape up to 400 mmol L-1 NaCl level. However, the very high concentrations of NaCl (400 and 500 mmol L-1) caused DNA damages. When physiological and biochemical parameters such as proline, chlorophyll a and b, peroxidase (POX), catalase (CAT), H2O2, malondialdehyde (MDA) contents were examined, oxidant molecules such as H2O2 (0.912-3.72 µmol g-1 Fwt) and MDA (7.1-34 nmol g-1 Fwt) gradually increased along with the increase of NaCl concentrations, p<0.05. On the other hand, antioxidant enzyme POX and an osmolyte molecule proline slightly increased up to 400 mmol L-1 NaCl level then slightly decreased after that. Similar issues were obtained from that of protease enzyme which indicates the power of protein hydrolysis in which a slight decrease (182-95 Unit mg-1 protein) over a dose of NaCl was evident. Chlorophyll contents and CAT activity were not affected upon increase of NaCl concentrations. This study showed that the halophyte C. acinaciformis L. can be easily used to remove salt up to 400 mmol L-1 NaCl concentrations from a saline-affected soil. Measuring DNA damage is concluded as a very useful parameter to find out what level of NaCl could be tolerated if a halophyte plant is aimed to remediate the saline soils.