Changes in antioxidant enzyme activity in response to salinity-induced oxidative stress during early growth of sweet basil

Sweet basil is one of the most widely used commercially cultivated plants worldwide. Here, we investigated the early growth and antioxidant enzyme activity of salt-stressed sweet basil seedlings. We subjected in vitro-grown sweet basil (Ocimum basilicum L. var. minimum) to different levels of sodium chloride (0, 10, 20 and 30 mM) and collected data per week during the first month of growth. The responses of antioxidant enzymes to salt stress were variable. Superoxide dismutase (SOD) exhibited similar patterns of increasing and decreasing activity in both shoots and root. By contrast, pyrogallol peroxidase (PPOX) and guaiacol peroxidase (GPOX) activity increased during plant growth but varied among seedling parts. Catalase (CAT) was the most salinity-sensitive enzyme examined, with activities varying depending on the plant part and stage of development. Our results also suggest that nutrient uptake is inhibited in basil under salt stress and that antioxidative defence mechanisms are induced in salinity-stressed sweet basil during early development. The changes in nonspecific antioxidant biomarkers observed in this study could be highly valuable for studying the mechanism underlying stress tolerance in O. basilicum L. var. minimum and could facilitate the development of tolerant basil cultivars.