Potentials for Salt Tolerance Improvement in Rapeseed

Abstract

Salt stress affects all phases of rapeseed growth and development, but seed germination and seedling growth are the most sensitive. In our previous studies, we have evaluated effect of salt stress on the germination process of rapeseed in controlled laboratory conditions. We tested eight rapeseed cultivars Banaćanka, Jasna, Kata, Zorica, Slavica, Anna, Ilia and Zlatna under salt stress (100, 150, 200 and 250 mmol/L NaCl). All tested cultivars had a certain level of tolerance to low NaCl treatments, while at higher concentrations significant damage was observed, which was reflected in the reduction of growth and the appearance of necrosis. Banaćanka and Zorica had the highest germination values in all salt stress levels, while Jasna and Zlatna varieties had the highest germination reduction. Between the tested genotypes, obvious differences were observed when analyzing the activity of antioxidant enzymes superoxide dismutase and guaiacol peroxidase (SOD, GPx), the amount of non – enzymatic antioxidants reduced glutathione (GSH) and the intensity of lipid peroxidation (LP), both in seedlings shoot and in the root. Induction of SOD activity by different concentrations of NaCl was observed in all examined cultivars. Tolerant varieties showed increased activity of antioxidant enzymes and in regard to this, higher SOD activity was found in cultivars Jasna and Kata. In all examined cultivars, there was a gradual increase in the intensity of LP with a higher concentration of NaCl. Cultivar Banaćanka showed the highest (237.21%) increase at the highest salt stress level, while Kata showed the lowest (147.73%), compared to the control. So far, over 500 drought and/or high-salinity stress-inducible genes were identified in B. napus by using different approaches. Some of the rapeseed genotypes, which have been identified in our study as potential sources of salt and other abiotic stresses tolerance (Banaćanka, Anna, Zorica) are selected for further study of the role of stress-inducible genes and the detection of the most effective genes that would be of interest for targeted genome editing in order to improve salt and drought tolerance of commercial rapeseed varieties.