Effects of hormonal priming and drought stress on activity and isozyme profiles of antioxidant enzymes in deteriorated seed of tall wheatgrass (Agropyron elongatum Host).

摘要

The effects of hormonal priming on physiological quality and antioxidant enzymes of aged seeds of tall wheatgrass were evaluated under control and drought (-0.5 MPa) conditions. Rate of germination, vigour index and growth of root, shoot and seedling were declined by stress conditions. According to the results, hormonal priming improved physiological quality of deteriorated seeds of tall wheatgrass under drought and control conditions. Germination percentage and rate of germination of primed seeds were higher than non-primed seeds under drought condition. 50 ppm of auxin increased germination of naturally aged seeds by 18% under drought condition. Likewise, cytokinin treatment resulted in the highest vigour index. Auxin decreased root length and increased number of seminal roots. For other hormones, seed priming by 100 ppm of gibberellin, 50 ppm of cytokinin, and 50 ppm of abscisic acid (ABA) improved seed performance under control and drought conditions. For antioxidant enzymes, both aging treatments (natural and accelerated) increased catalyse (CAT), glutathione reductase (GR) and peroxidase (POD) activities. Superoxide dismutase (SOD) activity and isozyme profiles were different between natural and accelerated seed aging. According to the results of this study, four and two SOD isozymes were detected in naturally and accelerated aging seeds, respectively. Comparing antioxidant enzymes during germination, in advance activity of CAT and POD were detected. According to the results, seed priming increased activity of antioxidant enzymes, however, hormonal priming was more effective. Variation in activity of antioxidant enzymes under various aging treatments could be a way of different molecular mechanisms of oxidative damage and therefore repair mechanism of seed deterioration is not similar in naturally and accelerated aging methods.