Abstract
The landscape application of sweet osmanthus (Osmanthus fragrans) with flower fragrance and high ornamental value is severely limited by salinity stress. Gamma irradiation applied to seeds enhanced their tolerance to salinity stress as reported in other plants. In this study, O. fragrans ‘Huangchuang Jingui’ seeds were pretreated with different doses of gamma irradiation, and tolerance of the seedlings germinated from the irradiated seeds to salinity stress and the changes of reactive oxygen species (ROS) production and ROS scavenging systems induced by gamma irradiation were observed. The results showed that seed pretreatment with different doses of gamma irradiation enhanced the tolerance of sweet osmanthus seedlings to salinity stress, and the positive effect induced by gamma irradiation was more remarkable with the increase of radiation dose (50–150 Gy). The pretreatment with high-dose irradiation decreased O2− production under salinity stress and mitigated the oxidative damage marked by a lower malondialdehyde (MDA) level, which could be related to the significant increase of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities in the seedlings germinated from the irradiated seeds compared to the corresponding control seedlings. In addition, the accumulation of proline in the irradiated seedlings may contribute to enhancing their tolerance to salt stress by the osmotic adjustment. The study demonstrated the importance of regulating plant ROS balance under salt stress and provided a potential approach to improve the tolerance of sweet osmanthus to salt stress.
Highlights
Salinity has been threatening more and more land in the world [1,2]
To determine the level of enhanced tolerance to salt stress induced by gamma irradiation, we investigated the morphological changes of two-year-old sweet osmanthus seedlings developed from the irradiated seeds
Note: Gy was used as the control; Gy was the seedlings germinated from are dependent on radiation doses [13]
Summary
Soil salinity greatly affects plant growth, development and productivity, posing a serious threat to agricultural and landscape plants in many regions of the world. Salt stress increases the concentration of toxic ions in plant cells, causes ion homeostasis disruption and results in oxidative damage with excess generation of reactive oxygen species (ROS) [3]. ROS production is controlled at basal levels and is beneficial to plants by supporting cellular proliferation, physiological function and viability [4]. The accumulation of ROS was accelerated by various environmental stresses such as salinity, drought, heat and high light [5,6,7,8], which caused damage to protein, DNA and lipid and thereby affecting normal cellular function [9,10].
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