SA regulates seed germination and growth in a dose-dependent manner in Nicotiana alata under salt stress
Using the modified Nicotiana alata as the test material,the seed germination and plant germination of Nicotiana alata under different concentration gradient exogenous salicylic acid(SA)treatments under 150 mmol·L-1 NaCl stress were studied.Growth status,peroxidase(POD)enzyme activity,superoxide dismutase(SOD)enzyme activity and reactive oxygen species(ROS)content and the relationship between them were analyzed.The results showed that appropriate amount of exogenous SA can alleviate the toxicity of salt stress to the germination of early flowering tobacco,and 0.05-1.00 mmol·L-1 SA treatment can increase the germination potential,germination rate,germination index and vigor index of early flowering tobacco seeds under salt stress.As the concentration of SA continued to increase,its alleviation effect decreased.Under the stress of 150 mmol·L-1 NaCl,the growth of tobacco has been severely inhibited,while the size and fresh weight of leaves and root system were significantly increased by spraying 0.5-1.5 mmol·L-1 SA;and spraying 0.5-2.0 mmol·L-1 SA The activities of SOD and POD in SA leaves showed a trend of first decreasing and then increasing;ROS content first decreasing and then increasing;chlorophyll content first increasing and then decreasing.It is shown that the regulation of salt tolerance by SA can occur in a dose-dependent manner,and exogenous application of an appropriate concentration of SA to increase the activity of antioxidant enzymes can effectively eliminate excess ROS,avoid ROS accumulation,and can reduce chlorophyll content in leaves and the process of photosystem and photosynthetic carbon assimilation.The damage of a variety of enzymes maintains a high photosynthetic rate.
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