Protective Role of Putrescine Against Salt Stress is Partially Related to the Improvement of Water Relation and Nutritional Imbalance in Cucumber

ABSTRACT

Polyamines play a variety of physiological roles in plant growth and development. To investigate whether exogenous putrescine (Put) has roles in protecting plants against salt stress, Put (100 μ M) was added to nutrient solution three days before cucumber (Cucumis sativusL. cv. “Jinyan No.4') seedlings were exposed to 100 mM sodium chloride (NaCl) treatment. Putrescine treatment significantly ameliorated the detrimental effects of NaCl on root growth and this was associated with a decrease of Na uptake and an increase in potassium accumulation in roots. Manganese (Mn) content in roots was decreased by salinity stress but increased by Put pretreatment. Furthermore, osmotic stress associated with NaCl treatment decreased leaf water potential and water content, while these effects were alleviated by Put pretreatment. The decreases in net photosynthetic rate (Pn) and stomatal conductance (Gs) by NaCl were also diminished by Put treatment. The results indicate that Put may play an important role in protecting cucumber plants against salt stress.

Keywords:

• K/Na ratio
• photosynthesis
• putrescine
• salt stress
• leaf water potential
• Cucumis sativus

ACKNOWLEDGMENTS

This work was supported by the National Natural Science Foundation of China (30500344 and 40571083), National Key Laboratory of Sustainable Agricultural and Soil Science, and National Outstanding Youth Scientist Foundation (30235029).