Ferulic acid pretreatment enhances dehydration-stress tolerance of cucumber seedlings

To examine whether ferulic acid (FA) could protect plants from dehydration stress and to investigate a mechanism for the protection, cucumber seedlings were pretreated with 0.5 mM FA for 2 d and then were exposed to dehydration induced by 10 % polyethylene glycol 6000. After pretreatment with FA, the activities of antioxidant enzymes (catalase, superoxide dismutase, and quaiacol peroxidase) in leaves were higher than under dehydration treatment alone which was in accordance with the increased transcript levels of respective genes. Moreover, the combination of FA pretreatment and dehydration reduced the content of superoxide radical, hydrogen peroxide, and malondialdehyde, and increased the relative water content and content of FA, proline, and soluble sugars in comparison with dehydration alone. We propose that pretreatment with FA protects cucumbers against dehydration stress by decrease of lipid peroxidation due to activation of antioxidant enzymes and by increase of proline and soluble sugar content in leaves.