Abscisic Acid May Alter the Salicylic Acid-Related Abiotic Stress Response in Maize

The effect of 0, 0.05 or 0.1 mm abscisic acid treatment on chilling tolerance and salicylic acid-related responses was investigated in young maize seedlings (Zea mays L., hybrid Norma). Although the pre-treatment of maize seedlings with abscisic acid slightly decreased the chlorophyll content, it also reduced the level of chilling injury caused by 6 days of cold treatment at 5 degrees C. Under normal growth conditions, increased levels of bound salicylic acid and of bound ortho-hydroxycinnamic acid were observed in the leaves during abscisic acid treatment. In the roots, abscisic acid did not affect the free and bound salicylic acid levels, but increased the amount of free and bound ortho-hydroxycinnamic acid. The activity of glutathione-S-transferase increased on the 3rd day of abscisic acid treatment, whereas it did not change when followed by cold stress, compared with the control leaves. In the roots, the activities of glutathione reductase, glutathione-S-transferase and ascorbate peroxidase increased during the abscisic acid treatment, and those of glutathione-S-transferase and ascorbate peroxidase were also stimulated when abscisic acid pre-treatment was followed by cold stress, compared with the control roots. Our results suggest that an overlap may exist between the abscisic acid-induced cold acclimation and the salicylic acid-related stress response.