Effects of nicosulfuron on plant growth and sugar metabolism in sweet maize (Zea mays L.)

The sulfonylurea herbicide nicosulfuron is efficient, harmless and selective at low doses and has been widely used in maize cultivation. In this study, a pair of corn sister lines, HK301 (nicosulfuron-tolerence, NT) and HK320 (nicosulfuron-sensitive, NS), was chosen to study the effect of nicosulfuron on plant growth and sugar metabolism in sweet maize (Zea mays L.) seedlings. All the experimental samples were subjected to treatment with water or 80 mg kg-1 of nicosulfuron when the sweet maize seedlings grew to the four-leaf stage. Nicosulfuron significantly inhibited the growth of NS line. The content of sucrose and the activities of sucrose phosphate synthase and sucrose synthase in the two inbred lines increased differentially under nicosulfuron stress compared with the respective control treatment. After nicosulfuron treatment, the activities of Hexokinase and 6-phosphofructokinase and the contents of pyruvic acid and citric acid in NS line decreased significantly compared with those of NT line, while the content of sucrose and activities of sucrose phosphate synthase and sucrose synthase increased significantly. The disruption of sugar metabolism in NS line led to a lower supply of energy for growth. This study showed that the glycolysis pathway and the tricarboxylic acid cycle were enhanced in nicosulfuron-tolerant line under nicosulfuron stress in enhancing the adaptability of sweet maize.