Effect of para-chlorophenoxyacetic acid on acid invertase gene expression and sucrose metabolism in tomato (Solanum lycopersicum) fruit
Tomato cv. Liaoyuanduoli (Solanum lycopersicum) plants were cultivated in a greenhouse to allow sampling of the second fruit in the first cluster and comparison with tomato fruit that developed following para-chlorophenoxyacetic acid (PCPA) treatment. Sugar content, activities of sugar related enzymes and the effects of PCPA treatment on gene expression of soluble acid invertase (AI) during tomato fruit development were studied. Enhanced activity of AI and increased gene expression of soluble AI in pectinic tissues, pericarp and dissepiments were observed during fruit development, resulting in an increase in fructose and glucose levels. Following PCPA treatment, the activity of AI was amplified and gene expression of soluble AI was accelerated during the mature period of fruit so that fructose and glucose were increased. Upon ripening and following PCPA treatment, the activity of AI and gene expression of soluble AI in pectinic tissues were more pronounced than those in pericarp and dissepiments, but the concentrations of fructose and glucose in pectinic tissues were lower than in pericarp and dissepiments. PCPA appeared to affect vacuolar acid invertase activity by regulating corresponding gene expression, resulting in hexose accumulation in ripening tomato fruit.
Key words: Para-chlorophenoxyacetic acid (PCPA), tomato, acid invertase, sucrose metabolism.