Effects of Different Concentrations of Abscisic Acid on Glucosinolates Contents in Pakchoi

To explore the regulatory effect of exogenous hormone on accumulation of the antitumor substance glucosinolate, plants of Shanghaiqing pakchoi (Brassica campestris L. ssp. chinensis (L.) Makino var. communis Tsen et Lee cv. Shanghaiqing) were treated by abscisic acid (ABA) with different concentrations (0, 5, 10 and 20 mg·L^-1) . The results showed that sprays of ABA solutions did not significantly affect biomass of pakchoi. 10 mg·L^-1 ABA treatment significantly decreased the content of aliphatic glucosinolates in pakchoi shoots. However, treatments of 5 and 10 mg·L^-1 ABA significantly increased the contents of indole glucosinolates and neoglucobrassicin. The content of aromatic glucosinolate significantly increased by ABA at 20 mg·L^-1. But 10 and 20 mg·L^-1ABA inhibited the increase in total glucosinolate content. In addition, 10 mg·L^-1 ABA treatment decreased the portion of aliphatic glucosinolates in packoi shoots, increasing the relative percentages of indole glucosinolates and aromatic glucosinolate. It could be concluded that exogenous ABA with different concentrations have different effects on the contents andcomposition of glucosinolates.