Effect of salt treatment on the glucosinolate-myrosinase system in Thellungiella salsuginea

Glucosinolates are specialized plant metabolites derived from amino acids. Found in many important crop species (e.g., oilseed rape, broccoli and cabbage), glucosinolates and their degradation products have important roles in plant defense and interactions with the environment. The objective of this research was to study the effects of salt stress on the glucosinolate-myrosinase system in Thellungiella halophila, which has been characterized as a model organism for studying the molecular mechanisms underlying salt tolerance in plants. In this study, Thellungiella plants were transferred into 1/2 Hoagland's solution containing 200 mM, 300 mM, 400 mM, or 500 mM NaCl for salinity stress at three different growth stages: (1) the young vegetative stage, (2) the late older rosette stage prior to the initiation of bolting, and (3) the early bolting stage. We analyzed the glucosinolate-myrosinase system in different organs and developmental stages of Thellungiella salsuginea under salt stress. NaCl treatment caused a significant variation in the patterns of aliphatic, aromatic, and indole glucosinolate concentrations, resulting in varying levels of total glucosinolates in different organs at three different developmental stages. Although the major class of glucosinolates in different organs varied, increased concentrations of glucosinolates were observed under certain salt conditions. Myrosinase activity was also measured, and statistical analysis clearly indicated no synergetic effect between myrosinase activity and glucosinolate levels. The functional implications of glucosinolate metabolism under salt stress conditions are discussed. In the present study, salt stress had a significant effect on glucosinolate levels and myrosinase activity in Thellungiella at different growth stages. The findings indicate that salt-induced increases in glucosinolate content may be involved in the salt stress response of Thellungiella, but the effects of salinity on glucosinolate biosynthesis and metabolism deserve further attention.