Does jasmonic acid mitigate the adverse effects of salt stress on wheat through the enhancement of ascorbate biosynthesis and the induction of glutamate dehydrogenase activity?

Background

Salt stress is one of the most common abiotic stresses, reducing plant growth and productivity. Thus, the development of suitable management practices to minimize the deleterious effects of salt stress has become necessary.

Aims

This study was conducted to investigate the possible mechanisms underlying salt tolerance conferred by jasmonic acid (JA).

Methods

Salt-stressed wheat seedlings were supplemented with 1 mM JA and/or 1 mM ibuprofen (IBU), an inhibitor of endogenous JA biosynthesis, in the culture medium.

Results

The obtained results showed that salt stress significantly decreased shoot and root dry weight production and relative water contents. This was associated with a noteworthy reduction in leaf and root ascorbate (AsA) concentrations, as well as glutamine synthetase (GS), glutamate synthase (GOGAT), and glutamate dehydrogenase (GDH) activities. Exogenously supplied JA did not affect GS and GOGAT activities in leaves and roots of salt-treated seedlings. However, noticeable enhancements were observed in growth, AsA concentrations, as well as GDH activities. Likewise, the inhibition of JA biosynthesis by IBU application was accompanied by a significant decrease in seedlings’ growth associated with a noticeable reduction in AsA concentrations and GDH activities. The decreases in growth and GDH activities were also obtained following inhibition of AsA biosynthesis by lycorine (Lyc) application. By contrast, increased GDH activities and enhanced growth were obtained following exogenous AsA supplementation, with or without JA biosynthesis inhibition.

Conclusions

The findings implied that exogenous JA enhanced AsA biosynthesis and induced GDH activity, which further promoted the growth of wheat seedlings in salt-stressed conditions. Therefore, the stimulation of AsA biosynthesis and GDH activity through JA application in the rhizosphere may be suggested as a vital strategy for strengthening the salt tolerance of wheat plants, at least at the seedling stage.