Does Methyl Jasmonate Effectively Protect Plants under Heavy Metal Contamination? Fatty Acid Content in Wheat Leaves Exposed to Cadmium with or without Exogenous Methyl Jasmonate Application

Abstract

The effect of methyl jasmonate (MJ) (1 µM) on wheat (Triticum aestivum L. cv. Moskovskaya 39), seedlings and the fatty acid (FA) content of leaves under optimal and cadmium (Cd) (100 µM) stress conditions wasinvestigated. Height and biomass accumulation was studied traditionally; the netphotosynthesis rate (Pn) was studied using a photosynthesis system, FAs’profile—GS-MS. No effect on the height and Pn rate of the MJ pre-treatment wheat at optimum growth conditions was found. MJ pre-treatment led to a decrease in the total amount of saturated (about 11%) and unsaturated (about 17%) identified FAs, except α-linoleic FA (ALA), which is probably associated with its involvement in energy-dependent processes. Under Cd impact, the MJ-treated plants had a higher biomass accumulation and Pn rate compared to untreated seedlings. Both MJ and Cd caused stress-induced elevation of palmitic acid (PA) versus an absence of myristic acid (MA), which is used for elongation. It is suggested that PA participates in alternative adaptation mechanisms (not only as a constituent of the lipid bilayer of biomembrane) of plants under stress. Overall, the dynamics of FAs showed an increase in the saturated FA that is important in the packing of the biomembrane. It is supposed that the positive effect of MJ is associated with lower Cd content in plants and a higher ALA content in leaves.

Effect of Zinc Excess on Some Physiological Parameters and on the Fatty Acids Profile of Sinapis alba L. and Brassica juncea L. (Czern)

“…This also supports the fact that caraway plants under Zn excess in parallel with SFA accumulation are capable of forming natural seeds [68]. Earlier, we already made this assumption when studying changes in the FA composition of wheat under the influence of Cd ions [66]. Probably the increase in particularly palmitic and stearic acids caused a "raft" formation that leads to obturating membranes that prevent the overintake of metal ions into cells.…”

“…But in this case, this increase was a result of a rise in SFAs, particularly palmitic and stearic acids. The increase in palmitic acid concentration under heavy metal influence was reported in several articles [59,[64][65][66]. Moreover, the possible role of palmitic acid in the stress tolerance of plants was described by Zhukov [67].…”

“…Moreover, the possible role of palmitic acid in the stress tolerance of plants was described by Zhukov [67]. The accumulation of SFAs is characteristic of plants that mainly accumulate metals in the roots (excluders), for example, wheat under Cd ions [66], caraway [68], coriander [64], and Arabidopsis lyrata under Zn ions [59].…”