Overexpression of the AtOPR3 Gene in Wheat Stimulates the Formation of Volatile Metabolites of the Hydroperoxide Lyase Branch of Oxylipin Biosynthesis

The allene oxide synthase (AOS) and hydroperoxide lyase (HPL) branches of the oxylipin biosynthesis pathway lead to the formation of different products from one substrate—13-hydroperoxy-(9,11,15)-octadecatrienoic acid (13-HPOT). It remains unknown how the distribution of 13-HPOT substrate between these branches is regulated in plants, and how the metabolites of each branch influence the activity of the parallel branch. In this work, the activity of HPL branch in the leaves of bread wheat (Triticum aestivum L.) of the Saratovskaya-60 variety, as well as transgenic plants overexpressing the gene for the biosynthesis of jasmonates from Arabidopsis thaliana AtOPR3 (12-OXOPHYTODIENOATE REDUCTASE 3), was investigated. The studies revealed a high content of HPL metabolites in the leaves, indicating a high activity of the HPL pathway of oxylipin biosynthesis in wheat. Overexpression of the AtOPR3 gene has been shown to lead to an increased content of HPL metabolites in the leaves, primarily cis-3-hexenal, as well as to changes in the profile of volatile compounds of the HPL branch released by damaged plants. After mechanical damage, leaves of transgenic wheat overexpressing AtOPR3 produced more cis-3-hexenol and cis-3-hexenyl acetate, but less trans-2-hexenal compared to nontransgenic plants. Changes in the content of HPL branch metabolites in leaf tissues and the mixture of released volatile compounds were more pronounced in transgenic lines with higher expression of AtOPR3. Thus, it was shown for the first time that genetic modification of the AOS branch of oxylipin biosynthesis leads to a change in the activity of the HPL branch in wheat plants.