Gene expression and metabolomics profiling of the common wheat obtaining leaf rust resistance by salicylic or jasmonic acid through a novel detached leaf rust assay

Wheat leaf rust caused by Puccinia triticina is a destructive fungal disease causing considerable grain yield loss. In this study, we developed a novel assay to test the rust resistance of detached wheat leaves on defined media with retarded senescence. We observed that salicylic and jasmonic acid confer leaf rust resistance to a susceptible Keumkang wheat (Triticum aestivium L.). Transcription analysis revealed that atchi8 was highly expressed with an increased chitinase activity in the salicylic acid-treated leaves, while expression of PR-9, atpodL, and PR-5 increased in the jasmonic acid-treated leaves. Additionally, the metabolic profile suggested that the phenylalanine pathway might link flavonoid production to leaf rust resistance in the salicylic acid-treated leaves, while the alanine, aspartate, and glutamate metabolism might control the production of other amino acids to enhance pathogen stress response in the jasmonic acid-treated leaves. Finally, all identified genes and metabolites could be potential targets for screening chemical compounds for leaf rust resistance. Future studies on the underlying mechanisms of leaf rust resistance obtained by exogenous treatment of salicylic and jasmonic acids remain necessary.